72 340 Dyno Numbers

[bandt]

Thought I would post these numbers for reference.

1972 340 block- bored .030 over, pistons replaced with 1970 stock higher compression, stock cast crank
RHS LA-X heads 2.02 intake valves, 1.65 exhaust, 62CC closed chamber
Proform 650 carb, Edelbrock Air Gap intake
Hughes 223/228-.506/.524 lift cam
1 5/8 headers
#'s were 335 h.p. 371 tq. at the rear wheels. Dynoed with a Doug Nash 4 speed and Ford 9" rear end. I think the carb is undersized now should have went 750 but I just got the carb last year. Crank horsepower would be about 10% more.

Its almost a 30% increase over the stock heads with 1.88 intakes and old mopar .484 cam that was in it before.

Brian

[brads70]

Sweet! 

[Chryco Psycho]

with the Proform carb you may actually be ok , you could redyno with a borrowed larger carb , but most of the HP gain would be up high in RPM & might be 15 HP more .
 Those are good #s & gains , must be a blast to drive now !!

[bandt]

Runs strong now. Was hoping to hit the 400 hp. mark but for a hydraulic cam these numbers are good. Basically it was a simple head and cam swap so I'm pleased with the results.

Thanks for your help along the way Neil you've been a great resource. Only thing left to do now is stroke it.

Brian

[Road_Runner]

Thanks for sharing this info.  I'm weighing my options between building my original 318 or dropping in a 340 with a similar build to yours.  I'd like to stay with iron manifolds for that stock 'look' and like you I'm considering stroking it if I go with the 340.  What are you running the 340 in, and how would you say it runs compared to any modern muscle cars: mustang/camaro/challenger you've driven or ridden in?

Later, Jim

[bandt]

Hey Jim,

Its in a 72 Challenger with a 727 behind it.
The 727 is a manual valve body slap stick shifter with a 4.10 gear. What do you mean by "compare"? Like are you talking power wise or handling? Hard to compare they are very different animals. Been in a couple Vets a 5.7 Hemi Charger R/T. These cars handle better have better top end and do things effortlessly.
The power of my car is decent it can blow the tires off without brakes, it does things with a lot of drama, tire smoke and noise. I wouldn't trade my 340 for something modern right now. Thats was part of owning an old muscle car for me, its loud and obnoxious. Doesn't look or sound like anything else on the road. I love it when I stop at a light and see the odd car guy roll down his window just to hear it better. As far as power and handling any one of the modern muscle cars could run circles around it. I'm fine with that when I drive past a car lot and see 5 more just like theres.

Brian

[Road_Runner]

Hi Brian,

Sorry I was so vague, I know there's no way our cars are going to hang in the corners with Vettes, etc. at least not without making them full track cars.  I was mainly asking about how hard it pulls away from a stop sign, is it fun to drop the hammer on and does it do everything you expect of it?  All subjective stuff really. I know everyone's expectations are different but I've never driven a 340 car, always had big blocks, so I'm trying to decide how worthwhile changing out my 318 for a 340 will be.  Based on your comments you couldn't be happier which tells me all I need to know.

Thanks, Jim

[bandt]

Sorry, yes very pleased with the results.

If you were to go with a stroked 340 you would not be dissappointed. Built right they can make some big numbers well into 400's and high 400 tq. at the rear wheels. Strokers need to breath so a good flowing head, 1.6 rockers and a roller cam are all well worth the money.


Brian

[Road_Runner]

Sorry, yes very pleased with the results.

If you were to go with a stroked 340 you would not be dissappointed. Built right they can make some big numbers well into 400's and high 400 tq. at the rear wheels. Strokers need to breath so a good flowing head, 1.6 rockers and a roller cam are all well worth the money.


Brian

I would definitely go for some strong numbers if I build the 340, but the one issue is like you said it would want to flow some air which realistically would force me to go with headers.  I don't know that it would make sense to build up a big motor and stay with stock manifolds.  Enjoy your motor, sounds stellar.

Later, Jim

[Chryco Psycho]

Thanks for your help along the way Neil you've been a great resource. Only thing left to do now is stroke it.

Brian

Anytime Brian , I am glad to help & I am glad you are happy with the results .
 400 RWHP is really tough  to get .

[72bluNblu]

I know there's no way our cars are going to hang in the corners with Vettes, etc. at least not without making them full track cars.

I think you would be surprised.

Our cars are capable of ~1G on the skidpad with the right set up. The Hotchkis E-max car pulled .93G on the skidpad, compared to .84G for a stock 2010 Challenger SRT8. Braking was only 5 feet longer for the '70 vs the SRT8, and 600ft slalom speeds were within 1mph.  ( Article is here http://www.insideline.com/dodge/challenger/2010/2010-dodge-challenger-srt-8-vs-1970-dodge-challenger.html

And for the most part, the Hotchkis car is just running the Hotchkis TVS system for suspension, which is still just a torsion bar set up with a leaf spring rear.

[johannes]

  Those are very nice numbers....   
What type of dyno was used to obtain these numbers?
 http://en.wikipedia.org/wiki/Dyno#Chassis_dynamometer

For comparison reasons, any chance you can show us the TQ-RPM curve plot?

[bandt]

Sorry not sure what make of Dyno it was.

 It is a neat set up these guys have. They have a rig they built to couple the engine to a 4 speed with a ford 9" with Good Year drag slicks strapped down to there floor dyno. Everything at there shop is Dyno'd RWHP not at the crank. They calculate powertrain loss at about 10% with there set up. I realize my 727 is going to have a bigger loss to turn.
They broke my cam in then we did pulls mostly to dial in timing. We did probably 7 pulls but I forgot the graph there.
I have to go back to get my idle set up on there wide band. I'm running rich but there was no point trying to set up idle on a 4 speed when its going in a auto.

Brian

[Chryco Psycho]

I would guess the losses would be higher , the 9 " is a horrible power eater

[bandt]

That works for me Neil the bigger the loss on there set up the closer to the actual loss on mine.

Brian