Horsepower Estimate?
- Thread starter 3RD Duster
- Start date
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I don't think anyone has said anything like that, few are saying mid 300 hp and some are saying less than 300 hp, I find it hard to believe even a low cr 340 with a decent cam headers and airgap ain't somewhere in the 300's hp. Saying under 300 hp gross seems ridiculous to me.
What was the 340 6 pack rated at.
I see nothing in the op's build that would add another 50 hp over the factory 275, maybe 15 -20 extra.
The Rpm intake is probably good for another 5 hp over the 340 unit given the combo. camshaft maybe 10 headers maybe 10.
Don't compare a low comp 340 to a 68 340. two different animals.
They cut them off at 5K rpm. 340's would spin OK to about 5300 before laying over with a stock camshaft/head. So there is some HP not "reported", same as the 425hp at 5K on a Hemi.
That cam is somewhere in the high 230's @.050, Not 210 like the stock cam. It is not a small upsizing of the cam, that is a big move ~ 30* more duration at .050 than the stock stick. Worth a bunch more than 10hp over the stock cam, more like 50hp alone. It will use the intake better than a stock cam ever could. It will make some steam up top regardless of the crappy 8.5 compression ratio when using headers. I'd bet as long as the valvetrain stays stable, it would easily turn 5600-5700 in a 340 before dogging over. Lift is still OK for the limitations of the stock port. Touch up the port bowl and it would really shine.
And the 240hp number is a net number not the gross number of prior years. Gross was still in the 270+ rated range
Just my 2 cents.
That cam is somewhere in the high 230's @.050, Not 210 like the stock cam. It is not a small upsizing of the cam, that is a big move ~ 30* more duration at .050 than the stock stick. Worth a bunch more than 10hp over the stock cam, more like 50hp alone. It will use the intake better than a stock cam ever could. It will make some steam up top regardless of the crappy 8.5 compression ratio when using headers. I'd bet as long as the valvetrain stays stable, it would easily turn 5600-5700 in a 340 before dogging over. Lift is still OK for the limitations of the stock port. Touch up the port bowl and it would really shine.
And the 240hp number is a net number not the gross number of prior years. Gross was still in the 270+ rated range
Just my 2 cents.
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ir3333
Well-Known Member
Well...you have responses from young guys, old guys, dynomometers, racers, magazine arcticles and the
ratings the factory provided. I'm betting you're having a tough time deciding what your number might be.
ratings the factory provided. I'm betting you're having a tough time deciding what your number might be.
That's fine, I just totally disagree, if your right 340 got one of the shittest engines then.
3 if you're lucky.
Seems like he's got two choices agree with the ones that think a 340 can't respond to basic upgrades like cam intake and headers and think it makes under 300 or that it does and is making like around the mid 300's.
4mulas
Fixem'up
245 hp is net hp, when talking built hp most are talking in dyno trim, which at very least is no accessories best tune, generally headers. Most engines in dyno trim are at least 30 + hp gross above net.
25 degrees ain't a small cam upgrade, generally we consider about a 5 degree bump as the next size up that's 5 cam sizes larger. I'm sure there's more aggressive 235 cams that would do even better.
A low cr 318 with a 218 cam and 4 bbl in dyno trim does 282 hp, I'm sure a 340 with better heads, intake and 17 degrees of more cam gonna do a lot better.
Here's a stock high cr 340 with various upgrades, so say if you took 20 hp or so off each peak for lower cr and 1.88 valve.
If you look at that 360 video in post #6 it final stage of mods is similar to phase 6 of this 340 making around 385 hp but stock cr.
Phase 1:Stock 340 baseline, Chrysler electronic ignitionPhase 2:Replace small production AVS with Edelbrock 800 CFM carbPhase 3:Replace factory HP manifolds with Hooker 151/48-inch headersPhase 4:Replace factory iron 340 HP intake with Edelbrock Performer RPM Air GapPhase 5:Replace SSI springs and retainers with Engle #604LS retainers and #993 springsPhase 6:Replace stock 340 HP cam with Comp Xtreme Energy 268
https://www.motortrend.com/articles/mopp-0102-1970-340-high-performance-mill-dyno/
If you look at that 360 video in post #6 it final stage of mods is similar to phase 6 of this 340 making around 385 hp but stock cr.
