How many HP is my 340 pushing?

[FredD]

Previous owner did not care about HP power, I do!
That being said, there is no Dyno anywhere close to where I live and I am really wondering how much HP my moded 340 might have.
I Have a 1968 340 X head bored 60 over, 10:5:1 compression, flat top pistons, forged crank, Mopar intake, Mopar performance cam lifter, 750 double pumper Holly carb and Holley Hi-Tek Air Cleaner, Jacobs ignition and borla exhaust. Not sure about the headers.

Car is a 1972 Dodge Challenger Rally.Transmission: 727 auto with shift kit, 355 sure grip with 3.50 gears.

So what do you guys think, I understand it wont be accurate, but if I could at least get a ballpark figure.
Thanks

 

[moparleo]

Too many variables to guess like timing, jetting, cam specs etc... .060 is a lot to overbore a 340 block. Hope it was sonic checked before the build. Get a fan shroud and keep an eye on engine temps.

 

[Adam]

You could try one of those desktop dyno apps; or you could take it to a drag strip and run the 1/4 mile, get the car weighed and that will allow you to compute the HP.

 

[FredD]

You could try one of those desktop dyno apps; or you could take it to a drag strip and run the 1/4 mile, get the car weighed and that will allow you to compute the HP.

Yeah no 1/4 mile close by either, there is sort of a 1/8 mile though.

 

[FredD]

Too many variables to guess like timing, jetting, cam specs etc... .060 is a lot to overbore a 340 block. Hope it was sonic checked before the build. Get a fan shroud and keep an eye on engine temps.

Engine is running very well and it's running very cool with only a belt fan, although I have a big radiator. Do you think I'm still in the 300 or 400 range? I find it is hard to tell because it sounds like I'm in the 500 range

 

[RUNCHARGER]

I would guess 300, but it's only a guess. Your 1/4 mile speed will tell the tale.

Sheldon

 

[Cazbah362]

350 +/- 25, cam, intake and work done to the heads would be the true factors in building HP for the consideration. Basically your description sounds like a stock 340, little more compression and cubes. You will get varying opinions here, but that is my guesstimation."

Really with that HP, that little E-Body should scoot. From what I have learned, putting the power to the ground efficiently will yield more than just HP and bolt-ons.

Nice ride and have fun.

Cp

 

[FredD]

350 +/- 25, cam, intake and work done to the heads would be the true factors in building HP for the consideration. Basically your description sounds like a stock 340, little more compression and cubes. You will get varying opinions here, but that is my guesstimation."

Really with that HP, that little E-Body should scoot. From what I have learned, putting the power to the ground efficiently will yield more than just HP and bolt-ons.

Nice ride and have fun.

Cp

I believe quite a lot was done, I still haven't got through the pile of receipt that came with the car, I'll look if I can maybe find more info and will update this post. Right now, unless I can race it, like other members have mention, I find it hard to guess or compare to my previous cars. But I tend to agree with your guess of 350 +/- mind you it seems faster then my 411 hp raptor.....maybe I should race my wife in the Raptor and find out

 

[Cazbah362]

I like the racing theory, but there are many factors. I've seen low HP cars make great times just due to their "setup." My stock SRT feels like a monster, but is only a high 13 low 14 second at the track. I live at 6600 feet, computer helps a lot.

Let us know if your wife whips ya, video is always nice.

And if you find out about those heads, let us know. Sounds like someone did a nice job on that motor.

 

[RUNCHARGER]

Your Raptor is probably 1500-2000 lbs heavier than the Challenger. That can feel like 150 HP.

Sheldon

 

[moparleo]

Engine is running very well and it's running very cool with only a belt fan, although I have a big radiator. Do you think I'm still in the 300 or 400 range? I find it is hard to tell because it sounds like I'm in the 500 range

What does 500 horse power sound like ?

 

[FredD]

What does 500 horse power sound like ?

It sounds gooooooood

 

[FredD]

I like the racing theory, but there are many factors. I've seen low HP cars make great times just due to their "setup." My stock SRT feels like a monster, but is only a high 13 low 14 second at the track. I live at 6600 feet, computer helps a lot.

Let us know if your wife whips ya, video is always nice.

And if you find out about those heads, let us know. Sounds like someone did a nice job on that motor.

Well my 2009 Jeep SRT was high 12 low 13 sec with Diablo tune and CAI. Sadly the wife will not race me , but just looked through all the receipts and WOW, goes back to 1982. Found the tranny rebuild, the paint (10k in 1997 and i still get compliments on it)and the engine build. I'll put a pic of the receipt.

 

[Cudakiller70]

Do you think there's more power to be had? Maybe try tuning with AFR?
Driveway Tech: How To Tune Your Carb Like A Pro With An Air/Fuel Ratio Gauge – We Show You How!

 

[Cazbah362]

I looked at your thread,very nice car and sounds good. Those SRT's haul @$$, love the Jeeps. At SRT school I won the Petty Experience in a Jeep.

I like CudaKillers input, AF gauge, 02 sensors and some tuning, you will find a whole new 340 in there. Also, great links or some how to's.

My 07 SRT is ready to be traded in or sold, I want a Scatpak for our next purchase. Really the wife's car, I just get to reset the computer every now and then when I wash, clean, fuel and take it in for service.

 

[moparleo]

Of course these recommendations depend on your tuning experience.

 

[Cudafever]

I bet You're 10.5 compression is 9.4 in reality. unless the heads are shaved, a lot, or it has a custom piston in it. it's really only 9.4.
My stock .030 over 340 with MP .474/280 cam advanced 4 degrees, 727 with 2800 stall. Cuda weighs in at 3760 with me in it.
Track dyno spit out 276 HP at 4400 foot track. I ran 14.20 in the 1/4. can't remember the mph, something like 89 mph.
With my high compression stroker motor it run 85 mph in the 1/8.
The 1/8 mile track is a 6600 feet and the calulators figure Hp in around 343 to 354 Hp.
Remember, these ### would be higher if i had the opportunity to race a Sea Level!!!!

 

[FredD]

I bet You're 10.5 compression is 9.4 in reality. unless the heads are shaved, a lot, or it has a custom piston in it. it's really only 9.4.
My stock .030 over 340 with MP .474/280 cam advanced 4 degrees, 727 with 2800 stall. Cuda weighs in at 3760 with me in it.
Track dyno spit out 276 HP at 4400 foot track. I ran 14.20 in the 1/4. can't remember the mph, something like 89 mph.
With my high compression stroker motor it run 85 mph in the 1/8.
The 1/8 mile track is a 6600 feet and the calulators figure Hp in around 343 to 354 Hp.
Remember, these ### would be higher if i had the opportunity to race a Sea Level!!!!

Nice thanks for the info.
I found the receipt for the engine build. What do you think?

 

[RUNCHARGER]

Don't race your Raptor with it. I maintain my 300HP estimatw from above.

Sheldon

 

[FredD]

Don't race your Raptor with it. I maintain my 300HP estimatw from above.

Sheldon

it came stock with 295, it has to be more then 300 now with the engine work...