Dimensions of GT-42-76R

[1dmbth]

I need the dimensions for GT42-76R Turbo, downpipe size etc.
I am going to have a set of headers made for my engine.
I am planning to run this turbo on my Stage 2.
Thanks

 

[John Wilde]

I need the dimensions for GT42-76R Turbo, downpipe size etc.
I am going to have a set of headers made for my engine.
I am planning to run this turbo on my Stage 2.
Thanks

T4 or T6 flanged?

 

[1dmbth]

John
Which one do you think I need or be best.
Thanks for your reply!

 

[John Wilde]

People are going to hate on me and say that you don't need the T6.
If you are building from scratch make room for the T6 if you can.
This will give the the ability to put a thumper style turbo or a GT47 in the future.
If you think you will never want to go any faster down the road you could do the T4. If it was me I will do the T6 because it would give me more options.
Let me know what you think!

 

[1dmbth]

I think you are exactly right is a good idea to plan for possible expansion.
I plan on driving this car on the street to car shows etc. I am going to keep the AC and ohter accesories on the car. The reason I need dimensions is that I am planning on having BAGN build me a set of headers with foward facing turbo.

The Cam Specs for my engine are:
Duration @ .050 Intake224 Exhaust 230
Gross Valve lift Intake .577 Exhaust .590
Lobe Separation 114.0

 

[John Wilde]

I think you are exactly right is a good idea to plan for possible expansion.
I plan on driving this car on the street to car shows etc. I am going to keep the AC and ohter accesories on the car. The reason I need dimensions is that I am planning on having BAGN build me a set of headers with foward facing turbo.

The Cam Specs for my engine are:
Duration @ .050 Intake224 Exhaust 230
Gross Valve lift Intake .577 Exhaust .590
Lobe Separation 114.0

Sounds great, let's see if we can get the specs on a T6 GT42 from Cal Hartline or someone from Precision.

 

[chevyII]

I wondered the same thing but thought the T6 would be overkill. Maybe not? do most guys running the 47/88 on the buick 6's run the T6 flange? I'm also having a set made,now you got me thinking again.

 

[John Wilde]

I wondered the same thing but thought the T6 would be overkill. Maybe not? do most guys running the 47/88 on the buick 6's run the T6 flange? I'm also having a set made,now you got me thinking again.

The T4 Flanged turbos with big wheels have serious back pressure issues.
The 47/88 mid frame would fit into this category.
We will be testing a T6 47/88 in the next couple days and we are a little worried it could have back pressure issues on this race motor.

You don't have to listen to me (join my wife) but if you are doing this from scratch and looking for 1000 ish or more just do the t6 and call it a day!

 

[chevyII]

let us know how it goes. I wonder if richie ran a t6 47/88 on his old v6? That would be the largest turbo i would run even if it wasnt street driven. 1000ish to the ground? I planned to start with a 42/76 and see how that works. I think they make that in a t6 also.

 

[John Wilde]

let us know how it goes. I wonder if richie ran a t6 47/88 on his old v6? That would be the largest turbo i would run even if it wasnt street driven. 1000ish to the ground? I planned to start with a 42/76 and see how that works. I think they make that in a t6 also.

Richie did run the T6 47/88 and the PT91.5 Thumper.
They do make the 42 with a T6, you should try it!

 

[1dmbth]

John
Do you think I should go with the A/R 1.01 or 1.15 with the T6.
If I keep asking you questions you may have to charge consultation fees!!

 

[Louie L.]

1dmbth,
Ill try to get you some rough measurements of the turbo on monday. Here are some pics to give you an idea on the size.

http://rides.webshots.com/album/465223266gecHVD


There is not much of anything I disagree with John on , but i dont think the T6 flange is necessary. Sure it makes more power, but how much more?.How much more power does he wanna make and deal with the possible breakage or xtra maintenance? Also the big flange may keep him from class racing if he chooses.
Just my .02

 

[1dmbth]

I really appreciate the help from you guys! I bought my Stage 2 engine in 2000 and I am ready to get my project moving along.

 

[John Wilde]

I agree with Louie that if you want to Buick Class Race the T6 is not needed with the 76MM and in fact it will limit you. However if you just want a bad mamajama and don't care about one or two buick races I would do the T6. This is of course based on the fact you will want to go faster one day. I am just crazy like that and always try to plan a head. For example we have just finished a car to run with a GT-47. We may need to go bigger to have enough power to compete. Guess what the headers were designed to only fit up to the GT47.....ooops.

Keep in mind on a 394 ci motor with twin GT42Rs and the smaller turbine housing
had back pressure issues with the T4 housing. That is only 197ci per turbo.
We went up two sizes in turbine housings and it fixed our problem. You should talk to precision on the AR, but I would think with the T6 you should get the smaller one, if the T4 maybe you should do the middle one.

 

[1dmbth]

There was a time when I first bought my stage 2 engine I was planning on building a 10.5 limited Street car. But things have changed so much that it takes huge money to compete. Plus I think it would be very tough to be competitive with the V-6. I live in NC and watched Richie race his car from the begining to the end of the V-6. He did very well and when his engine gave up he was barely getting beat then.

My point is I am going to build it the way I want to. If I can race it somewhere that fine and if not that's OK to. I would rather not have to change something later on if I can avoid it. I may have to anyway, but at this point I am leaning towards the T6 flange.

 

[John Wilde]

There was a time when I first bought my stage 2 engine I was planning on building a 10.5 limited Street car. But things have changed so much that it takes huge money to compete. Plus I think it would be very tough to be competitive with the V-6. I live in NC and watched Richie race his car from the begining to the end of the V-6. He did very well and when his engine gave up he was barely getting beat then.

My point is I am going to build it the way I want to. If I can race it somewhere that fine and if not that's OK to. I would rather not have to change something later on if I can avoid it. I may have to anyway, but at this point I am leaning towards the T6 flange.

Very good grasshopper!
Richie ran 3 different T6 turbos that I can remember.
Limited Street is really fast now, you would have better luck in EZ.
The thing is now some of the EZ guys go faster in the 1/8 than our TSM guys in the 1/4. Perspective is important, go talk to Richie when you get a chance!

 

[1dmbth]

I went to a lot races that Richie ran in and he took out a lot of V-8's. It was real funny because a lot of those Mustang boys were being cry babies about his car. I heard it all. A whole lot of people liked his car because it was different. I think he was on the edge of hitting a 4 second run with the V-6.
It was BAD.

 

[49-blues]

Where is Richie now?

 

[1dmbth]

He has a small block V-8 with turbo in his car now. I haven't heard about any runs with the new engine.

 

[chevyII]

sent PM about headers