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The length and weight of the boat may be a factor in what size engine you build. I thought Big cubic inch is when you're heading for 800 or so.SAR 820 EFI Marine Engine - Sonny's Racing Engines (sonnysracingengines.com)

Quote:

Originally Posted by articfriends (Post 4862007)

So we're actually talking "large inch SHORT 9.8 deck , STOCK 502 gen 6 block build" to narrow things down a little? There's been quite alot of debate/claims/information thru the years of 'how far you can bore a production gen 6. I will say this as far as boring a stock block to its "end", only do it IF it needs done because of bore wear/damage. doing it to gain 5 cubic inches isnt a great plan.
I had plans on building a pair of maxxed out 548s for my 33 scarab AVS, 13-1 or so compression, try a bunch of different heads and intakes while on my dyno on engine one, etc. Actually built engine one most the way, I had the cncd afr heads and ported promaxx heads to try. Then after dynoing several other E85 engines, saw how atrocious the BSFCS actually were even with the BSFC gain from the compression and abandoned the idea because of fuel tank size/fuel range. Sold that later, Smitty

always love your input smitty. Really looking forward to seeing what you do with the 33.

I agree, an NA E85 motor is a bad idea in a pleasure boat due to range anxiety.

If I had to have a compression motor in a boat, I’d go with 100LL, maybe spiked with a little additive. You could bump up to 13 to 1. I’d also seriously consider EFI to lean it out a bit at cruise rpm to help your range out.

I think if you’ve got a blower motor, it would be fun to have a set of E85 carbs and a party pulley for your shoot out or poker run days.

If I was building NA it would be straight to a tall deck 632 with SR20s and a profiler sniper ram. Exhaust is still a problem, I’d love to see eickerts/lightnings vs stainless gen 2 vs CMIs dynoed at 1000hp.

Quote:

Originally Posted by GPM (Post 4862075)

I've got to admit. I've never built 550+/-a few that didn't make 1000+ with a Dominator. But those went into race cars for NHRA Super classes. Complete different ball game.

Quote:

Originally Posted by ICDEDPPL (Post 4862070)

The first engine builder who was a nervous nelly and wanted me to buy the best of the best was having a stroke when we had to go 4.530 on a Big M block.thought there wasn`t eanought meat on the bone
As far as I know 4.600 is the limit ..... Dart sais

If you go 4.600 and it gets hurt you`re out of meat on the bone and you have to buy a new block no ?
Thats the issue I see with your plan Brad.

who was this clown?

4.6 is pretty standard now. The bullet boys claim they will go to 4.63.

apparently good machines like a rottler can do .005 or .01 overbores, and line to line coatings can even save pistons

Big inch Sonny's or Musi....mountain motors

Quote:

Originally Posted by Brad Christy (Post 4862009)

Smitty,

So, I've got this hair-brained idea (not that I have any immediate plans) of starting with a BigM tall deck, 4.25" stroke, bored to 4.6 (565ci) with 6.7" rods. My math puts CH at 1.575". Too much? 4.375" stroke and 4.54" bore gets you to about the same displacement (566ci), and a CR of 1.3125". It would seem Molnar sells rods of just about any length, that would allow the "fixing" of any CR stack-up. Is it that simple?

Anybody ever done this? Morbid curiosity.....

Thanks. Brad.
(937)545-8991

Go with the longest rod you can fit without getting into the bottom rings. It'll make more power.

Quote:

Originally Posted by F-2 Speedy (Post 4862092)

Big inch Sonny's or Musi....mountain motors

You referencing Sonny Leonard's?

on our 598s the wrist pin is 3/4 into the oil ring groove we use a oil rail carrier to get around it ,it carries the oil ring rails like a bridge

Quote:

Originally Posted by boostbros (Post 4862103)

on our 598s the wrist pin is 3/4 into the oil ring groove we use a oil rail carrier to get around it ,it carries the oil ring rails like a bridge

Low deck 598s? I’ve been curious what the rod and CH are on those.

If you put those pistons in a 10.2 how much stroke could it swing?

So your main question, is it feasible? Can it be done?

Short answer, it's just not worth it.

To properly build a reliable 700+hp with good torque costs just as much or more than a blower motor. Especially starting with a used up 502. So why do it?

The only reason I went NA is because my boat originally had 750hp supercat engines, it's a race boat with tractor pipes, and just "fits" the theme. Unfortunately they were extremely expensive and are less reliable than blower motors. We love them though! But we started from scratch, 572cu/in Dart blocks, lots of High end parts, dry sump, etc.

I know you are not going to believe me nor listen, people never do with offshore boating advice. The "Hope" to be able to do whatever they have convinced themselves that they want to do clouds judgement. And unfortunately, most people's budget isn't even close to their goals or dreams.