SkiDoc

iTrader: (4)

Who does everyone recommend for head work? Right here in Corvette city we have a company known as total engine airflow, that was just bought by Trick Flow, what would I need to tell them to do? I know inconnel exhaust valves are a given and severe duty valves, roller rockers, valve seats reground, Kaama recommended Bowl and pocket porting, is this a job I need a marine guy to do? Or can I let a good local builder do it? Also, right here in my town is the HQ of Holley, so I might get the friend of a friend buy some parts(B&M) at employee cost. What's everyone think would be less maintainence roots with intercooler or centrifugal intercooled? Thanks, Eric

KAAMA

iTrader: (1)

KYE,

While focusing on your goal of a reliable 600hp 454cid marine engine, I agree with cdscarab that you do NOT need aluminum heads to achieve this. I am trying to give you some advice that will keep your project as inexpensive as possible while still achieving your power goal.

You can run a hydraulic roller cam/lifters if you like, but I doubt it is necessary. However, they will make more power, and are pretty reliable these days. They ARE pricey though! But you can still retain the stock flat tappet cams/lifters you have now, acheive your power goals, and save $$$ at the same time.

The GM heads you have now will work---they will work even without going to a larger intake valve. However, you should have them checked out, comp valve job, install stainless steel valves and inconnels on the exhaust side. I would include a bowl/pocket port although you may not even really need it, but it's a nice little inexpensive power increase. If anything, the port that needs the most attention on a stock GM head is the exhaust port side---especially for a supercharger application. "JimV" knows these heads well, and will do a good job if you like (616) 735-0800----or a local competent speed shop should be able to BOWL/POCKET PORT the heads while paying attention to the short side radius's.

The roots style B&M 250 superhcarger with 4-5lbs of boost is adequate to get the job done for a reliable 600hp on a 454cid marine engine. You will have to do some homework, but the B&M 250 will only sit about as high as your stock engines do now---which is nice. I'm not sure what to say about the inner-cooler issue. Up here in Michigan, I know of several guys (one with a 35' HEAVY Cigarette with B&M 250's) who run roots style super chargers in their boats on Lake Michigan WITHOUT the use of an inner-cooler (superchiller) without any problems I know of. But it's cooler here in Michigan during the summers and the water isn't as warm in the Great Lakes as some of the smaller inland lakes ---especially in the south where you live. Superchargers eventually become "heat soaked" depending on how long you run them, and detonation can set in. Not knowing all about the Cig's engine details (heads, lbs of boost, etc) but the guy with the 35' Cig has 454cid engines with the B&M 250 superchargers and his engines dyno'd at about 665hp or so. I remember JimV showing me the dyno sheet of one particular stock 454cid engine (hyd flat tappet cam) with a B&M 250 supercharger, a single 850cfm carb that made about 623hp with about 5-6lbs of boost on Tom Earhart's dyno. This was back in the early to mid 1990's!!! I don't think even JimV ran an inner-cooler on his supercharged engine in his boat. I don't know of all the particulars of this engine, but you can call JimV and ask him---he can tell you of several different options.

If you're interested, I know of a couple of used B&M 250 blowers that need rebuilding at my engine builder's shop that may be for sale for a extremely reasonable price because of their condition, but you'd have to call and enquire about them. Crazyhorse even knows of them. My engine builder's shop is called "WESCO" ask for Dave. (616) 662-2250.

I am NOT an engine expert, therefore my advice is not set in stone. I can only tell you of what I have seen, and what I have experienced over the years of offshore performance boating. I hope your project goes well for you. Have fun.

SkiDoc

iTrader: (4)

I think it was interesting that no one mentioned Whipple, does anyone have experience with the 454 mag and a Whipple? This would probably allow me to run an intercooler and a stock hatch! Thanks Kaama those used 250's may be the ticket as I could have one of my patients run it through the factory here. Eric

SkiDoc

iTrader: (4)

I need opinions on a second direction I am considering. Like I said originally, I want to be able to run the motors hard. From the responses, it seems as if I will not be able to run these motors hard with just adding boost. I'm thinking of building a set of new motors that I could keep as I trade boats and put the stockers on the shelf until I sell the hull.
If I do this, I would like to build a 700 hp motor that I could run. Please give me your recipe for this. I can't go real exotic, but I would want to do it right, and I need the motors to be the same size in width as the 454 mags.
Would you bore a 502 to 540 or just start with a merlin block, what kind of crank , pistons, heads,valve train, would you use? I don't want to write a check, I want to build them as much as possible myself. I have always wanted to do this and now seems to be a good time!
Thanks, Eric

Hang Time 27

Do search of "540" on this forum section, and you'll get quite a bit of info to chew on too.........

BRUCE SEROFF

Most 540s , i've seen are making + - 650 hp at 5500 / 5600. If you want reliable 700 hp at low comp and low rpm., start off with a tall deck and insrease your cubes, like 572 or 598. 700hp will be easy at 5400 / 5500 with mild head work

check out this thread, which was fairly impressive
http://www.offshoreonly.com/forums/s...ad.php?t=89520

cdscarab

Eric, at this point, I think the real question is, what are you going to do for better drives? With the tech. thats availalble now, making 700 or even 850 horse from a big block is pretty easy if you use a good builder. The big trick will be making your drives last at those power levels. Not to be a kill joy, but before installing the 525 in my scarab, I had the B1 looked at and I had all but killed it with a 33o/454. This in about 500 hrs., the last half of which it was cooled by a drive shower. So I had it rebuilt with HD parts, hopefully for a few years of trouble free operation. The point is, alot of guys were popping XRs with Mercs 575, much less standard B1s with 700 horse. Before you go buying into BIG power, you should probably check with these guys to see what will stand up to the power your planning, and the bigger power that we all know you'll eventually be moving up to. I knew you couldn't resist the move up, no one can! Chuck

SkiDoc

iTrader: (4)

Chuck, I think your point is well taken, I know that I must upgrade the internals of the drives. I twisted a spline in my 502 mag with PC. Generally I am pretty easy on equipment, so I'll try just upgrading my existing drives. I think I'm going to try to find some 502's and make 540's with 8:1 compression and add blower's, intercoolers, low boost 4-5lbs, aluminum heads. If I can't find a good deal on used I will start with Merlin III. Eric

brian41

iTrader: (1)

I Have These For Sale

SkiDoc

iTrader: (4)

Brian, Tell me about there condition. How much? Are you going bigger?