Single billet Precision 67mm?

Trav40111 · 10-29-2009, 05:09 PM

Figured I'd post this here.. as it may get more attention..

I'm trying to avoid a laggy, out-dated turbo.. and figured I'd give a 67mm unit a try. This is based on the newer GT series stuff from Garrett, and is very efficient. The T67, with a Q-trim turbine, is rated 750-800hp. I plan on making around 600-650whp, but, want to keep some area under the curve.. I figure that a PT67 with Q-trim turbine, and .81 A/R T4 housing, will come into boost at around 2800-3K rpm.

This is on a 4 valve, 8.8:1 C/R motor, with some moderate head work, and stock cams. Ported 99 Cobra intake manifold..

I went ahead and ordered this, today..

Precision- Billet 6765, with .81 A/R T4 undivided housing. This turbo has made over 750whp on single turbo 3 liter Supra's.. so, I see no reason that I can't get some big numbers out of it as well. I talked to Precision about it today, and he assured me that 600whp on pump gas would not be a problem with my setup. He also said that his boss has a 3 valve with the older (non-billet) 67mm, and it starts making boost at about 2500rpm.. full boost (15psi) by 3200rpm. Sounds like it's exactly what I'm looking for.

Travis

LS1killer · 10-29-2009, 06:35 PM

if you dont like it I can have a UPS guy come pick it up for you and ship to my house

Trav40111 · 10-30-2009, 01:51 PM

lol.. I think it's going to kick @ss! Little lag, and should still pull big top end..

02SVTV6 · 10-30-2009, 06:57 PM

It's a 67 with a .81 on a 4V V8 motor with porting work how much lag do you really think your going to get ? I know local 4cyl cars running around here with 67s hell 76s...my 70 with a .96 will get full boost(11psi) in the 3400 range easy on stock heads stock cams...and when are you going to be in a situation when your going to be lagging ? from a roll? nope...from a dig ? ok at least you get a start on traction before it kicks in esp. with no traction might as well be a twin screw...sad when some kb/whipple guys have 600+ rwhp and still run 11s...mid 11s at that...worse if you are a turbo cobra with 650 and still do the same...just make sure ur in the 10s with it...

I bet that Supra was on 20+ psi for that 750

Trav40111 · 10-31-2009, 04:25 AM

Well, I wasn't really looking for sarcasm.. but, ok..

Have you run this turbo before? I see that you've got a dinosaur in the MP T70, which is basically a copy of Garrett's old T70 compressor (manufactured in the 70's). Very heavy compressor (about 1/3 more rotating mass than a 67mm billet wheel), and nowhere NEAR the efficiency of a the newer wheels from Garrett and/or Precision. I'm not knocking MP, because they actually build very decent turbochargers.. I'm just curious as to why you went with a 70mm, when you are saying that I should go with a 76mm? The 67 and 70mm turbochargers will make roughly the same power, but the 67 will spool up a little quicker. Plus, it's more efficient at higher boost levels, which means more power per pound of boost.

I'm not dumb when it comes to this subject.. I've designed/built turbo setups for over 10 years. I know how to properly size a turbocharger to a given engine/trans combo, to get the results that I'm looking for. So many people go overkill on turbochargers, and get unecessary lag/power loss. I'd love to have a twin screw, actually, but I simply can't afford it. I can fab up my own turbo manifolds/exhaust components, for about 1/2 of the price of a twin screw, so that's the most logical choice for me.

BTW, my last vehicle was a mid 10 second Lightning.. It ran that on ET Street's and pump gas.. It had a twin screw..

I'm happy with mid 10's.. I will have no problem getting there..

Travis

Trav40111 · 10-31-2009, 04:44 AM

Oh, and before that.. I had fabbed up a single 76mm ITS setup for the truck..

Guess what.. It was too laggy, and I didn't like it. ;)

Travis

02SVTV6 · 10-31-2009, 06:50 AM

But thats a singl 76 and what exhaust .96 ? were you on a Anti lag ? and that 70 is for a stock motor...78GTS built 5.4 and a Auto for the other setup lol FTW

nothing wrong with a 70 on a stock motor to go 10s

Trav40111 · 10-31-2009, 06:10 PM

.81 A/R T4 housing with a GT-Q trim turbine.. Ball bearing center section, to help with transient response, but, it was still laggy. I didn't run any sort of anit-lag..

If I would have put a 4K stall in the truck, it probably would have helped, but, it was a daily driver, and I wasn't looking for that. Much like the Mustang that I'm building right now.. If it runs mid 10's, I'm happy with that. But, I want a more useable powerband. This 67 will make just as much power as your 70mm, but, will come into boost at least 500rpm sooner.. The efficiency is much better at higher boost levels, as well.. so, I can run more boost/timing on pump gas.

Just personal preference my friend.. I want a car that's fun to drive on the street, that I can occasionally take to the track and run some decent numbers.

Travis

61mmstang94 · 11-01-2009, 12:25 PM

You'll be fine, but I'd go with a bigger exhaust housing on the turbo.

Trav40111 · 11-02-2009, 07:25 AM

I'm going to start with the .81 A/R housing.. If it looks like it's a choke point when I start tuning it, I'll swap to a bigger housing. I have a few P-trim, T4 housings in stock, so I can just swap it out on the dyno if I need to.

Travis