Clio turbo boost issues

As some know I have a turbo'd clio ever since it's was converted I've suffered boost drop off from 22psi to 12psi.

I done a bit digging around and everything seemed to point to the t2 7psi actuator that I was using in conjunction with a multi boost controller. The theory was that the spring was to weak to hold the wastegate shut whilst I was trying to force enough exhaust gasses through the turbine to hit 22psi

So i replaced it yesterday with a forge adjustable actuator fitted with there 10-15psi spring, I bypassed the boost controller and manually set the actuator to peak at 14.5 psi (even this drops off to 10psi at 6500rpm though)

When I reconnected the boost controller and set the gain to run 22 psi I was pissed to see the boost was still dropping off to 13psi.

Has any one got any pointers on where to look next as all my hoses are connected correctly and leak free.

Cheers

Steve

You got any pictures of your engine bay?

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Originally Posted by Bigfoot

You got any pictures of your engine bay?

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Nope not yet.

I supose I could whip the inlet manifold off, check the plugs are nice and tight, then apply some sealant round the inlet manifold joins.

Any ideas on whats the best sealant to use for this?

And also whats the simplest way (if there is a simple way) to pressure test the manifold?

Cheers

If it were inlet manifold/post t.body related, the engine would struggle to idle.

I think you'd hear the boost leaking away if you're losing ~10psi, as that's quite a fair drop.

Might be worth checking the exhaust manifold & gasket, and likewise, also check the wastegate itself is fully sealing/surrounding area isn't badly cracked & leaking exhaust gases through.

Failing that, could still be the actuator (assuming you've pre-loaded it correctly), as Forge's actuators have been know to lack durability.

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Originally Posted by SP33DY

Any ideas on whats the best sealant to use for this?

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I use the same stuff as Reno reconmend for the cam cover!! mine leaked like fcuk before i did it too! Although not as much as 10psi!!

I'm wondering if your turbo is man enough to keep up with the demands of the engine? maybe it just can't keep up?

dont think its the manifolds... im pretty sure you would here it otherwise...

thats alot of boost to go missing... i reckon its a boost leak somewhere in the boost circuit... to make sure.. take off everything.. check the pipe and put them back on again but take your time!! use new clips where needed to..

boost leaks can be very annoying!!

what is the turbo's history??

Well rather than chasing a phantom fault around, I decided to phone ktec and ask what pressure there high boost 300bhp turbo conversion was running.

It runs 1bar but drops off to 12psi higher in the rev range, so looks like its a good old fashioned case of the turbo being too small.

Now this presents me with a massive decision.

Do I

a) get a bigger turbo? which means moving to an external wastegate due to the space the turbo sits in being to small for a larger turbo and an internal wastegate/actuator assembly. As well as having to buy the turbo and the ext wastegate I'd also have to have my manifold and downpipe modified to fit.

or

b) put it all up for sale on cliosport and get a high boost supercharger fitted?


Cost wise they wil be about the same and I'd be looking at 350+

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Originally Posted by Slim

what is the turbo's history??

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The turbo is a gt2560r with a t3 comp housing and was brand new when I got it, it's done about 5k now but is in mint condition

Easiest way to check for boost leaks is take the airfilter hose off the front of the turbo and block the inlet with a can of pop or similar. Then get your compressor and plug it into a port on the plenum, servo outlet or FPR senor port etc. Set the compressor to say 10psi and pump up the boost system. check your boost gauge is reading the same as the compressor if it is then great, if not then you have a problem but at least it'll be easy to find becasue it'll be hissing!

[quote=SP33DY;112994]

It runs 1bar but drops off to 12psi higher in the rev range, so looks like its a good old fashioned case of the turbo being too small.
quote]


Ahhhh, nightmare... I thought this might be the case as you see the same boost drop as me and matt (ringworm) although ours isn't peaking as high. We've both put ours down to size of the blower.

Its a good job you've got plenty of cash ;)

well... it could be a wastegate issue... but i doubt it... normally a boost leak somewhere.. js do as he says with the compressor :)

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Originally Posted by Ashy

Easiest way to check for boost leaks is take the airfilter hose off the front of the turbo and block the inlet with a can of pop or similar. Then get your compressor and plug it into a port on the plenum, servo outlet or FPR senor port etc. Set the compressor to say 10psi and pump up the boost system. check your boost gauge is reading the same as the compressor if it is then great, if not then you have a problem but at least it'll be easy to find becasue it'll be hissing!

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Not a bad idea but I don't have a compressor.

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Originally Posted by SP33DY

Do I

a) ...

or

b) ...

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Or c), try some of the ideas mentioned before wasting your cash.

use a foot pump then :laugh:

or go to a petrol station where they fill up air to the tyres.. :scared:

Easier way to check for boost leaks, that'll cost you nothing - Simply occlude the turbo inlet pipe, start the engine, and see if it runs - If it does, ok, you have a boost leak. If it doesn't/it stalls, you don't have a boost leak, and it's exhaust manifold/turbo related.

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Originally Posted by Ashy

Ahhhh, nightmare... I thought this might be the case as you see the same boost drop as me and matt (ringworm) although ours isn't peaking as high. We've both put ours down to size of the blower.

Its a good job you've got plenty of cash ;)

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I wouldn't go as far as saying loads of cash, just an understanding girlfriend.

Obviously option c could be to stop obsessing with 300bhp and make do with what i've got.

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Originally Posted by SP33DY

The turbo is a gt2560r with a t3 comp housing and was brand new when I got it, it's done about 5k now but is in mint condition

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that compressor should be fine for a bit more than you're geting out of it. Turbine is on the small side, I'll bet you're still blowing the wastegate open (assuming it's not a big air leak).

Unless things have improved a lot, those forge wastegate springs are dreadful. You're better off with a decent Garrett actuator.

Right i've been and checked for airleaks using Marts method popped the induction filter off and shoved my hand over it with the engine running. Nearly lost my hand but it was an instant suction and engine stall.

Am going to let it cool down and adjust the actuator some more, basically all I did was adjust the bar untill it was about 5mm short of the wastegate pin, then struggled to pull it over it. I'll try and shorten it by a further 5mm nd see how it goes.

