gbtwo

iTrader: (4)

I'm doing a 427 LSX right now and I am debating between Twin Billet PT6266's(Gen1) or Twin Turbonetics 7268's (BB). Both are around $2k so I'm looking for anyone who can give me feedback on which set-up will spool better and have better street manors. Car is a 96 Impala at 4200lbs, I want to hit atleast 1000-1100hp at the rear wheels with room to potentially hit 1200-1400hp.

transam69230

iTrader: (49)

76/68 ( close enough to 72 ) is a terrible choice for a 427, they will choke out around 1100 on 25lbs on a 427, this was my exact combo 4years ago. The turbine wheel cannot keep up with the amount of exhaust flow the 427 makes and you end up with back pressure issues. I actually torched my head getting too aggressive with boost.

62/66s are probably also too small for you goals IMO, they will light off fast but I bet they will choke out as well around 1100ish.

I would shoot Forced Inductions new borg s371 with 83/75 turbine wheel. Packages nicely as they are the same size as the turbonetics units depending on the turbine housing.

I dropped my cubes down from a 427 to a 402, and switched to Workturbo S3E s374s with a GT42 turbine housing and it was a direct replacement for turbonetics 75/75s. Car is now making 1500rwhp on 40lbs of boost.

gbtwo

iTrader: (4)

Thanks for the feedback! I will look into the BW S371. Another unit I was looking at was a twin PT7675 set-up (Cast wheel, Journal bearing). Over-kill? Yes but I think they would spool nice and give me headway to grow into some future goals.

Bazman

Comes down to goals and how you want to experience it. The smaller units will not disappoint on street, going to twin 7675's and I can refer you to Viper guys (much larger engine) that would go smaller a 2nd time around. .. they'll make bacon alright - but scare the living crap out of you doing it... which is fine for a drag car or high end roll on/standing mile car... but if you want to actually enjoy it... a medium size is best - not too small (too harsh too soon), and not too large (nothing then everything). My 2 cents. Also, different turbo brands are not equal for similar sizing - twin billet BB Bullseye Power 6266 will easily achieve 1300rwhp, with room for more. It'd be nice if all brands had compressor maps

Based on the 2 choices you gave I'd say at 427 cubes the 6266 are a tad small (perfect for smaller motor), while the 7268 BB's are probably closest to being good at everything. Forget 7675's - too big.

slowlsx

iTrader: (28)

I dont know why guys are saying 7675's are too small for a 427.. that's ludicrous. Both of the other choices are not optimal for that many cubes. I'd look into FI's s371's or the SXE s372's which are out of the box from Borg

Bazman

Twin 7675's will of course work on a 427.... I'm just saying a slightly smaller unit will produce a better driving experience for 99% of driving . Guys go too big then scare themselves (except for the serious races that size accordingly). My baby 5273 Batmowheels can produce 1300hp with bigger turbine side. A 7268 is simply going to have a fatter curve and bring it in earlier than the larger 7675 is all. Both would work, the 6266 will max out but provide an incredible power curve on a 427 within their range. Comes down to what you want - top end or widest fattest power curve or ???

DBRODS

iTrader: (1)

Not all wheels are equal in flow, the PTE 66mm CEA turbine will flow 93lbs and the Turbonetics F1 68mm turbine will only flow about 80lbs. The PTE 6266 will make more power and spool faster than the Turbonetics 7268s. For a 427 twin 7675s will be killer.

transam69230

iTrader: (49)

I have had 3 sets of turbos on big power motors, and I would never do turbonetics ever again. They are junk!

I got 1.5yrs out of billet wheel ball bearing 75/75s I bought from Huron speed, had them rebuilt by a reputable shop, and failed again in 500 miles. I had the same shop do me a set of borgs s374s , and have had zero issues.

SLOW SEDAN

iTrader: (13)

Having had S369's 69/73 on a 5.3L, with another 100ci I wouldn't hesitate to run larger. The 76/75's would be a great choice for a 7.0L, the Precision 7675 LS series is under $1000 each so well within your budget. If you want a cheaper route guys have used the $400 Chinese 78/75's on some builds for good power.

Bazman

Great info... that's where it's hard for the average customer to figure out between brands because most do not advertise how much their units flow. I love my little Bullseyes, but when it's time to upgrade and go for more air at lower boost I'll need a compelling reason to spend double the price to stick with BEP and not go to Garret or Borg Warners. I've done a bit of research on the compressor maps available for both Garrett and BorgW and both make very good units to suit twins on an LS if you look beyond the normal shelf turbo (to make them work at more modest boost pressures). Both can average around 75% compressor efficiency from 3500rpm to 7000rpm with careful selection.... as for PTE or BEP - who would know because their maps are unavailable, though they do run strong

Ron_Stoppable

iTrader: (1)

R_trim 93GT

iTrader: (1)

I've personally used (2) Precision 6265s on a 427 in a C5 corvette and while the spool and torque delivery was amazingly quick, I would not select these two turbos if your end goal was 1200 to 1400rwhp.

RealQuick

iTrader: (14)

I have precision billet 62/66's for my 416ci LS3 and they hit hard on the street... goal was 1000rwhp @ 16-18psi. Initial dyno testing resulted in 844rwhp (13psi) and 913rwtq (15.5psi) on 93 + meth with only 13 deg @ pk tq and 15 deg @ pk hp. Should support 1100rwhp easily with more tuning and more boost... not sure if they are big enough to support much more though.

transam69230

iTrader: (49)

Back pressure ! Back pressure! 427 is a lot of cubes for 62/66s and you will run into back pressure issues over 1000rwhp. The small turbines on 62/66s will choke out.

SLOW SEDAN

iTrader: (13)

The longevity of his turbos leaves a bit to be desired, plus his billet wheels look an awful lot like the KTS wheels which can be found cheaper elsewhere. OP said he said he had a $2k budget, I doubt he can get two turbos from Jose for that anyways.

gbtwo

iTrader: (4)

So I called Jose at Forced Introduction and he said the PT 7675's would definitely reach my goal and be with-in budget. He also stated his concerns around PT and rate of failures. He ended up recommending the Borg Warner S372 SXE's (72/73), said they would spool faster and be able to hit my goal with room to grow. I was really set on the PT7675s because I have seen some very impressive numbers with them, but I was a little worried about reliability so I ended up going with the Borg Warners. Went with the T4 .91 Housings as well, can't wait until they arrive.

Bazman

Good choice, they won't disappoint.

After spending hours pouring over compressor maps and spreadsheets, my 386 rebuild choices will be between twin BWS300SXE's (91S72) and GarrettGT3582 or GTX3582's. Your extra cubes will want the BWS372's. It's going to fly :-)

blake b

iTrader: (11)

I had a 427LSX and made 1221whp/1176tq with AGP 6565s. I ran into boost control issues or I believe I could have made over 1300whp. A guy on camaro5 made 1337whp with the same turbos through a 4L80e and a 427LSX. I had an M6.

The AGP turbos are T3s and mine had .82 AR. I don't recall what the other guy had.

gbtwo

iTrader: (4)

I actually read about your build and actually talked to Kevin from AGP. He recommended the AGP 6565s as well but I ended up going with the Borg's because of the potential head room to crack 1500hp and plus the resale value. Over-all I was impressed with the 6565s and was very close to purchasing. Kevin was very knowledgeable!

gbtwo

iTrader: (4)

If you can afford the Garrett's I would see no reason reason to really go with the S369s. I wish I could have done 1 single GTX55 but it was out of budget, but like you said I'm sure I will love these S372s!