Originally Posted by Young Performance

The cam is impossible to tell at this point. I don't pick my cam until I have everything else pinned down. We would have to know what heads, comp. ratio, blower type and speed, etc. before picking the right cam. I could get in the ballpark now, but it would probably not be what I would end up with.
Actually, if you are doing an SC engine, I would use a 6.635 rod. JE does not make an inverted dome piston with a 1.25 comp. height. They only offer a 1.27. You can have a 1.25 made as a custom, but I would prefer a shelf piston for ease of replacement, should the need arise. With the 1.27 piston and a 6.7 rod, the piston will be .020 out the hole. If you use the 6.635, you can deck the block whatever you want the get the comp. ratio you are looking for. I have run the 6.7 rod and a .072 thick head gasket, but it is a pain. The older blocks use to have an extra .020 on the decks that they do not have anymore. The decks use to be 10.220, but not anymore.
JE also makes a piston with a 1.12 comp. height. I don't like to get under 1.25, but that is my personal preference. In a drag race motor it may be fine(I don't know for sure since I don't build drag race engines), but I don't trust them in a marine engine.
Ideally, in a perfect world, I like to see a 1.5 rod angle (rod length div. by stroke) It is not always a perfect world. With the 6.7 rod, you get a 1.4888 rod angle. With the 6.635 rod, you get a 1.4744. I can't begin to tell you how many times I have done this combo. This is the combo I use in EVERY SC engine I build.(that is a 598).
Rod angle is the reason I don't like or build a 632. If you use the 1.27 piston, you must use a 6.535 rod.(10.2-half of stroke(4.75)-comp. height(1.27) =6.555.
10.2 - 2.375 - 1.27 = 6.555. If you use a 6.535 rod, you are left with .020 to play with to deck the block to square it, or to leave the piston in the hole. However, you end up with a 1.3757 rod angle.
Hope this makes sense
Eddie

Originally Posted by Young Performance

I haven't has any trouble from aluminum as long as the engines get flushed religiously. If you do not flush them, they will bite you. If you flush them each and every time you run in salt water, you will be just fine. Now if you run on Sat. and are going to run again on Sun., you do not need to flush them. Just flush on Sun. when you finish.
An 8-71 is a little small for that many cubic inches. It will seriously limit hp potential. How much power are you looking to make? 5-6psi is probably all it will safely make with a 572-598 ci engine. You may be able to squeek out a little more boost with a good intercooler. Any more and you will just make heat. You should still easily make 850-900 hp without a problem. Hope this helps, Eddie.

Originally Posted by Comanche3Six

Dean
Great talking to you.
Thanks
Ed

Originally Posted by jeff1000man

Talked to Dean a few times and I read his posts. Never talked to Young, but I do read a lot of his posts and there is always good info in there. I am marking this thread as I am building a pair of 598's soon. Might be some good stuff on here.

Can I get away with a 10-71 BDS and no intercooler? If I start somewhere around 8.5:1 how much boost do you think I can still run on 87? I tune on 87 and run 93, but sometimes I still have to go with 87.

Planning on using a 345 Mrlin because of the price.

Any ideas on cam or possible HP?

Something else that I have noticed lately is that JE doesn't list a piston for a 4.375 or bigger stoke on the website.

What would your opinion of using a 4.375 crank instead of a 4.5. Engine would still be pretty close to 590CI? Wouldn't the rod angle be better?

With the blower, you could afford to loose a few CI, but pick up a few RPM's with better rod angle?

Check my math. Am I thinking correctly?

Originally Posted by Comanche3Six

Eddie
You make perfect sense and I appreciate you taking the time to help me.
Now I have to decide where my comfort zone is within.....horsepower.......dependability.......do llars.........
I'm in there somewhere!
Thanks
Ed

Originally Posted by AIR TIME

Me taking a guess would say 8.5 to 1 no cooler 87octane poof bang, you need a cooler and 93 octane, otherwise you will only get min boost with no cooler say 3 to 5 lbs 830hp to maybe 960hp still think no cooler more like 7.5 to 1 to live, my set up and the sister motor dynoed at 930hp with a cooler, with a cooler and DEAN 93octane and DEANS SPECIAL STUFF we are looking for 1050hp or more . I HAVE A 4.5 CRANK and the other motor had a 4.375 which was strange cause they were to go in one boat when me and my buddy bought them. he is at 582 or 588 after the new motor fell a part with like 5 hours. like I said I am just guessing at yours from what I know which will be a lot more after DEAN GETS THROUGH WITH ME. he explains a lot more than my local engine guy did for the last 12 years building 3 models of a 502 to a 509 or 510. Jim RIED is a good builder and makes a 598 801hp motor for about 16,000.. which is a good price, but I bet Dean could find more maybe in his custom intake which we will use on my 509 fall when I refreshen that motor for opa back up, I could never sell that one it was born as a black merc 390hp and now about 670hp was 647 dyno with BG 850 but made about 25hp more with nickerson 1050.

Originally Posted by jeff1000man

Supposedly I am all ready at 850 on a 540TD with 10-71's, running 93. Have ground out GM squares on there now. No chillers.

These were Dereberry's engines originally. Still sitting in the shopp after Ibroke a piston and took them out about a month ago. Actually have them for sale right now, unless I find something good to use them in. My 27 is to small for something that mean right now. I can hit 90+ with a 468 right now, with a 250 blower and chiller.

Just learning. Waiting to afford a big power boat.

What about the crank/ rod angle theory? Didn't hear anything about that?