klaw

I was intending on building a identical motor to the 500HPs I have in my bullet but would like to up the HP to about 650
So when (next Year) when I need to freshen those I can up the HP and have three Identical motors.

I have bought a HP500 it has been bored .030 over it is apart.

What would you put in it for 650 hp
I have pistons crank and rods all in good shape I know I will need some porting on the stock heads

would like to be normally asperated and with a carb as I dont have $ in budget for Fuel Injection

On my bullet I have Barry Grany 850 Marine Demon Carbs and would like to stay with that for a carb.

Cam and Intake recommendations Recomendations?

Klaw

Griff

To make 650hp, you're going to need heads. I think you'd be better off to make them into 540's.

stevesxm

griffs right. more inches are going to be the easiest and quickest way to get going. from there , compression ratio gives you the next chunk of foundation. more cam will make a big difference but reversion is obviously a consideration . rm builder (bob madera ? ) has been mentioned here countless times as the guy to talk to about the correct cam selection...

when you start talking about heads and big flow numbers with a carb, you start running the risk of making big hi reving hp but suffering in the mid range where you spend a lot of time unless you are racing...

i would start with the notion of a 10:1 540 with one of bobs cams and see where he thinks that leaves you and go from there.

klaw

my bullets motors were 9.25:1 and stock ported heads and both dynoed around 565

jeffswav

Thats the ticket, make it a 540 with one of Bobs cams. Bob set my cam up for 5400 RPM. If you want 650HP you will have to run more RPM. I wish I would have known a little more before I built mine. I started with a 454 bored it .030 over with 4.25 stroke to make a 489. If I could have found a 502 block I could have made a 540 for just a little more money.

Young Performance

About the best you will do with the stock heads(with a bunch of port work) and 509 ci is going to be about 600 hp. You either need to go to aluminum heads so you can raise the compression or build more inches. With aluminum heads and 10:1 you can easily make 1.27-1.28 hp per cubic inch.
Eddie

Griswald

Eddie,

What do you think hp could be with Dart 308s, 741 stick or similar, 9.5:1 540", with Dart intake and 850 carb?

kgz3

iTrader: (1)

i have a 591 ci bbc cheap good parts call me 309 925 4620

Young Performance

I assume the 308's are cast iron. Personally, I think 9.5:1 is a little high with cast iron heads in a boat, but that is my opinion. I'm sure some people will disagree. I don't like to really go over 9.3:1 with cast iron heads. I like to error on the side of caution. You have to realize that I have to build engines for guys who don't know the first thing about them and only know how to jam the sticks to the dashboard. If the tune is on and you treat it right, you should have no problem making it live. With that being said, I think you will be in the 625 hp neighborhood.
Eddie

Griswald

Yes, the 308s are iron. Compression ratio at 9:1 is perfectly acceptable. I was looking for a ballpark hp without upgrading the heads and winding it up too much. I appreciate the reply.