Torqueshaft

Got a buddy that is looking at getting a TC78 .96 at killer price...

Which naturally started a conversation on what would be the best displacment engine to take complete advantage of this turbo.

We know that it will be exh. limited and that with to many ci. the back pressure gets pretty high and limits its hp and rpm level.

This would be a max effort type build on race gas...Highest hp.

So it comes down to the question of...

More ci. less boost or less ci. and more boost...

Some of the choices are

4.8

(4.8 crank in a ls1 block) (312ci.)

5.3

(4.8 crank in a 6.0 block) (329ci.)

5.7

So...Lets hear it...

What is your opinion on what would match the turbo best...

I like the two destroked combo's...but then I am a bit biased as I have been wanting build both of them for awhile...

And as always, thanks for your input...

TurboAv

iTrader: (6)

Check the consumption charts on www.forcedinductions.com and plot the points to see where you are on the efficiency islands.

Torqueshaft

They don't have one for the tc78 but the t76 is close enough to use...

The problem is those are only compresser maps...

The problem with the the tc78 that we are looking at from what I can gather, is the size of the .96 t4 housing and its 3" down pipe limits its exh. flow and it build s back pressure.

yelo04goat

iTrader: (11)

312 would just be cool!

someting that could revv to the sky!!

also there is a group buy for larger turbine housings that you could get in on if you wanted more options for the TC..

rotary1307cc

iTrader: (5)

As small as you can

52172

iTrader: (2)

Go 4.8 or 5.3 with the .96ar

91blowthru

i also wondered this, i like the idea of the 4.8 crank/6.0 block....

id think somewheres around 300ci would be pretty good for that turbo in a street car...
id like to hear other theories/expierences...

93formto98T/A

iTrader: (28)

Any of those combos will work well but keep in mind the larger the CI the more DD friendly it will be due to more low end torque. Turbo motors are dogs out of boost and the more low end torque you can retain, the better. I would personally do the 5.7 or 6.0L. The small the the motor the more you will shift the powerband to the upper rpms-which is not as usable as low or midrange on the street...

mike13

iTrader: (27)

Not disagreeing except that his question is specific to the TC78 turbo, I had the TC76 .96a/r on a 383 patriot heads, cam and the backpressure really hurt the performance, only made 12lbs boost and would fall flat about 5000rpm.

cjmatt

iTrader: (4)

How do people have backpressure problems with the smaller a/r housing, couldnt you just run two wastegates?

01Z28Camaro

The exhaust housing acts like a funnel and prevents exhaust from exiting the engine efficiently on larger engines. My 408, 67 was like this very bad.

rotary1307cc

iTrader: (5)

yep, exactly

skinnies went 8's with a 5.3 and TC78

you need to do some research

ronnieforrester

iTrader: (3)

Could you point me in the right direction for the group buy for the turbine housings- i searched for it and couldn't find it.


thanks !

52172

iTrader: (2)

I would run the smallest CI even if it is a street car with the small .96ar turbine housing. I am running the same housing with a 5.7 ltr and it runs wonderful, but the top end could benefit a bit by going with a larger ar housing. I'm not complaining at all just know I would rather have the 1.02 ar or whatever it is over the .96. I have upped my boost with the 5.7ltr and gotten over 780 rwhp at 5800 and it was probibly peaking with the TC76. It all depends on where you want your peak power and what rpms you will mostly be at. If you don't want to rev over 6k then the .96 is your best shot otherwise move up to the larger ar.

52172

iTrader: (2)

We are spoiled with the torque we have with the ls1. Even a 4.8 ltr would have more torque for the street than most people are used too. The 4.8 ltr with the TC turbo would run into less back pressure issues than anything larger.....

Torqueshaft

Here you go...

https://ls1tech.com/forums/forced-in...sing-tc78.html

kmracer

iTrader: (1)

why build a motor around a turbo?

Ericmck2000

If i had a say here, i would say the 4.8 has more then enough torque out of boost.

http://www.youtube.com/watch?v=QRwmy_FBcjc

That was the tune only 4.8 hauling *** in my 4 or 5000 truck before i threw the blower on it. Halve that weight, and, you still have more then enough torque out of boost to push something.

hellbents10

iTrader: (10)

I would build a nice 4.8 or 5.3l for that hot side.

Torqueshaft

Because he is getting the turbo for a killer price...

Kinda like buying a piece of property for a great price and then figuring out what kind of house would be best to build on it...