What pressure is safe for a T25?

[Jimmy_GTT]

Hello,

I'll build in my new turbo tomorrow. It is a Stage 4 turbo from GT Tuning:
http://www.gttuning.com/turbos.htm

I have already a performance cam from K-tec. But I do not know if it is a 270 or 285 one. (no info) :sad2:
http://www.k-tecracing.com/show_product.asp?id=113

It has been built in 2 years ago. (without adjustable vernier pulley)

The engine has been completly rebuilded by that time. New pistons, linears... With standard compression.
Since that I'm using it with the original T2 with standard pressure.
The head has been ported a bit.

I have AFR / EGT in my car. The values are fine. The carb is nearly standard, as I remember the main jet is 125.

So my question is what pressure can I set for this config to remain safe, but get some extra hps?

[jantheeven]

I think it's safe for the turbo (which isn't a T25, but a T2/T25 hybrid) to crank the boost up to around 20 psi, but your standard carb won't like that. You'll have to modify the jets (especially air corrector and 2nd stage) to cope with the higher boost and fuel need.

[TNT ANDY]

I think it's safe for the turbo (which isn't a T25, but a T2/T25 hybrid) to crank the boost up to around 20 psi, but your standard carb won't like that. You'll have to modify the jets (especially air corrector and 2nd stage) to cope with the higher boost and fuel need.

IMO you're right on the limit there, I've wound my T2 / T25 up to 20psi and is fine on short quick blasts but put it under a fair amount of duty - ie on a track then it's not so good. mine worked best @ 18psi under stressfull conditions. Mine wont be seeing any more than 18psi, not even for midget slaying.

:cooter:

[jantheeven]

I like to live on the limit... :pimp:

[Jimmy_GTT]

I think it's safe for the turbo (which isn't a T25, but a T2/T25 hybrid) to crank the boost up to around 20 psi, but your standard carb won't like that. You'll have to modify the jets (especially air corrector and 2nd stage) to cope with the higher boost and fuel need.

Thanks guys!
I'll try it first with 18 psi. Where it should be measured? Where the soriginal boost pressure gauge is? (top of the carb) With the standard gauge it is about the middle of the red area?
I'll take care of the AFR. If I have to I can modify the air corrector. I have 0.8, 0.9... but I have driller! :)))
How to modify the 2nd stage? It is the other jet on the side of the carb which looks the same as air corrector?

THX!!!

[jantheeven]

You should measure boost @ the manifold instead of carb top mate...
Yes, 18 psi is about in the middle of the red area on your standard boost gauge.
2nd stage is E2 in the picture below... I had to drill mine to 1.2mm (standard size is 1mm)

http://old.rtoc.org/articles/i/autofolder/LEZDMZDJCNRIPDVIQDMK.jpg

[TNT!hammond]

IMO you're right on the limit there, I've wound my T2 / T25 up to 20psi and is fine on short quick blasts but put it under a fair amount of duty - ie on a track then it's not so good. mine worked best @ 18psi under stressfull conditions. Mine wont be seeing any more than 18psi, not even for midget slaying.

:cooter:


you have more chance of god adding you on facebook than you have of slaying this midget , fooooooooooooooooool :cooter:

[Jimmy_GTT]

You should measure boost @ the manifold instead of carb top mate...
Yes, 18 psi is about in the middle of the red area on your standard boost gauge.
2nd stage is E2 in the picture below... I had to drill mine to 1.2mm (standard size is 1mm)

http://old.rtoc.org/articles/i/autofolder/LEZDMZDJCNRIPDVIQDMK.jpg

Yes, I know where is it. Once I have drilled one to 2mm than the AFR was wery rich. :D
So with the gauge at its standard place if I reach the middle of the red area it is 18 psi at the carb top. It is about 16 psi @ manifold, isn't it? Or do you mean it is 18 psi at the manifold when the needle is in the middle of the red?

Jet marked as 'E' can remain standard? As I know it has also different sizes...
What size of air corrector do you use?

The ignition can remain standard?

[jantheeven]

Yes, I know where is it. Once I have drilled one to 2mm than the AFR was wery rich. :D
So with the gauge at its standard place if I reach the middle of the red area it is 18 psi at the carb top. It is about 16 psi @ manifold, isn't it? Or do you mean it is 18 psi at the manifold when the needle is in the middle of the red?

Jet marked as 'E' can remain standard? As I know it has also different sizes...
What size of air corrector do you use?

The ignition can remain standard?

I measure boost @ manifold and then 18 psi is the middle of the red area. You should invest in an after-market boost gauge, with digits on it ;) They're cheap enough. My standard carb's air corrector was 1mm, with 1.2mm 2nd stage (I now use a gp A carb). The jet marked as E is the 1st stage and can remain standard for every setup.

[jantheeven]

And yes, ignition can remain standard, as long as you don't get detonation or nasty stuff like that. Do bear in mind that my 1mm a/c and 1.2mm 2nd stage is taylored for my car and my setup... it may well be different for your car. But it's a safe starting point ;)

[Jimmy_GTT]

And yes, ignition can remain standard, as long as you don't get detonation or nasty stuff like that. Do bear in mind that my 1mm a/c and 1.2mm 2nd stage is taylored for my car and my setup... it may well be different for your car. But it's a safe starting point ;)

Yes! Thanks, I know it.
I'll take care of the AFR. But it is very good to what changes could be helpful.

[Andrew Cooke]

your cam is a ktec 260

http://www.rtoc.org/cam/?cam=std+GTT&lsa=&cam2=K-Tec+260&lsa2=&rocker=1.5&advance=0&vc=0.2

[Andrew Cooke]

do you know Ave?

http://www.rtoc.org/boards/member.php?u=222

[Jimmy_GTT]

Thanks for the info about the cam. It is quite similar to the Piper 270, isn't it?

Yes, I know him.

[Andrew Cooke]

Thanks for the info about the cam. It is quite similar to the Piper 270, isn't it?

Yes, I know him.

no, the 260 is more like the 285, but without the lift - and a bit more overlap.

http://www.rtoc.org/cam/?cam=Piper+285&lsa=&cam2=K-Tec+260&lsa2=&rocker=1.5&advance=0&vc=0.2

[Jimmy_GTT]

no, the 260 is more like the 285, but without the lift - and a bit more overlap.

http://www.rtoc.org/cam/?cam=Piper+285&lsa=&cam2=K-Tec+260&lsa2=&rocker=1.5&advance=0&vc=0.2

Yes, you are right. Anyway the car is more powerful above 5000 rpm than with the std. cam.
I hope it will well fit for the T2/T25 hybrid.