Need some help here? At a loss...
 

So I'm mind boggled. When I first bought my boat 00 Bajah2xithad rebuilt low hrs. 509 Sep forged pistons, scatt rods and Arizona speed and marine camshaft M1 4lbs and stock heads. 26 pitch worked over by I don't know who... Labbed prop. Bravo 4 blade. Boat did 72mph @ 6,000ft elevation. So I put on a smallerpulley 6.5lbsboat did 75mph at5,450rpm and running wide band at 13.30 lean.... WellI soldM1bought M3 went out and tried test run on 5lbs. Blew head gasket between 6 and 8. Boat seemed to be flying. Didn't check rpm or speed. So while I was in there and heads off. I thought why not throw some aluminum ones on. So I found some procomps. Through them on with mls gaskets along with roller rockers. Well, with biggerblowerand headsI boughta bravo 28offshelflabbed prop. Went out tuned it on 5lbs. 70mph 4,700 rpms roughly. So I said okay... More boost... 9lbs here we go... Tuned it to 12.6 afr 68mph. I got pissed ripped heads off bought afr 315 had milled to raisecompression. Did leak down test 8 to 10% compression went up from procomps heads of 110 to 145 lbs in each cylinder. So new afr's M3 9lbs 12.6 afr and 34* timing 72mph at about 4,900 roughly. I'm flipping lost. I just ordered smallest pulley. I'm going big or going home. Is this 28 junk? Would it hurt me this bad? Id try my old 26 But soldit likea idiot.... Help me please!

I have been playing around a lot with props lately and found that diameter makes a big difference too. For every 1/4 " I went down in diameter I gained 200 rpm using the same pitch prop. I am running a 24x15.25 4 blade cleaver and the same prop in a round ear will barely plane my boat and runs 800 rpm less. Its amazing how much different props run. I had a 29x14.25 and it took 1200hp in my boat to turn it. Good luck man. Hopefully you can find somone to let you try different props without having to buy them.

Hum... Really has me thinking now... Yeah on the box that my 28 pitch prop came in. It said 625 HP needed. I'm thinking in my head. I know I've got to be Well above that! But then again I'm sure a lot of factors play in to it aswell. Hull design, weight, ect. So... I'm interested in your diameter thoery here. Has me thinking... I wonder if when I went from 26 to 28 that I changed diameters? I Really don't know props to Well. Especially when it comes to cupping...

What is your max rpm suposed to be. If its 5500 then I would say you should have kept the 26p. If its 6000 then I would have gone down in pitch not up. If you went from a 4 blade to a three blade I would have tried a 27p. I have spent my whole summer trying props. I spent a good hour on the first motor trying props and threw a rod bearing. Had to buy a new motor and start all over again. I would figure out what rpm you wanr at wot. For example. If you want 5500 and your running 4900 then drop 3 pitch sizes. You can go down in diameter but If you drop it too much you will lose bite when you start to crest. Round ear props shoukd work good on your boat because you need bow lift. Cleavers work better on my boat because I don't need bow lift. I'm just learning myself through trial and error. Mostly error.

Shooting for 5,500 to 5,600 rpms. And so what size around and pitch you think? And bravo? Or.... ?

Call bblades

I would try and stay between a 14.25 and 15.25 in diameter. Just figure gaining 200 rpm for every pitch size you go down from your current prop size. I would just try and get your max rpms at wot. Its hard to find a prop that will do everything just perfect for you. Like plane off fast and have top speed but if you can find one that works you can tweak it as you go like having it balanced,labbed,blueprinted and they can even progressive pitch it. There are some real experts out there I just never ran across any. Talked to dozens of people on the phone,in person,online and in the end I just had to try different props.

What are you running for exhaust ?

Are you sure you are building that much hp? Maybe there is something messing up your timing or something.

Don't want to sound like a DIK, but heres my thoughts.

First of all, your tuning to a target AFR that is for sure gonna melt $hit. 13's and 12.6 is no where near where you want to be. Try low 11's before moving further.

Your swapping parts and milling heads, changing props and pulleys, and all kinds of stuff.

If you torched the head gaskets, theres a good chance you did some other damage, like hurt a ring land or two.

With your new cranking compression of 145psi, I think you better hold off on the small pulley before you destroy those new AFR heads.

Why don't we slow down, and get back to the basics. Your spending a lot of money to go slower, and breaking a lot of $hit in the process. Glad you ditched the procomp heads too.

Lets see the cam specs. Throwing all the boost in the world aint gonna help if the cam is lame and cant put it to use with the new AFR heads. And for Christs sake, put some fuel in the dam thing! Most people assume adding fuel will kill power, but on a boosted engine, especially marine, you'll find the addition fuel will actually make more power.

