Could I prevail upon one of you guys to figure out the horsepower of my truck so I can impress someone? Pleeeaaaassseeee? *grin* I'm emailing him now.. so if any of you guys are on, please let me know what you need to know about my truck to figure that out.

Thanks!

 

He'll probably just laugh at you, computer determined horsepower numbers are usually suspect by everyone that has anything to do with engine building. Some programs can be pretty accurate, however, the condition of the engine has a lot to do with it. Keep in mind this will be at the flywheel, with everything tuned to perfection.

I need:
The heads you're using.
The intake.
The carburetor.
Exhaust (headers, mufflers?)
Compression ratio - dont guess here, give pistons used if possible and combustion chamber volume
Bore & Stroke (include any overbore)
Camshaft manufacturer and part number. Maybe I'll have it on file, maybe I wont. If I dont I'll ask you to get specs on it. More on that later if I dont have it on file.

 

I need:
The heads you're using. 428 C8AE-H
The intake. Edelbrock Performer 390
The carburetor.Edelbrock 1406
Exhaust (headers, mufflers?) Tri-Y Headers, Flowmaster 30's, dual 3 inch
Compression ratio - 10.5:1
Bore & Stroke (include any overbore) 4.13 x 3.98
Camshaft manufacturer and part number. Melling MTF4

Can you also figure it using the same, but with the Holley 770TA carb?

ThanK you so much!

 

Ok, I'm getting 340hp @ 4500rpm with the 1406, and 347hp @ 4500rpm with the 770.

I read in your other thread that those could be 390 heads, so I used standard 390 valve sizes (2.02" intake, 1.55" exhaust). If they're CJ valves let me know.

Hope that helps!

 

484 intake lift/510 ex lift
duration 204 in/214 ex

Does that help?

 

Yep, thats the cam I used in calculating the above numbers. I think there are much better cams out there. You can also pick up some performance by porting the heads or using edelbrock heads.

 

Thanks! And I'll keep that in mind when I've got money! *grin*

 

how much power and torque should i be putting out of my freshly rebuilt 390 with med riser 4v intake with a 2" swirl torque carb spacer and a 600 cfm Holley, 9.5 comp., crane cam with a .458/.484 lift, headers, dual 2.5" exhaust with Flowmaster 50s? Desktop Dyno figures are appreciated.

 

What heads are you running? Ported?

 

rusty, i'm running the stock heads which were rebuilt with new seats, seals, milled, valve job. no porting or polishing has been done.

 

Just a guess probably 325-350 hp and 410 tq, but I defer to Rusty70 with the DD.

--Mike

 

I couldn't find that crane cam. Do you have a part number?

 

The only one I saw that comes close is the 343971.. Got me interested too.

--Mike

 

i don't know now if it was a crane cam or not. all i know from the machine shop is that they regularly use crane cams, don't know if its another brand or not. how would the 971 idle on a 390? Anyone with desktop dynos can you run me some numbers for my 390 setup?

 

Well, the 971 is an EXTREMELY mild cam, with less duration than the stock cam. And its still got more lift than the cam you specified. It would idle very smooth, but it would ping like crazy since its meant for low compression apps.

We cant run any desktop dyno numbers without the exact specifications for your cam. We just cant, they would be too far off.

The only cam that comes close is the Edelbrock Performer cam, it has .460" intake lift and .480" exhaust lift. With that, you're looking at 284hp @ 4000rpm, and 455ft-lbs @ 2000rpm. You could definately use a bigger cam. If you swap it to the Crane 343941, which is very popular around here (I use one myself) you're looking at 331hp @ 4500rpm, and 416ft-lbs steady from 2500rpm to 3500rpm. Torque curve is extremely flat.

You could also benefit a lot from porting your heads.