Cripwalker

I'm turbocharging my 2002 Corvette and I'm looking to make 450 on low boost and 550 on high boost. I'm going pretty conservative because it's my daily and I'm spirited driving on backroads and the interstate, not drag racing. I'm looking to make between 5-8 psi or whatever it takes to meet my goals and my priority is low lag (going to be using an AEM electronic boost controller. Would a Borg S300 66/73 be a good match for these goals? If not, what would you recommend.

gametech

iTrader: (1)

I am going to do something I never do, and suggest you would be better off with an NA setup. Your stated goals for usage and power level just don't make much sense to turbo. You will be adding significant weight to the car, but not making enough extra power to overcome the disadvantages of doing so. If you had not specifically stated road race and autocross ,my opinion would be entirely different.

Cripwalker

I see where you're coming from and I had considered an N/A build originally but let me explain why I'm going with a turbo. First is cost: I could either spend three grand on heads, cam, intake, headers, etc and get to the 400-450 hp range or I could spend the same money building a turbo kit and achieve the same power with the option to turn it up to 550+ when I'm racing somebody or want to do pulls. Second is drivability and fuel efficiency. I do lots of city driving as well as long road trips and as I'm sure you know when cruising, a turbo doesn't have much effect on drivability and fuel economy while a big cam certainly would. Third, I just love the idea of a turbo and making big turbo noises and all that.

I understand your concerns with a turbo for road racing and autocross applications but you can disregard these points as they make up an incredibly small percentage of my actual driving. I used road racing and autocross as examples as I was more trying to explain that maximum horsepower is not my goal and I'm looking for a smaller turbo that will spool quicker lower in the rpm range. I do lots of spirited driving on backroads and the interstate but not so much digs from a red light so I equated it to road racing vs drag racing however I've edited my post to make it more clear. I appreciate your response and if you know any turbos that fit my criteria let me know

LS1Formulation

iTrader: (13)

I can guarantee you a turbo setup will cost you far more than doing a heads/cam/intake swap. If you can get it done for $3K, I'd be extremely surprised. The nickel and dime parts will add up VERY quickly. I have blown through my budget on my build by around $5K, and I wasn't going for the best of the best with anything I bought. Plus, I do all my own work. For example, what trans do you have? Regardless of auto or manual, a 4L60E with a heavy shot of boosted torque down low is on borrowed time, and a T-56 with a stock clutch is going to have a burned up clutch before you know it. Sure, you can put the turbo on and hope for the best, but either of those transmissions will have a failure of some sort after a bunch of spirited driving. Up to you if you want to go that route, but I speak from experience. You'll see in my sig that both of my cars have built drivetrains. I learned the hard way that building power before beefing up the drivetrain is a recipe for broken parts.

Cripwalker

I agree with you that supporting mods are very important for adding power. My T56 is currently getting rebuilt by Hawks Motorsports and I'll be doing a McLeod RST twin disk clutch either before or while the turbo is going on. I think those two are the main concerns for my expected horsepower level but I'm prepared to beef up the differential output shafts, CV axles, torque tube, and maybe even the differential if need be. I plan to keep my build around $3k because I'm using a cheap On3 turbo, summit racing BOV and wastegate, along with budget flowtech headers and I'll be fabricating all the plumbing myself. The only real splurge will be an AEM electronic boost controller to ensure early and consistent turbo spooling.

I think I've decided on an On3 7665 turbo and I think it's an appropriate size for my goals, let me know what you think. I am dead set on a turbo seat up and I've ruled out heads/cam/intake due to drivability, horsepower constraints, and fuel mileage.

NicD

iTrader: (7)

All of these requirements, just screams don't turbo it. I've yet to see a turbo'd C5 not get hot or overheat with a turbo setup without extensive cooling mods.

Cripwalker

If it wasn't for the fact I put 5-10 thousand miles a year on the car I may consider doing h/c and intake. As far as cooling, I plan to upgrade my radiator and greatly increase engine bay ventilation. I know I'm new to F/I and all of the replies have been from very experienced builders but I just don't understand why everyone is so against a turbo for my goals. A 550hp N/A setup would ruin the daily driver aspect of this car if I could even reach that number and I feel like a relatively small and fast spooling turbo like a 7665 would be great for the street and spirited driving while reaching 500-600 horsepower and maintaining stock driving characteristics when cruising. Other than cooling, what are your concerns?

LS1Formulation

iTrader: (13)

If you're fabbing all your tubing, then you're money ahead. So it's definitely doable. Just remember little stuff, like a 2 bar MAP, and possibly an adapter harness, etc... I literally have like $125 into fitting a ZR1 MAP to my FAST intake. It's an expense I wasn't thinking about, but it had to be done. Lots of things will creep up on you, lol. I'm far from a turbo expert, I am certain someone with more experience will chime in here... But if not, a sub-70MM turbo is going to spool up fast. Even what I have should spool fast, and I have a smaller engine. I think, however, that turbos seem to work better when the exhaust side and intake side are close to the same size. That 76/65 might not spool as quickly because the compressor wheel is bigger, and the smaller turbine will choke off sooner. I would think the 66/73 you mentioned might be a better choice. Either way, I can't imagine you not making 450-550 to the wheels. My cam and bolt ons LS3 makes 466 to the wheels!

