Open,I'm no dyno expert,I would say the accessorys rob maybe 25 hp tops,Smitty

getting parts together for one at this time. Dart big M, forged 4.25, forged JE 9.4:1, Crane 731, Caveman's full port Merlins, IMCO Powerflow Ex., for pleasure, need intake and carb recommendation?

88fount33,
I had been debating the intake last year when I built my motor. I was sitting on the fence between an oval or square port intake. I started a thread here last year on this. There is alot of good information on this .

http://www.offshoreonly.com/forums/s...rt+rectangular

oval port heads are for cabin cruisers ! rectanular are for speed boats.

I think you misread my post. I was talking about oval port intakes.

same deal!

Thats a rather broad statement. Care to back that up with some facts?

Not quite sure I would agree with that.

What rpms do you want your peak torque to come in at?


Oval port create higher port velocity. Flatter torque curve.
I would say under 5000rpm.

Rectangular port creates more of a peak curve.
lower velocity moving more air.
Capable of much higher then 5000rpm.

In short these are very broad statements as well.
Its all in the combos as demostrated in this post.

Stick with a proven combo!

Stay tuned as we try to get 1200 ponines out of 557's
with Dart pro 1 18 degree heads

Gerry

Eldebrock RPM heads with Team G intake, full port and polish by Champion Marine. Intake port matched
10.1 comp
741
850 barry grant 920 cfm
1.9" and 2.3" valves
CMI's
sheet is dyno room headers w/o acc
purrs like a kitty at idle
would idle a t 500 r's if I would let it
no in and out of gear issues at all
do have a pressure relief valve due to the crossover
Gary Grimes speced out the part and put on his relief valve
Put over 300 hrs on it and tore it down this spring with no issues.

I have oval port heads that have made 795 Horsepower on a 9.5:1 1X4 card wet sump "B" class engine. They make power on this combo all the way to 7400 rpm. Remember these are 510 cu.in. engines only! There are many combinations out there ....but only some make real horsepower.