Wondering if the difference between a 383 and a 355 is going to be that huge, or am I just better off spending the extra money saved by giong 355 on a really good set of heads? Plans are to supercharge, and some nitrous, maybe a 100 shot or so. I have a powerdyne kit, 4.5 psi, but ive got a 6 psi pulley, and a 7" crank pulley, which by may calculations should put out about 7.5 psi. and just about max out the small unit. I already own the powerdyne, so its a limiting factor as of now. If I go 383, I have read it may impose a restriction since its a small s/c. Basically, im aiming for around 450-500 RWHP and I want it to be street friendly and able to drive to events in other states. I have an opportunity to buy a 383 kit for $750 but I need more details on it as I think it has hyper pistons and they would need replaced with forged,but its complete flywheel to balancer. Is it worth the extra $$ ill be spending to go 383 or is it not a good idea for my goals and would I be better off 355?

 

i would go 355

 

I would do a 383 but seriously consider going with a different supercharger.

 

a bigger s/c is even more $$, plus the pistons, plus block work, im sure it wont get as good of fuel mileage, which defeats most of my goals for the project. I already own the powerdyne. I want this thing to be streetable to drive between states, maybe FL to NY. I dont wanna spend another $5k more building more than what im looking for especially since I want to go with a nice set of heads like afr 210's or so. Then we all know how you end up building the rest of the car around the engine because the chassis cant handle the power. Streetable and reliable are my goals, while maintaining the best fuel mileage possible. It can be done, you just need to make a plan and stick to it buildwise. Im leaning more towards the 355 right now.

 

mildly ported stock casting heads, appropriate cam, on a 355 would be my suggestion, as the cheapest possible thing to put together. not to firmiliar with the powerdyne units, but stock lt1 longblock and 7psi on an s-trim with just longtubes (dumping, probably could see more power with an X-pipe) has netted me 400whp through a 9" and 28" slicks. 450 to the wheels would be a forged bottom end and a pulley change away.

 

For that, a 383 would be better because it would make the power at a lower rpm with less boost.

 

If you are sticking with the powerdyne, or if you only see yourself upgrading to maybe an S-trim or something equivalent in the future, I'd go 355, stock crank, forged pistons, eagle H-beam rods.

I would not spend all the money on some AFR 210's for this combo. The blower won't feed the heads and you don't need this aggressive of a head for the combo you are planning. I'd just get a nice set of Lloyd Eliott or equivalent stage 2 heads, mild streetable blower cam (around 218/230 or equivalent at .050"), and you will make great power for the minimal amount of investment. No extra block clearancing, no new oil pan or hammering on the old one to make it fit, cheaper heads that will flow close to what the AFR 210's do in the lift range that you will be running (since you won't be running a solid roller with .600"+ lift. That's the way I would build it...and in the future if you want a little more boost and performance, go up to an S-trim and the setup is still optimal for that.

I used to have that same powerdyne kit on my LT1 before the current car and I'm pretty familiar with it's capabilities and that is how I would build it.