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!Originally Posted by SP33DY
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!
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.
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...
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
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!
The only thing steering me away from it being a component fault is that others are suffering the same problem.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?
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
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.
Posting Permissions
Reply With Quote
