Please Explain how larger turbos work...

[Vett-Klr]

Ok, I had a TE-60 last year. I bought a GTA-67 this year and can barely match the times I had with the 60. With a larger turbo do I need more boost to see its effects? Will a smaller turbo at the same boost as a larger one perform just as well?
I am only running 19PSI with the 67, what is its sweet spot? Do I need to turn up the boost?

Best pass so far on 19PSI
11.80 @117
1.97 60 foot

Is my car capable of a 10.99 pass? I assumed it was, but I'm not even close. Am I fooling myself? I am seeing a degree of KR at 19PSI, should I back off some timing? Mods in sig..

Dave

 

[wickedtt]

Ok, I had a TE-60 last year. I bought a GTA-67 this year and can barely match the times I had with the 60. With a larger turbo do I need more boost to see its effects? Will a smaller turbo at the same boost as a larger one perform just as well?
I am only running 19PSI with the 67, what is its sweet spot? Do I need to turn up the boost?

Best pass so far on 19PSI
11.80 @117
1.97 60 foot

Is my car capable of a 10.99 pass? I assumed it was, but I'm not even close. Am I fooling myself? I am seeing a degree of KR at 19PSI, should I back off some timing? Mods in sig..

Dave

that turbo makes more power with your combo at about 24-25 psi

 

[bison]

Ok, I had a TE-60 last year. I bought a GTA-67 this year and can barely match the times I had with the 60. With a larger turbo do I need more boost to see its effects? Will a smaller turbo at the same boost as a larger one perform just as well?
I am only running 19PSI with the 67, what is its sweet spot? Do I need to turn up the boost?

Best pass so far on 19PSI
11.80 @117
1.97 60 foot

Is my car capable of a 10.99 pass? I assumed it was, but I'm not even close. Am I fooling myself? I am seeing a degree of KR at 19PSI, should I back off some timing? Mods in sig..

Dave

You should be building your combo around the turbo you will be running. To use the 67 wheel to its fullest potential you need to be at 25-27 psi and the engine should spend most of its time between 5100 and 5900 rpm. This is where you will be in the sweet spot on a 231 ci with this turbo. Add more octane or go with alky injection. You want none to almost no retard. Imo more than .5 degrees is too much over 500 hp on these engines. Fwiw i ran a PT 67 p-trim up to 27.5 psi with 24* and went easy 10.90's at 127 mph at 3700 lbs with foot brake launches. I had everything you do but had a stock MAFS, stock headers with 50lb injectors, alky and a slightly smaller flat cam. You should be able to run 10.70's with a decent 60' and some more boost.

 

[RUQWKNF]

Agreed.
Just to add, you sixty foot is killing your ET. If you were to get your 60ft down to the high 1.5 to low 1.6 range, your ET will drop significantly. Also, 117mph in a perfect world is good for 11.40 - 11.30s easily. So, going from a 1.92 down to a 1.60 would on paper = .32 of a second off your ET. In reality, it is worth a little bit more. 11.40s and 11.30s are not out of the question with that same tune and boost level. Now if you turn the boost up to 27psi and it's tuned for zero knock retard and with a 1.60 - 1.5x short time, high 10's with your combo should be no problem.

Here is the published compressor map for the 67 wheel from ATPs site.
FREEBIEEE!!!

HTH

Patrick

 

[Vett-Klr]

Thanks guys, I guess there is hope for a 10 second pass. I'll work out the KR turn up the boost and report back...