Ct20 Vs Ct26

[Leeky]

Seeing as the ct20b will have to come off anyway to fit the new manifold, should i consider changing turbo?

I know the reason they put the ct20b on the rev3 engine rather than the rev2's ct26 was because the smaller ct20 was more responsive and boosted to the same levels the rev2 ct26 ran at.

But Bibbs has a hybrid ct26 and im wondering if that would make more horse power for me at the same time i dont want to loose responsiveness..

[knowlson]

But Bibbs has a hybrid ct26 and im wondering if that would make more horse power for me at the same time i dont want to loose responsiveness..

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Stick it on anyway is that the turbo technics one??

[Leeky]

Yep thats the turbo technics one.

Yeah what the hell, i'll stick it on and see how it goes

[mikeb]

smaller ct20 was more responsive and boosted to the same levels the rev2 ct26 ran at.

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I thought it was the other way round, the ct26 spools earlier, but runs out of puff at high rpm, the ct20b takes longer to make boost but holds to to 7k rpm. I think the ct20b can sustain higher boost pressures too.

Unless your current turbo is dead, I think it would be a step backwards to put a ct26 on (or sideways to a hybrid version). Could be wrong though.

[Bibbs]

smaller ct20 was more responsive and boosted to the same levels the rev2 ct26 ran at.

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I thought it was the other way round, the ct26 spools earlier, but runs out of puff at high rpm, the ct20b takes longer to make boost but holds to to 7k rpm. I think the ct20b can sustain higher boost pressures too.

Unless your current turbo is dead, I think it would be a step backwards to put a ct26 on (or sideways to a hybrid version). Could be wrong though.

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You are right .. Leeky is wrong (nothing new ;))

The rev2 spools about 500rpm earlier and dies about 6500 .. where the rev3 spools later and holds boost longer ..

The advantage is mine is a hybrid CT26a .. one of the Mk3 soop and has a larger intake.

[Leeky]

Ahhhh i see, i stand corrected :D But the ct20b IS a smaller turbo than the ct26 isnt it?

I can't understand how the smaller turbo takes longer to spool up?

One of life's little mysteries i guess ;)

[mikeb]

There are lots of parameters that determine a turbos performance, A/R being one of the most significant:

"A/R stands for area ratio and is a mathematical description of the cross sectional area of the turbine housing inlet divided by the radius described by the center of the turbine wheel to the center of the turbine housing inlet. This ratio stays constant throughout the volute (snail looking part) of the housing as it tapers from the tight part of the snail Shell to the turbine-housing inlet."

"A large A/R housing has good flow, less backpressure and creates more top end power at the same boost pressure by improving the volumetric efficiency. It will also spool slower. Conversely a small A/R housing has less flow and more backpressure but has quicker turbo spool up characteristics."

[daktari]

So am i right in thinking that a hybrid CT20/26 would spool up quicker and hold boost longer? Or shall i carry on eating my cow pie? :D

[dawesy]

if you are thinking of changing your turbo then look for a different unit ( mitsi TD06/6, garrett or gready unit) as hybrid CT's dont seem to be all that reliable. i have had one that suffered oil seal probs and i know a few others that have suffered similar. i have just picked up a second hand (but exellent condition) Greddy TD06 20G from a 500bhp supra for about £400 incl shipping to the UK from Japan. so keep your eys peeled.'

even a stage 2 CT20 (equal to a stage 3 CT26) will only give enough air for around 350bhp (forged rebuild required)

[Sketchy]

As above have all said really. Essentially at CT20 is a hybrid CT26. Fensport do up to a stage 2 Hyrbrid CT20 which is about the same as a stage 3 CT26. However both are limited in the performance ability. Alex Knight Has a CT20 hybrid running with a Apexi power FC and standard chargecooler, standard injectors but at increased rail pressure and at 1.3bar he got 358 BHP with injectors running about 80% duty, The turbo is good up to 1.5bar but the standard injectors are well out of puff by that time even with the raised rail pressure. He's currently looking at uprating to 850cc injectors, then he'll be able to up the pressure safely and see what he gets.

Dought the CT hybrids could be much use if you looking to go over 400BHP + there expensive don't get much change from £800 for the stage 2 CT20. However they are a direct bolt on and you don't have to worry about getting manifold adapters and oil lines and downpipes etc as you do with other makes.

Hybrid CT still suffer from Boost creep with big exhaust.

However if you going to all the expense of a new turbo I would go for the GT2871R hybrid good for up to around 450BHP and as a internal wastegate so not sooo much of a hassle to fit, and it's still pretty quick spooling 1bar at 3,200RPM so not far off the CT's.

Either way you'll need to think about uprated fueling and ECU.

[dawesy]

i had blitz 850cc injectors and motec and could still only get 1.7 bar on a st2 CT20. adrian said it was well out of its efficiancy range at that. i actually turned the boost down to 1.5 and it felt quicker. by the way im running an erl WI system with a mix of water+methanol too

[screechmr2]

the ct hybrids are good for very little lag and decent power but they are too inefficient and cooling them becomes a problem with higher power as they simply can't cope with sustained high boost