What is your HP to cube ratio?

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USCG CHARGER

USCG CHARGER

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I have been told that with my 416 I should only look to be around 600-630 HP b/c of the HP rule of thumb (1.5 hp per CI ) meaning 1.5x416=total hp?

However I have a buddy that has a 393 SB mopar with W8 heads that made 730hp.

I was hoping to break into the 700hp realm with this setup.
 
I dont think you can always rely on a formula like that. that really depends on the build each one is different.
 
each engine is going to have it own horse power per cubic inched base on the components in the engine....heads...cam..intake..carb..compression...
 
Mine is somewhere between 1.176 to 1.25, though mine is just a healthy street build.
 
70aarcuda said:
each engine is going to have it own horse power per cubic inched base on the components in the engine....heads...cam..intake..carb..compression...
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So how can I determine mine?
Callies Dragon slayer 4" crank
Carrillo Rods 6.200"
CP pistons 11:1 CR
solid roller cam 250/256 @ 050 675 lift
T&D 1.6 rockers
Schuback lifters
W9 heads 370 flow @ .750
2.17 intake valve 1.60 exh valve
stainless stepped 2" primary merged 3.5" headers
W9 intake
1000cfm pro-system carb
 
You won't know until you dyno it, or make a few passes. Who told you you'll only reach 1.5? You've got the hardware to exceed that, except maybe the camshaft.
 
as moper said...you gotta dyno the engine or run the car down the track to generate a hp number...

then divide it by the cubic inches...
 
Those knuckle heads on yellowbullet... phuckin phord and chebby dudes
 
I think there is a formula that has to do with the headflow that is superior to the HP/CID rule. Try this calculator, although it doesnt take compression into effect. http://www.wallaceracing.com/calcafhp.php
For instance, I put 28 inches of water , 220CFM @5000 for a "562" (J and X similar) and 403 for my CID and got 417@5533rpm.
 
It's just bench racing. You change one thing, you have to change everything.. cam straight up? cam advanced? what is c/l?; cr actual with cam bleed off? etc. So many things affect each other. How much total does it want? what is a/f at all rpms?.

Dyno. The rear ones, add 20% for crank hp.
 
green1 said:
And it is just that; theory of people that don't run/test their theory car.
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It just all in good fun.. I wanted something to dream about before the motor goes in next month. Harmless fun.
 
yeah it's a little younger crowd. Some good info there too though.. lots of fast cars too.
 
Some die hard 1/4 racers there though. No bs whos kissing up to who there.
 
We can theory to death, agreed, fun with some; some will argue to the moon, without racing. So many variables, last 2 weeks, took a Charger 440 to dyno. Best pull 339 at year, dyno showed bog on sec opening. Fixed carb (still lean at opening, but better) and replaced that procomp pos dist, that had a bent shaft from the factory. Still 339hp. Move total time all over the place; 339 again.
 
green1 said:
We can theory to death, agreed, fun with some; some will argue to the moon, without racing. So many variables, last 2 weeks, took a Charger 440 to dyno. Best pull 339 at year, dyno showed bog on sec opening. Fixed carb (still lean at opening, but better) and replaced that procomp pos dist, that had a bent shaft from the factory. Still 339hp. Move total time all over the place; 339 again.
Click to expand...
You running full exhaust?
 
well to answer your question there is no "rule"... the engine will make what its gonna make and then / with the ci and there you go...

now a good number is at least 1:1 so 1hp to 1ci... when you get above that its good...

my slant is about 240whp/235ci so 1.02:1
 
Here's the guy that built the current engine in my Duster: http://www.dragracingonline.com/columns/baker/xiii_2-4.html

I've seen a de-stroked 350 Chevy ( approx 312 - 316 ci ) pump out 700 hp (carbs only - no juice, turbo or blower) on the dyno and Bob was trying to figure out what was wrong with the low hp. The engine that he built for my '72 Duster had more hp and torque than his racing Duster due to the new technology and I drive it on the street...... scary at times! I need him to build me a new engine using my 340ci w/4 inch crank, now, I just have to figure out how to hide it from the wife!
 
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