Whats the maximum boost that can be expected from a T38 and whats the max that it can be run at?

Was working on a cossie today with a t38 but I cant get the boost pressure above 20psi even with the actuator pipe disconnected.
Theres no air leaks, and the actuator is definetley holding shut.

Relevant engine spec is;
turbo technics t38
92.5mm bore
7.2:1 CR
BD14 cams
swedish inlet manifold
rs500 intercooler
2wd exhaust manifold

Anyone got any ideas to why i cant get any more boost pressure.
Is there any chance that the wastgate flap inside the turbo isnt closing fully?

 

ive got the same problem with my tt t38.. wont go above 20 psi... although when i spoke to them on the phone about it the bloke told me that it shouldnt be run any more than that anyway... i tried tightening th actuator rod and it bent the wastegate arm.. i had an inconnel arm fitted but dont want to fiddle with it any more else it will start costing me more...

 

i no sheady ran over 32 psi using that turbo i think it was on mad yums old conversion i will have mine on dyno very soon

 

i have heard of a few running that sort of boost.. had mine for over a year and its never ran any more than 20psi.. only done a few miles too.. think ill see if they can have another look at it while its still in warranty...
although it still goes better than my old t34 running 30 odd..

 

What sort of preload have you got on the actuator?
What actuator are you using?

 

I know on another post about T38's Stu saud he had mapped a few with 40 psi spike and know of a few people running 30+ psi.

 

Id say the rod has to be stetched about 5-6mm to attach to the lever.
Its a -31 actuator, the one that came new with the turbo.

I spoke to TT this morning and they said i should see at least 30psi unless there was an air leak...but im 100% sure that theres no leaks.

 

Remove actuator and use a bit of lockwire to hold wastegate arm shut, then try again. Then you can be sure if its actuator or not.

Ive had this problem when cossie manifold was leaking on boost, even though, strangely, you couldnt hear it.
Checked the nuts tho and were loose as...

 

..have you tried a bleed valve?

 

my TT T38 runs 30 psi with no problems, if you have no air leaks, good actuator (genuine garrett i use) & the wastegate is shutting then you should start looking at your boost pipes, the airbox to turbo intake pipe can suck itself flat, i got Paul Roose to do me a 5 ply intake pipe for mine, the other silicone pipe was not up to the job.
for a quick try you could remove the pipe, run the car up the road & see if its any better.

 

ill be trying a new actuator for mine when it comes out again.. if that dont work ill send it back to be looked at i think..

 

let me know if you get it sorted.. might give me some ideas to sorting mine out...

 

is it going through the amal valve?

if so have you removed the restricotr in it

 

No, there was a bleed valve on it, but i though this could be the problem and i took it off completley. Now there is nothing connected to the actuator, so in theory the turbo should be making maximum boost.


You could be onto something with this intake pipe...I.ll give it a go tomorrow.



I have tried this already but still no joy....tis a bit of a puzzler to be honest

 

no amal valve on mine.. i have wondered about the actuator which is the one that came new from TT -31.. the spring feels strong but i was told that the diaphram in a -34 is different?? and this might help it make more boost. its going to cost 80 quid for a new one to find out tho...
i know i should take it to a tuner but wanted to do all i can before it goes to save paying for jobs that i can do myself.. i was told to swap the exhaust cam for a std one from the bd10 .. i cant see how this would help though..

 

This turbo was on a nearly standard spec cossie before with no problems....Is there any chance that mods on this engine allow more free flowing air (BD14s with standard verniers, Inlet manifold, etc), hence causing the turbo not to be able to build the same pressure....
Just a thought...

 

If you just have the actuator piped directly to the housing you will run minimum boost. The amal valve, bleed valve,air injectors bleed off some pressure meaning the turbo will make more boost before lifting the wastegate.

 

my tt t38 is on a similar spec engine to the spec above ... my old t34 never had any problems making boost on the same engine..

 

i know of one peaking at 37psi

 

you NEED to have an amal valve or bleed valve on it to make more the 1-1,2bar of boost, as said earlyer the amal valve or bleed valve takes some of the pressur from the actuator and that causes the turbo to make more boost.
It it still wont make more then 20psi, then either the turbo is crap or there is a MAJOR boost leak some where.
Exh. manifold doesen`t mean THAT much tho.
Could also be if u get so much knock that the ecu retards the ignition so it WONT make any boost?

 

i hope mine is not down to a dodgey turbo.. it cost me enough from turbo technics.. mine is using air injectors.. i have tried having hardly any preload on the actuator with it only just under tension then a quarter of a hole then half a hole and it made no difference to the boost level 23 psi no matter what i do to it... i was told by a tuner that tightening the actuator will raise the boost but does not do a thing on mine.. not sure if its worth buying a -34 just to try and get more boost or is it a waste of 80 quid...

 

shouldnt need a -34, unless you have issues, -31 should be adequate.

doing myself out of business really, as im selling a -34 at the moment

 

im only considering trying the -34 as ive not got any more ideas of what to try next... ive got a std ex cam to fit but cant see this doing anything everything in the engine bay is new so no split hoses or intercooler im sure on a few occasions i have seen the boost go up to 30 psi but for the odd second.. all sensors brand new so maybe me seeing this was just my eyes playing up.. as they are not that new.. even got a new exhaust as i was told that the old one with a missing middle box could have been the cause..

 

take the hose of the compresor housing so that the pipe isnt conected to any thing that will make it more boost if it dosnt then you have a leak do a presure test on the system ..and as for the cam shaft dont bother it wount make no differnce on the boost side of things
hope this helps

 

ill give it a go on mine when it gets taxed for the summer... i did wonder about the cam swap so i brought a std one but have not fitted it yet.. whats the best way for me to do a pressure test at home....??

 

Well the car isnt properly set up yet and the top end ignition timing is set very conservative, but the car still makes great power at 20psi...wud this affect the boost that much??

 

What is your boost level mapped for in the chip? The point of air injectors is to maintain the programmed boost levels.

 

supposed to be 30 psi... if i have no joy sorting it myself ill have t just pay to have it looked at.. just didnt want to pay out only to be told that it cannot be sorted out or that i have to go away again to buy more parts as i would rather do that first then have it looked at... also the 500 mile round trip to a tunner puts me off a bit as i already do 1k ish driving a week..

 

if it was some sort of problem with the turbos not being able to make the boost what could be the cause of this..? any ideas..

 

Had a bit of a fiddle yesterday, and it turns out that the turbo inlet pipe was apparentley collapsing and causing some restrictions.
Could barely get 20psi before and can I get 25psi now with the pipe removed.

The wastegate is tied shut with wire at the moment, but 25psi still seems very low for a T38 max boost...anyone else got any suggestions???

 

Took the exhaust downpipe off yesterday and i found the problem. The wastegate arm had bent and the button wasnt seating properly. I bent it back into line and sure enough I can get 30psi now...dunno how long it will last now or if it will just bent again.

Suppose the antilag had nothing to do with this happening!!!