aquaforce

Well I stroked it from 4" to 4 1/4", jacked up the compression to 9.6 and punched it for 496 cid. With the extra squeeze on the bearings from this power increase the oil temps go up with it from added pressure on the bearings. Rpm's won't go above 5,500 for the most part but the cam is rated at 6,200.

What will your compression ratio be? As this goes up the oil temps are what determines the cooler need.

THat motor stock from merc had a small water cooled oil cooler on it. Normally on the port side mounted down around the pan rail area. With a typical marine CR the stock one can still work for you but if you mod the engine beyond, I think I have been told 70hp, then the cooler needs to start ramping up. The impeller in the drive does just fine on the Alpha to get the water up through the coolers and into the engine so I would expect yours to do ok.

I suppose you could use air cooled but I haven't seen it done.
The longer the throttles are on the dash the faster the oil heats up. The engine can control at say 165-180 and the engine oil temps exceed 230° fast with hard driving or high HP.

masonbig1

My compression was 8.6 stock, and with .030 off the heads, I doubt its more than 8.7 now. I plan on propping the boat to around 5k wot, but have been told my bottom end will take 5500 no problem. my goal is 70 mph gps with this old girl.

i see what you're saying about the engine temp and the difference of the oil temp. Looks like I'm gonna hunt up an oil cooler, as my block didn't have the cooler adapter or oil filter adapter on it when I bought it.

Thanks for the input, this is my first boat and quite a learning experience.

masonbig1

Oops... Double tap

sprink58

Don't forget to set aside some $$$ for one more little goody you're going to need with all that power and torque....Bravo

masonbig1

I know, I know.lol Hopefully I can get this season and next season out the Alpha with a little luck and careful throttle application. I fully intend on a bravo swap after paint and interior is done while I get some water time with her. Also plan on better manifolds or headers at that time, along with a way more aggressive cam shaft. I've been looking around at some bravo parts, I think I could put one together reasonably priced.

This being my first boat, its still new and fun, also it does hurt to make mistakes that cost time and money. I f I had known I was gonna put a big block in her, I def wouldn't have bought a new alpha replacement, instead I would have started the bravo swap.

aquaforce

I know about learning this stuff. My engine building has been a huge learning curve. Coming from drag racing I expected an easy slide. I learned very fast marine is a different animal.

I had nearly the same interest; 70 MPH with a build up and 500 HP. I can tell you that it takes 500hp or better with at least 9.1 CR to hit 70 with 24' and 24 deg deadrise. If you want 70mph you can do it with an Alpha. Holding that speed for long durations will really strain it but all the 87 production 7.4l were paired with Alpha.

masonbig1

I know about learning this stuff. My engine building has been a huge learning curve. Coming from drag racing I expected an easy slide. I learned very fast marine is a different animal.


Same here! Wow, what a difference, and learning real quick how basically de-tuned the engines are. I know full well with my engine, with just a lil compression boost, more timing than the 30 degrees I plan to run, and good exhaust she would make a nice street motor!

I thought the 223ls was really a 22' with 23deg deadrise??? he swim platform was counted in the total length for 24ft?

I'm estimating 475hp, really hopes it hits the 70mph mark. if not, after paint and interior, a bigger bumpstick and headers oughta do it! I'd really like headers now, as my exhaust is really keeping this engine from getting past my estimated output... But I'm already past the max power for my Alpha anyhow..

sprink58

Hell Mason...you're starting to push the limits of a standard Bravo now!!! You might as well pick up a spare Alpha to have ready when the SEI you have now blows. At least you'll have a get by until they send you the warranty replacement.

But you know what...as long as you are on a lake and not too far from home it's no big deal. As for me...I cant afford to be 20~30 miles offshore halfway between Florida and the Bahamas and have a drive failure.

My brother in Destin is doing a '83 F3 with a 454 on Bravo I now....gonna be interesting how it turns out. there is a dude down here that has one (F3) with a 454 on a Bravo...runs 65 easy but porpoises bad over 70. He's running a 25" Mirage 3 blade with 1.5 gears.

aquaforce

I know of a certain 242 as a reference to the speed and required power. Since your running/wetted length is less and boat weight is less a little lower power would be required for the same speed.

Simply put, marine is about making power under full detonation conditions. Tough challenge. Most high HP marine engines could be cammed different on the street to make some serious ground shaking power.

Don't sweat the Alpha too much. It will hold with you for a good while. I got all into getting rid of my Alpha when it had one more issue than I cared to fix. Swapping out for the Bravo1 and getting everything it needed and doing it right got into some money and time. I have changed my 242SS to a Bravo1 system since I stroked this 496 but the previous Alpha was living fine behind a 400hp 454.

masonbig1

But you know what...as long as you are on a lake and not too far from home it's no big deal. As for me...I cant afford to be 20~30 miles offshore halfway between Florida and the Bahamas and have a drive failure.


Sprink, you're 100% right. My lake isnt too big, so even if i get stranded bc a grenaded drive or engine, I have plenty have crackers and beer onboard to survive on before I get a tow. Now if I was in your shoes, I def would have a different outlook.

Aqua- I know my static compression is about 8.6/8.7, that was the reasoning of me advancing my cam to a 106icl from the factory 109, wanted to build some extra cylinder pressure without milling a ton off the heads or swapping pistons. this engine has been a budget build, but with decent parts. I have less than 5k in the engine still, even with purchase price included. It was a running engine when I bought it, minus the fact #6 had 100psi. which turned out to be a valve issue, but since I had it tore down, and the crank was a little iffy, decide to hone the bores, cut the crank and a new set of rings was in order.