How much HP can you get with a 502 Block
 

How much horsepower can I get out of a 502 Block and still run on super unleaded pump gas.
What do I need to do?

This is what I have:
Dart 502 Blocks - roller motor with Crane parts
250 B&M Blower.
Single 850 carb.
No Intercooler.
I currently have 605hp & 5500rpm.

If you add an intercooler, and another carb, change cam, you could see 800 hp. I would try for more than that with those blowers. If you want over 800 you need to go to bigger blowers.

I suppose 2 850 carbs is what you mean?
What intercooler could you recommend?

Whipple intercooler

Chris

You should be able to make close to 700hp with about 6# of boost. You need more carb for sure. What heads??? That could be limiting you as well.

Unless you really crank up the boost and get a chiller, you won't see much more than that with a 250 blower.

I am not sure what heads I have. They were the original heads that came off the 600SC HAWK engines from Cigarette. I had the heads reworked. I think I am running about 6-7lbs of boost now and I am producing 605-610hp at 5500rpm according to the dyno. Last year, I think I was running out of gas in my carbs when cruising 3500rpm. I could feel the boat loose a little power after about 25-30 seconds. I increased the electric fuel pump pressure to 6-7lbs this year and have not had this problem.
So, it looks like I may need a new Cam Shaft, new heads, an intercooler, more carb and more fuel pressure.....on both motors! After doing all this, my engines will be too high for my engine hatch. This is going to cost some major $$.

Thanks for your input, if anything else comes to mind, please share. To bad there is not an intercooler that does not increase the height of your motors.....like an intercooler/manifold all wrapped in one nice package.

The heads on the 600 Hawks were just GM rect ports. They are limiting you, but you should still be able to get into the high 600hp range. Cam change and more carb.

Call Dustin Whipple. I think his intercooler is only about an 1" taller on your combo.

Stroke it to a 540 - watch those numbers grow!

Whipple's intercooler will only add about 1 1/2" with their manifold, but it will lighten your wallet about $4000. They are the best, but they are not cheap. Personally, I would not spend that much on those blowers. Get rid of the 250's and get some 8-71's or build some bigger NA engines. Take what you have to 555 or 565 ci, leave it naturally aspirated with some good aluminum heads and you will make over 700 hp and won't need to cut the hatch. However, it will cost some money. You won't be able to make over 650 hp with what you have and keep the engine or the blower together. Good luck.
Eddie