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The mkiv Supra Owners Club

CT12 and CT26 Turbos


Wez

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Hello,

 

I just called fensport and asked them about there blue printed replacement stock turbos, the guy on the phone said they are based on the factory CT26 turbos, are these the stock turbos for a UK spec supra and will they just bolt onto a J-Spec.

 

I believe that the J-Spec supra has two CT12`s turbos not CT26`s is this true?

 

The modded CT26 turbos from fensport are about £550 I think.

 

Also has anyone ported there wastegate on a J-Spec supra to solve the boost creep issues when removing both cats?

 

 

:stupid:

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Guest Martin F

Jesus, that is very poor from Fensport. You did tell them that you had a MKIV Supra didn't you ?

 

They are usually very good.

 

CT26 = MKIII Supra Turbo (and a few other cars)

CT12(B)=MKIV Supra TT

 

You would struggle big time to fit a CT-26 on a MKIV.

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Guest Martin F

CT12.

 

 

Confused you should be.

 

I'm not sure whether the B on the end designates the turbo's as jap spec. Anybody ?

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I've just got a hybrid for my Mk3 (arriving today, yippee!), and I paid just under £700 for it all in from Turbo Technics. Identical spec turbo from Fensport was about a grand . . . good company but don't buy turbos from them! Especially if they are expensive *and* they don't know what they are talking about!

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hope this helps. does anyone figure out the specs of a hybrid stage 3 ct12b?????? that would be very very interessting......

 

Sequential Turbo's

 

CT12B(Japanese)

Turbine Size 60mm/48mm (big/small end of same blade)

Compressor Size 62mm/39mm (big/small end of same blade)

Turbine material Ceramic

Scroll area (mm^2) 600

A/R ratio 0.42

 

CT12B(export)

Turbine Size 52mm/44mm (big/small end of same blade)

Compressor Size 58mm/39mm (big/small end of same blade)

Turbine material Steel

Scroll area (mm^2) 740

A/R ratio 0.53

 

P.S.: Source go to Specs on top of the page

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I have modded the sequentials to parallel operation and used the prespool valve as a second wastegate. PITA to do, but works fine. You lose the sequential operation of course...

 

It is possible to enlarge and gas flow the stock wastegate a BIT, but it is only a bit. Never bothered as i doubt it will make sufficient difference to be worthwhile, but i may be wrong. No harm in trying.

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Chris, et al

 

A friend told me that he had converted to parallel "true twin turbo" mode, and that the point at which the turbos start boosting had risen to around 4000 RPM from 2800. Can you verify this, and how would you rate the car for "street" use as opposed to track in this configuration?

 

I have read that you cannot control boost on the Supra once you fit a catless downpipe, and wondered about the stock wastegates. I guess that the CT12 turbo uses an internal W/G design, as my turbo'd Celica's stock CT26 did. How larger can the stock W/G go? Is there a housing that would allow us to use an external W/G? I consider restricting the exhaust just to get decent boost control is rather a work-around than a solution.

 

Thanks for any info...

 

Paul

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Originally posted by paulrenn

Chris, et al

 

A friend told me that he had converted to parallel "true twin turbo" mode, and that the point at which the turbos start boosting had risen to around 4000 RPM from 2800. Can you verify this, and how would you rate the car for "street" use as opposed to track in this configuration?

 

I have read that you cannot control boost on the Supra once you fit a catless downpipe, and wondered about the stock wastegates. I guess that the CT12 turbo uses an internal W/G design, as my turbo'd Celica's stock CT26 did. How larger can the stock W/G go? Is there a housing that would allow us to use an external W/G? I consider restricting the exhaust just to get decent boost control is rather a work-around than a solution.

 

Thanks for any info...

 

Paul

 

Errr...the 2,800rpm is when T1 would come on line in sequential operation. In twin operation the SHARE that same volume of intake and exhaust gas. Because it is shared it takes longer to spool the two instead of spooling one then the other.

 

God I'm bad at explaining this stuff...

 

Anyway with True Twin Mode you will NOT get boost till after 3,500RPM

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Hi Alex

 

Yeah, that's right, I'm just wondering how "driveable" that makes it; I mean, it might be intolerable for normal street use. On the track its a different matter, as you are (or should be) keeping the car in the higher rev range anyhow.

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The fueling for starters has to be adjusted as the ECU still thinks the 1st turbo comes on line at 2,000rpm+ It will run rich till the two turbo's get up to speed.

 

As for drivability yes it will be more lethargic at low revs but with TT mode you get full boost off of BOTH Turbo's...and you will get more topend power.

 

Though there are other methods of getting more power out of T1...not through a Boost Controller.

 

Have a look at the Dyno Chart thread started by Eyefi

 

http://supra.highspeedhostinggroup.net/public_html/vbb/showthread.php?s=&threadid=7

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I made some test with my gtech a year ago, seq vs ttc mod. there was no diffrence in top end power at all. I was on the dyno and tried the ettc (mkiv.com tech articles) mod vs seq no power gain.

You will gain some power when you remove your exhaus gas control valve. thats the most restrictions in the system. if you remove this egcv you have to assimilate the egcv pipe to the dimension of the exhaust pipe from turbo #1.

try the ettc mod it costs only the switch and about 20 min work.

you will find it at mkiv.com tech articles.

markus

 

p.s.: nobody with hybrid spec here? I would like to compare them with the factory specs......

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