88blkbrd

I've heard that 9.0:1 is a good goal for compression ratio when using iron heads. Additionally, I hear 1 point of compression is added to that goal (10:1) when using aluminum heads. I am opting for aluminum heads from Trick Flow (for use with a carb setup) with a 62cc combustion chamber (for a calculated ratio of 9.99:1, calculated by hand with all info I have available). The heads I'm looking at flow 195cc, with max lift of 0.600". My HP goal is 400HP at the flywheel. Do the trick Flow heads have a good reputation? And is my first statement an accurate representation of what are realistic goals as far as compression ratio is concerned. I would like to run pump gas, and it doesn't look like I'll have any issues with that at these compression ratios. For whatever it's worth I'm running a comp magnum cam with these specs:
Cam Style: Hydraulic roller tappet
Basic Operating RPM Range: 2,500-6,000
Intake Duration at 050 inch Lift: 230
Exhaust Duration at 050 inch Lift: 230
Duration at 050 inch Lift: 230 int./230 exh.
Advertised Intake Duration: 286
Advertised Exhaust Duration: 286
Advertised Duration: 286 int./286 exh.
Intake Valve Lift with Factory Rocker Arm Ratio: 0.560 in.
Exhaust Valve Lift with Factory Rocker Arm Ratio: 0.560 in.
Valve Lift with Factory Rocker Arm Ratio: 0.560 int./0.560 exh. lift
Lobe Separation (degrees): 110
Intake Valve Lash: 0.000 in.
Exhaust Valve Lash: 0.000 in.
Computer Controlled Compatible: No
Grind Number: CS 286H-R10

Also, as you see above, they spec the cam as "with factory rocker arm ratio." I've got a 1989 L98 (5.7L) block, the factory rocker arm ratio is 1.5:1, right?

Any help would be appreciated.

Thanks,
Steve

Sonix

iTrader: (1)

The whole "one full point" is kinda BS IMHO. I think a half a point or so is more realistic.
Still, your goal, and your setup is a very very good combo.
A straight pattern cam isn't that common anymore, but should make good torque, and with aftermarket heads should work quite well.

I wouldn't hesitate at all at building that exact combo.
Yes, 1.5:1 ratio.
Any other more specific questions?

jamon8

iTrader: (3)

lobe sep of 110- better be a carb motor

88blkbrd

Thanks for the reply Sonix, this is my first engine build and I wanted to make sure I am think along the right lines to meet my goal. I don't have any other questions as of right now, but if I think of any I'll post them.

And, yes jamon8, I am certainly running a carb setup. I realize that cam is too extreme for a fuel injected setup.

Thanks for the help,
Steve