Clio turbo boost issues

[SP33DY]

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.

[SP33DY]

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...........

[Bigfoot]

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.

[Andrew Cooke]

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.

[SP33DY]

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.

[Andrew Cooke]

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.

[Mart]

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.

[Rob@Backyardracing]

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?

[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 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.

[Mart]

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

[Mart]

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

[Rob@Backyardracing]

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

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.

[SP33DY]

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

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?

[Mart]

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.

Ok, show me some proof then

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.

[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.

[SP33DY]

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.

[Big Jim]

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.

[SP33DY]

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.

[Andrew Cooke]

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 .

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

[Andrew Cooke]

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.

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

[Big Jim]

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!!!)

[SP33DY]

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.

[Mart]

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

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.

Did you read the above?

[SP33DY]

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.

[Mart]

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...

[Scoff]

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.

[Scoff]

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

[SP33DY]

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

[Scoff]

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

[Rob@Backyardracing]

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

[SP33DY]

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.

[Markey Mark (BD)]

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.

[SP33DY]

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.

[Rob@Backyardracing]

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.

[SP33DY]

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.

[SP33DY]

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

[Markey Mark (BD)]

Where does the pipework run round the engine mate?

[SP33DY]

Sorry mate this is the only photo from the top

[Rob@Backyardracing]

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

[Matt Cole]

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.

[SP33DY]

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.

[Matt Cole]

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.

[SP33DY]

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



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

[SP33DY]

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?

[Ashy]

It must do,

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



ebay never lies!!

[Matt Cole]

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! 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.

[SP33DY]

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?

[Adam L]

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.

[Ashy]

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?

[SP33DY]

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?