Cripwalker

Yeah I see what you mean about the compressor wheel sizes and VS Racing makes a pretty affordable 66/73 that looks like a good option. I'll also be sure to set at least $500 aside for those smaller expenses because I don't want to be caught off guard by those especially on a university student budget lol. I've heard some people talking about the possibility of overrevving and subsequently overheating a smaller turbo with a bigger v8 engine like my 5.7. Do you think this will be an issue? I'll be using a 50mm wastegate and placing it in an optimal area of the exhaust side such as the outside of a bend as other forum members have recommended.

ScottStaypuff

If you want a turbo, here's my recommendation:

​​​​​​https://turbo4less.com/product/vsr-73mm-g42-journal-bearing-t4-dual-v-band-and-reverse-options-copy/


​​​​​

​​​​Maybe also consider an LSA supercharger set up? I don't know if they fit Corvettes...

https://boostdistrict.com/products/b...harger-upgrade

Also for that horsepower goal maybe a Torquestorm would be a good fit.

https://torqstorm.com/

gametech

iTrader: (1)

I have personally seen heavy trailers towed thousands of miles with an lq9 6.0 with a little 67mm Garrett clone. Your 5.7 in a corvette will not hurt any of the turbos mentioned in this thread so far.

dw456post

MMMM---500 bucks is not even close to being enough for extras.
Stock fuel system? new fuel pump, new injectors.
You may be moving front accessories for the turbo piping. New brackets?
Sounds like a fun build though. I have a blower, but I considered a turbo. Blower is simpler, but costs about double your 3 grand budget.
Good Luck!!

The BallSS

iTrader: (9)

Here's the problem with wanting 450whp for normal driving and 550whp for goofing off, once you drive it at 550whp, you won't want to go back down to 450whp.
No one ever does.
Soon after, 550whp won't be enough and then you fall down the endless rabbit hole of more powaaaaa and money.
Keep it NA, do heads, cam, intake, headers and maybe scoop up a used aluminum 6.0L or 6.2L short block down the road for bit more.
Mileage difference at cruise whether turbo or NA will be negligible but every other creature comfort will be unaffected leaving it NA.
If you want more for pulls, toss a little giggle juice at it.
A 150hp shot will also add 200tq which I think some folks forget about and you can bolt it on in an afternoon and hide the system if you want to be sneaky.

jayyyw

You'll have to relocate your alternator, delete your power steering, maybe delete your a/c (depending where you put the alternator), possibly relocate ABS. Fitting a turbo in a vette takes a lot of planning and relocating. I've done it a few times, but in a C6. $3000 may get you close, but dialed in, it's going to cost way more than an extra $500. The first time I turbo'd my C6, I had $15k from selling the old motor and still had to add about $3000 out of pocket. Obviously, that's including some expenses you won't need to worry about but it's still not cheap and I did all my own work, including the fabrication of the kit.

NicD

iTrader: (7)

Cooling is a huge factor but reliability is right next to it as you said it's your daily driver.
1: Don't **** with your daily driver.
2: If you must **** with your daily driver do something that will be damn near 100% reliable, like a heads/cam setup.
3: Don't **** with your daily driver.
I see more people blow their **** up with forced induction where as a good N/A build will be 100x more reliable for 99% of the people out there.

The BallSS

iTrader: (9)

^^^ Words of wisdom right here.

ScottStaypuff

I like the nitrous idea. For 3k OP could go pretty far with some NA mods and a nitrous kit with supporting mods. Any leftover money could be used for handling mods. Then later do a Procharger or something if you want more.


I had a 1999 Neon at one time and went that route, 100 shot with HCI (I did use a 2.4 liter Stratus block for it). I also had some baby slicks but I got that car to run 12.48s consistently with minimal weight reduction on 93 octane. I could have easily gone 11s if e85 had been available. Imagine what you could do with a Vette with similar mods!

The BallSS

iTrader: (9)

My last car was a 02 Camaro SS six-speed 7875 car, maybe 700whp and it was pretty fast but there was a local C5 six-speed bolt-on car w/ a 200hp shot of spray who doing 40mph roll racing would leave in 3rd gear because he had an extra 250tq on tap and he would always be right with me up to 140-150mph.
He'd win if I wasn't dead on with my shifts and shift point, always a really good race.

ScottStaypuff

People forget about all that nitrous torque.

LS1Formulation

iTrader: (13)

Until it gets accidentally engaged below 3000 RPM and your crank gets intimate with the pavement, lol.