Brad Zastrow

I am running two 572's (1010hp) that were built as blower motors. After blowing up a few I did find out that much horsepower needs some serious internal componets to live. You are setting yourself up for heartache chasing maps, injectors, intakes and ignition. Your base engine will not make it. Start from scratch with a bigger cube engine and build with the right stuff. Everything needs to be overkill. Fuel delivery is very important. Hugh fuel lines, pumps and return lines. Drivetrain needs to be state of art or problems will arise. Cooling system? Oil system? Intercooler? Now you need to look at your outdrive........

jspeeddemon

I am running 548 ci which is a 4.530 bore with a 4.25 stroke crankshaft. I used 95 lb injectors, and have the WB O2 sensor, also use exhaust pyrometeres welded in to two cylinders. My system is bank to bank which is between batch and sequential, you can share files easily by email. FAST gives a base program to start and tune from there, it is not that complicated. I don't use IAC, and with my cam using a 114 CL, my idle is strong. With the FAST I can dial the timing up at idle which really helps. I cannot see any negatives to the fuel injection and blown combo at all, in fact it is much more tuneable than carbureated. It's like having a carburetor with a whole bunch of circuts instead of 2 or 3. It is just newer and people get afraid of what they don't totally understand, I think.
What type of exhaust are you using. Several others on the site are running fuel injected FAST and ACCEL systems and seem to be pleased as well. Probe industries has a web site, what you need is a 90 degree elbow for a 90 mm throttle body to a 4150 manifold. How much of your system are you planning on using?
I bought my throttle body for $200.00 off of Ebay. I imagine if you bought everything else you could use your computer, and I think they make a wiring harness for driving low impedance injectors with your computer.
However if your diving in, you might be better to sell your system and purchase the aftermarket system completely, rather than mixing and bandaiding.
I tried to dyno the motor three years ago and wasted a futile day trying to get the Procharger setup to work blowing thru the carburetors. I eventually got it close by placing the motor in my drag boat and tuned it till close, then installed in my Eliminator. Ran well but sooted the transom awfully bad. This combo still soots a little at idle but not running judging from the water mark.
I'll will guess it is 1000+ but can't really say for sure. But it is a 550 ci bbc with Canfield 355 that flow 385 on intakes and 280 on the exhausts on the bench, 12 lbs of boost. Someone put that in a Desktop dyno using a .655 lift symmetrical lobe design with [email protected].
Limited time this year due to lots of rain but I will tell that this motor pulls like a monster from a 70 mph punch, actually having to feed the throttle sparingly to keep it from breaking the prop loose.
Hell just let me sell you the whole deal and I want to move up to a twin engine boat anyway and build two of these monsters. It's ready to go all top to bottom, with just a little tuning left to do on the top end.

jspeeddemon

Yeah it gets a little stupid trying to tune it on the top, that's exactly why it is not completed. I have it plenty fat and just need to make several passes to lean it down, will always leave it a hair rich for margin of error and air changes. I agree with you about plug readings and WB O2's. I also use a pyrometer in the exhaust, so I triple check my data. First time I've ever had a motor run almost identical plugs in every cylinder, due to not having problems with fuel droplets suspension, becasue there is none. Especially when your cramming 12 lbs of boost thru that high rise intake, darn thing looks like a tunnel ram with a single carb top anyway.

Brad Zastrow

Drag racing setups in boats and cars is some what different than offshore boats. What works for 6-9 seconds will not always work for hours under hard load at 4000-6000 rpm in a boat. A common theme seems to be 540CI block or more. 1000hp need a total setup to live from the crank to the prop. Mercury racing gets big bucks for their package with a number six and 1000hp for a reason.

jspeeddemon

Yeah you know that is definitely true, but Mercury, Cobra, sterling, or anyone else doesn't have anymore reliable parts in their motors than I have as well as many others on this board. The difference between them and do it yourselfers on this board is that they have a known combo that works, from repetitively building an exact package. As well most have a dry sump oil system. I feel real comfortable about my 4340 crank, billet rods, JE blower pistons, a nice set of aluminum heads, 12 quart oil pan, Jesel rocker system, Inconel exhaust valves, severe duty intakes. Further I built mine for around mid twenties including my Procharger and fuel injection. Mine has not one drag racing part in it, however it accelerates like a drag car in my 26' daytona. I certainly would feel comfortable holding mine wide open for more than 10, 15, or 20 seconds and have done it many times. It's just that it is fast enough that it's hard to find somewhere to do it where I boat. You can build a combo that is on the edge, maybe only reliable for short blasts, but that is the difference between forged and billet stuff. The reason Mercury and others charge so much for their hardware is they have a lot of overhead, and they are setting the industry standard. There is less than $25,000 of hard parts in any of their combos, add it up yourself. They may chrge 50,75, or $100,000 for motor and drive combo. However you can build a comparable copy of their stuff for half the price, if you have mechanical ability to do it. Their isn't any black magic in their valve covers, just good parts. My intention is to duplicate my combo on to another motor and put them both in a large cat, so I can hold them both wide open for long hauls. Nothing holding you back but dollars and sense.

Kanookstr

One more very important thing that wasn't mentioned???
Which gen 502 are we talking about??? I have had problems with the gen 5 at 7 + psi boost blowing the head gasket where the vally wall is thinest around the missing head bolt??? thus resulting in milky oil.... I didn't have problems at 6 psi and 50 lb injectors for 300+ hrs. But once I switched to 7+psi of boost, I've blown that part of the gasket twice in 40 hrs .
This winter I'm swaping for the next gen block with the extra head bolt
good luck

jspeeddemon

An old engine builders trick is to take a punch and dimple the area around the cylinders and between them to keep the head gasket from walking. I have as much as 12 lbs of boost and never blown a head gasket yet.

HPJunkie

Mine is a gen 5 and have run 7 psi for 2 years about 120 hours and newer did the gasket. Keep in mind that I'm at top rpm/speed for 10 seconds at a time. That is also what I was referring to when I mentioned a "drag" motor. Some of you guys want to run 20 miles wide open at a poker run. My 25' boat goes about 94 mph and It doesnt do big chop or other wakes so I cant stay up there long, I do get there quick and usually win by the time I hit 90 mph. Most time is cruising from place to place at 25-4000 rpm. I do have the big chevy parts forged crank, 7/16 rods with new bolts, and Je pistons all balanced and blueprinted to spec. In an offshore application I would like better parts also.

paradigm shift

It is not always how FAST YOU GO but HOW LONG YOU GO FAST!!!

Sorry M BAD

HPJunkie

Good point! I like that! Thats what I'll tell her. Greg