Bazman

I run a single T4 rear mount and have 300hp at the wheels by 2600rpm, I'd like to keep close to that as it makes for a great drive with the tall 3.07:1 gears. But the small 67 turbo with 0.81A/R creates massive back pressure which makes a wastegate useless.

Question, if I spent the coin to have a custom billet wheel T6 made, could it boost from 2000rpm with say 5lb by 2500-2700rpm?

Who'd make the most reliable unit?

I like the new ET billet BW wheells. I know they make big power at high boost but I need lots of HP per lb of boost as I run low boost (10lb) and only need to make 800hp. (more than that is a waste on my street rubber)

thanks for input guys

MUSTANGBRKR02

iTrader: (91)

Why go to the T6 and the heavy BW units when a Precision 7675CEA will get you there and more than likely bolt right up with minimal modifications. The T6 BW units are twice the size and weigh in around 50lbs where as the T4's are usually 20-25lbs.

toytech93

iTrader: (2)

I see no reason for a T6 setup. I'd recommend a larger exhaust wheel

Bazman

50lb? Eek! That kills that idea. I've heard some bad things about Precision but maybe their billet stuff is good?

necrocannibal

iTrader: (5)

I'm running a Precision 7675CEA on a 383 and it spools very quickly and full boost is insane.

Bazman

Sounds awesome, I'm guessing its a front mount. Ok make me jealous - what rpms can you see boost coming in at?

necrocannibal

iTrader: (5)

It is a front mount but I haven't driven it a lot yet because I just got it back but boost comes in pretty quick, I would say somewhere around 3000 maybe even lower. It spools very fast.

MUSTANGBRKR02

iTrader: (91)

Most of the recent problems have been with their large frame units like the 106mm.

MUSTANGBRKR02

iTrader: (91)

Turbonetics also now makes a 7675 in the TC series turbos although I haven't seen very many HP numbers from them. I believe they are billet wheel and ball bearing aswell.

necrocannibal

iTrader: (5)

I actually went out and drove the car and watched my rpms and is getting well in to boost by 2500 rpms.

Bazman

That would be perfect!! However for me to get that on a rear mount I'd have to use one size smaller AR or put up with the boost coming in a few hundred rpm later.

Sales@Tick

iTrader: (3)

A good turbo cam to increase air flow demand at low RPM will bring boost on faster if the compressor is capable of supplying that demand.

WS6HUMMER

iTrader: (19)

This is something that I'm really interested in, what would make one compressor capable where another wouldn't?

Sales@Tick

iTrader: (3)

It's design.

For instance...A T76 versus a T88.

T76:



The 4th plot is 3600rpm. This is based on a "normal" stock bottom end 346 c.i. LS1 engine. As you can see it should be able to make 20psi by 3600rpm with that turbo. This is a WOT situation with full load.

We take the same engine and the same airflow demand and plot it on a T88 compressor map:



Again the 4th plot is 3600rpm. As you can see the wheel is really too big for the engine and there isn't enough available exhaust flow to put enough energy to the turbine to generate boost.

What's interesting to note is that the compressor map is broader at 1.7 pressure ratio than it is at 2.3 and that there might be just enough available exhaust energy to make 10psi at 3200rpm, but probably not 20psi at 3600rpm.

If you had a race car with a 4000+ stall converter that could come up on the trans brake and launch above 4000rpm it would probably work out OK.

ZGLASS

iTrader: (11)

my rear mount pt7175 .81 on a 5.3, 20lbs pump/meth

WS6HUMMER

iTrader: (19)

Thanks for explaining that to me, I really appreciate it!