I had the .96ar, the 1.15 will slow your spool time. If you were looking for the max power I'd say stay with what you have, but since you want snappy spool and don't care about all out power I'd see if you could swap for a .96.

 

Yes its stock bottom end. And yes to the other question the pt7676 will bolt right up.

The 76/68 would not be my own personal choice as the 68mm exhuast wheel will choke way to quick, the 1.15 a/r is just going to slow your spool. Stick with the .96 a/r. From what I've seen a lot of guys go with them bc they are a lot cheaper then the PT units


IMO the PT7675 is the best sized turbo for the 5.7 for a fun street car. I'm still running my blower cam from when it was procharged yet, I'm sure if i switched over to a turbo grind cam I would have made a little bit more power.

 

Yes it will choke the car if he's trying to set a horsepower record, but he can easily attain his horsepower goals with the 76/68 and the spool is almost instant.

I've had both and I feel like I know exactly what this guy is wanting. I've had it. Lol. when I switched to the 78/75 it still spooled quick compared to a large frame turbo, but doesn't reach full boost until about 500-600 rpms later. (It makes a difference)

 

For 550whp, quick spool, and budget friendly, I sugest the On3 76mm...it has a small 65mm turbine exducer. It will start choking around 600whp.

Otherwise go with a 7675 or a 7875. You can made a solid 650whp on about 12-14 lbs.

 

I agree a 100% with you, he will make 550 no sweat. But I know how fast 550 started to feel pretty slow, Only reason I say go bigger to the OP, is the time, hassle, and extra money spent of switching to a little bit bigger turbo after he's sick of the smaller one. Plus we don't know if he's doing it or a shop

 

If I can make 550rwhp no sweat and with no ill effects aside from no room to grow, then I'll definitely go small. Even if 550rwhp starts to feel slow, this project is limited by the fact that I don't want to build or swap the engine at all, so in a way I actually kind of want to limit myself. I understand why everyone wants to turn it up, but at the same time I'm a perfectionist and I view it as a project. I have a clearly defined goal and I intend to meet that without compromise. If my goal changes, that's a new project and I'll treat it as such. If I had an underutilized turbo I would never be able to resist the nagging feeling to turn it up, then scope creep will kick in and project just got a whole lot bigger and potentially less reliable. If I ever decide to take it to that next level, buying and switching out a turbo will be the least of my worries. Doing the work myself FWIW.

Thanks again guys, the input is truly appreciated.

 

Sounds like you know your goals and are sticking to them, good job! I'd love to see it when you're done, ever hit Woodward? usually a group of f-bodys at the Ducati store Friday/Saturdays

 

My tnetics 7575 billet ball bearing .96 ar turbo was real fun on my bone stock ls1.. for a street car and u wanting the quickest spool, go billet ball bearing, which unfortunately BW doesnt offer. Im running a BW now and LOVE it, even with my motor almost bein to much for the s480, its noticably slower to spool. I would go precision or tnetics 76mm range and billet BB for ultimate fun and full boost around 3k rpm, which is awesome meaning ull hear it spooling down low.. its the best of. both worlds, will spool probly as quick assa smaller BW would, and can make more power.. You can always run a smaller turbo, but with having a stock ls1 youll have to run a high amount of boost, which isnt good either for a stock motor.

 

Steve - Thank you. I'm on MiFbody and have been out to the Ducati meetup once with my old car. Problem was I spent years building it, then sold it shortly after finishing it. I plan to make it out there a few times this summer although the car will probably be bone stock until the end of summer.

Kmspeedie - Fair point. I'm also considering a smaller Precision unit as well with a ball-bearing. I know it adds a lot of cost, but for my goals it might be worth it. I also assumed when people say the smaller turbo will be "more efficient" at lower boost levels it still meant 93-octane-friendly boost levels (10psi or less I would think) since I stated that as my goal. There will be no meth on this car. I do have other professionals I am going to consult on my turbo selection as well, just wanted to check in here as well in hopes someone might have actually used one of these smaller turbos in a similar setup.

Thanks!

 

My original setup was with a turbonetics T66 (made 556 whp through he T56 and a 12 bolt, the fun part was the 600ft lbs of torque) which i still have sitting on a shelf if you're interested. I also have a set of 317 truck heads that had a valve job done sitting on a shelf you could use to drop your compression ratio. Biggest difference is that mine was a rear mount setup, I had max boost at about 3k rpms.