jeff1000man

So do you even know what pistons are in the engine? What is your comp ratio? Is it a flat top or a dome?

ubet28

Its all stock 500hp internals. The whole thing has been apart checked to marine tolerances and the block was honed. The motor guy said he thought the motor had around 100 hrs on it again this is just what he thought . There really isn't a way to tell for sure with a carbed motor is there? The guy that cleaned and took motor apart said it had sat for a long time.

All the internal stuff was reused expect the cam and lifters and new rings and bearings the rest was just cleaned up. I was going to do the 540 when it was apart but motor guy said not two. That i would be better off with buying a block and building a 540. So when i sold the 500 it would bring more money together than selling it in pieces.

Which brings me to now just not sure what to do. I have come to the conclusion that i would be happy with 80 mph if i can do it with the 500 i will be perfectly happy.

The heads were also freshened up. Besides the cam and 2 lifters everything else was in good shape.

jeff1000man

Honestly if that is what you are working with and you are going to use a blower. Just change the cam and bolt a blower to the existing engine. See what you get. Heads aren't as important when you introduce booost into the equation. If you buy that whipple, just use what you have. See what you can get out ot it. You can always upgrade further later on down the road. It will give you something to look forward to.

ubet28

I was considering this. I was kinda leaning the other way just buying the heads and not having to worry about the boost.
So in your opinion were is the money better spent blower or heads?

I guess what i am asking is if i bought just the heads like brodix or afr what kinda HP do you think i would see?

And what kind i would see with just the blower and stock heads?

And if i did both what kinda gains i would see? All i am looking for is ballpark #'s. So i can see if the cost verse hp is worth it to me. The gains are total Hp figuring the motor is 470hp to start with.

I was thinking a set of heads ready to bolt on 3000.00 and gains of 550 to 575 hp

Blower will say ball park cost 5000.00 the cheaper the better but will spend the cash to get whats right. gains 600 to 650 HP.

With both heads and blower 8000.00 gains 700 to 750.

Which ever way is a huge jump from the 385 hp i had before.

jeff1000man

Your to high on your expectations. The boost numbers are possible, but you will need a lot of boost and that is going to take away reliability.

NA is going to be hard because that engine doesn't make much compression.

If you just left it alons and changed the cam. Maybe go to a 950 custom carb on top of the intake that came with originally on the HP500. Maybe grind the casting marks out of the ports on the heads and see what happens. If it picks up pretty good, then you will know how much more engine you need to build to get to your goal of 80. You can change parts out on the top end of the engine without taking it out of the boat, so upgrading will be easier.

I can get you ready to bolt on AFR's that are CNC machined for less than that.

I will PM you my number. Call me tomorrow. If you still want to do heads I can get you good deal on AFR's.

Griff

HOLY CHIT!!!!!!$657

ezstriper

yes they make unilite marine units, they have a slightly differnt advance curve and a blue marine cap...Rob

Griff

I think your best bet to reach your 80 mph goal is to supercharge it.

A stock 500hp should run 70-72mph in a 25 OL if its dialed in.
You need 10 mph and that will mean about 150hp increase. A set of heads will give you maybe 50hp and 3mph.
A 250 or the Whipple will get you to the 650hp range without changing the heads.

ubet28

This is the route i have been leaning towards i am just worried about reliability with the blower. I don't want to have to run a ton of boost to reach my goal and loose the reliability of the motor. I guess what i am saying is if i can reach 75 with heads and stay reliable that would be better than 80 if i have to run a bunch of boost not reliable.

jeff1000man

You know I just realized you were putting this into a BAJA. You need to measure your clearance on the front of the engine and make sure you have room for the blower pulley etc without cutting into the bulkheads. I am working with a guy right now who has a 27OL, and we couldn't even dream of fitting ANY blower int there without cuting into the back of the seat for clearance. We went the simple route and built a big inch rat motor and CMI's instead.