Real 440 HP ratings

[Mean 318]

I have herd for insurance purposes that Chrysler used to under rate the horse power their motors put out, I am just curious how much hp the stock 440 put out, and how much the 440 HP 4bbl put out. Chrysler says 350hp, and 375hp.

[mally69]

i have always heard that but i think they are close to what there rated from the factory

[Ghoste]

Some of the Mopars were certainly underated but it likely had as much to do with trying to pull one over on race sanction bodies as anything else.  The Race Hemi and 340 leap quickly to mind.
Chevy was notorious for grossly overating the street engines and grossly underating the race engines but I think those two 440 figures are pretty close as well.

[max]

i kinda have mixed thoughts on that. on one hand i have "read" that the 440 hp was a 410 horse power and the 440+6 was actually 430 horse power.

i always thought those #'s were a bit high but also looking back at the early 426 wedge single 4bbl engines, they were rated at 365 horse power.

so it's hard for me to believe they went from 426 cid 365hp to a larger 440 cid with better heads and only picked up 10 hp.

i guess we will never really know.

[Ghoste]

I know I have a magazine article here somewhere (I'm thinking one of the last issues of Musclecar Review from the late 90's) that compared a number of muscle car engine ratings to a real life standard.  I'll try to find it but my "archive" is more than a little unorganized so wish me luck.

[mally69]

what somone should do is build a 440 to all factory specs and simply dyno it

what do you guys think

[Ghoste]

We'd still find a way to argue about it. 

[Chryco Psycho]

the 340 & hemi were under rated & have proven so on the dyno the 440 seems  to be relatively close , the last 440+6 I built made 125 more HP than rated from the factory & still used stock exhaust manifolds etc & looked stock   

[Ghoste]

So you're cheating? 

[mally69]

yea

[Chryco Psycho]

Oh yeah , stock is boring !!

[Rolling_Thunder]

I know my 383 is relatively stock...      9:1 compression, headers, aluminum intake and 750 carb...  makes 273rwhp ....      not alot...     but remember the 383 was rated at 335bhp in 1968....       this was with 10:1 compression and without any accessories being driven...     


one question -  does the change in hp rating system effect what real world numbers are today as oppose to what the "book" says they were back then?     say my 273rwhp is  315hp at the crank...     how does that compare to the factory rated 335?   

[Chryco Psycho]

really the # is just an indicater of what it is making , gross was an optomistic # at best , the dyno I use reads low so generally RWto Gross is approx 1.6 , so 273 on his dyno would be approx 435 gross HP , net hp is somewhere between RW & Gross HP