Just a little project I finished up today... And the results kinda were expected, but also a bit of a suprise... So hopefully, this little bit might dispel some of the myths surrounding "peanut port" heads and their potential as a good jet boat engine cylinder head option.
Roundy 461... This is kind of an odd engine to dyno since typically nobody wants to dyno a warmed over Marine Power 330 engine that gets our typical mild stocker upgrades... They just go, "I want a little more"... And I just give them a little more. So for the sake of just something to do... Add a little knowledge... And give this guy a completely tuned package that he can plug in and go without worrying about killing it from not being tuned properly... We went ahead and dynoed it. Here is the break down: started life as a standard peanut port late 80's-early 90's Marine Power 330hp jet package. Typically they make about 310-330hp at about 4500rpm and then just run out of steam beyond that. Typically found in your production 21' open bow boats. We took this package, did our port work and typical marine treatment to the heads... Machined up the block with our typical line hone, deck, bore, etc... Balanced the rotating assembly... Put in 9:1 hyperutectic pistons, Schneider custom ground hydraulic flat cam... Roller rockers... Edelbrock rpm intake, holley 750... Basically did everything we do to what we consider OUR version of a stock marine engine. The result: it made 456hp@5000rpm and 558ft/tq@3700rpm. Idles pretty smooth at 750rpm. Considering we picked up over 100hp and extended the power range 500rpm... I'm gonna say we didn't do too bad with heads most people consider junk and just throw away. Here is proof that a properly thought out and executed peanut port 461 can make over 450hp and a ton of torque... Perfect for that cruiser 21' open bow jet with an A impeller and inducer (since 550ft/tq @ 3700rpm is gonna cavitate a weaksauce pump when you smash the go pedal)...
Or a large prop i/o... If you swing that way...😳
Peanut ports junk? Can't make decent power for a jet with them? I'm gonna go with... myth busted.
As soon as I figure out how to put the video up... I will... But I do have a photo attached, so that should show some effort was put forth...lol 😜
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