The only other thing I can possibly think off is the valve overlap when in the phased state, It's something I had the mapper briefly look at before but think I might look at it alot closer now, Scoffs disabled his with obvious good results.

Andrew the only reason I got a forge was I couldn't find a suitable actuator from anywhere, I'm tied to a T2 size actuator due to the space limitations of where the turbo sits, plus the actuator lugs are welded onto the T3 compressor housing which means its a non standard length, after looking everywhere the only place left was forge.

oppps at what point did mart tell you to put your hand over the inlet of your turbo ;)

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Originally Posted by dave j gtt

oppps at what point did mart tell you to put your hand over the inlet of your turbo ;)

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He told me to stick my fingers in the compressor housing to try and stop the blades from spinning.:)

My induction filter sits about 60cm from my turbo so it was a safe approach.

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Originally Posted by SP33DY

Right i've been and checked for airleaks using Marts method popped the induction filter off and shoved my hand over it with the engine running. Nearly lost my hand but it was an instant suction and engine stall.

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Ok, so that eliminates any leakage from turbo inlet to t.body. The fact you have a good idle (when you aren't occluding the inlet!) also now eliminates the t.body, inlet manifold, and inlet manifold gasket, so the problem is on the exhaust side of things; ie, gasket leaking, exhaust manifold cracked, turbo not upto the job, wastegate not sealing/area cracked, or still the actuator (pre-load incorrect, or simply not upto the job still).

Right i've just been out and tensioned the actuator some more, its preloaded about 10mm now took it out for a spin and 12.6psi was all she would give me. It took a team effort of me and my dad to get the bloody thing hooked back on.

So I pulled the vacuum pipe of the actuator and went back out again using my trusty right foot to try and regulate the boost in third, managed to maintain 20-22psi upto 5500rpm which was a bit hectic, so definatley think it's the actuator at fault.

Am going to leave it for tonight and pull the actuator off tomorrow and have a look at what colour spring has been provided.

As you mentioned while your at it id deactivate the phaser, turbo cars dont like overlap, specaily if your a higher booster.. Log your mani/TIP pressure and temps with and without the phaser and report back, be interesting to see... Im sure scoff prob has messed about with this with results?

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Originally Posted by SP33DY

Right i've just been out and tensioned the actuator some more, its preloaded about 10mm now took it out for a spin and 12.6psi was all she would give me. It took a team effort of me and my dad to get the bloody thing hooked back on.

So I pulled the vacuum pipe of the actuator and went back out again using my trusty right foot to try and regulate the boost in third, managed to maintain 20-22psi upto 5500rpm which was a bit hectic, so definatley think it's the actuator at fault.

Am going to leave it for tonight and pull the actuator off tomorrow and have a look at what colour spring has been provided.

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if pulling the pipe off allows the boost up the actuator must be able to hold shut.

I think your boost controller may be the problem, do you need a smaller restrictor between the controller and the inlet. BTW, does your actuator pipe go on the engine side of the throttle body, or not?

Quote:

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Originally Posted by SP33DY

So I pulled the vacuum pipe of the actuator and went back out again using my trusty right foot to try and regulate the boost in third, managed to maintain 20-22psi upto 5500rpm which was a bit hectic, so definatley think it's the actuator at fault.

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That doesn't make any sense? (to me anyway) I was under the impression you had a boost controller? I thought they worked as a 12v solenoid valve where by they just bleed off any boosted air until the car hits your pre-set boot level and they click over / stop bleeding and let the actuator see the boost pressure to open the wastegate at that pre-set level?

If thats true then it shouldn't make any difference running without a vac pipe or running with the controller? Unless the controller is set too low? Or my understanding of how a boost controller works is totaly wrong!

I thought your problem was that due to the small size of the back end on your turbo the exhasut gass pressure was forcing the wastegate open and causing the boost leak then?

Like Rob says maybe when you are running in the phased state and you have a lot of overlap maybe this is increasing the amount of pressure in the exhaust manifold, I don't have any problems on mine although im running less boost with a bigger actuator!

I don't think explained myself very well in the last post.

I fitted the actuator and to set it up bypassed the boost controller.

I preloaded it so that it peaks at 14.5 but it was dropping back off to 10. This was obviously better than the 7 psi previously fitted so I expected to see some form of gain.

I then re introduced the boost controller to the circuit and was disappointed to see it peaked at 22psi and dropped off to 13 psi.

After that I carried out Marts entertaining test, as well as taking the top mani off and checking the plugs.

Removed the boost controller and preloaded the actuator further it really was super stiff to fit and felt far too tight but I gave it a shot anyway. This is where a strange thing happend, rather than the boost being higher it had actually lowered it to the steadiest boost reading I've ever seen 12.6 psi.

Getting frustrated at this I pulled the vacuum pipe off, sealed it and took it for a spin
obviously I could only use part throttle to control the boost and but I was able to maintain 20ish psi up to 5500rpm (I was in third and heading into silly figures whilst trying to watch my inconvienently placed boost gauge/controller) this gave me hope that the turbo can maintain the boost, however this was only at part throttle and when using the boost controller, and applying wide open throttles it peaks at 22psi then heads south agin quickly.

Hope thats a better explanation

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Originally Posted by SP33DY

Hope thats a better explanation

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it is, and shows that it's a boost controller problem.

Do you think that the reason for the steady reading is the actuator is correctly tensioned for 12.6 psi?


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Ashy

the actuator will only hold what it'll hold. However your test with the vac pipe shows that the turbo is capable of making more boost as the wastegate is not being forced open by the exhaust gas pressure!! Therfore as Andy says if thats true then the problem lies with the controller as for some reason it is letting the boost pressure through to the actuator before you reach your set cracking pressure.

Sorry this should of been in here, i posted it in the wrong thread!! :ashamed:
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Originally Posted by Andrew Cooke

if pulling the pipe off allows the boost up the actuator must be able to hold shut.

I think your boost controller may be the problem, do you need a smaller restrictor between the controller and the inlet. BTW, does your actuator pipe go on the engine side of the throttle body, or not?

