Stock ct-26 to 57-trim and no power

[shipkiller]

I don't know if this is normal.
I had a stock-ct26 with a shimmed wastegate (around 9psi of boost). the turbo was DONE.
I bought a ct-26 with a 57 trim and it was almost brand new (was used once on a drift car, he made over 400whp with it). I tried it and there is no power, my old ct-26 made way more power

Does the installation went wrong I have a massive boostleak or what (I have NO symptoms of a boost leak), the 57 trim reach around +3x100 mm/hg on the stock gauge. Is it the lack of psi that make it less powerful?

 

[radiod]

300mm/hg = 5.8 psi. That's a significant drop. I'd check for boost leaks regardless, tighten down all the intercooler piping to start seeing as it was taken off during the swap. What mods are on the car? Any codes?

 

[shipkiller]

the 57 trim wastegate was not shimmed (I should say)
no code
3" downpipe and straight exhaust
k/n air filter

550cc and lex maf are waiting in my basement (it's rainning I can't install them today)

EDIT: I don't know if I'M stupid but I though that even with a bit less psi (6 instead of 9) the extra CFM from the bigger trim would provide similar or MORE power

Please enlight me folks!

 

[radiod]

With a 3" turbo back exhaust you should be getting more pressure than that, you're losing it somewhere. My car has no trouble building in excess of 11psi, no mods to the turbo or boost controllers.

 

[speedfreak]

try a MBC or another wastegate if you have one

 

[supraguy@aol]

Shim the wastegate, that'll give you a bit.
Then do as these guys say- check to make sure you tightened all connectors.

 

[shipkiller]

I just double checked every hose going from the turbo to the IC and the IC to the TB. they are all fine.
looks like my 57trim just gone back to the stock boost pressure (the same as the ct-26 before shimming).

another thing, my idle drop to 500rpm then slowly climb back to 750 when I let go of the throttle in neutral above 2.5krpm, but I just resetted the ECU (efi fuse) so that might be that

 

[radiod]

You could give this a shot...

http://www.supramania.com/forums/showthread.php?19718-DIY-Boost-Leak-Tester

 

[CyFi6]

There are different wastegates out there, the automatic transmission vehicles had a 4.8 to 6 PSI wastegate, so that might be the one installed on your turbo. Nothing wrong, but it will create less boost than you are used to.

 

[shipkiller]

Yeah that's what I was asking earlier
Should the 57 trim with 5.8psi be as powerful as the worn-out ct-26 at ~9psi

 

[hvyman]

Sounds normal. When i had my 7m with 57 trim it only made around 5psi. need to boost it more and then you will see the power difference.

I think its out of its efficiency range at 5 psi.

 

[shipkiller]

Sounds normal. When i had my 7m with 57 trim it only made around 5psi. need to boost it more and then you will see the power difference.

I think its out of its efficiency range at 5 psi.

That's what my buddy just told me (on the phone). He also stated that the stock intercooler has a pressure drop of like 2.5~3 psi.
I will hook up a aftermarket boost gauge, shim the waste and check to see if the magic happens

Thanks!

 

[hvyman]

The stock intercooler is very well designed for its time.

 

[SideWinderGX]

...which was over 20 years ago, and that doesn't negate what he said about pressure drop anyways. Not to mention heat soak.

I'm sure you'll upgrade your intercooler down the line and notice a difference, but for now you're just going to need to push the turbo more and you'll see a big power increase. Probably hit fuel cut if you're (un)lucky.

 

[NashMan]

sticking flapper door aka waste gate

 

[supraguy@aol]

sticking flapper door aka waste gate

Could be that too, assuming that it's sticking open slightly.
More reason to shim the wastegate.

 

[shipkiller]

yes the wastegate will be shimmed by 8mm tomorrow.
yes I have a spearco replica lying in my basement, but no piping for it. I'm waiting for someone with fab skill and a tig to make a 2.5" aluminium piping from turbo to the spearco and back to the TB. no more boost leak if I go this way (and much much more nice on the eye).
550cc and maf going in tomorrow.
also I got a mechanical boostgauge, I know where to plug it (instead of the stock unit sender) but how do I pass the vacuum line to the interior? (how to pass it through the firewall????)

you guys are really helpful, I love supramania!!

 

[hvyman]

Get a little grommet from the parts store and drill a hole in the firewall. Or look for an existing whole.

 

[CyFi6]

Speedo cable grommet is an easy spot, right behind the cylinder head.

 

[NashMan]

Could be that too, assuming that it's sticking open slightly.
More reason to shim the wastegate.

wrong sorry


what you do is make sure it moves freely some times it takes little hogging with die grind to get rid of the binde out


i had this on couple of cars just make sure shit is flu lent