Cheapest way to make 300 crank hp from a 5.2 magnum

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Rockerdude

Rockerdude

Rock n' Roll and A-bodies
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Hey guys, I'm getting ready to really tear into my 5.2 and start doing some upgrades. I already have an air gap intake on order, and I'm planning to use this cam http://m.summitracing.com/parts/cca-20-746-9 . I also plan on using the exhaust manifolds of of this motor, which should flow pretty well. I plan on having the heads cleaned up and replaceing the springs, I might attempt a gasket match on the intake and exhaust ports. Anyone have some input?
 
I think you'll need to put some more work into those heads and look for a good set of headers.
 
I would run hedders, but in my engine bay (early-a) space is limited. I have 273 manifolds on my 318 with 360 heads in the car now and they suck flow wise.
 
If you do not have power steering, you can use the Dakota manifolds with the 2.125" opening. They were only available in the early 90s but also in the 1500 trucks as well. I think with those manifolds you'll be spot on the 300 mark with everything else you've mentioned. The magnum heads are good pieces. With headers, it would be a no brainer for 300 HP.
 
300 crank from a 5.2 is supper easy. I think an air gap nice carb, headers, nice exhaust system and a small upgraded cam will do the trick no problem all for under 1g
 
Fst73_360 said:
300 crank from a 5.2 is supper easy. I think an air gap nice carb, headers, nice exhaust system and a small upgraded cam will do the trick no problem all for under 1g
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Puzackly.
 
Awesome. My thoughts exactly. Thanks for everything!
 
StrokerScamp said:
If you do not have power steering, you can use the Dakota manifolds with the 2.125" opening. They were only available in the early 90s but also in the 1500 trucks as well. I think with those manifolds you'll be spot on the 300 mark with everything else you've mentioned. The magnum heads are good pieces. With headers, it would be a no brainer for 300 HP.
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The manifolds I have are off this motor originally, they are from a 1996 Ram.
 
Rockerdude said:
The manifolds I have are off this motor originally, they are from a 1996 Ram.
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Measure the outlets on them. If they are 2.125, they are the good ones. Even if they are not, they are still much better than the original early A V8 mannyfolds. I would use them regardless.
 
The heads get extremely narrow on the pushrod pinch area. I spent several hours porting a set that are on my 97 Ram 5.9. Gasket match, smooth the pinch so it is a ramp instead of step, and there was a lot of material under the valve seat.

The exhaust manifold is a ball and socket style, and even though the opening is smaller, there is a LOT of meat here. I would think the could be opened up quite a bit. While the log style of the manifold is more restrictive then headers, a gasket match, and open the collector would at least ensure that these areas are not limiting any more then needed. Consider a new timing chain, I have put two on this motor, both were loose and sloppy way too soon.
 
Thanks again guys, I will likely use a good quality double roller chain in my motor.
 
5.2 magnums make 235 net hp which is around 300 gross hp, most engine ran on a engine dyno are gross power numbers, airgap, duals, mild cam swap stock cams have little lift.
 
Fst73_360 said:
300 crank from a 5.2 is supper easy. I think an air gap nice carb, headers, nice exhaust system and a small upgraded cam will do the trick no problem all for under 1g
Click to expand...

Read below, headers are not part of the program.

Rockerdude said:
I would run hedders, but in my engine bay (early-a) space is limited. I have 273 manifolds on my 318 with 360 heads in the car now and they suck flow wise.
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No head work needed except lift clearance. The retainer to seal should be checked and clearances made if need be. The 1.6 rocker ratio ... is it figured in with the lift mentioned? I see it sez roller cam. So, I'd like to assume it is a cam for the Magnum engine/head.
Porting wise. Leave the heads alone. Use the parts you listed and you will have what you want.

As far as exhaust goes, off the exhaust manifolds you'll be running, just do it simple. Dual exhaust with a X or H pipe @ no larger than 2-1/2. Mandrel bent if possible.
 
You should be able to hit your goal with that cam.
 
rumblefish360 said:
Read below, headers are not part of the program.




No head work needed except lift clearance. The retainer to seal should be checked and clearances made if need be. The 1.6 rocker ratio ... is it figured in with the lift mentioned? I see it sez roller cam. So, I'd like to assume it is a cam for the Magnum engine/head.
Porting wise. Leave the heads alone. Use the parts you listed and you will have what you want.

As far as exhaust goes, off the exhaust manifolds you'll be running, just do it simple. Dual exhaust with a X or H pipe @ no larger than 2-1/2. Mandrel bent if possible.
Click to expand...

Then 340 manifolds?
 
He already has the Magnum manifolds. The best Magnum manifolds are what stroker was talking about. According to the MP engines book, use one of each though I forget which one from each engine is to be used.
 
I saw a dyno and a story somewhere years and years ago, when I was a kid, someone took a stock 93 5.2, tore the injection off, added a air gap, and a mopar electronic ignition, and got 270HP......... I remember they used to brag the 318 had more HP than the 454 of certain times...... of course, the 454 had more power, in the real world, but, still..........

That's nothing to scoff at.

However, anyone who has owned a magnum 318 knows that it is weaker than a stale jar of kool aid until 3000RPM or so....... That's what happens when you put big heads on little motors, but, they went cheap.... (same reason an old 2bbl 318 would outpull a 4bbl 327 truck engine, when the going got heavy. small heads, torque. my 95 Dodge truck, like any 318 power truck with 3.55 gears and 16" tires, won't push the truck on flat ground in OD with a 15MPH mile head wind...

But, you're looking for HP and higher RPM performance, 1800RPM power doesn't matter to you.

OK, I'm done rambling, I'm tired, gnite.
 
Alrighty, so I ended up having my stock cam reground to .224/224 at .050 and 496/496 lift at 1.6 with a 112 lsa. Also decided to do a bit of porting on my stock heads with my friend Logan, nothing too fancy, just cleaning up the guide bosses and some smoothing here and there. Possibly also gasket matching both intake and exhaust ports. Pushing for 1hp per cube at the flywheel!
 
1 Hp per cubic inch shouldn't be a problem, 10:1 and headers would put you close to 400HP. Since your gonna do some porting I'd port the manifolds as well.
 
I'm sure you want a pump gas motor. At 10:1 you won't have one, not even with Magnum heads. Be careful there. Most I'd go would 9.2. The .8 difference won't be worth it in power and you'll have an engine that needs to be spiked with race gas or octane booster.
 
I wasn't recommending 10:1 just meant the 400hp 318 recipes out there he has cam, intake and head flow just lacking 10:1 and headers so 318Hp shouldn't be a problem.
 
273 said:
I wasn't recommending 10:1 just meant the 400hp 318 recipes out there he has cam, intake and head flow just lacking 10:1 and headers so 318Hp shouldn't be a problem.
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I gotchya. He COULD do 10:1 on pump gas but then you're talkin about the expense of settin up quench and all that.....that's a rabbit hole sho nuff. lol
 
No 10 to 1 here, maybe more like 9.2 to 1 after some head milling.
 
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