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The pipe runs from an outlet on the comp housing.

The boost controller reading is taken from the inlet manifold.

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Originally Posted by SP33DY

The pipe runs from an outlet on the comp housing.

The boost controller reading is taken from the inlet manifold.

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for driveability the boost controller reading should be from the other side of the butterfly. It won't won't sort your problem, but it will drive better.

which boost controller are you using?

It's the gizzmo ms-ibc here

http://www.gizzmoelectronics.com/Product_MSIBC.html

Not sure which side of the manifold your suggesting Andrew but it's currently taken from the engine side of the TB not the induction side.

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Originally Posted by SP33DY

Not sure which side of the manifold your suggesting Andrew but it's currently taken from the engine side of the TB not the induction side.

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which is wrong..

Admittedly it does say in the destructions that the pressure port should be connected to the inlet manifold.

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Originally Posted by SP33DY

Admittedly it does say in the destructions that the pressure port should be connected to the inlet manifold.

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it does, but the throttle should restrict airflow to the engine, otherwise how can you control wheelspin? If the controller is trying to maintain full boost in the plenum irrespective of throttle angle you're going to crash. Thing is, Drag racers don't worry about that, they just want ****loads of boost.

How are the pipes connected to the solenoid? Do you have a restrictor? What are you gain and duty cycles set to? Have you tried upping the gain?

The pressure port which provides the readings for the boost controller is tapped into the inlet manifold as we've already established.

The boost controller solenoid is ran from a direct port on the compressor housing through the solenoid and into the actuator.

The gain is set at 10 and the duty cycle is set to 50 which did give 22psi.

Quote:

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Originally Posted by SP33DY

The pressure port which provides the readings for the boost controller is tapped into the inlet manifold as we've already established.

The boost controller solenoid is ran from a direct port on the compressor housing through the solenoid and into the actuator.

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OK, so you have 3 ports on the solenoid, and 2 pipes going to it, which is which?

The solenoid can be configured for internal or external wastegates but mines (obviously set for internal) with flow from the compressor in on 3 out on 2 to the actuator as per the instructions.

Quote:

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Originally Posted by SP33DY

The gain is set at 10 and the duty cycle is set to 50 which did give 22psi.

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try winding that gain right up, you might want to increase the duty cycle too, I'm guessing here as I don't have your controller. If you could see the duty cycle it'd probably all make sense. Try connecting a handheld multimeter across the solenoid to see what your controller is doing.

Quote:

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Originally Posted by SP33DY

The solenoid can be configured for internal or external wastegates but mines (obviously set for internal) with flow from the compressor in on 3 out on 2 to the actuator as per the instructions.

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Ok, just checked the internals of that valve, as suggested by Ashy, 0% duty will connect the actuator to the boost circuit (low boost), and 100% will block the pipe from the boost circuit, and leave the actuator open to air.

Your problem is either the configuration of the boost controller, or that the controller is junk.

I'm pretty sure the solenoid is functioning but your right it could be an error on my part setting it up.

I'll sit down with a brew and the instructions:coffee: tomorrow and have a look, i might even go to the extremes of putting an osciloscope on the solenoid to make sure the duty cycles are accurate.

Anyway thats me done for this evening, cheers for the help it's much appreciated.:niceone:

I think the solenoid is OK. Can you drive/make boost with the scope connected? Once you drop a couple of PSI below target (22psi?) the duty cycle should have ramped up to 100% to try and maintain boost. It should also be 100% off boost, and until just short of full boost.

Assuming you get it all working, you may find that to make 22psi you need 60% duty at 3000rpm and 80% at 6000rpm (measured on the scope) I'd set the target duty cycle to somewhere between these. As stated in the manual you want the maximum gain that still gives you a stable boost (some up and down is OK).

Hmmm. I thought you mentioned previously that you had bypassed the boost controller & fed the actuator straight off the comp' housing?

If that's the case, that's eliminated any external boost control issues.

Andy, most, if not all, ebc's I've seen fit inline between the comp' housing & actuator, but still take a pressure reference from map.

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Originally Posted by Mart

Andy, most, if not all, ebc's I've seen fit inline between the comp' housing & actuator, but still take a pressure reference from map.

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maybe that's why they have crap throttle control....

Can't say I've ever experienced that mate.

I don't think I've ever heard of anyone plumbing the map/pressure reference pre-throttle?

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Originally Posted by SP33DY

I wouldn't go as far as saying loads of cash, just an understanding girlfriend.

Obviously option c could be to stop obsessing with 300bhp and make do with what i've got.

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300 horses???

what gearbox you using?
Coops runs 15+ psi on his clio and every weekend nearly in the summer he was fitting gearboxs!!
i think hes pushing 260 ish horses - 115mph approx exit speeds.
thats just off the top of my head.

Quote:

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Originally Posted by Mart

Can't say I've ever experienced that mate.

I don't think I've ever heard of anyone plumbing the map/pressure reference pre-throttle?

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no? have a look how the GTT is connected...
my GTiR is that way standard
and any production car that I've looked at.

I thought we we're talking about the (map) reference take off point, not how the ebc actuator control line is plumbed.

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Originally Posted by Mart

I thought we we're talking about the (map) reference take off point, not how the ebc actuator control line is plumbed.

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we are.

think about it, the controller will do all it can to make the boost you set at the point you measure it.

If you measure the boost post throttle and feather the throttle the boost controller will close the wastegate to try and keep the boost up, until such point that the turbo just can't blow hard enough past the throttle to maintain the boost.

If you measure the boost before the throttle the controller will maintain boost at that point, and your throttle will work as a throttle.

Try it on the Evo, see if it's easier to drive. (note the MAP sensor for the ECU still needs to be post throttle)

Well I had a read of the instructions and got the car back out.

I bypassed the boost controller solenoid so that the actuator was providing full control and went for a pootle. It peaked and held pretty steady at 12.6 before slowly tapering off to 10.9

I'm just accepting that the actuator is preloaded to 12.6 psi and as it's such a pain in the ar$e to adjust I'm just gonna leave it at that.

So i reconnected the boost solenoid and preset it as follows.

