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Discussion Starter #1
Friend of mine just bought a 408 with LS3 heads on it. Was wondering what kind of power it should make with untouched LS3s and with the right camshaft of course. It will have a victor jr intake and a 850 carb. 1-7/8 longtubes, yada yada. Hoping to run high 6's/high 10s N/A on pump gas.
 

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What compression?
 

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I have one in my drive way, stock LS3's, cam is 252/264 660/669 111 lsa. Made 530 rwhp. @ 5000 rpm it made 495 rwhp. This is through a LS3 intake, no fast. Also it was through a 4L65, and IRS
 

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Discussion Starter #4
Compression should be just a touch under 11:1 I believe. Flat top diamond pistons...stock 6.0 gaskets...heads have not been milled.

I have one in my drive way, stock LS3's, cam is 252/264 660/669 111 lsa. Made 530 rwhp. @ 5000 rpm it made 495 rwhp. This is through a LS3 intake, no fast. Also it was through a 4L65, and IRS
Thats impressive!! The cam we have is a bit smaller, but its not too far off from yours. Its 248/254 620ish lift on a 112.
 

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Id be worried if it only ran high 6s!

Should make low to mid 500s to the tire, high 400s if its in an auto.
I guess I have not given the stock ls3 heads enough credit.

Most full blown street cars that make high 400s to the tire only run 6.70s-90s depending on weight of course. This is a full weight '78 Malibu minus A/C and Heat. Full exhaust, Th400, 3.73 gear on a radial. I don't know what it weighs, but I would be happy as hell with 6.80s on motor.
 

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My 408 with L92s made "low showing numbers" but ran very well at the track. With the motor running lean on e85, it made 462whp on nuts, 630 on a 150 with 700lbs of bottle pressure, and 750 on a 200 hit with 900lbs of bottle pressure. 251/259 660 lift 114+3 TSP cam.

Swapping out for an after market LS3 head/solid roller/Tunnel ram/fogger setup. I'm just trying to see how fast we can go with those cubes before I start seriously focusing on my new motor.
 

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My 408 with L92s made "low showing numbers" but ran very well at the track. With the motor running lean on e85, it made 462whp on nuts, 630 on a 150 with 700lbs of bottle pressure, and 750 on a 200 hit with 900lbs of bottle pressure. 251/259 660 lift 114+3 TSP cam.

Swapping out for an after market LS3 head/solid roller/Tunnel ram/fogger setup. I'm just trying to see how fast we can go with those cubes before I start seriously focusing on my new motor.
Should roll out pretty good boss
 

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hush ur mouth and put ur nose in the corner son! :cool:
Oh snap!!! LOL!!!

From what I found at a quick glance, a full weight Malibu should be around 3,100-3,200ish. From what I have seen the sqaure port heads are no slouch, even in stock form. Should be a pretty quick ride even on motor.
 

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Discussion Starter #13
Thanks for the responses fellas!

Oh snap!!! LOL!!!

From what I found at a quick glance, a full weight Malibu should be around 3,100-3,200ish. From what I have seen the sqaure port heads are no slouch, even in stock form. Should be a pretty quick ride even on motor.
I was thinking around 3400 with him in it, but if thats the case then its probably at least 100-150lbs lighter than that. The heater box has been removed, no a/c, no stereo. Has drag wheels, no cage (yet), stock tank. He's about 165lbs or so.

The converter will be the difference maker. Don't know what its gonna do with the current one, but only one way to find out. It was kinda tight and was set up for a 406 sbc with about 150 less HP. Should loosen up some with this combo I believe.
 

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we had a flat top 413 motor with stock ls3 heads, e85 carb, through a powerglide and a dana, in a 2410 pound truck went a best of 5.88 in the eighth. i think your combo should run 6.60s/6.70s all motor on pump gas.
 

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I'm building a 408 now with a SDPC LS3 cnc head. I'm going to engine dyno it with a carb NA when done. Then it will go injected and procharged after that. I can post some numbers when we get it run.
 
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