I've got a decision to make and am trying to decide if there are any cons to building a 396 instead of a 383. Would durability be the same? What about overheating? What are the differences between going with a 5.85" rod or a 6" rod when speaking performance wise? What about cam size...would my current cam (222/230, .533/.544, 112lsa), be too small? I know torque would improve significantly over the standard 350 lt1 but what about horsepower when considering that I will be using the same stage 2 heads and cam? I've seen that the kits are similarly priced, why would you not want to go with more cubic inches?

 

Are you going to run nitrous or a blower? That is partially a deciding factor, ringlands will be a bit weak for a non NA app on a 396.

If your staying NA the crank can be less expensive for a 383, less clearancing is needed also. If your going all out NA then maybe a 396 is the way to go, although I myself would probably chicken out and stay 383. There is also a 3.8" stroke option.

 

I was considering either going with a 150 shot or possibly even putting my 7# procharger back on. I was wondering why more people don't go with larger cubic inch motor.

 

If you're talking forced induction, the reason is exactly as Dr. Mudge suggested. The ring lands are shorter on the 396. A 383 is the way to go on a blower or heavy nitrous shot. But if it was NA all the way, I'd take the extra cubes.

 

Last year I ran a 383 motor w/6" rods and JE 28cc pistons. This year, I'm building a 396 motor w/6" rods and Diamond 12cc pistons. The Diamond pistons (even w/longer stroke) are .050" taller, have .190" longer skirt, and more metal on the top ring land...here are some photos to help illustrate this point:

JE 28cc piston for 383 w/6" rod...click on below:

http://photos.yahoo.com/bc/christets...c=ph%26.view=t

metal around ring land (the new piston is the Diamond 396 6" rod):

http://photos.yahoo.com/bc/christets...c=ph%26.view=t

skirt JE piston:

http://photos.yahoo.com/bc/christets...c=ph%26.view=t

Skirt Diamond piston:

http://photos.yahoo.com/bc/christets...c=ph%26.view=t

Comparison JE 383 6" -vs- Diamond 396 6":

http://photos.yahoo.com/bc/christets...c=ph%26.view=t

I hope the photos posted right. If so, you can see that the 396 6" rod piston from Diamond has thicker ring lands and longer skirts than the JE 28cc piece...just my $.02.

 

The first photo above is a picture of a one of two pistons I broke after not letting my car adequately cool down between a couple of full power pulls (9:1 cr, 18-20 psi boost, race gas, a little too much timing, and a heat-soaked intercooler = boom!!)

 

If it were me and I would look at what my heads flowed and go from there. Let's say heads flow 275/200 int/exh then I would build a 383 6" rods, if heads were 300+/ 225+ I'd build 396 with 5.85" rods. Either motor would likely need slightly more cam than 220/230.

 

This has been discussed quite a few times, do a search and you will get loads of info. Also this would be better suited for LT1 Tech, Thanks.