Channel 1- 10 duty 0 gain result 11.9
Channel 2- 20 duty 0 gain result 12.4
Channel 3- 30 duty 0 gain result 14
Channel 4- 40 duty 0 gain result 18.1
Channel 5- 50 duty 0 gain result 20.8
Channel 6- 53 duty 0 gain result 22.1

All the above were dropping off t0 12/13psi

So I stuck with channel 6 and started upping the gain

at 10 gain it dropped to 14psi at 20 it dropped to 15psi and when turned up to 30 it was hovering around 16psi.

So it looks as though we've finally got to the bottom of the problem.

It's booked in for mapping on Fri so will get the mapper to have a bit of experiment when its on the rollers. I'll probably settle for something like 40 duty and maybe something in the region of 40 gain. This should hopefully see a smoother boost curve which is held all the way through the rev range, as to be honest with 22psi it comes in with quite a bang.

Obviously having 6 channels I might retain one as my "german car tormentor" setting for those dual carriage way blats (you know the one when some one pulls out of the fast lane then puts there foot down so you can't get passed).

Anyway thanks to everyone who helped me out with more so Mart and Andrew who were both on the button with the actuator being incorrectly preloaded and the boost controller no set up correctly.

I'll let you know what it make on fri but it's been pretty consistant with 260 at 12psi so should (fingers crosed) make a little bit more.

Right, just got off the dyno and 267bhp and 260 torque is all shes giving.

We tried turning the VVT off and lost power through the first two thirds of the rev range and made no difference at the top end. So that eliminates the valve over lap and boost being blown straight through when both valves are open together.

Despite what I believed, with the boost not dropping off back to 12 psi (in the above post) it still is.

Paul (the mapper) was even kind enough to plug his smoke generator in to check for boost leaks to which there was none (I know we proved that with the old fist in the induction pipe. But it never hurts to double check with a different method).

Scoff also suggested it could be down to the timing which we played with to no avail.

So what to do now.

The problem I've got now is that anything I do is gonna cost alot and probably give little gain, ie headwork with larger valves=£700+, custom turbo cams=£600, larger turbo=£800+ etc...

Ideally if i could mate my T3 compressor housing (ideal as its small enough to fit in the engine bay and has the actuator mount point welded on) to something like a GT28rs with a .86 back end it should give me a better top end. However I'm unsure if this is possible or the what it would cost. I'll give Adam L a ring and see what his take is on it.

Oh well let the search continue...........

What boost controller you running on? Im using a GReddy Profec II I got it so it holds 15psi, well I didn't because as you it was just playing with the figures until it worked. Ill turn it on at the weekend and see what settings with gain and so on to see if it helps you out.

what is your boost controller currently set at?

target boost, duty and gain?

did you manage to attach something to look at what the duty is doing? Obviously with gain 0 it will be set at what you set it, and it will ignore the boost target. From your basic tests I'd guess you need duty of around 60, and start at 50% gain.

The boost controller is set to 50 duty and 25 gain, according to the boost graph this is giving me 1.3 bar dropping off to 0.8 bar.

There is another lad running an identical set up to me (including boost controller) and Paul pulled up his graph and it was almost identical to mine. Everyone who I've been in contact with who has this set up is suffering the same as me.

Anyway I've just spoke to Adam L (who was kind enough to take a bit of time out and chat about my problems, thanks mate) he believes it's unlikely to be the turbo as they run fine on nissans etc...

So what's really left to look at?

I don't think it'll be the cylinder head and cams, as Scoffs putting almost double the boost through his with no dramas.

My induction kit is an open air filter arrangement running through approx 60cm of 63mm diameter samco/alu hosing.

My exhaust consists of a 2 1/2"downpipe coupled to a 2 1/4" system there is a slight reduction in overall diameter at the rear of the cat where it drops to 2" but apart from that it's quite free flowing.

did you get a boost plot from the RR? why aren't you using more gain?

You really need to measure what your duty is at high revs/boost.

Did the guy run his smoke machine through the turbo to see if the wastegate was leaking/scroll cracked through?

Can't understand why he didn't pull the boost controller & just feed the actuator straight off the comp' housing. Even if the actuator isn't upto the job, it's easy enough to force the wastegate shut, and then see if it builds & holds boost, just for testing purposes of course.

2 1/4 inch exhaust is not very big at all, most people run 2 1/2 inch on a gtt making 230hp or so! id get back on the rollers, and do another pull with just your downpipe on, (i.e remove the exhaust) that may also explain a little about your boost dropping off at high rpm, the exhaust is choking it. if you dont pick up power from binning the exhaust i`ll show my bum ;)

your hp should be a fair bit higher that your torque also on a modern 16v motor like that, suggests your torque must be dropping of quite suddenly aswell.
what turbine a/r is your turbo?

Andrew- Yes I've got a boost plot, the reason we stuck with that gain is because the boost started overshooting the preset 20.8 psi and hitting 24-25 before the controller could stabalise it back down.

Mart- we just took the filter off and rammed it in. So the turbo housing and everything else was checked.

Rob- TBH mate I've been thinking the same ever since I put the last post up. Had a bit dig around looking at what evo's, scoobies, 200sx's are running to make anywhere near 300bhp and shock horror 3" straight through. Might be worth getting a 3" 100 cell sports cat and running 3" inches from the downpipe back.

Its a .64 turbine.

But unless you were looking at the turbine/wheel/wastegate, how would you know if it (wastegate/area) was leaking?

And don't believe the hype about exhaust bore - My Evo was originally running a 2.5" system @ ~400hp.

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Originally Posted by Mart

And don't believe the hype about exhaust bore - My Evo was originally running a 2.5" system @ ~400hp.

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lol, id say its fairly well proven, im not saying you cant sqeeze xxxhp through xinch bore, im saying he will definatly pick up power, we picked up a **** load on the civic when we jumped to 3 inch.

Quote:

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Originally Posted by Mart

But unless you were looking at the turbine/wheel/wastegate, how would you know if it (wastegate/area) was leaking?

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I see what your saying, now that would be a ball ache to check.

