I'm been contemplating the next stage of upgrades for my 96 LT4 combo that sees lots of fun competition-autocross, road racing, drags, and hopefully some top end runs.

The NA direction seams the easiest, most reliable, and most driveable, but have to wonder at the numbers some of your modded systems are producing...500+ WHP. Something that is rather difficult to achieve on motor alone.

Reliability is a major concern as one event experience had nearly every turbo/blown car fail before it was complete-got to finish to win...but watching them go when they did was very impressive.

How many folks employ the blown power on 'strenuous' events?
Can 550+ WHP be used effectively on an autocross course?

Common sense says the longer events will benefit the most-road racing, top ends...

Comments?

 

I'm contemplating the same thing.

The power curve in a blown engine is a lot better, making power right off idle.

I know of a least two national SM2 drivers that have 600chp engines in thier C5's

Cooling is the biggest issue for road courses.

 

Ok, now if you are doing all of that its hard to say what would be the best option. For drivability, definately forced induction is the way to go. When you stroke out a motor, throw huge heads and a huge cam on it, you loose all of your stock driveability. Come to think of it, I'm not sure you could even reach 500rwhp on a LT4 block n/a. Now if you threw a shot of nitrous on it then you could.

The other thing you need to realize is that the 500+rwhp turbo and blower cars here require a rebuilt forged engine AND forced induction.

For the drags and top end runs I would say definately go turbo for the most power. For the road racing and Auto-X, where there is alot of pedal changes, I would think the predictability of the supercharger would be much nicer.

Using 500+hp is a matter of practice and knowing the car. If you are comming to a curve and you could slam the gas in your car now, you'll have to re-teach yourself to find the limit with the new power.

If you are looking for 350-400rwhp I would say go N/A, but for 500rwhp go forced induction.

 

What do you mean "if I do all that"?...Isn't that what Corvettes are for?

Seriously, you make several good points. The reliability issue especially the heat concern is very valid. I've got the largest radiator available and I will still hit 227 at hot tracks with oil temps near max acceptable (~300 degrees). I've even cracked both OEM exhaust manifolds! The intercooler addition seems like a problem.

Like you mentioned there seems to be a gap between 450 to 500 WHP...where NA reaches the limit and blown starts with a 'mild' kit. I think 450 is reacheable for the average joe without going to forced induction, but things may get a bit more frisky as a daily driver.

Currently, the car is ~400 WHP (Dynojet) with great driveability even with the 296/304 duration GM847 camshaft, 219 cc heads, and 11.9 CR. During autocross it stays almost entirely in 1st gear and works quite well as well as the other events-but with factory cars coming out with more HP...I got to stay with the Jones!

I will be replacing the rings/bearings along with better quality heads on the next go around...swapping pistons for low cr models won't be much more work if a blower is selected-but the extra $6-8000 for the kit is tough to accept for that jump and the power isn't useable. Useable defined as being able to put it down thru a R type compound 275 size tire.

Thanks for the comments...and 'MN' when will your forward turbo 'kit' be offered?

 

I know what you mean, I have a newspaper article on my desk right now that states the 2008 SRT10 Viper is going to have 600hp. I'm guessing in the next year or two the Z06 will do something to catch that and drag the base engine up a notch too.

400rwhp is pretty darn good for a N/A car. If you have all of the upgrades to handle the higher horsepower(fuel pump, injectors) then you won't need to spend 6-8K for a blower. But getting around things like belt slip and what not may haunt you. Things become much more complex when you run forced induction.

Useable hp if you stay in first gear is probably going to be slim if you drop a blower on the car, if you used second gear you could probably do it though, and with the extra horsepower you may be speeding up faster on the straits to need another gear. Its tough to say. With my old worn tires I could break them free at 70mph if I down shifted and went. Once I replaced them with 315's it held traction after the 1-2 shift and the fishtails were much less. I contribute most of that to the newer rubber.

As far as my "turbo kit" that isn't going to happen. I'm still making changes to it and most people don't want to give up their A/C or build their own heater box. But if I ever do make another kit for another one of my cars I did learn alot of stuff about piping and what not.

 

Have to give it some more thought. As mentioned the superchargers/turbos have their own issues that can be cumbersome to eliminate.

Sorry to hear you setup won't be offered aftermarket. I'm not sold on the rear mount layout as of yet.

I believe my setup still has some room to grow...just not sure if I should make the jump now or end up doing it later costing more money. :-)

Cheers!