370 or 408 for turbo?
May 13, 2012 | 12:05 PM
#1
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From: louisiana
370 or 408 for turbo?
There's no replacement for displacement...I kno this lol, but from a budget point of view, what would be ideal? It seems to me a 408 would need a bigger turbo and better flowing heads. So far the details are lq4 block, compstar rods, 317 heads, proflo intake and a 76 mm turbo. I'm about to order the callis crankshaft. Honest goals here is a 11 second truck(97 z71, 4l80, 3.42s, 4600 pounds) 15 psi through a 370 should have no problem right? Or do I need to go for the 408?Max HP I'm guessing 800 to 900? If the 408 is worth it, it will just take me longer to build it, what do you guys think?
May 13, 2012 | 12:41 PM
#3
you will have no problems with a 4600lb truck going 11's i go 11's with a 4.8 at 13# and truck weighs 5050. check out the aes 390 before you buy a crank. they run a 3.8 stroke so somewhat middle of the road from stock and the 4.0 stroker. it gives you the displacement but not some of the "problems" that the 4.0 stroke has
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May 13, 2012 | 03:59 PM
#8
straight from frasier at AES
Overlap is considered an important factor of crankshaft strength, hence why GM made "400 main" vs. "350 main" when they increased the crankshaft stroke for 400 SBC. This picture should better explain.
No,
Compression height dictates the real estate available for the ring lands. As you shorten compression height rings are supported by less material, top ring land generally is compensated to be thinner. Thinner top land any extra heat applied to the piston (detonation) will cause the aluminum to contract.
Thicker top ring land is able to absorb the heat, less chances of cracking or affecting the structure of the piston.
This cylinder had 44% leak down
Heres a picture of our Cp Piston next to a "408" piston
No,
Compression height dictates the real estate available for the ring lands. As you shorten compression height rings are supported by less material, top ring land generally is compensated to be thinner. Thinner top land any extra heat applied to the piston (detonation) will cause the aluminum to contract.
Thicker top ring land is able to absorb the heat, less chances of cracking or affecting the structure of the piston.
This cylinder had 44% leak down
Heres a picture of our Cp Piston next to a "408" piston
May 13, 2012 | 04:02 PM
#9
so you know i dont have any of these combinations but i do know if i ever go built motor it will be that 390. ive seen enough proof that its one hell of a motor. just want you to be aware of your options incase you hadnt known about it thats all