Phase 1:Stock 340 baseline, Chrysler electronic ignitionPhase 2:Replace small production AVS with Edelbrock 800 CFM carbPhase 3:Replace factory HP manifolds with Hooker 151/48-inch headersPhase 4:Replace factory iron 340 HP intake with Edelbrock Performer RPM Air GapPhase 5:Replace SSI springs and retainers with Engle #604LS retainers and #993 springsPhase 6:Replace stock 340 HP cam with Comp Xtreme Energy 268
| Dyno Results | ||||||
| Westech Performance Group | ||||||
| Superflow Dyno | ||||||
| Horsepower | ||||||
| RPM | Phase 1 | Phase 2 | Phase 3 | Phase 4 | Phase 5 | Phase 6 |
| 3000 | 185.2 | 195.5 | 199.6 | 206.4 | 206.2 | 214.7 |
| 3200 | 195.4 | 206.1 | 213.9 | 220.7 | 220.8 | 229.3 |
| 3400 | 208.9 | 224.6 | 233.0 | 240.6 | 240.5 | 251.5 |
| 3600 | 224.8 | 238.7 | 252.7 | 260.8 | 259.9 | 275.7 |
| 3800 | 236.4 | 253.7 | 266.6 | 277.0 | 276.9 | 298.1 |
| 4000 | 249.5 | 267.6 | 280.0 | 291.8 | 291.8 | 311.7 |
| 4200 | 259.3 | 278.9 | 292.9 | 306.0 | 306.2 | 327.1 |
| 4400 | 265.0 | 287.1 | 304.3 | 321.3 | 321.3 | 344.6 |
| 4600 | 268.8 | 297.2 | 313.3 | 335.2 | 334.7 | 355.9 |
| 4800 | 274.7 | 306.8 | 321.1 | 343.1 | 342.5 | 366.7 |
| 5000 | 278.5 | 312.7 | 329.1 | 352.6 | 350.4 | 377.0 |
| 5100 | 280.2 | 316.9 | 330.6 | 354.5 | 352.4 | 381.3 |
| 5200 | 281.3 | 316.9 | 330.8 | 353.6 | 353.6 | 384.3 |
| 5400 | 273.7 | 314.9 | 329.3 | 350.8 | 355.4 | 386.1 |
| 5500 | 273.5 | 313.9 | 330.4 | 350.7 | 355.9 | 387.4 |
| 5600 | 269.3 | 314.5 | 330.2 | 350.9 | 353.5 | 389.4 |
| 5700 | 312.7 | 329.3 | 348.6 | 353.3 | 391.6 | |
| 5800 | 308.8 | 326.2 | 347.6 | 351.4 | 387.2 | |
| 6000 | 329.2 | 353.4 | 383.7 | |||
| 6200 | 314.8 | 373.7 |
https://www.motortrend.com/articles/mopp-0102-1970-340-high-performance-mill-dyno/
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BSB67
Well-Known Member
We don’t know the details or quality of the build, or the assembly, or the tune. Very best case IMO, 340 hp. Worst case, 270hp.
The OP is 2 hrs from three drag strips. Said differently, the answer is 2 hrs. away. And he’d learn so much more.
To the OP, if you want meaningful information on how the car and engine performs and what to do to make it better, go to the track.
If you want to tell people the hp, tell them the highest number stated on this thread. How would anyone know differently?
The OP is 2 hrs from three drag strips. Said differently, the answer is 2 hrs. away. And he’d learn so much more.
To the OP, if you want meaningful information on how the car and engine performs and what to do to make it better, go to the track.
If you want to tell people the hp, tell them the highest number stated on this thread. How would anyone know differently?
