NC Engine Builder
Grumpy Old Man
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Its application dependent, not a set in stone figure
Horsepower Estimate?
- Thread starter 3RD Duster
- Start date
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That's what they say here's a 8.5:1 650 hp vs 10:1 700 hp a 7.6% peak hp difference NA of two fairly close engines but at lower rpms the difference was smaller.
Anyone want to give me a horsepower estimate
Not enough!!!
Not enough!!!
RIGHT ANSWER! Says the man with two feet of daylight under his front tires...
Ant
Well-Known Member
654846648948595884212086559258853557890532689521808665330740135073680532075372076108636907512469065325700997645432223446668907664313417889076433244570975542226964948i06426075316890613749 ⅜ Horsepower.
ir3333
Well-Known Member
Stock hi compression 340's were rated at 275 hp and later lo compression 340's were 240 hp.
just compare yours to stock numbers. If you want another 40 remove the air cleaner, water
pump, alternator, and exhaust like they do on the dyno to get a max crankshaft total.
just compare yours to stock numbers. If you want another 40 remove the air cleaner, water
pump, alternator, and exhaust like they do on the dyno to get a max crankshaft total.
33IMP
Well-Known Member
Agree. And Wallace's numbers will be right. But I'll bet the o.p. won't be happy. Wallace numbers are for cars built and tuned for the strip. Street cars typically show poor numbers.
If o.p. does make a pass, I would ignore all the numbers except the mph numbers to determine power.
nhra hp factor for 340s based on mph run in the 1/4 mile for stock class racing are 295 to 325 hp
275 is a joke maybe with a plug wire pulled
How can anyone be a member here for 16 years and a mopar guy and not know better then that
340 A bodys had a nick name of big block killers and 275hp would not get that job done
68 to 70 340s stock tuned with a good carb not the stock pos carb make 330hp headers cam 360 hp head work 380 390 hp
71 340 had the good carb stock 325 hp as proven in stock class racing wiping the floor vs almost everything
The low comp 73 340 pos is still rated 290 plus hp by nhra what the comp loses the T/quad made up for
Just the facts
There no reason people shouldn't be able to estimate to a reasonable degree, based off 56 years of past 340 builds, other than possibly low ish cr he has a decent combo, all cr does is raise or lower the entire powerband a few percent.
I never cease to be amazed at how much dudes get their panties in a wad when debating the different variants of SBM lol.
We have this common fascination with a VERY niche engine guys, I hope you can remember that at times.
We have this common fascination with a VERY niche engine guys, I hope you can remember that at times.
ir3333
Well-Known Member
Sorry guys...i only know of 2 stock 340 builds.
One dynoed 276 and the other was 286 hp. The Dulchich stock rebuild was around 280 i believe?
The 71 engines with the 800 thermoquad will gain another 15 hp and could eclipse 300 hp above 5000 rpm.
...and i think the earliest 340's only had a 565 cfm carb, but that is something i read.
One dynoed 276 and the other was 286 hp. The Dulchich stock rebuild was around 280 i believe?
The 71 engines with the 800 thermoquad will gain another 15 hp and could eclipse 300 hp above 5000 rpm.
...and i think the earliest 340's only had a 565 cfm carb, but that is something i read.
The drag strip doesnt lie
mph run weight of car= hp
nhra is the final word
2 rebuilds vs 10k drag strip runs under class rules buy the national hot rod association
ir3333
Well-Known Member
I stand corrected, disregard my posts guys.
Lol
People get but hurt in a hurry with the truth. I do believe an optimized purely stock engine would probably make around 300 HP. Stock.
ir3333
Well-Known Member
Here's one for you numbers guys.
69 dart with a 340, 3.23 gears, 215 70R14 tires and stock converter at 3400 lbs. 14.05 @98 mph
What would the dragstrip calculated hp be?
69 dart with a 340, 3.23 gears, 215 70R14 tires and stock converter at 3400 lbs. 14.05 @98 mph
What would the dragstrip calculated hp be?
Ironmike
Well-Known Member
might as well my 2 cents in.
I think on a calibrated dyno..........248 at the crank, after some minor tuning pulls. That cam and compression are NOT "best buddies"
But who cares? If it runs well and doesn't leak........enjoy it!
I think on a calibrated dyno..........248 at the crank, after some minor tuning pulls. That cam and compression are NOT "best buddies"
But who cares? If it runs well and doesn't leak........enjoy it!
If the cam is cut on a 108 LSA, put it in at 100-102. That will get some grunt back out of it.
Should make in the 300-350's when tuned up properly
If a 360 with 9.5 compression and a xe268 makes roughly 350, this should be just fine around the same neighborhood.
Should make in the 300-350's when tuned up properly
If a 360 with 9.5 compression and a xe268 makes roughly 350, this should be just fine around the same neighborhood.
I don't know what a high cr 340 makes hp wise, I don't think it overly matters, but net rating is fairly reliable number, most engines seem to make at least 30 hp more hp in dyno trim over net rating so that would be around 275 hp gross for the low cr one, so I highly doubt the high cr 340 don't make more than the low cr, 300 hp sounds about right too me.
290
Well if a 340 can't make 300 hp with a decent cam, headers and airgap, then the sbm is a pretty shitty engine then.
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