76gts or gt 42/76

[JZ 97 SS 1500]

Norbs,
I cannot give you exact stall RPM's . But i can tell you that my current motor (260 ci) spools the 42-76 fast! This is on the same converter i used on the TSM motor. I believe this converter is about 4k rpm on a 109. I havent looked at it close enough on the new motor. 1.01 housing. It spools quick enough for me to wanna try the next housing up... 1.2???

Next size up is a 1.15. But remember they are all divided so you have to factor that divide to get actual A/R ratio, or what it would be equivalent to in an undivided housing.

Jose

 

[norbs]

Next size up is a 1.15. But remember they are all divided so you have to factor that divide to get actual A/R ratio, or what it would be equivalent to in an undivided housing.

Jose

How do you calculate that??

 

[John Wilde]

How do you calculate that??

Good question, I can tell you that twin GT42R with the 74MM had too much back pressure for Chris's car with the smaller turbine ARs.
Chris went two sizes up and it was a whole new ball game.
Keep in mind his car had only 197ci per turbo.
Think about this when you are choosing your AR.
You may want to start with the GT42 76 and the 1.15AR.
If it does not work try Louie's 1.01!

 

[norbs]

Until i get some solid facts here on a/r's i am not ordering anything. I do know a pte71 gtq with a .81 undivided a/r does not spool well on my car at all, with the 3500 converter.

 

[ttypewhite]

Norbs put a non ported compressor housing on your 71GTQ and call it a day. You have not maxed out that turbo yet. What you have is more then enough to get you in the 9's. Are you just out for that time slip, or does your streetability account for anything????

 

[norbs]

I want it to be streetable of course, and i was thinking of going that option, as the turbo housing is alot smaller than my 70 housing. Just wondered how much the ported compressor housing is really hurting me. I do know for a fact bolting on the 71 gtq i lose about 5% hp over the LT-70.

 

[JZ 97 SS 1500]

How do you calculate that??

Norbs just shoot me a pm.

 

[lazaris]

Don't know if it helps any but my buddy Orlando has a 3-bolt 74GTQ on his 234ci iron headed motor and if I remember correctly he is using an Art Carr 3600 stall NL converter (also keep in mind he runs an open exhaust).... Car has run 9.96 @137mph and the turbo spools fast enough to occasionally point the car towards the wall

I would think the GT42-76 with a bigger exh wheel, compressor wheel, and larger shaft size and most likely a larger 4 bolt exhaust housing will spool slower than a 3 bolt GTQ-74.

 

[86brick]

I would think the GT42-76 with a bigger exh wheel, compressor wheel, and larger shaft size and most likely a larger 4 bolt exhaust housing will spool slower than a 3 bolt GTQ-74.

True, but to be honest a gt42-76 on an iron headed stock cube 109 is like tits on a bull anyhow

 

[daverr]

True, but to be honest a gt42-76 on an iron headed stock cube 109 is like tits on a bull anyhow

Then how are supra`s making over 1000 rwhp??? certainly not with a small turbo.

 

[chevyII]

GT47/88 and alittle NOS

 

[Dusty Bradford]

Then how are supra`s making over 1000 rwhp??? certainly not with a small turbo.

Because their engines are light years ahead of our 109's. I'm sure Steve was saying why would any of us need a 1200hp capable turbo on a stock block. Our stock blocks can't handle anywhere near the same power as a Supra engine.

 

[turboanthoni]

Gee did I open a can of worms or what?

 

[86brick]

Because their engines are light years ahead of our 109's. I'm sure Steve was saying why would any of us need a 1200hp capable turbo on a stock block. Our stock blocks can't handle anywhere near the same power as a Supra engine.

Exactly!

 

[John Wilde]

Exactly!

Don't quote me but I think someone has a 3.8 stage 1 with TA Heads and a Sheetmetal intake in the works.

 

[86brick]

If that's the case then it would obviously be a different story for him I was just going off what's in his sig.~ "iron heads 109, stock headers,210 cam"

 

[norbs]

Don't quote me but I think someone has a 3.8 stage 1 with TA Heads and a Sheetmetal intake in the works.

Thats a long way off, lots off issues to deal with first!

 

[John Wilde]

Thats a long way off, lots off issues to deal with first!

I am not sure what you are talking about!

 

[norbs]

Still on the search for a few parts John. If you would donate your 76 for testing purposes i will accept no problem.

 

[John Wilde]

Still on the search for a few parts John. If you would donate your 76 for testing purposes i will accept no problem.

I don't have anything or I would let you try it.
Sorry!