340 4 barrel and 340 6 barrel: were they really UNDERrated?
- Thread starter Kern Dog
- Start date
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Jersey Devil
Well-Known Member
Yes they were under-rated but they Obviously "Sensationalized / Inflated" being a MOPAR magazine. Also, probably had Open full length headers, Fully tuned Carbs and Ignition, Bowl work, Roller rockers, No filter element, electric water pump and no accessories. LOL. 340 six pack was a 325hp+/- engine. 340 4bbl was probably a 300hp engine.
That's the problem with gross hp rates what is an acceptable way to measure gross hp ? Obviously not roller rockers and bowl work, but no filter, electric water pump, full tune are generally how most engines are dyno'd. Headers are mostly used to but debatable if fair for measuring an old muscle car engines factory rating.. I say headers are fair if you dyno all the old engines the same way, Like the video I posted in post #6 340 vs the world (the 340 cam made that test partially invalid)
Why? I'm not trying to be argumentative, I just wanna learn sumffin cause I don't see it.
Jersey Devil
Well-Known Member
It's impossible to retest them now as blue-printing the engine will free up HP and no one can set the carbs/ ignition exactly to factory specs. Even rebuilding them with " Reproduction parts" isn't the same. I think the most honest rating are what NHRA imposed on "Stock" engine HP Ratings. I've read it was 328hp for the 340 6pack, 299hp- 314hp 340- 4bbl. depending on transmission. The article also said that Low compression 8.5cr in the 72-73 340 where NHRA rated at 285hp. The article also said the 440 6pk was NHRA rated at 417hp.
The 340 is a legend, and I love them. But they are still picking up ET from the factory as the years pass by... Used to be low 14's.. then somebody got one to go 13.9 - from the showroom! But, as years go by, the ET has been dropping on factory 340's... Won't be long we'll have a few out there turning 12.7's from the factory showroom floor!!
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The ones I really like and respect are those FAST cars. I know they're not stock, but to get cars to go that quick on stock tires is nutty.The 340 is a legend, and I love them. But they are still picking up ET from the factory as the years pass by... Used to be low 14's.. then somebody got one to go 13.9 - from the showroom! But, as years go by, the ET has been dropping on factory 340's... Won't be long we'll have a few out there turning 12.7's from the factory showroom floor!!
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we are 20 years away from the 340 Duster running those numbers... from the factory!! !! !!
Don't forget about the 360 Duster. In the article above from CC they ran a 727 360 w/3.55's at 14.60. But what if it had the optional 4-speed. Gearing was way better, and even though it didn't come with 3.91's add that and what will the ET be? 13.99 most likely
ET is meaningless, the MPH is the only indicator of output. Same track-same car-same driver-same conditions-same tires,....how often does that happen?? Those will all affect the MPH, but track/elevation/conditions (provided the proper elevation tune), hold the greatest influence. Among conditions, temp & high winds, tail or head can make You a hero or kill You. With the miserable tires they had to run, a lead foot & poorly prepped track(much more common "back in the day") could lead to very consistant poor times & speeds.The 340 is a legend, and I love them. But they are still picking up ET from the factory as the years pass by... Used to be low 14's.. then somebody got one to go 13.9 - from the showroom! But, as years go by, the ET has been dropping on factory 340's... Won't be long we'll have a few out there turning 12.7's from the factory showroom floor!!
The thing about the 340 cars is they just hit the ground running. Chrysler really had a a very good small block runner that they put in cars with good weight distribution strong rear ends and arguably some of the best transmissions available by any manufacturer. They were quick winding and weren't so heavy on torque that you couldn't hook them up fairly easily when I used to street race I never got beat out of the hole. Sure there were some cars out there that would do it but none I raced. So i just caught so many people by surprise not one GTO or Mach 1 or roadrunner or 442 ever thought a little Dart swinger had a chance but before they knew it they were almost two car links in the dust but they had to make up. When you started beating some of the street bullies the 340 reputation and legend was sealed.
I'm just going to say.. to those that keep repeating ET is meaningless... ET is not meaningless. Heads up race, if I run a 13.0 and you run a 13.9 - you lose the race! Period. i don't care if I go 101 mph you go 107 mph. You lost. You pay for pizza! The hot chick gets in my car to get to the pizza! Our friends laugh at you while eating the pizza!! But in the end, we all ate pizza! LOL just saying, it's not meaningless.