Imco performance manifold with risers.

I agree with mild thunder. Your throwing a lot of money at it with no gain. Something must be off. A 509 with 9 psi and afr heads seems like it would be making a good bit of power. I know it's a different boat, but I have a 509 with mild ported stock heads, 741 cam running 6.5 psi with a super chiller spinning a 32p bravo 1 to 5800.

What intake are you running? Maybe I missed that part.

Adding to the lean you have way too much timing as well. I think you need to do a thorough compression test on all holes and go from there. Also we would need more info like cam specs and compression.

First of I don't think you're being a Dick. Second I'm open minded and here seeking help. I'm very Well rounded around race engines as I build my 8 second camaro that makes just shy of 1,250hp to the tire. I'm running meth injection on the boat and therefor 12.6 is still safe. Especially at 6,000ft elevation as the "quality" of air isn't as great as sea level. Plus I want you to read a link here.

http://www.offshoreonly.com/forums/g...ed-motors.html

Stock intake... Smitty who has similar build said 34* is great. He runs m3 12lbs. I don't know cam spec. Does anyone know what Arizona speed and marines comp cam specs are. I'm a thinking it has weird duration split and blowing it out the exhaust. And all cylinders were leak down tested and compression tested. There's not very many hrs on this motor. Now FYI I have heard of a few people that have takin their 60mph N/A boats to Mead and they end up going 71mph and needing to reprop. I repeat Lakes around here are 6,000ft elevation. Strawberry is 9k (thin air) But still boat should be doing better then old combo. I'm thinking prop issue or camshaft issue. But just got a pulley today that should give me 3 more lbs of boost. Someone mentioned that the new prop could not be giving me good transit lift and diving my nose down. I dunno...

You never mentioned your running methanol. Then that changes things . Tryin to run 12.6 afr on 92 octane under boost in a boat scared the crap out of me.

No need to post links for me to read. I've been running blowers on my stuff for a long time, never hurt a piston, valve, or head gasket.

I've played with pro chargers a bit too. I helped my buddy with his M4 inter cooled 522 that made 1162hp on pump gas, no meth, with edelbrock alum heads.

Sorry, thought I mentioned that. Well I started out at 11.7afr 68mph 12.0 70mph 12.6 73 to 72mph. I guess I call Arizona speed and marine and ask for specs. Then hope and prey that's Really the cam that is in this thing. Ugh... I guess I can hook up this 91mm turbo I got laying in my garage. Set boost to 23lbs on top of the m3 on 13lbs and see where I end up... LOL No Really though. I'll runner till she blows. Then build me a 555 and start from scratch. I'm at a loss...

I'd get the cam specs for sure.

Did you determine and eliminate why you blew the head gasket?

I say AFR 11.5 max and timing 30 total MAX.... I don't care what your doing in a car, the car don't run WOT for 10 minutes at a time....

If your blowing head gaskets there is lean issues.... period....lifting head or otherwise... use cometics and head studs to be safe, not always needed, but not a bad idea...

You can tune on the meth, but that's not smart as if it don't come on your screwed, I run meth in my Cobra on street with blower, but I tune as if its not there, I use it for safe zone...

of course it went faster leaning it out, always will, just not for long.... keep a blower boat engine safe and it will be fine!!!!

I'm sure it blew from extra volume of air over the M1. They were cheap del pro gaskets that were in there. I used cometics and head studs when I threw new afr heads on.

I might have mentioned my timing table being at about 34 degrees at 6000 rpm's at one point but recently reviewing my efi program I see that my spark table is at 35.9 at 5800 at 100 map and my timing boost correction table pulls out 3.9 of that down to 32 when under hard boost, my 6000 rpm number is a touch higher at 36.9 - 3.9 under boost but you better be real sure of your octane quality and have a knock sensor if your going to push it right to the edge like that so I would NOT run that much timing if you just went from 110 psi of cyl press to 145 and added a bunch of boost just to be safe.
As far as your current problem, the obvious thing to do would be to try a 26 labbed prop and see what that yields, a dyno session would be next if its still slow and doesn't rpm and you cannot find anything else. I did not dyno my motor the last time I freshened it and I am regretting it now as I am missing some rpm's and speed on very top and it is very hard to get perfect and safe conditions to do testing/tuning to figure it out and I have wasted a lot of time chasing this crap. I will NEVER skip the dyno again as it is so much easier to see where you are at and solve these problems without having to buzz up and down the river at 100 mph while trying to find a problem without killing yourself or breaking stuff, Smitty

Sounds to me like all you upgrades are making the motor detonate and your loosing performance... You were ok leaning it out a bit but as soon as you put some compression in the motor you lost performance. An easy way to tell would be to slow down the blower and see if you pick up some performance.