Thread: Comp\ratio

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454 TRUCK BLOCK 20 OVER FLAT TOP PISTONS 702 CLOSED CHAMBER 98CC HEADS FROM 1966 CAM IS EXTREME ENERGY 224\230 AT 50 515\520 LIFT 110 LOBE SEP HP AND TORQUE I THINK SHOULD BE 450 -450 WHAT DO YOU GUYS THINK OF MY STREET RAT...........

Should move along pretty nicely....I did a desktop dyno on it, had to estimate some of your engine cause you didnt say...here's what I put in. Stock heads, with chamber size you mentioned, no porting, stock valve size. Your compression ratio with stock head gasket, .025 deck height (about stock) and flat top pistons comes out to just about 9.0/1. I also figured a 750 cfm carb with a dual plane intake. Headers too, although Im not sure? Peak HP was 380 at 5000 rpm and peak torque was 371 at 3500 rpm....not as good as you might have thought, but not bad! How does it feel, that's what counts. John

headers are1 7/8 long tube steel head gaskets 780 vac sec performer rpm msd ign.. the same combo i have is in master engine builder magazine at 487 hp now thats a little different 100 hp i think that dyno needs a beer thanks for the reply johnny..............................

Yeah, every one is going to be a little different, you might think it's the same engine, but it doesnt take much to make a difference. Like I said, it doesnt matter too much, except for bragging rights. Get it done on a chassis dyno if it's really important to you. Most guys that I know who have done that have been Greatly dissapointed!! As far as the Desktop Dyno, I dont go by it as gospel truth in the numbers, but it's fairly accurate when you put in correct info....I use it mostly to see what swapping cams, carbs, intakes, heads, etc. will do to the numbers.

Oh, I mis-typed, your torque was 471 at 3500, not 371....and with your steel head gasket, it's .020 thick, which makes your C/R about 9.5, a half point higher...new numbers are (drum roll) 391 HP and 481 torque

481 ft/lbs of torque @ 3,500 is gonna make one helluva nice street/strip motor.