Horsepower guesstimate on this 440

[MoparMotel]

Hey,

My buddy bought a 78 motor home 440 that the owner said was rebuilt to basically stock specs whatever it came with. My friend bought it for $1,200 and put a set of hooker headers, comp .501 lift cam, Edelbrock performer intake, demon 850 carb, and MSD electronic ignition in it.

We seem to be having a little debate about horsepower. He's thinking the 450hp range but I keep thinking aren't these motors like 7.8:1 compression if stock specs? I'm thinking like 350hp.

The motor is in a '74 Power Wagon regular cab short bed with a Dana 70 with 3.55 gears and an automatic 727.

I raced him the other night in my 9:1 compression stock 383 with a 270/470 comp cam in my '68 charger and had 3 car lengths on him at 80mph when I let off.

Just curious on who's closer on hp estimate!

[MoparMotel]

Forgot to add... My car is a stock 383 magnum with the exception of 270/470 cam, and Edelbrock 800 thunder AVS carb and I have 3.23 gears with 727 trans... My motor has 9:1 pistons in it, engine builder put those in even though I told him put 10:1 in it 

[fy469rtse]

300 to 325 max, at the rear wheels 180 roughly to 250 ,
Why ? I have seen a lot of well thought out motors and seen the results on dyno, later at rear wheels , ! Big difference, it's the same reason I haven't posted my dyno results, will wait for chassis dyno , parasitic drive line loss can be a lot more than you think

[Cooter]

Compression equals power. That engine might be making 300. Hp.
swap out pistons for six pack replacements, rebalance, then you'll see a big difference.

[BSB67]

Forgot to add... My car is a stock 383 magnum with the exception of 270/470 cam, and Edelbrock 800 thunder AVS carb and I have 3.23 gears with 727 trans... My motor has 9:1 pistons in it, engine builder put those in even though I told him put 10:1 in it 

He put those pistons in it because there are no 10:1 pistons for a 383 with 906 heads.  You probably have a good piston for the 915 heads.  Anyways, you are probably at the 325 hp level.  If the the car weights are the same, he is probably 30+ hp less than you.

For your street race to hp relationship to be reasonably reflective of hp differences, neither car should have had any wheel spin.  You need to start at a speed that neither car will spin the tires, and which ever one pulls away will have the larger power to weight ratio.

[MoparMotel]

We did an off the line start which we both babied it until we got rolling then hammered it then we did a 25mph roll where both of our 727's kicked down to first and away we went... I have to admit it was pretty funny he thought he was going to smoke me and I figured he had maybe a little more hp and tq than me but I started walking away from him quick...when we got back he jumped out of the truck and said "man my fuel pump is going out I had no fuel on the top end".... Yeah right lol

[firefighter3931]

The power wagon is probably 500-600lbs heavier than your car so that would certainly hurt him. A well tuned 383 is certainly no slouch.....good job. Try not to rub it in too much. 


Ron

[Cooter]

Serves that putz right. Who the hell drag races a heavy ass truck, with a weak ass, overcammed 440 against a car?

That's bout as stupid as racing street bikes against cars.
only thing that I've seen dimmer would be that YT video where two rednecks hook to 4x4's together.