I think if I dont have any joy I might pull the down pipe off and have a look.

So you think a big bore exhaust might be a waste?

Quote:

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Originally Posted by Rob@Backyardracing

lol, id say its fairly well proven, im not saying you cant sqeeze xxxhp through xinch bore, im saying he will definatly pick up power, we picked up a **** load on the civic when we jumped to 3 inch.

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Ok, show me some proof then :D

I'm not saying it's not feasible to gain power that way, but I don't think that's the problem in this instance.

For reference my engine makes 2% more power with its 2.5" exhaust removed. With the exhaust on I measured about 7psi of backpressure @ WOT. None of it though stops the turbo making boost so I don't think that'll be the cause of this problem.

Scoff, how long is your exhaust run? and is it straight through?

I'm just wondering if the cat and the centre silencer and the rear silencers are proving to be restrictive?

In all honesty I could probably get away with just a sports cat and the rest straight through.

I know this might be me being a d*ck but have you checked the pressure drop across the whole inlet from actuator take off point (ie comp outlet) to manifold? If the boost drop is the peak and immediate drop you get with soft actuator springs then I'll shut up and get back in my box, but if it's an rpm related drop then it could be a massive pressure drop due to a flow restriction. I've not seen the installation so this is just a suggestion but try taking the actuator signal straight from the inlet plenum and seeing what the boost does. I'm not suggesting you try to run like this, just that it will eliminate another possibility.

Mate your not being a nob at all, and to be honest it's not that diificult to do and a pretty good idea.

What I'll do is remove/bypass the boost controller solenoid whilst we know that the actuator will provide a manifold pressure of 12.6 dropping of to 10.9 I'll then plumb it in to take the reading direct from the comp housing (along with the actuator feed) and simply see what the actuator is seeing.

I'll post the results up probably tomorrow evening.

Quote:

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Originally Posted by SP33DY

Andrew- Yes I've got a boost plot, the reason we stuck with that gain is because the boost started overshooting the preset 20.8 psi and hitting .

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maybe you went the wrong way, more gain and less duty?

Quote:

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Originally Posted by Big Jim Racing

I know this might be me being a d*ck but have you checked the pressure drop across the whole inlet from actuator take off point (ie comp outlet) to manifold? If the boost drop is the peak and immediate drop you get with soft actuator springs then I'll shut up and get back in my box, but if it's an rpm related drop then it could be a massive pressure drop due to a flow restriction. I've not seen the installation so this is just a suggestion but try taking the actuator signal straight from the inlet plenum and seeing what the boost does. I'm not suggesting you try to run like this, just that it will eliminate another possibility.

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the boost controller is referenced to the plenum, so I can't see that this would be a problem.

Fair enough, it's just that the clue which seemed significant to me was that when the actuator was disconnected, the boost wasn't limited. This could be the case if the actuator was seeing the boost at the turbo outlet, but the various restrictions on the way to the engine were causing the drop. With the signal removed the turbo could then make the 30-odd psi necessary for the engine to see 22.

I always take actuator signals from as close to the throttle as poss to reduce, as far as possible, these kinds of problems.

I may be missing something, but I also don't see how a boost controller can give you less than the mechanical actuator setting. (Unless of course you have a high pressure source, or a dual port actuator and pull some vacuum on the back of it - but I think you'd know if that was happenning!!!)

Jim your right it's impossible for the boost to drop below the actuator preset (12.6 in this case).

I meant to check the pressure drop between the T/B and comp housing yesterday but I was mega busy and never had a chance.

I still think that it could be partially exhaust related but i'm struggling to find any definitive answer.

I did sit down and work out all the equations here

http://www.turbobygarrett.com/turbob...o_tech103.html

to see if the turbo was outside of it's effeiciency window but by my calculations it should easily flow 300.

I might pull the airfilter off and see if thats providing any restriction but after that I'm toying wit the idea of a new 3" downpipe, 3" sports cat and straight through system.

I'll PM Scoff and Ashy first to see what bore theres are and how many silencers their running.

Quote:

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Originally Posted by Mart

And don't believe the hype about exhaust bore - My Evo was originally running a 2.5" system @ ~400hp.

---

Quote:

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Originally Posted by Scoff

For reference my engine makes 2% more power with its 2.5" exhaust removed. With the exhaust on I measured about 7psi of backpressure @ WOT. None of it though stops the turbo making boost so I don't think that'll be the cause of this problem.

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Did you read the above?

Yes I did Mart,

I appreciate you comments ref the evo but I'm sure as a designed turbo car it likely to have a much better flowing exhaust over mine as standard (i've been looking at evo standard cats on ebay and most are 3" in diameter). And I've PM'd Scoff just to see what his exhaust run length is and how many silencers he's got.

If its a case that, as you've stated, a 2 1/2" exhaust will flow 400 maybe it's something as simple as theres too many retrictions to exhaust flow as realistically it runs through a Ktec designed log manifold,then through the turbo, to a stock 182 cat, through a centre silencer, the through an additional rear silencer. So all in it's a long way away from a straight through system.

That was 2.5" bore, on a longer car/system, with 2 silencers & the cat' still in situ.

Btw, o.e Mitsubishi cat's aren't 3" bore...

I've just read this thread and answered your pm sp33dy. I think like andy says your just blowing the penny open, so that actuator wants changing for something you know will work.

I bet that on the dyno you could have pulled the pipe off the actuator at high revs and the boost would hardly have rose, assuming the controller was at its minimum duty at that point trying to keep boost up.

it would have been really handy to watch the duty to the solenloid while on the dyno, it would have told you what was happening :)

Well heres todays update to this problem.

I've just been out in the car and had a play with the boost pipe work.

First I bypassed the boost controller so that the actuator had boost control, i then connected the pipe for my boost gauge reference to the compressor housing. This gave me a steady 14psi dropping about half a psi at about 7000rpm.

So I reconnected the solenoid (leaving the reference at the comp housing) and twiddled with the duty cycles till she was hitting 20psi. I then went for a couple of high RPM wide open throttle runs and the boost stayed at 20psi all the way up past 5800rpm before dropping slightly to 18.9-19.2psi.

