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Oct 24, 2012 | 03:10 PM

dradernh

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Newb Here - 1st Post

I'm considering the LS3 376/480 for a track car project. Chevy says 480 HP/475 TQ for the motor & I need something around 370/370 at the wheels to make my class limit. (The limit at my weight is 370 calc'd. as HP X 2/3 + TQ X 1/3, so the two don't need to be equal but the total must add up to no more than 370.)

I'm assuming the published numbers are with 93 octane, and if I further assume 15% driveline loss, that will leave me at approx. 408/404 at the wheels using the published output at the crank. What I'm wondering is this: if I run 87 octane, what is the percentage rear wheel output loss I'm likely to see? Experience with BMW motors tells me it's right around 2% (i.e., I'd have around 398/394 at the wheels after going to 87 octane).

More generally, what is the convention for reducing the output of these motors? Can it be tuned out? Intake restrictor plates? Any help will be most appreciated.

Oct 24, 2012 | 03:24 PM

zacht

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whats the car its going in? do you already have an ls motor??? you can damn near start with any ls power plant and meet those goals...

Oct 24, 2012 | 03:29 PM

dradernh

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It's going into a BMW E36 M3. Nope, don't have the LS yet.

Good point re: where to start. I just ran down the crate motor catalog & picked out the LS3 "hot cam" unit as the best place to start. Probably should have asked for advice first, huh? lol

Oct 24, 2012 | 03:44 PM

zacht

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so you already have the LS3 376 crate? you can tune it down..run a restrictive exhaust/ maybe smaller throttle body...

Oct 24, 2012 | 04:27 PM

outkast6991

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From: lancaster,pa

A bolt on 6.0 behind a stick will be in your ball park numbers. Maybe pull a little fuel/spark to hit the target as well

Oct 24, 2012 | 04:56 PM

dradernh

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Quote:

Originally Posted by zacht

so you already have the LS3 376 crate? you can tune it down..run a restrictive exhaust/ maybe smaller throttle body...

No, no, haven't bought a motor yet. That's one reason I thought I'd check in here for advice. I sort of picked the 376/480 mill thinking I could fit it into my current class, and could also open it up further if I decided to move up a class. Also, given the cost of labor up here in the Northeast, I figured a crate motor would be a good place to start: new, drop-in (with a conversion kit for the E36), huge bang-for-the-buck, terrific aftermarket if I want to mod it, etc., etc.

Quote:

Originally Posted by outkast6991

A bolt on 6.0 behind a stick will be in your ball park numbers. Maybe pull a little fuel/spark to hit the target as well

I've seen that. I'm afraid the cost of these crate motors has left me like a kid in a candy store - the price per HP when comparing a standard LS3 with one that has the hot cam makes me want the one with more HP because it's so damn cheap compared to adding power to a BMW motor. Even though the cost difference is small, maybe I should just focus in on the motor that gets me what I need now, knowing that modding it later has a relatively modest cost to it.

Last edited by dradernh; Oct 24, 2012 at 05:11 PM.

Oct 24, 2012 | 08:29 PM

zacht

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you can get a whole pullout 5.3/4l60e cheap...with the harness and all accessories...my buddy got one for 2200 shipped to his door...

6.0/4l80e can be had cheap as well...hell even a pullout ls2 out of a gto with a trans and all the accesorys/harness is like 3k cheaper than that ls3 crate...and you get a lot more...