JaniH

Need some help to choose a camshaft and compression ratio. Srp 17cc solid dome piston that can be milled to set the compression from 9.1 to 10.6. Euro 98 5% ethanol fuel, equalient to us 93. The piston to wall clearance is honed for a mild boost in mind for the future. Valves are ferrea 6000 so that may be a problem in boosted aplication, dont know? looking for around 600hp n/a power so, 3psi should make +700hp and 6psi +800hp. 26ft chris craft stinger 5300lbs dry weight, rised X-dimension, bravo drive. planning was not an issue with old 500hp 509cid engine. was thinking 10 to 1 for NA and 9 to 1 for mild boost, but cant deside wich cam to use, comp has the duration and the other cam has the lift.

-GM gen6 block 4.5" bore.
-Eagle 4" forged crank.
-6.385" eagle H-beams.
-SRP forged pistons.
-Cometic MLS head gaskets, 0.04" quench.
-Flotek 290cc, 112cc chamber, 2.3"/1.88" ferrea 6000 series.
-Gm dogbone lifters or howards max effort (gaterman) retrofitt lifters in hand.
-Two cam options in hand, comp 236/236 050" 112lsa or custom 3lobe 228/230 for intakes 236 éxhaust. cam cards in pictures.
-Weiand Hi-ram converted to 8 point efi with 2x4brl 1000cfm throttle bodies.
-Mrtech ecu, sequential or semi sequential fuel, logig level wasted spark ignition.
-Stainless marine exhaust, 6" taller/dry to transom risers.

Tartilla

If you used bushed rods, you could leave the CR higher for NA, and if you ever go boosted you could do a quick tear down/inspection and machine them to a more friendly boosted CR.

Flotek 290s are a good head choice.

Eric Weingartner on YT has many vids on Floteks and Promaxx 290/317 BBC heads with direct 496 dyno mule comparisons. 317s at the same compression as the 290s performed really well..and even made more power in the mid range part of the time. All at WOT of course. He goes into detail why the 317 port may be more efficient for airspeed, as it has a more consistent port.

The Stainless Marine standard size with 3" ports and dry risers are sufficient for 700hp without resistance. @ 2.2CFM/hp.
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Higher LSA would help with reversion, and if you went Supercharged in the future.

Mike Jones cams may have some options for you, vs off the shelf. I think he also has some good lifter options.
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Mike has a cam question sheet to fill out. Very easy solution for a 2nd opinion and likely a more tailored cam solution.

Rookie

iTrader: (4)

If those were the only cam choices, I'd go with the Comp cams and run 1.8 rockers. at the least on the exhaust side. 0.340" lobes are going to be easy on the valve train. (I do actually run 1.8's on my exhaust side) I really wouldn't be putting the 3 lobe gimmick cam in. After looking at the part number, who would be supplying that cam??
Why are these the only 2 cam choices? Are they cams that you already have?

sutphen 30

the one,,the only,,cslob,,could smell that garbage a mile away.

JaniH

I allready have these two cams. That gimmick has run in 9.5 comp peanut port 509cid. 530hp 5400rpm, 620lbft 3600rpm, i have nothing bad to say about it! Somehow i like the low lift of the comp cam, that may be easy for the valvetrain. Wonder where the engine would peak whit this cam? I would quess near 6000rpm atleast with 1.8 rockers. I have 1.7 crane golds wich are 1.76 i real life.

ICDEDPPL

iTrader: (1)

Personally , I like my CR lower, closer to 8.0:1 for blower and seat pressure clower to 200# but if you`re not running to 6000rpm probably fine.
Fill your cylinders with fuel and air instead of metal.
I wanted to go 7.5:1 but the the head gasket would have to be pretty thick.

JaniH

Damn it was hard to decide put the domes are now machined to 6cc, wich gives me 9.8 to 1 comp for N/A power. Now trying find the perfrect lobes, and imo howards has the most interesting cams with less duration split. Someone said that picking a cam more complex than picking a wife.

GPM

In my opinion and from trial and error, less than 8 degrees of split didn't work that well on N/A or blown BBC

Rookie

iTrader: (4)

Call Comp with the lobe #'s and separation you want, à la carte. Done...

JaniH

Sporl perfomance suggested his 240/245 @050, 646/646 lift, 114lsa. Does anybody have any experince with sporl cams?