Can the intercooler and pipe work really be that restrictive? to the point that with just the actuator I'm losing 1.4 psi but at 20 psi I'm losing a whopping 8psi?

This is the intercooler from ktec

http://www.k-tecracing.com/show_product.asp?id=2828

Which looks suspiciously like this one on ebay for £79

http://cgi.ebay.co.uk/MEDIUM-UNIVERS...item20ae28e335

8psi is a lot to loose, I don't have anywhere near that much loss. You're sure you're getting full throttle ? (joke ;) )

you say you have a drop to 2" on your exhaust system, that cant be good, probably not responsable for an 8lb drop, but i`ll bet its some, more importantly its power for free, your not straining anything more, or adding timing etc, just pull it off and go for a drive, it wont be crazy loud with that small turbo on there, i`ll bet you pick up a minimum of 20hp on the rollers. try it, if im wrong, i`ll take it like a man :cooter:

I've got a de cat pipe that I'm going to throw back in, I took it out at MOT time and had to use a 1/4 bar in the lamda sensor hole to wiggle it out as it was mega tigh,t as such I damaged the threads so will try and clean them up.

Then I think its going to be a case of searching for a better flowing intercooler as the ebay special does'nt seem to be up to the airflow required for 300bhp,

Any one got any suggestions/experiences they would like to share?

As with everthingon this car, the space where it sits is tight and its current size is H18cmxW70cmxD6.5cm

The maximum you could squeeze into the area is H22cmxW85xD10cm so any cars anyone know's that run anywhere near that feel free to point them out.

Much appreciated for all the advice everyone.

Quote:

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Originally Posted by SP33DY

Then I think its going to be a case of searching for a better flowing intercooler as the ebay special does'nt seem to be up to the airflow required for 300bhp,

---

You sure its the intercooler thats causing the pressure drop and not the boost pipe run mate? Just and idea before you go out buying a new intercooler and find you have the same problem.

This again is something that has crossed my mind.

But to be honest whilst it is only 2" diameter pipe work, it's all mandrel bent alloy pipe and samco hoses with no kinks or tight bends. Admittedly it is smaller in diameter than the intercooler pipework used on the earlier cars converted by ktec.

When I first went for mapping the RR owner did say that it was a pretty poor intercooler. Have just been trawling through ebay looking at the same intercooler as mine and found them as cheap as £59 coupled with claims of good enough for upto 300bhp.

i wouldnt worry about the intercooler, that would be the last thing id change.
we run an ebay £89 cooler on the civic at 30lb boost, no problems here.
bigger bore pipework might help though, 2 1/4, or better still 2 1/2.

The only problem Rob, is the outlet on the comp housing is a 2" job.

I've just been looking at some photos of ktecs demo car that they took to the tuning shows a few years ago and the intercooler on that is massive.

There are a few intercoolers on ebay under a ton that would fit in the space i quoted above the only prob is the inlet/outlet are slightly larger, but nothing reducer couplings couldn't solve.

Heres a photo of the intercooler on the car to give a true representation of the size.


http://i274.photobucket.com/albums/j...ntercooler.jpg

Where does the pipework run round the engine mate?

Sorry mate this is the only photo from the top

http://i274.photobucket.com/albums/j...R/IMGP0343.jpg

most small frame turbos are 2" outlet, makes no differance, just get a reducing hose, still worth increasing bore of your pipe run. i bet your throttle body is over 2" bore, so why feed it with smaller bore piperun

Its nowt to do with the cooler or the pipe size. Look at the meg 225's, tiny turbo oulets, tiny (sub 40mm dia) boost runs, inlet manifold and a throttle body so small tom thumb couldn't get his nob in! Nigh on 300 bhp from a decent turbo and larger injectors. The exhaust does want to be a resonable size throughout.

Don't forget Matt one of the first things people with megsport's do is ditch the intercooler for a larger one. and looking at pics of a stock megane cooler it miles bigger than mine.

In fact looking at most aftermarket/standard 2 litre intercoolers they all seem to be considerably larger.

Steve, i must admit i havent measured the stock 225 cooler, but the forge replacement still isn't massive and is mainly change due to core efficiency and not mass flow rate. As a rule (IMO) due to the extra friction in the cooler, the core cross section should be larger than the piping to and from it. 20% larger springs to mind. Measure up and let us know.

Matt heres a pic of a stock meg cooler and a forge item

http://i274.photobucket.com/albums/j...OUR/meg225.jpg

my core length is 600mm depth is 65mm and height I'm sure its 165mm (but for somereason 145mm is also sticking in my mind) I really need to have another check but it's pitch black and lashing down outside so it won't be happening tonight :)

Had a chance to measure my intercooler core and its a whopping 550mmx140mmx66mm

Heres a link to it on ebay

http://cgi.ebay.co.uk/ws/eBayISAPI.d...=STRK:MEWAX:IT

Does anyone think it'll be big enough to flow 300bhp?

It must do,

* 2.25" (57mm) Inlet and Outlet
* Maximum Pressure: 45psi
* Max Horsepower Capacity : 350hp



ebay never lies!!

Quote:

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Originally Posted by Ashy

It must do,

* 2.25" (57mm) Inlet and Outlet
* Maximum Pressure: 45psi
* Max Horsepower Capacity : 350hp



ebay never lies!!

---

lol, i'll second that mr smashy!:D For those that may think ebay tells fibs, i would check your charge temps and then do a pressure drop test across the cooler. I would say IMO 4-5psi difference would suggest a **** cooler.

Matt I've already done a pressure test at the comp housing and at the inlet manifold.

At the comp housing it was hitting 20 psi and dropping off to 19 at 7000rpm, At the inlet the most I've seen at 6k + is 12psi.

So I'd guess that the intercooler is to restrictive and heating up the inlet temps.

With that kind off restriction against the compressor wheel would it have a counter effect on the turbine and slow it down?

The comp wheel won't slow in speed or be surging on that frame, as it's run by the exhaust side. If you're hitting 7k rpm, the turbo is going to be seeing well over 100k rpm and will be far from stalling.

