Verse1

Hey guys im pretty set on running a TC76 on my stock A4 LS1 and was just wondering what thoughts are on rear sizing?

I was thinking the .96 rear would be fine as my car is a daily driver and im not planing on spinning it past around 6200rpm. Im hoping to have a full 8psi by around 3000rpm and spool around the 2200-2500rpm mark. Can anyone give me some advice?

Thanks Nick

6speediroc

iTrader: (5)

Check out:

https://ls1tech.com/forums/forced-in...vs-tc76-7.html

I'm going with a 1.15 on a 370. The 68mm exh wheel will spool fast and the larger AR will help with flow. The smaller AR's will tend to choke the motor at higher RPM.

HydroStream6

iTrader: (16)

If you have an auto get the largest AR you can for that turbine wheel.

Verse1

It has 3 different size rears .96 1.00 1.15, wouldn't the 1.15 be too big on a standard 346 daily driver?
I still want full boost around the 3000-3500rpm mark.

Why does being an auto make a difference to which size rear to run?

HydroStream6

iTrader: (16)

An auto trans helps spool time dramatically. The turbine wheel on the TC76 is a F1-68. It's tiny. Even on only 346 ci I would go for the 1.15 housing.

Tally TransAm

iTrader: (17)

auto i would get the largest possible like said above.

i have a .96 on mine and shift at 6200. it peaks around 5800-5900 and doesnt drop off too bad. this is at 10#s. when i turn it up i plan on having to replace the backside

Verse1

Thanks for the info, can you tell me when it spools and what RPM you have the full 10# @?

Tally TransAm

iTrader: (17)

gets into boost at about 2300-2400 and full boost at about 3400 rpm

Verse1

What difference in spool rates would the auto make? What you have going on with yours sounds perfect to me but if the auto would spool say 3-400rpm sooner then i'll go the bigger rear.

Does anyone have any info on the differences the same set up combo with either manual or auto would make?

Johnv

Go the 1.15 AR.
The beauty of an auto is once in boost its staying there till you let off the throttle,
a manual every time you shift gear the turbo slows and has to respool.

chance575

You say rear sizing, Is this a front mount or rear mount setup

Verse1

Can you tell me what sort of spool/boost RPM yours does? I know its a different capacity but i'll get an idea of what these turbo's are like.

Its a front mount set up.

Johnv

Mine is a 383 m6, I have a 1.32 ar housing, it's making boost by 1800 rpm and at 16 psi by 3500 rpm.

DrTurbo

iTrader: (3)

76 with the 1.15A/R is the way to go.

Verse1

Thanks for all the input guys, decided on the TC78 w/ 1.15ar