Assume equal compression, equal cylinder head/intake/TB/exhaust/drivetrain. Would the 408 SIGNIFIGANTLY outperform the 395, in either HP or TQ? I am thinking of a aluminum blocked 12:1 395, some good LS6 or AFR heads, and a large (240+) cam. How much more HP/TQ would the 408 produce than the 395, assuming everything above is the same for both motors? Enough to make up for the ~80 lb weight difference? Thanks, shawn

 

well for starters the 395 wont rev as high as it has a longer stroke.

 

depends on how u get 395 ci ... and how u get 408 ci...

if the only difference is the bore size then ur talkin no more than 20hp/tq... probably like 15 imo.

 

Have you looked into the LS2 block? 900 bucks for a 4.000" bore aluminum block is pretty nice.

I am thinking about it. Just want to wait a little while to see what changes have to be made.

Brad

 

exactly!! Well when he mentioned 80 lb weight difference I assume he is talking a 6.0 l iron block vs an ls1 block which equates to a 4.0 bore 4.0 stroke vs a 3.9 bore 4.125 stroke whick is why I said it won't rev as high.

 

I think everything else being the same, the 408 will make about 30 more hp and prolly also more tq.

 

everything being the same just 13 ci will not be 30 hp it will be less. this is not the same comparison though it is with different strokes so the iron block will rev higher and make more hp that way also with the slight advantage of larger ci. so 30 hp is probibly very realistic numbers probibly even more.

 

I would go 408. the more cubes the better!

 

Take a look at Fastech. They have a 395 that did pretty well. They also spun it pretty high. I think the dyno is in the dyno forum.

 

thats funny because my 395 all stoke makes power to 6800 rpm.

i dont think the extra weight is worth it even if it could give you
an extra 30hp.

 

Well if you consider the best NA engines make around 2.37HP per cube the power difference at best would be 2.37 x 13.

Chris

 

That was my car. It makes a little over 500 with nice heads and a big *** cam.

If I put the same heads/cam on a 408, I bet it would make about 530.

 

for example, an all bore 382 will make more hp than an all stroke 382

I just didnt want another 100lbs in the front of my Vette since I'm gonna start road racing it

 

Show me a NA LS1 that makes 2.37/cube and I will buy it on the spot.

you realize you are saying that a stock 346 CI motor would make:

346
x 2.37
-----------
820 hp

I dont think so. More like 1.37/CI for the best motors.

 

Thats not my point. You take the best tuned Cup engines and thats what they make about 2.37 per cube. Now you take a street engine your lucky to to make 1.25 per cube. My point is 13 more cube is not going to make a big difference even if it could make 2.37HP per cube.

Chris

 

I believe I would be more worried about things like rod angle and placement of the wrist pin in cunjunction with the oil rings. You will have a more efficent motor with the 408 that will prolly last longer due to the better rod angle and better placement of the oil rings. A 4.125 stroke will wear on the rings faster and crowd your oil rings because the wrist pin is moved up so far. Personally, I'd still build the 395 because I don't mind a little work every now and then and I stll think the motor will last a good while. A just don't think the little bit of added hp would be worth the weight. Now if you do the LS2 block, that's a diffrent story.

 

save the weight, it ain't worth 13 cubes.

 

go with an ls2 block and save the weight and you won't have to give up any cubes.