How much HP
 

I just finished rebuilding my engine and I was wondering what HP should I expect.

502MPI Gen 6
Cam 741
1.8 rollers on intake @ 2.19 Valves
1.7 roller on exhaust @ 1.88 Valves
Cyclone Headers with dry exhaust
reprogram ECM
Short runner intake
Ported heads with tri angle valve seating.
MSD kit
K&N Flame arrestor

Any suggestions.:rolleyes:

High 500's to low 600

High 500's:evilb: I was thinking somewhere around 525. Well that's good news. So I should expect high 70's on my 22 scarab.:evilb: :evilb:

I would think it would get into the low 80's, depending on the lower unit and prop.

2'' shorty Imco lower, 27 Quad 4 lab finish and 26 P5 lad finish by Throttle up.

I would say closer to 525 as you were thinking. A lot more factors than you listed. It will depend a lot on the what heads and comp ratio.

550?

Griff, as regarding the ratio is 9:1, as for the heads I worked on the standard GM head cause I ran out of money:( and secondly since we use the boat in salt water only, aluminuim heads was not an option. I think that 525 is more realastic but what is above that, it's always a plus.

Thanks to all that sent their suggestions

Have fun and play safe.

Id guess in the mid 5s too. with the 741 cam are you gonna spin it to 5800ish, isnt that cam good for up to 6000, i suppose your whole setup dictates that too.
a guy locally ran his aound 74 with stock 502 so i would guess right around 80 or more.
b70

Eyeburn, close to 80 was my final goal. Now I have to wait until I'll run it and see whats gonna be the end results. I will keep you posted.

It should be at around 520-530 Not going to an aluminum head cost you about 75 hp.

Smitty, I know that with aluminum heads I would have made more HP but I couldn't do otherwise cause I use the boat in salt water, and already I had to buy a new intake cause of that.

Less 75 hp = less 3-4 mph:(

I also ran out of funds cause knowing that I was upgrading the engine, I had get a full dual ram hydraulic steering as well, and that means more $$$$$

Dart Iron Eagles are a good flowing alternative. Send them to Jim V and they will flow as good as any conventional aluminum head.

PatriYacht, who is Jim V?? can you give me his e-mail add cause I am considering already to change the heads for next season.:D

JimV is a member here on OSO. Here is his website.
http://hometown.aol.com/valakoracehe...raceheads.html

520-540 hp my guess,the intake your using makes good low end torque but suffers on top end,even with runners shorten.Stock gm heads hold engine back,aluminum afr hard coat anodized with cnc porting worth 50-70 hp with same camshaft,I have also used dart iron eagles,they make good power,although donnot use the first versions of them(5-7years ago)they use to crack and fill your engine full of water.Dart stop making them,but then put them back into production,claimed the problem was in the harding process and they got it all straight.We work on these type of engines all the time and dyno test every thing we build

If you did nothing except put the 741 cam in it, you would be at 525 HP,(or more) as thats the setup that Merc uses on the 525 EFI. Just putting any aluminum heads on isn't always good for anything. Aluminum heads by themselves are not magic. Yea, using AFR's will gain big numbers for a big check. If you have taken your rect port GM heads, and done a decent port job on them, you will be amazed at how well they work. The same applies to your intake. Add the decent exhaust, CR of about 9-1 and I'll stand by my number.

The duke, as I said before I took my heads and intake to be ported at a local engineer, then we even made port matching while fitting them to the engine. As I saw from Jim V's website, mine are very close to his finish product. Now all I have to do, is wait for the summer and try it out.

Thanks

Just be aware that the stock GM rectangle port heads have a tendency to CRACK between the seats. If you can't afford aluminum heads at least replace the cast iron GM heads with some good aftermarket cast iron heads if you can swing it. Otherwise, you're taking a risk with the GM heads cracking---I have seen it happen to guys many times over the years---especially after they have dumped a lot of their hard earned $$$ into their engine projects. Have fun.

For this coming season I'm gonna use the GM heads, then for the next I'm thinking to get a set of Merlin II with intake valve size of 2.30