What the max hp using stock magnum heads

-
Brooks James

Brooks James

VET, CPT, Huey Medevac Pilot
FABO Gold Member
Joined
Dec 12, 2020
Messages
4,863
Reaction score
3,188
Location
Fruitland Park Fl
360 magnum
Stock block, pistons, heads, crank
Adv cam specs 274/498 intake
286/512 exh
Air gap
750 holley
Dougs D453 1 5/8 headers
150 shot of nitrous

Im hoping for 500 hp will the heads allow it
 
I believe the factory 5.9 magnum is 9.1 compression. The factory 380hp crate motor used a production line engine originally. 288/292 advertised duration 230/234 @.050 .501/.513 lift for the cam . Factory dyno tested at 380hp with a 650cfm carb with a 750 carb they were over 400hp. That was with upgraded springs, locks and retainers.

150 shot of nos probably 500hp or so.
 
Brooks James said:
360 magnum
Stock block, pistons, heads, crank
Adv cam specs 274/498 intake
286/512 exh
Air gap
750 holley
Dougs D453 1 5/8 headers
150 shot of nitrous

I'm hoping for 500 hp will the heads allow it
Click to expand...
I'm a bit grouchy this morning so.........

When I wanted to know that kind of crap I just built it to find out.

If you build it he will come!

Ahh......I mean you will know......and..... We will know.
 
IQ52 said:
I'm a bit grouchy this morning so.........

When I wanted to know that kind of crap I just built it to find out.

If you build it he will come!

Ahh......I mean you will know......and..... We will know.
Click to expand...
:rofl:
 
There is a theoretical theory (see what I did there?) that you can predict (n/a) the
max power an engine can make, from cylinder head flow. There is lots more complexity to it, but bascally... 2hp per cfm.
So if your heads flow 300cfm, then the most to expect would be roughly 600hp.
From what I have read, stock magnums are good for around 220 cfm, so...400 on motor should be very doable.
Then add as much nitrous as you dare.
Engine masters got 600hp out of a 305 Chevy with a stock short block, before they blew it up. 250 shot. Nitrous guru Monte Smith said it shouldn't have blown up, even at that level. He said they didn't pull enough timing out of it.
 
IQ52 said:
I'm a bit grouchy this morning so.........

When I wanted to know that kind of crap I just built it to find out.

If you build it he will come!

Ahh......I mean you will know......and..... We will know.
Click to expand...
.
I don't think he is even breathing hard.
 
Here’s the rated 380hp 5.9l making 409 hp

upload_2021-8-25_17-4-42.jpeg
 
More Cr and duration will gain more power but the max who knows
 
Brooks James said:
Thanks, i went there using 14.7 atmospheric pressure at see level.at 220 CFM it came to 570 hp
Click to expand...
@Brooks James No, no. The calculator wanted the measured depression that the heads were flowed at . Typical through the industry is 28".
If you run the calculator again, you will get a little over 400 hp.
At 14.7 atmospheric pressure those heads probably flow about 100cfm.
Edit : if you run that calculator at 28", and 185 cfm to account for the intake manifold, you get a realistic 351 hp. Add 150 shot and voila! 500hp.
 
Last edited:
I had this combo for years, stock 5.9 with a cam and springs. 9.5 3800 stall, 4.10 gear, 1 5/8 jr headers, air gap and a 650. 12.20 on motor 10.90s on a 150 shot. 3300 lb duster
 
33IMP said:
There is a theoretical theory (see what I did there?) that you can predict (n/a) the
max power an engine can make, from cylinder head flow. There is lots more complexity to it, but bascally... 2hp per cfm.
So if your heads flow 300cfm, then the most to expect would be roughly 600hp.
From what I have read, stock magnums are good for around 220 cfm, so...400 on motor should be very doable.
Then add as much nitrous as you dare.
Engine masters got 600hp out of a 305 Chevy with a stock short block, before they blew it up. 250 shot. Nitrous guru Monte Smith said it shouldn't have blown up, even at that level. He said they didn't pull enough timing out of it.
Click to expand...
220 that's happy numbers. 220 if there are RTs

Screenshot_20210825-173756.png
 
1bad360duster said:
I had this combo for years, stock 5.9 with a cam and springs. 9.5 3800 stall, 4.10 gear, 1 5/8 jr headers, air gap and a 650. 12.20 on motor 10.90s on a 150 shot. 3300 lb duster
Click to expand...
Similar, 750 holley, 3.91 on a 24.5 tire= 4.30
3500 converter, same 3300,
I will be tickled pink with 10.90
 
But to answer your initial question 500 is totally doable, how many times will that's all in how well you develop your system. I am by no means an expert but I have been compiling parts and information to safely spray my 340 with 150 shot.
 
Brooks James said:
Similar, 750 holley, 3.91 on a 24.5 tire= 4.30
3500 converter, same 3300,
I will be tickled pink with 10.90
Click to expand...
you're not going to do a 10.90 on a 24" tire.
I see nothing in your combo that will produce the power for a 10.90. even with the juice.
 
fishmens67 said:
you're not going to do a 10.90 on a 24" tire.
I see nothing in your combo that will produce the power for a 10.90. even with the juice.
Click to expand...
I think the cam might be a little small and gears to low for 10.90.

The 380 crate motors put 3,200-3,300 pound a-bodies into the 11.80-11.90 consistently and some 11.50. With no spray add nos and maybe drop a second?
 
The key will be hooking really hard. My 904 had 2.75 low first and dead hooked on a 295 drag radial. 1.4x 60 foots on n20. Had years of n20 runs on it. Timing always very conservative
 
You must log in or register to reply here.
-

Back
Top