Any Idea What The Horsepower of this 340 combo would be??

[woody9512]

Looking for an educated guess as to the estimated horsepower of this 340 engine combo
340 in 71 Cuda 4 speed (3:55 gears)  Standard Bore 340
                                                  10.2-1 approx Comp
                                                  Rebuilt Original T.Q Carb and stock intake.
                                                  Ported 308 heads with 2.02 valves.
                                                  TTI headers with 2 1/2 inch exhaust with x pipe
                                                Engle K58 Hyd Cam 514 lift  231/231 duration @ .50

Thanks!
"Tim"

[Oldschool]

I would guesstimate 350-375 ish.....       

[Carlwalski]

Around 330-340hp. 

[MEK-Dangerfield]

You don't have something wild there, so my vote is 280-300HP tops. That is being optimistic. What size is the original carb(CFM-wise)? You can do better with an aftermarket intake and bigger carb, I'm sure.


  Mike

[Carlwalski]

Here is my 340ci-4bbl build specs paid for by the previous owner. 


Cylinder Heads:

 - Factory W2 oval port intakes
 - D-Port exhaust
 - Extensive port
 - bowl and combustion chamber mods
 - Hardened exhaust valve seat inserts
 - Ferrea 2.02 intakes
 - 1.6 exhausts
 - Comp-cam 995-16
 - Valve springs 1.70" installed height, 130lbs at the seat
 - Comp cams 740-16 10 degree retainers & 10 degree valve locks
 - Crane roller rockers 1.5 ratio
 - Offset intake rockers, straight exhaust rockers
 - 450 340 STEEL CRANK
 - Penned rods
 - intake and headers all port matched
 - High volume sump and oil pump.

Carb: 900cfm Demon


Camshaft:

Comp cams 20-224-4 extreme energy, 110 degree lobe centers, .488" intake valve lift, .491" exhaust valve lift, 230 degree duration @ .50" intake, 236 degree duration @ .50" exhaust. RPM operation range 1800-6000rpm. Comp cams custom length pushrods, comp cams hydraulic lifters. jr double row steel timing gear set.

No dyno unfortunately but the engine builder guesstimated 350-360hp at the flywheel with a 727.  I should see more power to the rear wheels with the Keisler conversion too. I think the W2 heads and big carb help plenty.

[422STROKER]

Stock was mostlikely underrated at 275 so you should be over 300hp with the add ons.  An new intake and carb would match that exhaust set up better.

Tom

[Chryco Psycho]

I agree with Ken , from my testing I wouldl guess 240 RWHP x 1.6 to gross hp so around 380

[matt63]

I would estimate 330 based on 275hp stock rating. The original 275bhp may have been underrated but I don't think it included the losses from the accessories either.  Also, I've wondered what the power train losses really are.  I thought that 20-25% max would be about right.  I'm guessing most of the energy is lost due to friction (heat).  Perhaps the losses are fixed ie higher hp engines have a lower % loss - so many questions so few answers

[Jacksboys]

I would guesstimate 350-375 ish.....       

In May 2007 issue of Mopar Muscle, there was a T/A Challenger with something not too far from your combo:

340 +.040
9.8:1 comp.
Comp Cam XE268H
Six-Pac carbs and intake
Stock exhaust manifolds
Electronic Ignition

It made 358 hp at 5,800 rpm.

Hope this helps. 

[woody9512]

Thanks one and all for the replies.......As usual very Much Appreciated!!!
"Tim"

[woody9512]

MEK - Dangerfield.........
   The carb is a stock newly rebuilt TQ....I think it would flow around 800cfm in that area. 
You say that your estimate as to actual horsepower would be 280-300 tops and that's being optimistic you said with my engine combo. I don't understand how that could be because as  I understand it a 340 engine in 1971 came right from the factory with about 275 horsepower to start with and this comb I want info on has a much more more aggressive cam than stock....ported heads and also headers?? 
"Woody"

[PlumCraZRT]

Don't matter as long as you spank the ricers!

[woody9512]

Some of those ricers and getting pretty hopped up these days
"Tim"

[Oldschool]

Some of those ricers and getting pretty hopped up these days
"Tim"

Then send 'em to me and I'll take care of 'em for ya........                        

[360 'CUDA]

I would go with the low 300s hp also.  Not that 320 HP at the rear wheels is bad. Keep the weight down and stick the car to the ground.
12 seconds in the quarter are very doable with a combo like that