57 trim CT26 - slow spool and early fuel cut

[Mikael_7m]

I installed an unclipped 57 trim on my built 7M (probes, mhg, arps, recod head etc) a few months ago, and i've been putting off asking these questions but something doesn't seem right.

Firstly, IIRC people have said that the 57 trim spools just as quick as a stock ct26. Is this true? For instance with my stock ct26 cruising at 80 km/h, i'd drop it into 3rd go WOT and it would spool up to full boost in not even a full second. With my 57 trim it takes about double that time. Also seems to take a lot longer to make positive pressure. Just want to see everyone else's experiences.

Secondly, I am hitting fuel cut at 10-11 psi, where my friend with a 60-1 ct26 can hit 12-13psi before hitting fuel cut. I have checked for boost leaks with a boost tester. Have not found any.

Faulty wastegate, boost leaks, vacuum leaks, what else can be the culprit? Or is this what is considered normal.

Tell me what you think guys!

 

[OfnaRcR4]

First just know that these cars are 20 years old and they were not all maintained the same. Then realise that fuel cut its controlled by how much air the engine pulls in, not by how many psi it will peak. As far as slow spool, check for a pre turbo exhaust leak.

 

[IndigoMKII]

Yes, the 57 trim CT26 does spool slower than stock. Think about it, more rotational mass with the bigger compressor wheel means slower spool time. My 57 was about 300-400 rpms slower than my friends stock CT but when the 57 trim came on, there was no competition.

Slow spool can also be caused by a weaker wastegate spring, there are ways of curing this though.
1. You can shim the wastegate which will help with the slow spool by holding the wastegate shut tighter but this will raise your final PSI.
2. You can install an electric boost controller and set everything as low as possible, so the wastegate won't see pressure til the EBC allows it.
3. You can buy the new stiffer spring wastegate from driftmotion.

 

[Dan_Gyoba]

Some upgraded CT26 turbos also have the exhaust wheel clipped which will slow spool.

Clipping the exhaust wheel is supposed to allow for higher flow at the top end, and reduce/prevent boost creep.

 

[IndigoMKII]

Some upgraded CT26 turbos also have the exhaust wheel clipped which will slow spool.

Clipping the exhaust wheel is supposed to allow for higher flow at the top end, and reduce/prevent boost creep.

I installed an unclipped 57 trim on my built 7M (probes, mhg, arps, recod head etc) a few months ago, and i've been putting off asking these questions but something doesn't seem right.

For those that like to not read the entire post.

 

[Nick M]

Clipping the exhaust wheel is supposed to allow for higher flow at the top end, and reduce/prevent boost creep.

My 2 cents....Don't bother. Get a T4 compressor with a flange to mount the stock manifold. While my Boss Jr is no longer available, the JT series is still out there.

 

[OfnaRcR4]

Honestly, I've had lots of fun with my 57 trim. New turbo is in the future though due to excessive shaft play. Crossing fingers it won't hit the housing for a few more thousand miles.

 

[Beals]

could be like a fuel issue, maybe get your injectors checked to see their flowing right? But I'd check the wastegate first your new turbo shouldn't feel 'slow' unless its at low rpm but once it gets up their it should open up.

 

[Mikael_7m]

So you guys think it may be the wastegate? I was under the assumption that it would have been a new wastegate with a freshly rebuilt turbo. Not sure if Aaron from driftmotion replaces that part or not.

 

[thevork]

^That would be my guess.
You can try to shimm the wastegate (turn your BC off) to see if the slower spooling problem minimizes.
When you're shimming the wastegate it's like "helping" your old wastegate spring. And Aaron does not replace your WG at a turbo upgrade.

 

[Backlash2032]

It says in the description on DM to include your WG so he can verify it's functioning correctly.

I'd assume he would replace it at extra cost if it doesn't.

Sent from my terrible HTC Rezound using Tapatalk. Don't buy HTC...

 

[pete05]

Did you sort this out Mikael?

 

[Mikael_7m]

couldn't make it spool any quicker Pete, I just turned up the boost after installing the Lex afm and 550s. I adjusted the afm screw and since haven't hit fuel cut, even at 18-19 psi.

To be honest it seems that this turbo in particular is just slow to spool. I can recall it spooling slowly even with the stock intercooler in comparison to the old stock ct26.

 

[atmperformance]

could it be a clogged cat?