[Mk2] [Turbo] CT26 boost tail off.

Posts about anything do to with modifying your car such as fitting aftermarket parts, bodykit, or tuning the engine for more performance.

Moderators: IMOC Moderators, IMOC Committee Members

User avatar
Ryan S
IMOC Moderator
Posts: 10902
Joined: Sat Dec 10, 2005 1:32 pm
Location: Bonnie Dundee
Contact:

[Mk2] [Turbo] CT26 boost tail off.

Post by Ryan S »

Ok folks, so the turbo i have for the car is a ct26 with 34k on it. Last time i used a ct26 was in my old rev2, I loved it, Spool up is ridiculous but the boost tail off after 5krpm was awful. I would run 1 bar and it'd drop to 10psi. I used to think it was just the ct26 being in efficient (engine sucking more air than turbo can provide) but after a bit of digging around I've read it could actually be related to the actuator. Any opinions on this?
steven63
Posts: 63
Joined: Fri Nov 28, 2014 9:24 pm
Location: preston

ct26

Post by steven63 »

The stock ct26 will never hold 15psi to the red line but fitting a stronger actuator will make it hold 15psi to 5,500rpm
User avatar
Ryan S
IMOC Moderator
Posts: 10902
Joined: Sat Dec 10, 2005 1:32 pm
Location: Bonnie Dundee
Contact:

Re: ct26

Post by Ryan S »

steven63 wrote:The stock ct26 will never hold 15psi to the red line but fitting a stronger actuator will make it hold 15psi to 5,500rpm


That was always my understanding of it too, Was just reading some guy in the states holds 15psi till redline no issues. Although it's not important i guess. It's only gonna be on for a short time.
pbmr2
Posts: 929
Joined: Fri Jun 18, 2010 12:49 pm

Re: ct26

Post by pbmr2 »

Ryan S wrote:
steven63 wrote:The stock ct26 will never hold 15psi to the red line but fitting a stronger actuator will make it hold 15psi to 5,500rpm


That was always my understanding of it too, Was just reading some guy in the states holds 15psi till redline no issues. Although it's not important i guess. It's only gonna be on for a short time.


Is he also making 400rwhp on a ct26? :D
User avatar
Ryan S
IMOC Moderator
Posts: 10902
Joined: Sat Dec 10, 2005 1:32 pm
Location: Bonnie Dundee
Contact:

Re: [Mk2] [Turbo] CT26 boost tail off.

Post by Ryan S »

hahaha!! Aye I guess he probably is!! In fairness my friend who's donated the turbo says he never had issues with the boost tailing off. His car was 34k miles though which makes me wonder if it is the actuator or is it the turbo? Just curios of course as I'll be changing the turbo asap :)
User avatar
Ryan S
IMOC Moderator
Posts: 10902
Joined: Sat Dec 10, 2005 1:32 pm
Location: Bonnie Dundee
Contact:

Re: [Mk2] [Turbo] CT26 boost tail off.

Post by Ryan S »

hahaha!! Aye I guess he probably is!! In fairness my friend who's donated the turbo says he never had issues with the boost tailing off. His car was 34k miles though which makes me wonder if it is the actuator or is it the turbo? Just curios of course as I'll be changing the turbo asap and most likely be running less than a bar of boost :)
Last edited by Ryan S on Sun Aug 19, 2018 4:50 pm, edited 1 time in total.
User avatar
Ryan S
IMOC Moderator
Posts: 10902
Joined: Sat Dec 10, 2005 1:32 pm
Location: Bonnie Dundee
Contact:

Re: [Mk2] [Turbo] CT26 boost tail off.

Post by Ryan S »

Double post.
SonicSW20
Posts: 3681
Joined: Mon Nov 29, 2010 7:54 pm

Re: [Mk2] [Turbo] CT26 boost tail off.

Post by SonicSW20 »

A hybrid CT26 should hold better to the redline. A stock one won't.
User avatar
Ryan S
IMOC Moderator
Posts: 10902
Joined: Sat Dec 10, 2005 1:32 pm
Location: Bonnie Dundee
Contact:

Re: [Mk2] [Turbo] CT26 boost tail off.

Post by Ryan S »

Gazza_DJ wrote:A hybrid CT26 should hold better to the redline. A stock one won't.


Yeah more curious as to why it won't though. Although I don't usually trust what american sites say mind you. But on the other hand my friend says his held boost just fine.
SonicSW20
Posts: 3681
Joined: Mon Nov 29, 2010 7:54 pm

Re: [Mk2] [Turbo] CT26 boost tail off.

Post by SonicSW20 »

Ryan S wrote:
Gazza_DJ wrote:A hybrid CT26 should hold better to the redline. A stock one won't.


Yeah more curious as to why it won't though. Although I don't usually trust what american sites say mind you. But on the other hand my friend says his held boost just fine.


