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Been doing a lot of research lately about my build and future upgrades..... One of them being a turbo upgrade.
Currently running a 370" 9.0-1 compression ported ls3 heads, VS Racing 69/73 billet .91ar twins, LJMS TT stage 3 cam, 3800 stall converter, 3.70 rear gear, 3500lbs, E85. Car is about 50% drag 50% street. Just want to make a responsive 1000whp, with the ability to support a 408ci at 1200whp.
The car is pretty laggy on the street, and at the track takes about the end of first gear to hit wastegate pressure, I can build about 6-7 pounds footbraking with 2 step at 3800. Next step is transbrake....
Doing some research and using a match bot, reading compressor maps, puts me right on the money for using a 69/73 as far as efficiency. But I see guys running 6266s or smaller on 400+ cubic inches making 1300+whp.
Are Borg warner just lazy or would it benefit me to go to a better brand like precision or a Jose FI built turbo? Would a 66/68 be a better spooling option? Biggest question I want it to obviously be worth it and a noticeable change.
Overall, sounds like a nice setup. I think the 9:1 static Compression ratio and the Stage 3 cam, coupled perhaps with some tuning (spark advance) might be some of the contributing issues regarding lag. I went with smaller GT35 twins last year(now S480) and it would blow the tires (315x35x17 MT Drag radials) from just stomping the gas from a dead stop. Shot up to 29.5 psi in a heartbeat till I got the boost controller set back to a more sane 21. That setup was Isky Triple 12 cam,, 10.0 compression 5.3 E85.
i asked viren from VS racing to size my twins for best street spooling. He recommended the billet wheel 6762 for the 6.0. Haven't drove it yet, but sounds like the next size down from your setup.
i asked viren from VS racing to size my twins for best street spooling. He recommended the billet wheel 6762 for the 6.0. Haven't drove it yet, but sounds like the next size down from your setup.
Might be the next size down from him but not from other manufactures, which is mainly what I'm curious about. If maybe going more name brand would help power and spool. Good luck though should be awesome !
Have to look at the sum of the parts, not just them individually... Those turbos are probably decent for what they are, but with 9:1 compression and that camshaft, the weaknesses come out. The giant turbine craze became a thing because of similar hardware combinations. If you want the big cam sound and you want the power...you have to deal with the lag. Dropping turbo size and changing nothing else would help the responsiveness, but you will lose top end potential due to added exhaust reversion.
Perhaps I'm mistaken but I read awhile back that realistically, only Garrett generates Compressor maps because the analysis is so costly and time consuming. I'm conjecturing here but maybe that map is being supplied on the basis the wheel sizes intersect with your models. It may well be that your units are not as efficient as the Garret counterparts.
Originally Posted by 973800CamaroRS
would there be a better option out there ? Precision or a Jose pair ? But like I did a compressor map shows these being great ?
would there be a better option out there ? Precision or a Jose pair ? But like I did a compressor map shows these being great ?
If you are serious about getting better response, look at a pair of EFR turbos. The titanium aluminide turbine wheels are no joke...they're barely heavier than the compressor. I've run them before, very impressive turbos.
Originally Posted by mightyquickz28
Perhaps I'm mistaken but I read awhile back that realistically, only Garrett generates Compressor maps because the analysis is so costly and time consuming. I'm conjecturing here but maybe that map is being supplied on the basis the wheel sizes intersect with your models. It may well be that your units are not as efficient as the Garret counterparts.
Every OEM supplier that manufactures turbos fully characterizes them. That's how the design is validated against its requirements. I know because I've done the 'compressor map vs real world' validation myself up and down Eisenhower grade in Colorado
The Borg SXE 369s are terrible and I imagine the Chinese VS copies are probably worse. Put a pair of PTE 6766s on there and never look back.
Twin VSR 7875's don't spool any worse than my S369's. In fact the "probably worse Chinese VS copies" have trapped 190+ MPH so they seem to be just fine for average guys wanting decent power.
Originally Posted by 973800CamaroRS
Currently running a 370" 9.0-1 compression Just want to make a responsive 1000whp, with the ability to support a 408ci at 1200whp.
Why did you build a 9.0:1 engine if you wanted it to be responsive? SBE unit would be more responsive and hold 1000.
Twin VSR 7875's don't spool any worse than my S369's. In fact the "probably worse Chinese VS copies" have trapped 190+ MPH so they seem to be just fine for average guys wanting decent power.
Why did you build a 9.0:1 engine if you wanted it to be responsive? SBE unit would be more responsive and hold 1000.
Well I built the motor 6 years ago I didn't know anything about flex fuel and there wasn't E85 in the area. The engine is still in great shape and healthy so I would rather not tear the motor apart if a simple turbo swap would help me now. The motor has been flawless whereas most cant say that with their junkyard SBE.
Have you tried anything else besides the VS to have something to compare it to ? Honestly I don't and that's why I'm asking.
Last edited by 973800CamaroRS; Jun 14, 2021 at 03:11 PM.
Reason: update
Well I built the motor 6 years ago I didn't know anything about flex fuel and there wasn't E85 in the area. The engine is still in great shape and healthy so I would rather not tear the motor apart if a simple turbo swap would help me now. The motor has been flawless whereas most cant say that with their junkyard SBE.
Have you tried anything else besides the VS to have something to compare it to ? Honestly I don't and that's why I'm asking.
I get it, was just wondering. A head swap with smaller chambers could help you along with E85 now to be a bit more snappy and easier than tearing the whole engine down. A smaller cam would be snappier on the street than the stage 3 231/243, I went from a larger cam to the 222/233 and helped street driving a good bit and still revs to almost 8000 easily.
I've had multiple Precision, Borg, FI (borg and garrett based), Garrett, etc in addition to a myriad of knockoffs.
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Compressor Map VS Real world 