In short, what i'm saying is you don't have a turbo problem, like our conversation the other day. Even the turbo outlet is the least of your worries.:)

Quote:

---

Originally Posted by SP33DY

At the comp housing it was hitting 20 psi and dropping off to 19 at 7000rpm, At the inlet the most I've seen at 6k + is 12psi.

---

If that really is the case and you are seeing a 8psi pressure drop from the turbo to the plenum are you sure you dont have a massive boost leak? I mean you dont see a drop of that size across the venturi on a GT carb (which is 25mm dia)!!

Why not try running the actuator direct from a port in the plenum?

The actuator is opening the wastegate at 14psi(when connected to the comp housing)

Therefore if I run the actuator from the inlet manifold where the most pressure I've ever seen is 12psi at 6000rpm+ on WOT surely the turbo will over spin? as the actuator will have the wastegate closed with full exhaust gasses passing through the turbine?

Maybe it is a boost leak but only under pressure? and thats why the fist in the induction kit and the smoke test didn't show it? or maybe my monstrous intercooler is to restrictive? Remeber this is a common trait with all of ktecs clio conversions. Surely they all can't have boost leaks? :)

I'm seriously considering buying a new intercooler, as looking at the coolers on every other 2 litre turbo car they are considerably larger.

Even the stock meggy one a couple of posts back is massive in comparison and the first thing people do is ditch them so they can get over 250 bhp.

The choices are either get an ebay special a little bit bigger than the one I have for sub £100, or splurge on a forge item at £286 less discount?

Quote:

---

Originally Posted by SP33DY

Therefore if I run the actuator from the inlet manifold where the most pressure I've ever seen is 12psi at 6000rpm+ on WOT surely the turbo will over spin? as the actuator will have the wastegate closed with full exhaust gasses passing through the turbine?

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Maybe thats why youve only ever seen 12psi At the manifold then? The turbo shouldn't be over worked unless you have a massive boost leak!

I've never carried out a "smoke leak test" so can't really comment on how effective it is but IMO the only way to test a boost circuit is at pressure? Surely?

I would carry out a propper pressure test before condeming your intercooler or pipe run. Otherwise you will be throuwing money away hand over fist!

The problem is Ashy that mines not the only clio turbo to have exactly the same symptoms.

Every ktec clio is the same.

Besides I don't have access to the bungs, compressor etc... to carry out a pressurised test.

Is there no way of taking the intercooler size (140mmx550mmx66mm) and calculating the air flow?

Just take the intercooler off and bypass it! see what happens then... Just try it on a really cold morning!

Quote:

---

Originally Posted by SP33DY

Is there no way of taking the intercooler size (140mmx550mmx66mm) and calculating the air flow?

---

no, but if you measure pressure before and after the IC at full noise you will know whether or not it's restrictive. If it's more than 2psi you want a better IC.

You could also try and look inside the cap and estimate the cross section of the runners to see how it compares to the 2" dia pipe you're using (ideally that pipe should be bigger than your throttle plate).

2" dia = ~2000mm2

Andrew whats the best way of going about measuring the boost pre/post intercooler?

As it all sits in the bottom of the front bumper and I'll have to take it off to get access to it.

Ashy's idea isn't bad as i could run the boost just off the actuator and measure boost at both the inlet and the comp housing. Obviously the colder the weather the better.

Has anyone actually sketched out the dimensions of my intercooler to see how small it is? It's laughable.

How big is a renault 5's? Obviously its a different shape but all the same just out of curiosity.

Quote:

---

Originally Posted by SP33DY

Has anyone actually sketched out the dimensions of my intercooler to see how small it is? It's laughable.

---

it's 4.5 times the cross section of your boost pipes, so if 1/4 of that area is flowing air it's probably not too bad. Most intercoolers are too big. Have a look at the one in my avatar, that a Focus WRC core, it's fully on view, it doesn't poke up behind the bumper.

your intercooler size is not the problem, no way.

intercoolers dont stop working at a given hp level, so asking if my cooler will flow 300hp" is a pointless question, of course it will. it may not be very efficent at those levels, but it will wont stop flowing gas, you`ll just get higher and higher charge temps, and higer pressure drops.
if your loosing 8psi somewhere, simply take boost readings with your boost gauge from differant points of your boost circuit and go drive the car until you find the source.

regarding the standard megans only having tiny boost pipes and throttle plate, thats simply because its a production car, which needs to be responsive, with a large spread of torque. Small throttle bodies and boost pipes increase gas velocity, which means more torque, but ultimatly restricts gas flow, which is hp.

Thats my point Rob it looks as though the intercooler is restricting the air flow to the point that even though my turbo is working flat out the most the intercooler will flow is enough air to create 12psi of positive air pressure in the inlet manifold.

I can only imagine that my inlet temps will be stupidly high as well.

nah, not a chance its that restrictive too make your turbo over-spool 8psi.

now it could have a hole in it somewhere that would cause the turbo to over spool infinatly if it never sees the desired boost signal. but again, you`d hear it i reckon, and a hole that big would of showed up on your smoke test i reckon.

just get another boost gauge, and plumb 2 in, 1 pre cooler, 1 post cooler, easy.

but i really think your barking up the wrong tree with the cooler idea :)

TBH Rob I'm just using a process of elimination to try and identifying the problem.

Both Scoff and Ashy have the same inlet manifold and T/B as me, without problems.

My turbo with the boost controller set to 20psi and using the compressor housing pressure as the reference source is holding 20psi past 5800rpm and only dropping to 19 at 7000rpm.

However when I rig it so that the reference source is the inlet manifold the most i ever see WOT at 5k+ rpm is 12 psi.

Now whilst I'm no turbo expert, surely if there is a maximum flow rate for the intercooler and I'm trying to exceed it it will cause a boost drop?

But also on the flip side if my turbo is spooling with the wastegate shut, and all the pressure being produced is being restricted won't this have a reverse effect on slowing the turbine to the point thats it's self regulating?

Unfortunatley for checking the boost pre and post intercooler there is no convenient place to use on the intercooler pipe work so the best I could do is fit them at the inlet manifold and compressor housing.

