new mopar muscle magazine 340 dyno

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No surprise here the 340 was always under-rated except to those who own them..and here is a perfect example of why to run headers they picked up 32 h.p. by just swapping out the factory exhaust manifolds..I've always said 340's rule!!!
 
340's were always said to be around 325 HP really, they were notoriously underrated for insurance or whatever reasons. AJ/ FormS recently wrote something very appropriate about this. So the results at HRM are not surprising. Also consider that the rebuild for the magazine probably was to much better specs than back in the day...
 
Good read. I'd say they picked up a little power with quality machine work, the bowl cut, roller rockers with the correct ratio and the 40 ounces they took out of the rotating assembly.
 
justinp61 said:
Good read. I'd say they picked up a little power with quality machine work, the bowl cut, roller rockers with the correct ratio and the 40 ounces they took out of the rotating assembly.
Click to expand...
Yeah, to be frank, they are underselling the impact of the bowl cut, stainless valves, & rockers on the output. But, it is a standard updated style rebuild w/a relatively small
cam so, still good numbers all in all.
 
did the factory test with an air filter, fan, mufflers, alternator, fuel pump-about 30 hp
 
Better machining, roller rockers closer to a true 1.5 ratio, and a bunch of other stuff will boost the HP output. Stock stamped rockers are lucky to have a 1.4 ratio in lots of cases.

If these thing in OEM configuration REALLY made anywhere near 325hp, why did none of the stock test ever have any of the A body cars running 100+ MPH?
 
Well, will I'd say for starters, the dyno engine didn't have all same parts the installed engine did as well as heavier than actual weight listed for the test car vs. what you yourself drive. There is also the pro driver with the pro runner "Super Tuning" the engine for what it is worth.
Just sayin....
 
NHRA factored the HP in the 340s from 299 to 320, so not far off the mark.
 
How often do you really see a true apples to apples comparison in a magazine engine test? There's almost always some improvement.

Funny how they had clearance issues at the retainer, and then used beehive springs to bandaid the problem. Maybe fixing the geometry would have taken care of that, too. Any problem in this pic with the same rockers, and standard springs?
0503161102.jpg

I've never had anyone tell me they had clearance issues after correcting the geometry this way.
 
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