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I'd burn that article, no chance in hell the 8.25" is lighter than the 8.75" rear by 30#, or any#. With clutch pedal & linkage/bellcrank, return spring, over center spring, t/o fork, shifter assy & linkage, I don't believe for a second a 4-gear is (-)30# either. There is almost -0- weight difference between a 23 & 18 spline A833, the material strength & manner the gear teeth are cut, & bearings are the only difference.
and this is why we talk about the "car". NO ENGINE races down the track by itself. Has to be in car. Put a stock 340 on a dragster and it will MPH/ET much faster. But it's not on a dragster. It's in a Duster. And from the factory, it's the car that goes down the track, not just an engine making MPH. So, we have to talk the entire package. That package is what makes the ET, regardless of what MPH it ran.
You're insinuating that 'good ole' memories' are making them faster than they really were, when that's just not the case, & the "legendary output" would've been proven by the average MPH's recorded at the time....not the ET's. Thousands of those 340's were raced all over the country, You can spin the bujeezus out of the tires & run a 15.50 in a car capable of running mid twelves, We're discussing apparent power output 'in the day'.
I get that. However, many of these pages are about "what it ran off the showroom floor". I was addressing that. As I stated somewhere in this thread, MPH show "potential ET". I don't think they rolled off the showroom floor in "full potential" form.
Lol, that's a fact, most of the crew I hung around were far from running full potential in the early '80's -'90's....We ran whatever tires We'd scrounge up, few of Us put cheater slicks or slicks on until later on...when You're running high 13's on street tires @110mph,......You leaving just a tick on the table....lol.
110 mph would be 12 flat ideally... but time lost in the 60 ft (and beyond) cannot be made up for the rest of the way. It's time lost...
With a pair of M&H Racemaster D.O.T. 295/50-15's that Olds ran 12.25-12.30. It will still spin them some....
Rear axle weight is one of the last things to worry about when dealing with an automotive unit.
One weighs more and is more efficient, all a trade off.
Same as guys complaining about putting an extra wire run in a car, making it safer... but but but it's 5 more pounds, from a guy that weigh close to 3 bills. Hysterical stuff.. If you aren't running an index car, eat fewer cheeseburgers, the car will pick up more from you at 2 bills than 3 and the car is safer.
Chassis is the limiter for the muscle car era showroom cars, end of story. They have plenty of steam to run low 13's (340's), some into the 12's (440-6/Hemi an A12 hit a 12 IIRC), not likely going to happen as they rolled off the floor.
One weighs more and is more efficient, all a trade off.
Same as guys complaining about putting an extra wire run in a car, making it safer... but but but it's 5 more pounds, from a guy that weigh close to 3 bills. Hysterical stuff.. If you aren't running an index car, eat fewer cheeseburgers, the car will pick up more from you at 2 bills than 3 and the car is safer.
Chassis is the limiter for the muscle car era showroom cars, end of story. They have plenty of steam to run low 13's (340's), some into the 12's (440-6/Hemi an A12 hit a 12 IIRC), not likely going to happen as they rolled off the floor.
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Jim Lusk
Well-Known Member
Ok, so ran the formula on my wife's 68 GTS convertible that I drove horribly one night at Baylands in Fremont, CA. Specs were STOCK '73 short block, 2.02 heads, stock '68 intake, factory exhaust, Direct Connection ignition, STOCK 727, 3.23 open 8-3/4. I spun badly deep into 2nd and shifted late on both shifts. Ran a 15.50 at 92. By that formula the car was capable of running a 14.38. Perhaps...on a perfect day with a perfect driver...
So, with 3.23's and stock converter you won't optimize the math. 92 mph with an optimal 60 ft would get you that. So maybe a 3600 stall and 4.10 gears w/slicks. The way your car is set up, I'd say 92 mph should get you high 14's to 15 flat. Most car that aren't bracket cars won't reach that math.
My Duster ran 105 mph @ 12.8's. Math says I should be running 12.5's. I too have 3.23's with a stock converter. It's hard to hit the math without a great 60 ft time for the combo.
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Jersey Devil
Well-Known Member
True, MPH shows Horsepower in the form of lbs/HP. ET, just shows you, " How well" you are using that HP.
That's a known fact way back in the 80s. I have plenty of magazines from that time explaining it.
This is easily Proven by the fact that chassis tuning, gearing, etc has a Big influence on ET and not much on MPH.
Using a HP based on ET, will show how much pf your power is effectively being used.
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