I'd be interested to see what boost is in the comp housing when I'm trying to hit 22psi at the inlet manifold.

Fairly sure it's been explained several times now that the turbine speed won't slow. Exhaust gas pressure will far outweigh boost circuit pressure. Period.

Unless it's leaking, or the cores have all collapsed, the intercooler won't be the problem either.

Have you checked the turbo/wastegate side of things yet??

Maybe try/eliminate what's been (repeatedly) suggested first perhaps...

Quote:

---

Originally Posted by SP33DY

TBH Rob I'm just using a process of elimination to try and identifying the problem.

Both Scoff and Ashy have the same inlet manifold and T/B as me

---

I don't use the Clio throttle (much too small ;) ) but for sure that won't be your problem.

Mart I appreciate that it's been suggested that I should carryout a boost test on either side of the intercooler, the problem is there is no convienient point to break into the circuit. Also the intercooler pipe work is custom steel tubing which means theres little scope for introducing additional piping into the circuit as it's physically impossible as a slight movement at one end means the other end is miles out.

Don't lose patience with me, but I'm genuinely struggling to see how the restriction in the intercooler set up won't have a negative effect on the exhaust side of things.

Looking at it simply when the engine is at 3500rpm, the wastegate is shut we have 22psi and X amount of gasses passing through the engine and into the turbine.

Now if we run at 7000rpm again the wastegate is shut so surely we'll have double the amount of exhaust gasses passing through the turbine? and therefore double the turbine speed? which in turn should mean double the compressor wheel speed and more boost than 12psi? as we already know it isn't where is the extra boost going? unless the restriction is regulating the turbine speed so that the boost is limited?

To me there must be some form of regulation going on otherwise surely the turbo would spin to infinty and beyond?

I also appreciate you've sugested checking the turbin wastegate area of the turbo, but remember this is happening to at least 3 other ktec turbo clio's who I've been in contact with so surely all 4 of us cant have a faulty turbo?

I genuinely dont think it's the actuator as the difference between spring pressure between the 7psi and the forge 10-15psi thats fitted is unbelievable. Besides they both dropped boost to 12psi even though they were both pressure cheked to see what they were operating at, at the comp housing (just using the actuator as boost control) the 7 psi was set at 6.9 and the current forge is set at 14.

sp33dy, the relationship between the inlet and turbine is not really as simple as that.

First up, the wastegate is not shut at full boost. If it was, boost would still be climbing. It'll hover open just enough to allow sufficient gas through the turbine to drive the compressor to the desired boost while letting the rest out via the wastegate. Think of it as a pressure relief valve for the exhaust manifold. (sorry, I don't mean to sound like Mr turbo 101!!)

When you choke up the engine with whatever restriction you seem to have the result is that you make less power, and yes, exhaust gas is reduced proportionally. But since the wastegate was busy venting plenty off excess exhaust gas earlier without the restriction it still has enough gas to drive the compressor fully. Only when the wastegate is 100% shut and the engine cannot produce enough gas to drive the turbo, then you will have boost dropping off @ the compressor outlet. You have a constant pressure at the compressor outlet, so you have sufficient exhaust gas to drive your turbo.

Sounds to me like you need to either hang a temporary intercooler in there or weld some ports into your boost pipes before and after the cooler to check for the possible pressure drop.

Thanks Scoff looks like I'll have to get in touch with Ashy about getting the ports welded on.

I'll be sure to just have them fitted to the pipework so that if I do need to change intercoolers I'll still be able to use them.

I wonder if Ashy has a boost gauge I could borrow as I'm curious to see what the comp housing pressure is, when my boost controller is connected to the inlet and set for 22psi? but obviously dropping off to 12psi

Quote:

---

Originally Posted by SP33DY

Thanks Scoff looks like I'll have to get in touch with Ashy about getting the ports welded on.

I'll be sure to just have them fitted to the pipework so that if I do need to change intercoolers I'll still be able to use them.

I wonder if Ashy has a boost gauge I could borrow as I'm curious to see what the comp housing pressure is, when my boost controller is connected to the inlet and set for 22psi? but obviously dropping off to 12psi

---

I do have one you could borrow but its only 1bar...

Like I said earlier just buy 1m of 52mm bore silicon hose and fit it in place of the intercooler it'll do the job.

I once had a 3" crack in my Gt Tuning Bread bin intercooler and the T28 blower still made 21psi (manifold) and like I said on a gt thats through a 25mm venturi!

I've got a compressor if you need to do a pressure test just times tight at the moment.

I would never of known if I hadn't done a pressure test!

https://www.rtoc.org/boards/picture.p...pictureid=9336

Quote:

---

Originally Posted by Ashy

I do have one you could borrow but its only 1bar... I'll connect it to the inlet manifold then, no chance of that exceeding 12psi :)

Like I said earlier just buy 1m of 52mm bore silicon hose and fit it in place of the intercooler it'll do the job. I'll get geeking on the bay.

I once had a 3" crack in my Gt Tuning Bread bin intercooler and the T28 blower still made 21psi (manifold) and like I said on a gt thats through a 25mm venturi!

I've got a compressor if you need to do a pressure test just times tight at the moment. I've got a tac liteweight at work (field compressor I could use) but how did you go about sealing everything? as surely there will be some leakage through the engine?

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The only thing steering me away from it being a component fault is that others are suffering the same problem.

BTW ktec have said its the mapping? and that if I buy there new all singing ecu in jan then I'll be putting out 300 easy.

Holy cow ! I am gonna take mine out and check it tomorrow, didnt realise they could split along a weld like that :(

Quote:

---

Originally Posted by SP33DY

BTW ktec have said its the mapping? and that if I buy there new all singing ecu in jan then I'll be putting out 300 easy.

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:cooter: :laugh: :cry:

Quote:

---

Originally Posted by SP33DY

I've got a compressor if you need to do a pressure test just times tight at the moment. I've got a tac liteweight at work (field compressor I could use) but how did you go about sealing everything? as surely there will be some leakage through the engine?

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A very small amount past the rings maybe but you'll not notice it. You only ned to seal the comp housing up on the blower, thats it.