Help! I lost the bottom end of my motor in my '00 and need to replace it. I primarily use the car for track days but I still keep it street legal (Calif). Now that I'm going to replace it I would really appreciate any suggestions of what to put in there. A GM crate motor sounds good, especially with the warranty that comes with it. The local speed shop is suggesting a 383 with more aggressive heads and intake. They also mentioned belt drive for the cam. It'd be nice to have a higher reving motor since I've got 4:10's in the rear. I'd be great to hear how you guys would build it out. Thanks.

 

^^I don't know what you mean by track days. Road racing or drags?

Either way you are better off with a forged motor.

Assuming you road race and you want a motor than spins I would stay away from a stroker because they can't spin as high as the 346 due to longer crank. In road racing horsepower is the last area needing improvement. Work on the suspension and brakes, and don't forget the driver.

410s are pretty steep for road racing.

 

Find a shop that specializes in corvettes. The mere fact that these guys suggested a belt drive shows me they know nothing about your car. What area are you from?

 

I agree you are much better off with a forged motor, I am not sure why it is that everyone seems to think you cannot spin a longer stroked motor.. it is all about the valvetrain and where the cam is setup to make power. There is no reason why you cannot spin a 382, 402, 408, 416 or 427 to 7500 RPM if you wanted to. It is done all of the time,

Hope that helps. I can put together a bottom end for you, pretty much anything you want, but sending a motor from TN to CA might be a bit much, let me know if you are interested.


Good advice here for sure.

 

Independent1, this car is used for road racing. No supermarket duty. I usually trailer the car to the tracks unless I'm at Laguna Seca which is only 30 miles away from the San Jose area where I live. I run RA1's or Hoosiers that are DOT approved so I just drive her down cause some days I'm just lazy.

I know the 410's are steep and that's why I'm looking for a motor that'll wind out a bit more than the LS1 did. With higher reving motor it should be a great combination. With over 60 track days I agree that horsepower is less important than brakes/rotors, tires, and the rest of the suspension. But, since I've got great braking and cornering in this car, it's an opportunity to pick up some straightaway speed. Driving? Well, just say I try. (My best time at Laguna Seca was 1:44 with a stock motor).

Hey Blown what is a forged motor? Forgive the ignorance but the motor I've been using came with the car and this is the first time I've had to find a replacement. Would it be Calif legal? What options do I have?

 

"Forged" basically refers to either building or rebuilding an engine with aftermarket components, specifically at a min, using aftermarket forged rods and pistons. These components are stronger than stock.

You shound have no issues with compliance although I would recommend that you use someone in your area to tune the car and confirm compliance with your specific laws.

If you have specific questions, PM me or call me at 865-389-2040

 

Forged means that theyre usually heat treated and cnc instead of cast for strength. Question, on your stock bottom end, what was your h/c combo, hp/trq, and why did you think it gave? As I get ready to install my h/c and mods, Im trying to gauge the strength of a stock LS1 bottom end. Did you have the setup for a while? How many miles? sorry for the 21 questions, just curious.

BTW, most s/c packages are street (CARB) legal. Go with Procharger and STS and Im sure they'll hook you up with a really stout engine combo. Good luck and have fun shopping.

 

The car was on a dyno last July and it put out 349hp and 365tq. Adding a few more for the cold air ram made the car very competitive on the road tracks here in California. The motor was stock but I added long tube headers and '04 Z06 exhaust (some tracks have a 94db max). Other than that all the other work has been in tires, brakes and suspension.

I bought the car with 87K miles and it now has 98K. Most all of those miles are track time. The dyno revealed the valve springs were getting weak and it showed up with a drop off of hp & tq above 5800 rpms. I'm not sure what a h/c combo is. If its compression, I did a leak-down test in the fall and all the cylinders were pretty good with a 4% leak in only one cylinder. Not bad for this many miles.

 

h/c refers to heads/cam

 

While you can spin a motor, including big displacement motors to 7500 rpm from a durability standpoint it is harder on a big displacement motor to spin it that high. It is also going to cost you more.

If you have to modulate the throttle than you got more power than you can use so why pay extra for something you will not use?

 

^^
FWIW, when I was considering tracking (HPDE) a vette I looked at a bunch of options including superchargers and turbos (often referred to as forced induction). I figured more power the faster I go!!

While researching the issue I came a cross a very interesting and revealing post. This guy had a Z06 that he ran at the track. He was also an instructor. When his Z06 was stock he ran a lap in 60 seconds. He later did a heads/cam job on his car and his time was around 59 seconds/lap. Still not satisfied he went the forged route along with twin turbos putting out over 700 rwhp. Now, when his car works for him, which is not as often as he would like, he does a over 58 seconds.

So power is not the answer. I would think a well thought out LS-2 or LS-6 motor will easily net you at least 450 rwhp and at least 400 rwtq, possibly more.

A good cam you might want to consider is the LG motorsports G5-X3. It's a big cam that will put power out right on up to 7000 rpm with the right heads and bolt-ons.

I have heard a number of horror stories about stroker motors that burned excessive amounts of oil. Exactly, why no one really knows for sure.

I would highly recommend posting over in the road racing section and ask for advice on a motor. They are a very helpful group over there and I have learned a lot from them.

 

Build something thats works specific for your needs. You'll see that the cars with the most hp arent always the best in some cases. Build a package that will keep you happy regardless of dyno numbers.

Thnx for the info on your old motor. Now the fun starts, got your credit card ready!

 

check out texas speed's motors! you can get there 408 for abought the same price as the crate from chevy. jmho!

 

Since you're going to be R&R the drive train, now's a good time to change the rear gears. There are a lot of guys that you could trade out your rear with for 3.42 and they would take your 4.10's.

A well put together LS2 with some nice AFR heads or CNC one's with the other bolt on goodies will net you somewhere around 450 /450 at the wheels.

Better heads and cam will allow you to spin to 7500 RPM's. Blown Z06 (aka Nick) does a lot of motors and TTi Turbo installs. Shipping a motor is about $300 bucks.

Good luck with rebuild.

 

Thanks for all the info fellows. It looks like it comes down to either a stroker or a LS2 or LS6 crate motor. Dependability is what my main concern is. I don't want the motor breaking in 20K miles. And, as it was said before, track times are really about suspension and driving not how much hp is under the hood. I know, I've chased a few of those modified Miatas that have 1/4 my hp.

 

^^Don't do a crate motor!! Go with a forged motor. You will get more reliability from the forged motor.

The miatas weigh a lot less than a vette and have good power to weight ratio. In racing, extra weight is a bad thing. It adversely affects all aspects of performance (acceleration, braking, and cornering).

I would stick with a stock cubed motor Ls6 (346) or LS 2 (364). You can buy short block for around $3K, and then add heads, cam, intake,etc.

 

If your block is still good, get it cleaned up and magna-fluxed(check for hairline cracks). Drop in a good stroker forged bottom end, like a dragonslayer crank, forged pistons and rods. With a decent set of heads and a mild cam, even on stock intake, you'll have a 383 with great power and torque and you'll find you can do it for pretty cheap, at least cheaper than a crate motor. Just my $.02