Thread: 500 hp/550 lb-ft from a 390?

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Hey Jeff, welcome aboard and thanks for the obviously intelligent opening post.

I'm retired and enjoy putting together combinations on my playtoy, DynoSim version 4.20 software. I'm no different from most of the other motorheads on this forum, having wrenched on hot rods for 50 years, doing most everything from stock rebuilds to drag race motors, front end/rear end rebuilding to clip swaps, frame swaps and engine swaps (my favorite). Anyway, I'm 67 now and can't do many of the things (physically) that I used to be able to do, so I placate myself with this playtoy and passing on stuff from my noggin to others who can use it to their advantage. Many, many knowledgeable people have helped me in the past, so I feel a responsibility to help others with what I have learned. Now that you know who I am, let's tackle this FE.

I have built only a couple of these motor in the past, so I don't have all the detail knowledge that others on this board have, but in the end it's just another air pump and so will respond to the usual changes in my opinion.

There's a plethora of combos that will work for you, this is just one of them.

390 block bored +0.030".
390 crank
Rods: I'll leave this to others who have more knowledge of the FE
Pistons: Speed Pro L2291F30 forged.
http://store.summitracing.com/partde...0&autoview=sku
Heads: Edelbrock 60069, 170cc intake runners, 72cc chambers, 2.09" intake, 1.66" exhaust.
http://store.summitracing.com/partde...5&autoview=sku
Intake: Dual-plane, high-rise such as the Performer RPM or Weiand Stealth.
Carb: 850 CFM
Headers: large primaries, equal-length, long-tube. (real headers, not those cheezy shortie units).
Cam: CompCams 33-230-4 hydraulic flat tappet, installed 2 degrees retarded.
http://www.compcams.com/Cam_Specs/Ca...?csid=934&sb=0
Static compression ratio: 9.90:1
Dynamic compression ratio: 8.28:1
Volumetric efficiency: 102.8% @ 5000 rpm's.
BMEP pressure: 205.2 @ 5000 rpm's.
Juggle the block deck height and gasket thickness to achieve a squish of 0.035" to 0.045". With a tight squish and optimized ignition timing, this motor should easily run on pump gas with zero detonation.
RPM HP TQ
2000 160 419
2500 196 412
3000 248 434
3500 319 478
4000 388 509
4500 460 536
5000 512 538
5500 535 510
6000 550 481
6500 514 415
This cam clicks off like a switch at 6100. There's a dogleg in the torque curve at 2000-2500 that I don't much like, but I was able to minimize it by retarding the cam 2 degrees.

Now Jeff, there are many who poo-poo the results of these software dyno pulls and in some cases I have to agree with them that the numbers are optimistic. The beauty of the software is that you can COMPARE different parts and how they react with each other. It's not necessarily the definitive number, but the comparison that makes the software valuable. I tried 6 different cams, advancing and retarding them, 3 different intakes, 2 different pistons, 3 different carbs and 4 different static compression ratios to get the results shown here.

I have compared results from this software to hard-core dyno pulls and it seems to be within about 2% on the numbers.

I'll run some other combinations if I can find head flow numbers. If you come up with any, post them and I'll plug them in. By the way, here are the numbers on the Edelbrocks....
0.100 88 64
0.200 153 113
0.300 195 148
0.400 233 171
0.500 265 183
0.600 270 200