390 Stroker
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390 Stroker
I currently have a 390 with the performer rpm package, and next year I would like to stroke the motor.. I use the motor in a mud truck and would like something that would turn 44" tires, I was looking at the 416????? anybody have any info on stroker kits for a 390? and how much horsepower potential is available with the motor, I guess I am around 400 right now I would like a lot more..................TOO MUCH IS NEVER ENOUGH!!!!!!!!!!!!!!1
Post Fiend
Joined: Jan 2003
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From: Iowa
Welcome to FTE! 
Stroking it wont get you more horsepower unless it increases the compression. What it will do is move the power band lower in the RPM range and increase torque.
Using a 428 crank you get 410 cubic inches. Scat makes a few stroker cranks for FE's. One is a 428 crank, another is a 4.125" stroke crank, and another is a 4.25" stroke.
In a 390 bored .030" oversize, you'd get 431.4ci with the 4.125" crank. With the 4.25" crank you'd get 444.5ci.
If you want more horsepower, port the heads! Keith Craft can make 'em flow like the toilet bowl. Really, I hear he does very good work. Give him a call.
Now remember, the price for this advice is you have to keep us updated!
Stroking it wont get you more horsepower unless it increases the compression. What it will do is move the power band lower in the RPM range and increase torque.
Using a 428 crank you get 410 cubic inches. Scat makes a few stroker cranks for FE's. One is a 428 crank, another is a 4.125" stroke crank, and another is a 4.25" stroke.
In a 390 bored .030" oversize, you'd get 431.4ci with the 4.125" crank. With the 4.25" crank you'd get 444.5ci.
If you want more horsepower, port the heads! Keith Craft can make 'em flow like the toilet bowl. Really, I hear he does very good work. Give him a call.
Now remember, the price for this advice is you have to keep us updated!
Elder User
Joined: Nov 2003
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Take a look a www.DSCmotorsport.com
As far as stroking your engine like Rusty said your options are to use a 410/428 crank and get anywhere from 410 to 422 cubes. You can get an offset ground 390 crank that has a stroke of 4.02 I think and uses chrysler slant 6 rods. Then Scat makes 410/428 cranks, I think they might have a 4.00 stroke crank and I know they have 4.125 and 4.25 stroker kits. The cheapest deal will be the 410/428 crank. Keep us informed.
As far as stroking your engine like Rusty said your options are to use a 410/428 crank and get anywhere from 410 to 422 cubes. You can get an offset ground 390 crank that has a stroke of 4.02 I think and uses chrysler slant 6 rods. Then Scat makes 410/428 cranks, I think they might have a 4.00 stroke crank and I know they have 4.125 and 4.25 stroker kits. The cheapest deal will be the 410/428 crank. Keep us informed.
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From: G-burg area in PA
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From: Littleton, CO
Post Fiend
Joined: Jan 2003
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From: Iowa
Originally Posted by Mike G
Edit: And it's back on the stand.
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From: Evanston, WY
Originally Posted by rusty70f100
Stroking it wont get you more horsepower unless it increases the compression. What it will do is move the power band lower in the RPM range and increase torque.
I agree that if you don't change the cam, and increase in stroke is going to move the powerband down the range. If, however, the torque at any given RPM goes up, so does the horsepower. Since HP is the factor of RPM and Torque, divided by 5252, increasing either input increases HP. If the cam is capable of feeding the cylinders, increasing stroke will increase Tq, and by extension HP, across the powerband. Increasing stroke doesn't mean that the engine can no longer make high-end HP, it just means that it may require a cam change to do it.
I am currently helping a local kid build a stroker 390 for his truck. We went to Doug at precision oil pumps to pick up a 4.25 stroke crank, 6.7" Big Block Chevy rods, and a set of 9.9:1 diamond pistons. We decided on the Comp 282S solid flat tappet, and Performer RPM aluminum heads and manifold. It works out to 446ci, and should be an animal.
-Scouder
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Lead Driver
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From: Texas
Originally Posted by rusty70f100
While reading through that, keep in mind that he's spent WAY too much money on what he wanted to do.
Edit: And it's back on the stand.
Edit: And it's back on the stand.
man, that really hurts....
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Lead Driver
Joined: Apr 2001
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From: Texas
Som bad luck, and some poor attention to detail on my part....
I'm just not sure what he meant by "spent way too much for what he wanted to do" . It's not easy to build an FE to power a 3/4 ton truck that should work like a truck and be quick at the track. I wanted to have my cake and eat it to....
I'm just not sure what he meant by "spent way too much for what he wanted to do" . It's not easy to build an FE to power a 3/4 ton truck that should work like a truck and be quick at the track. I wanted to have my cake and eat it to....
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You can and will, just stay at it and learn as much as you can I guess. I get along with pretty much everyone on here and no offense to anyone but all of us including myself (like a lower orfice in our body) have opinions.
Post Fiend
Joined: Jan 2003
Posts: 8,600
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From: Iowa
Greg: Well, how much you got into that thing now? I would have done things a little differently is all. Just bugging ya man, you should really be out driving that thing by now. But yeah, we all have bad luck at some time. I'm sure I'll get mine sometime soon, you can laugh at me then. What goes around comes around, you'll most likely get your chance sooner rather than later. 
On the HP / stroker issue, if you increase only the stroke, and keep the cam, heads, compression, and everything else exactly the same, the torque goes up (increasing horsepower) but the RPM that it is made at goes down (decreasing horsepower). So it's a wash. Try it in Desktop Dyno.
But in the real world, increasing stroke increases compression ratio 99% of the time. And that WILL make more horsepower. Plus, you usually put in a bigger cam, put bigger heads on it to feed the extra cubic inches, and those make more horsepower. Also, with a stroker motor you can make your horsepower at a resonable RPM, which is easier on the engine.
I guess I should have qualified it a little more.
On the HP / stroker issue, if you increase only the stroke, and keep the cam, heads, compression, and everything else exactly the same, the torque goes up (increasing horsepower) but the RPM that it is made at goes down (decreasing horsepower). So it's a wash. Try it in Desktop Dyno.
But in the real world, increasing stroke increases compression ratio 99% of the time. And that WILL make more horsepower. Plus, you usually put in a bigger cam, put bigger heads on it to feed the extra cubic inches, and those make more horsepower. Also, with a stroker motor you can make your horsepower at a resonable RPM, which is easier on the engine.
I guess I should have qualified it a little more.
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