390 in mud bogger
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Junior User
Joined: Apr 2004
Posts: 53
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From: bassano alberta canada
390 in mud bogger
im just waying my options right now. these are the ruels, ceep it under 600 hp before nos, pump gas. what could i do to a 78 390 out of a f250. want to keep stalk crank and heads, but will chang everything else. any help would br much apretated thak you. it will also be running single stage nos(100hp to 300 hp).and will be running open headers
Last edited by rig_pig30; Sep 1, 2004 at 10:55 PM. Reason: forgot some info
New User
Joined: Feb 2004
Posts: 10
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From: Eugene,OR
Definately going to have to spring for different heads, and if its in a 78 f250 are you positive its a 390? Could still be a 390 but just to be sure. But yeah, for what your talking about the first step is to have your block checked to make sure your 390 can handle 500+ hp
Post Fiend
Joined: Jan 2003
Posts: 8,600
Likes: 4
From: Iowa
Yep just let it breathe. I think the standard 390 rods would be fine in this motor. My way of thinking is, in a mud bogger you want plenty of low end torque to launch you out of the mud without delay. You dont want to have to wait for the rpm's to get up there before you really start moving. Thus, I have selected a cam to provide you with low rpm torque and plenty of high rpm power. Let the nitrous do it's job at high rpms. Plus, lower rpms are good for engine longevity. This solution should provide more than enough power:
DO THE OILING MODS!!!
A few suggestions:
1. Get the edelbrock heads ported by Keith Craft. Stage 2's should work well. CJ valves
2. Crane 343941 hydraulic roller cam
3. TRW L2291 Forged pistons
4. Dual plane Edelbrock Performer RPM intake
5. 750cfm vacuum secondary
6. .041" thick copper shim head gaskets, results in about 9.78 compression ratio
Before nitrous, this motor should produce 476hp @ 6000rpm, and 467ft-lbs @ 4500rpm, according to DD2k. On nitrous at 100hp, you're up to 576hp @ 6000rpm, and 679ft-lbs @ 2000rpm. At the 300hp level, you're up to 776hp @ 6000rpm. However, I think if you engaged the 300hp system at an rpm lower than 4500, you'd break things in short order, since it would produce so much torque. I think about 200hp is as high as you want to go on the nitrous, engaging it 3000rpm. At 3000rpm, on the 200hp setting, you're getting 796ft-lbs. That's PLENTY to turn a mud bogger tire.
DO THE OILING MODS!!!
A few suggestions:
1. Get the edelbrock heads ported by Keith Craft. Stage 2's should work well. CJ valves
2. Crane 343941 hydraulic roller cam
3. TRW L2291 Forged pistons
4. Dual plane Edelbrock Performer RPM intake
5. 750cfm vacuum secondary
6. .041" thick copper shim head gaskets, results in about 9.78 compression ratio
Before nitrous, this motor should produce 476hp @ 6000rpm, and 467ft-lbs @ 4500rpm, according to DD2k. On nitrous at 100hp, you're up to 576hp @ 6000rpm, and 679ft-lbs @ 2000rpm. At the 300hp level, you're up to 776hp @ 6000rpm. However, I think if you engaged the 300hp system at an rpm lower than 4500, you'd break things in short order, since it would produce so much torque. I think about 200hp is as high as you want to go on the nitrous, engaging it 3000rpm. At 3000rpm, on the 200hp setting, you're getting 796ft-lbs. That's PLENTY to turn a mud bogger tire.
