390 cubic inch stroker can someone explain me this ??

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ValerianMagnum

ValerianMagnum

the little car that could
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heres a video that i found on youtube , how can a 390 stroker make this poor amount of horsepower whren a stock 5.9 carbed can reach 320 hp and 420 ft pounds of torque , my 380 hp crate is a 9.0 compression ratio and kicks out 410 hp and 440 pounds of torque ,

video description : and link : [ame="https://www.youtube.com/watch?v=JZuDj9VvfDI&feature=youtu.be"]Dyno pull of my 318 stroker (390) - YouTube[/ame]

Dyno pull of my 318 with a 4" stroker kit, bringing the displacement to 390 cubic inches. It's a very simple and mild street engine combo, consisting of 9.3:1 compression, a mild hydraulic cam, and bowl ported but otherwise stock iron magnum truck heads. It made 367 HP @ 5,300 rpm, and 407 foot pounds of torque @ 4,100 rpm. This engine is going in my 1989 Jeep Wrangler. Special thanks to Performance Only in Delray Beach, FL for the excellent machine work, building of the engine and tuning. Thanks to Eddie "Elvis" Miller at The Engine Works for working the dyno and providing tuning assistance.

Cam specs :

http://www.jeepforum.com/forum/f22/magnum-force-mopar-mans-build-1412306/index5.html


For that amount of money i would be very disapointed to have that power , the cam looks okay , compression is there , intake , headers ... what can be the reason of this poor amount of power , thx !
 
I just looked at his location. 4000 feet in altitude would account for a loss in power. Unless he plans to take the jeep elsewhere after his hitch he would have been best off to bump the compression a little. All in all, I don't think 367 HP at his altitude is all that bad out of a 318. I also didn't see the carb listed.
 
A crappy designed engine.
 
I'm gonna start with, "Wrong cam" and what was done to the heads? At 390 cubes, I would expect a little more myself. But, what the heck do I know?
 
Not sure what intake and carb is on there, the cam should be big enough to make well over 400HP. I don't know what the altitude correction should be and that doesn't look like the best dyno setup I have seen maybe it's stingy?
 
Maybe they were looking for a happy medium between power and economy.Grunt for the Jeep maybe?
 
Darter6 said:
Maybe they were looking for a happy medium between power and economy.Grunt for the Jeep maybe?
Click to expand...


Entirely possible. The torque figure is pretty respectable. Would be good in a Jeep or truck.
 
First of its a good thing we dont race flow or dynobenches,second with all the inflated numbers floating around, that build feels like a fresh reminder of reality:)


I would not have expected much more power out of that engine,especialy considering the altitude and small heads. look at it like this put a real good set of heads on that thing and watch it make a bunch more power at higher rpms but it would also become a whole lot more sensitive to gear and converter use.
 
He's running stock heads with mild porting that's why. The engine can't breathe, I can hear it in the dyno pull. I bet if you looked at the dyno print out, the volumetric efficiency would be low.
 
That engine will be a great 4x4 motor, torque rules off road.

For what it is worth, a guy at work bought a blueprint 408 and the dyno sheet said 376 hp.
It actually runs nice in his 71 dart, good usable street power, it fries the **** out of the tires.
 
That engine was dyno'd in FL at sea level. That was a little awkward seeing Dan up and walking...
It's a small cam, small hedd engine. If you don't feed the cubes, they don't make the power. With Dan's machining it was not any problem with machining or assembly, and Elvis knows how to tune them. It's not a poor design, it fits HIS design.
 
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