Crank aerating the oil and losing pressure? Is that why you reduced stroke?

Have it dynoed and broken in on the dyno.

The 632 came in the boat when I bought it and ran really good and strong for 2.5 years for me so I really can't complain.... BUT as I got more and more seat time in the boat and doing poker runs actually running it higher RPM for longer periods of time till it grenaded, block destroyed and all. When I tore it down to see whats salvageable almost every bearing was burned up and rods had evidence of overheating. 99.9% sure the one bearing spun and snapped the rod, cracked the cylinder wall, and block pan rail, etc. The bigger crank of 632 aerates the oil and even though you may not see a drop in oil pressure, the aerated oil just doens't lubricate properly, esp at high RPMs... This is just a quick summary of things I've read, spoken with a few enthusiasts, and confirmed by at least 3 engine builders when I discussed what to replace this motor with. That said, if you went dry sump system the 632 or bigger would be great, but I'm just not willing to risk it from what I saw inside my engine once torn down. It was a bad ass motor tho while it lasted! That said, I never had the dyno sheet but did talk to the engine builder before I bought the boat and he said it made 850hp, but when I talked to all these other engine builders and I asked what the combo would make with the heads and cam combo, none said it'd make anywhere near the 850 he claimed. Bottom line I have gotten from the engine builders and enthusiasts so far is the flow #s of the AFR and old cam just don't support 850hp. Others I have talked to mentioned either very generous dynos or correction factors turned up to meet a customers goal #. When I used Desktop Dyno with all the specs, it shows this new 598 being stronger as well. FINGERS CROSSED


Solid points Smitty... It's the current headers I have so hopefully shouldn't hurt me anymore than I was before with the 632 since I am hoping to just get back to about where I was before or a touch more. I can always upgrade them as they get older but thats a big expense I don't want to take on just yet. Maybe even the Stainless Marine Gen 3?
But I can easily upgrade the carbuerator or have Nickerson rework it for this motor. I actually should take a look an see what CFM the dominator is... Nickerson built it for the 632 before I bought the boat, so it may be bigger than I am assuming.


Precisely why... I never really saw a drop in oil pressure, but every bearing was all burned up and evidence on the rods of overheating as well.


That's the plan... Might not be complete till later in the Fall, just excited and curious to see what others think it may make for power and if any suggestions/concerns to address before its fuly built so I can tackle them now.

I ran the BB2 Xtra CNC ported, Dart tunnel ram converted to EFI, 2 , 1200cfm throttle bodies, 2.375 primaries 4.5 collectors. I never dynoed it without the Procharger. A similar 583 that I built with the same heads, cam and intake made 778 hp and 742 torque. With a small shot of NOS it made 1027 hp and 998 torque. I ran 9:1 compression in both motors. I personally wouldn't use anything shorter than a 6.7 rod with a 4.5 crank.

We did FLOW test the E tops, 2 runners on both sides flowed 296 CFM the other 2 were 248 CFM, not good for HP.

So on my Sim you show about 800 hp/760 tq w your 1 7/8 headers, short runners plus 1050 carb, if header size is theoretically changed to 2 1/4 with longer runners and 1250 carb, shows closer to 840. Keep in mind Sim numbers IF you do the manifold and exhaust efficiency correctly are a "best case" scenario, I have only beaten the Sim in best state of tune on my dyno a couple of times.

What oil pan do you have?

Thanks articfriends.... Does it show what RPM that 800/760 is at? Also, any chance you can you run the Sim with my old 632 just for comparison?

The old pan was a KE/Hardin XS Offshore pan. Never saw any evidence of windage on the guage, but I wouldn't use this one again as its a steel pan and was rusting from the outside in. Was finding pieces of flaked metal in the bilge but had no idea where it was coming from, and when I pulled the motor it was almost paper thin in some areas.

New pan going in is a Moroso 20385... All aluminum, with billet end main bearing surfaces, trick windage tray, double kick outs, etc. Came recommended from the engine builder and another buddy runs it in his 29 Kryptonite with good luck. Apparently its the builders go to pan for motors with windage issues or to simply avoid in the first place, and he said he's never seen a motor have any with this pan so we shall see.

same heads off your 632, cam specs?
your current combo on my sim tq peaks at 5000/ hp peaks at 5900 to 6000