WS Sick

Everything being the same in the motors you can expect a little more HP in a 383, but a much flatter and fatter torque curve, Add more head flow and cross section (and remove intake trace restriciton, including manifold restriction) optimize cam timing and it could well be 100 hp at the crank.

Evil Eric

400 is attainable much cheaper with a 355 block if you get a decent custom grind cam and touched up heads.

Sweetred95ta

I just meant from replacing the crank.

WS Sick

Problem with that is it would take a magic cam to make 400 RWHP with just touched up factory heads on a 355 LT1 (unless you ran 13.5 :1 compression).

And you still have to upgrade all the accompanying systems to handle that as well (injectors, exhaust, etc) So if youre buying a crank anyway youre not spending any more money.

red blur

So what I'm thinking right now is that I want a 383 with forged internals. Because it will be my daily driver, I think that a 355 needing to get higher RPM to see same power would defeat the purpose of getting good gas mileage. I could use less effort with the 383 to get going because of the torque, and I could use a more mild cam setup with a 383 and still see 400HP.

Is that right? Am I correct in thinking it will take a larger cam in a 355 (less MPG) to see the same results with a smaller cam/heads in a 383 (better MPG)? I'm not going pro stock or anything, but if I'm going to rebuild a motor I want it to be extremely streetable and still have the grunt when I need it.

Is that accurate?

WS Sick

If you use factory casting heads you will need a larger cam. If you get some nice larger port after market heads that forw better you can go smaller on the cam duration.

1racerdude

The larger the HEADS and intake tract the SMALLER the cam for the same HP level.
Choose your heads and build the engine around them. Get the intake tract from the filter(K&N 12" long) to the piston flowing as much as ya can afford,keep the DCR above 8.5 with your chosen cam and it will run like a raped ape. With a cam in the 240* range and matched to the heads it's driving manners will be real good.
Don't want to hear 'bout the cam being too large,'cause a stroker will tame a cam way down. To me 260* ain't too large for the street.
For 450RWHP that's 540FWHP and that's real doable with a 383.


EDIT: 280CFM at the piston will make 575FWHP with everything else being spot on.

1racerdude

"O" BTW that 280 is after the deduction of the 10/12% loss for the rest of the intake track.
Ya would have to have a head that flowed 308/310 CFM before the deduction.

red blur

so if I had heads that flowed 280 then I'd be looking at around 475-500 FWHP which still puts me at 400+ RWHP. So a good set of heads, then start piecing it all together from there? I don't mind spending some money if it going to be the foundation of my power. I'll save up for those heads and then make everything work together from there. Is that right?

BTW--don't know if I've said this yet. THANK YOU!!! I'm not a newbie until it comes to internals. I know how the stuff works, but its making the right parts work together that I am learning about. You guys (all of you) are contirbuting a lot! Thanks!!!

1racerdude

280CFM minus the 10%(may be more)=252CFM which is capable of supporting 518FWHP when used in a MAX effort engine. That would be 425RWHP with an auto.

Yes heads first then the other things to match and DON'T forget the DCR as that is the next most important thing,then ya can choose a cam.

Glad we could help.

Sweetred95ta

If you thought this head and intake stuff was hard to comprehend, wait until you start messing with the DCR.

red blur

Yeah, I just researched it. Any layman's term manuals out there to comprehend? I'm going crosseyed

1racerdude

NO

It is the compression the engine actually sees when it's running.
Go on line and find a calculator and inter the right spec's and it will tell ya.
Ya have to have the ADVERTISED cam spec's not @50.
If ya want I can figure it for ya and tell ya what to do as far as pistons, chamber CC's,cam,ect.
Ya got to tell me what ya want for heads and cam though. Whether ya are going with the factory castings or after market.

WS Sick

That aint no joke. I recently was shown a small program that lets you play with all that. I immediately stopped hearing the voices in my head.

Evil Eric

I should have added that I have a tad over 400hp (well more than that at the flywheel) with the dyno sheets to prove it and I have are a 355 all forged block @ 12.x:1 compression, le1 heads and a custom comp grind cam. Stock fuel and ignition system, save for 8mm plug wires.