So would 475 be more resonable?

 

LOL sry man didn't mean to sound like an *** just trying to say out of all the parts you listed good they maybe you didn't list some of the most important things to give a good power estimate. Who is porting the heads and what they are expected to flow along with any intake porting and cam. Now you did list a cam but with that cam you probably wont make your goal I would look into a custom ro something bigger even the gm847 would probably make more hp. and sine you are planing a 383 500FWHP is a fine goal or 475. as long as you are happy with the results who cares. being a 383 you might only make 420rwhp but have loads of torque all over.

 

No, its cool. But I have looked into this a bit and not just throwing something together. The porting and polishing is being done through a guy that came recommended through a local car club. Its a father & son business, been building motors since 1974, was reccommended by two shops in the area as well. They built a motor for a guy in the club with a '90 IROC L98 but he stayed with the 350. The intake will be ported as well to match the heads. I looked at the GM847 and it seems comparable to the CC306 with an edge to the GM847. You do bring up several interesting points. This is not a track car and may see the strip every now and then but mostly the street. I'm told 383s are known more for TQ then HP. So, yeah, maybe your right and I'm not looking at the big picture. Looking at it that way I would then hope I'd be making over 400 at the wheels with lots of TQ. Now, smooth and tight is better for TQ, right? Bigger and wider is better for HP? I guess thats going to be the factor in the head flow right?

 

I agree in that the heads will be the most important issue. Spend your money on the heads. Also you will need the intake manifold ported to match the flow of the heads. From what I have read Lloyd can do this. You don't want the intake choking the heads.

You will need all the supporting mods such as a 58mm throttle body, good cold air intake and a good flowing exhaust system. One local guru swears by the monoblade throttle body on the LT1.

 

That I cant answer and wont even try do not really have enough knowledge about flow to answer all i can say is I still haven't decided on who i will go with for head porting. One opinion of advice check if the shop you want to have port your heads has done any lt1s before. even thought very similar they do differer from regular SBC heads in chamber size and flow.

 

What? You just gave me all that info about the "cons" of my setup and that it wont make the power I was hoping and suggestions and now your saying you dont have the knowledge?

 

its not that i cant suggest things its that the small vs large port thing has been debated over and over and just causes a big argument. example Ai biggest port is 200cc LEs is 208cc which is better both are pretty much equal. a 383 needs a bigger port though to flow the air for the extra cubes so I wouldn't go to small. Best advice would be to talk to llyod elliot (eportworks.com) or other head porters about your set-up even if you want to use the shop you mentioned you will get a general idea of what you need. from the information i have gather during my build though you will want something with a mid to big port.

 

I got ya. The general consensus from what I researched seems to be wider=more power less torque smaller=less power more torque. Some of it consisted of the L98 with its long, tight runner design choked power but made gobs of torque - 245HP 350TQ. The LT1 with its short, open runner design punched up the power to 300 but TQ suffered with 320. In an article in Car Craft they built a 383 LT4 for a truck having the LT4 heads ported and polished but they kept the stock valves noting that going larger would suffer torque and torque was paramount in their build.

 

If you put more effort into the heads, then yes, you should hit 500 FWHP.

 

Ported and polished, gasket matched to ported intake, 3 angle valve job.

 

Ported and polished is very generic terminology. That's what I was reacting to. Starting with stock castings, you need about as good port work as is available to hit 500hp. Also, and I am not sure of this but am fairly certain, you need quite a bit of intake work on a stock LT1 intake to approach this kind of hp. There are also many better cams than the CC306 out there, though I think you could make 500hp with it if everything else were right. To make best use of that cam, you also need a bit more static compression.

Rich

 

I dont know what to tell you about the port job. This guy doesnt seem to have a set up like a "stage, level, phase or package" of port jobs. He came recommended and refferenced by several other guys. Been in the business for 25 or more years. The CC306 cam seems to have given other LT1 owners in the 340-370rwhp range with stock heads.

 

Years in buisiness might be a good thing if the guy is capable of learning and evolving.
On the otherhand if he still thinks 2.02 valves and a 3/4 race cam are the hot ticket well then it is a BAD thing.

RESULTS are the only thing that matters, results from a similar application at that. The more I learn the more I realize that not even happy customers are an indicator of a good job. Seen a lot of guys thank vendors that screwed them bad.
The guy could be awesome with some old school setups and not understand the sublties of the more modern high velocity heads

 

I happen to own one of these 396 long blocks. I usually put down 480HP at the wheels with a 100 shot but then I gotta clean the whole engine bay because im shooting oil out of everywhere. lol

 

Why worry about exactly how much hp it will make? Just advising you to spend money where it will do the most good and let the numbers come in where they come in.

Rich