Someone with more technical knowledge than me can explain further, but essentially it's to do with the volume of air the CT26 is capable of moving. While it can move enough air at say 14psi at 3500RPM, it cannot move enough air to maintain 14psi at twice that RPM. Or perhaps someone with more knowledge than me will come along and say I'm completely wrong :lol:
User avatar
Ryan S
IMOC Moderator
Posts: 10902
Joined: Sat Dec 10, 2005 1:32 pm
Location: Bonnie Dundee
Contact:

Re: [Mk2] [Turbo] CT26 boost tail off.

Post by Ryan S »

Yeah that's what I always thought. Just hearing that people haven't had this issue sparked some interest in the ol' ct26 again :)
androo007
Posts: 2363
Joined: Mon Mar 03, 2014 1:43 pm

Re: [Mk2] [Turbo] CT26 boost tail off.

Post by androo007 »

Yeah as above. The ct26 just can't flow enough air. That's why there's so much interest still in rev 3 conversions (injectors ecu turbo etc).

Depends what you're after. Is JAAASHs gt28 still for sale ? Wicked quick spool and would do mid 300s
User avatar
Ryan S
IMOC Moderator
Posts: 10902
Joined: Sat Dec 10, 2005 1:32 pm
Location: Bonnie Dundee
Contact:

Re: [Mk2] [Turbo] CT26 boost tail off.

Post by Ryan S »

androo007 wrote:Yeah as above. The ct26 just can't flow enough air. That's why there's so much interest still in rev 3 conversions (injectors ecu turbo etc).

Depends what you're after. Is JAAASHs gt28 still for sale ? Wicked quick spool and would do mid 300s


No not after anything just now. Was just interested to hear if anyone else had a ct26 that didn't tail off. I'll most likely go 3071 or the borg warner equivalent. The turbo i just sold is ridiculously cheap now and available in the uk.
androo007
Posts: 2363
Joined: Mon Mar 03, 2014 1:43 pm

Re: [Mk2] [Turbo] CT26 boost tail off.

Post by androo007 »

Ah gotcha :thumleft:

The answer is no :lol:
SonicSW20
Posts: 3681
Joined: Mon Nov 29, 2010 7:54 pm

Re: [Mk2] [Turbo] CT26 boost tail off.

Post by SonicSW20 »

If his boost readings are correct, chances are the dude has a hybrid and doesn't realise. Not unreasonable for that to be the case - externally it'll look the same and unless you know just how small a CT26 compressor is you probably wouldn't notice a larger wheel and the housing being machined. There aren't many original CT26's left, and if you're spending £££ on rebuilding it most will opt to spend a little bit more on a hybrid rebuild option.
User avatar
Ryan S
IMOC Moderator
Posts: 10902
Joined: Sat Dec 10, 2005 1:32 pm
Location: Bonnie Dundee
Contact:

Re: [Mk2] [Turbo] CT26 boost tail off.

Post by Ryan S »

Gazza_DJ wrote:If his boost readings are correct, chances are the dude has a hybrid and doesn't realise. Not unreasonable for that to be the case - externally it'll look the same and unless you know just how small a CT26 compressor is you probably wouldn't notice a larger wheel and the housing being machined. There aren't many original CT26's left, and if you're spending £££ on rebuilding it most will opt to spend a little bit more on a hybrid rebuild option.


Yeah i guess that could be the case. The tail off never bothered me, I always preferred the way my rev2 went to my rev 3. So savage!
mr2magic
Posts: 643
Joined: Fri Apr 09, 2010 9:33 am
Location: Hannover, Germany

Re: [Mk2] [Turbo] CT26 boost tail off.

Post by mr2magic »

It's not that the compressor cannot flow enough air...it's the exhaust housing thats the problem. At 5k in 4th and above the sheer mass of exhaust gases flowing through the turbine housing is such that it starts to choke. The turbine begins to slow down reducing boost. The CT27 addressed this by optimizing the turbine housing for more/better flow.
User avatar
Ryan S
IMOC Moderator
Posts: 10902
Joined: Sat Dec 10, 2005 1:32 pm
Location: Bonnie Dundee
Contact:

Re: [Mk2] [Turbo] CT26 boost tail off.

Post by Ryan S »

Are there any other turbos with the ct20/26 flange on them? Again I'm not looking for anything, Just curious as to what bolt on upgrades are available. I'll be shooting for 500bhp (next year) so anything bolt on is out of the question.
SonicSW20
Posts: 3681
Joined: Mon Nov 29, 2010 7:54 pm

Re: [Mk2] [Turbo] CT26 boost tail off.

Post by SonicSW20 »

ATS do a GT28 kit that comes with adapters that work with the OEM downpipe - http://www.atsracing.net/Parts/Index/GT28RS

Other than CT based hybrids that's pretty much it I think.
User avatar
Ryan S
IMOC Moderator
Posts: 10902
Joined: Sat Dec 10, 2005 1:32 pm
Location: Bonnie Dundee
Contact:

Re: [Mk2] [Turbo] CT26 boost tail off.

Post by Ryan S »

Yeah didn't think there was much. I actually had the 3071wg that ats offer in this link. Had a custom vband housing though
Post Reply

Return to “Modifications”