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nhra hp factor for the 340-6pk was 320
but wtf do they know only thousands of runs used to get that ratings
motors torn down to make sure they were correct
nhra 71 340 324 hp rating
68 to 70 nhra rating 310 hp
BSB67
Well-Known Member
For the blueprinted engine. Not even close to what we’re talking about here.
ir3333
Well-Known Member
273's dyno test shows a stock 340 at 280hp @5100 rpm. Factory rating was 275 hp
If you compare your build to these figures and adjust for your builds' differances you
should be pretty close to your actual number.
If you compare your build to these figures and adjust for your builds' differances you
should be pretty close to your actual number.
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BSB67
Well-Known Member
From Mopar:
marksmopar1
Well-Known Member
I have a 340 fresh off the Dyno, more compression 40 over and less cam, fresh 2.02 X heads. Pulled 355hp . I’d say yours with low compression but larger cam will be in the 325 range .. but every answer is speculation
I had a 73 Dart Sport 340. I had the engine rebuilt to 70 specs; steel crank replaced the cast iron one. The only issue I had was I had to replace the harmonic balancer and the timing chain cover. The late 340s had its top dead center mark on the timing chain cover on the driver side, where the early 340s had it on the passenger side. I also installed a Comp Cams 292, a 3500 stall Turbo Action converter and 4.56 Sure-Grip unit. That was one nice car to drive. It had a detuned 340, similar to the engine I had in my 69 GTS, and it had an automatic transmission compared to the four speed that I had in the 69. The 69 was a lot of fun to drive, but it wasn't very streetable.
I know a guy raced 50 plus years same cuda
Bought it brand new 69 cuda a56 340 auto
Not a blue printed motor
tried every cam every gear ratio every intake all the carbs
His final combo stock cam advanced abit tm5 single plane door stop 700 dp 50s street tires everything else stock including the mufflers quiet as mouse all you could hear was the motor 1 Hell of a sleeper car ran 13.1 for 40years
Basement filled with trophys from sunday racing at new england dragway
He had a stroke didnt race a couple years took it up for grudge night i saw it run 13.3@101 blowing black smoke out the cuda tips it bogged the carb was trash from sitting
Nothing but intake and carb on top of that its the intake everyone calls a door stop on here
ir3333
Well-Known Member
I think most call the original Torker a doorstop as well that being a single plane would rob lo rpm torque.I ran one in a stock 340 and it would blow the tires out easily at lo rpm and pull fine from idle up. Anybody can say anything on the internet and most mean well, but are often repeating things they have only heard. When you read a post that says "I tried this, and this is what happened" it may be more helpful.
Anyone want to give me a horsepower estimate? This is all I know about the 340.
1973 block
Bored 30 over
J Heads (probably not ported)
New pistons and rods (no idea what they are)
New lifters (?)
8.5:1 compression (could be higher...not sure about head gasket thickness)
474/280 purple cam
RPM Air Gap intake
Holley 650
Hooker Headers
So many unanswered questions and a way to small of a carb in my eyes. We don’t even know if the heads were given a valve job and a valve job on a set of stock heads can make or break the guessing game. I had a set of “stocker heads” on my bench and I know how they did what they did. I just don’t know the particulars of what they did.
1973 block
Bored 30 over
J Heads (probably not ported)
New pistons and rods (no idea what they are)
New lifters (?)
8.5:1 compression (could be higher...not sure about head gasket thickness)
474/280 purple cam
RPM Air Gap intake
Holley 650
Hooker Headers
So many unanswered questions and a way to small of a carb in my eyes. We don’t even know if the heads were given a valve job and a valve job on a set of stock heads can make or break the guessing game. I had a set of “stocker heads” on my bench and I know how they did what they did. I just don’t know the particulars of what they did.
BSB67
Well-Known Member
There can be 20-30 hp difference between a poorly done set of heads and a well done set. I’m not talking about porting.
Here’s an original Torquer intake on a touched up Speedmaster head. Before and after number on the “Ugly Torquer”.
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