Quote:
Originally Posted by Hib Halverson
Well, I'm kinda fixated on the 368 because, if I did it, it'd have to be for under 10 grand and to go 385, I'd need a crankshaft which I bet costs $4000.
My 350 already makes about 500-hp via the port work and other engine mods I have already. I can easily spin the tires, which are F1 Supercars. A good 385 which is streetable, is going to make 580 or so and a good 415 is over 600. All that would do is spin the tires more, but not make the car that much quicker. Obviously, if I put slicks on the car, it'd be a different story...but then I'd be breaking driveline parts.
A comment was made about a 368 with different intake cams failing California's smog check. No doubt, the reason I'm still not sure about the cams is just that–the smog check. Actually the smog check is also why I may have to retain my ported stock exhaust manifolds and cats.
I'm not a drag racer (at least not a frequent one) and I think a 540-550-hp 368, coupled with the right suspension upgrades (right now, other than revalved SRC shocks, my suspension is stock) and a 3.73 axle (right now, the ratio is stock) would make a really fun car. It won't catch my 12 Z06 on a road course, but it will keep it in sight.
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Frank is right - Lots of options:
You're going to buy sleeves, pistons, rings, bearings anyway, so bigger is possible for very little more $$ e.g., 385. And, you keep your stock crank and cams and get close to 600 CHP, provided the porting is increased to handle it.
somewhere above 385 you can transition to 402 via off-set grinding the crank. At 385 you should be able to get to close to 575 CHP, on stock cams (read: Kalifornia emmissions requirements in mind).
There's porting, and there's porting... A lot has changed since porting was done in the 90s. One of the often said ditties is, "If you port the intake, you'll give up low/mid range torque for top end". Well, apparently the LT5 was starving for air from the git-go (read: doesn't appear to apply in this case!). Have you seen Marc Haibecks office "wall paper"? It is becoming covered with dyno graphs that show many motors not only making substantial power improvements, but without sacrificing torque anywhere in the band! The point is, HOW your porting is done (dare I say by whom?), could be important. (Some of these gurus are porting LT5 stuff almost weekly. And, now there is a proven CNC head porting program in IL for the LT5 to consider (@ about $2500 inclucing taking the motor apart and putting it back together with the ported heads).
I guess the bottom line goes back to what I said earlier about the 368. Hib, you dropped a lot of big names around w/ regard to your project. But, truth is where you find it, and a lot of big names have refocused on other (e.g, LSx) projects - seldom do work on LT5s anymore. Yet, there are still some well known, dyed in the wool DOHC purists that are still dedicated to the LT5, that may have something to offer and won't cost you a fortune.
I'm just sayin...
P.