dynojet horsepower

[metcoll]

I know of posted before with my results..440 bored 030 six pack pistons,lunati cam mild 452 heads rpm intake 750 holley dbl pump msd ing. 13/4 headers...rwhp was 327...car feels decent and I know quartermile mph would be true indicator but do you think numbers would show higher without the 4.56  gears & 4200 stall converter ..thx

[PRH]

The gearing wouldn't change the numbers much.

On my friends dynojet, in a "typical" street car with an auto trans, it's roughly a 20% loss from numbers achieved on an engine dyno with the same motor.
Accessories, how good the exhaust is, etc, all factor in.

I have seen a few occasions where the numbers really didnt agree at all(chassis dyno numbers way low).

Using the 327hp number, and assuming it's correct....... Would indicate 410-ish at the crank.

Depending on the quality of the build and the parts used, that might not be way off.

Personally, I don't feel a chassis dyno is the right tool for evaluating an engine combo or its true output.

Weather will be good enough for track time fairly soon, then you can see if the build met your goals or not.

If you post the details of the motor(cr, cam specs, valve sizes, head flow, etc), several here could give a reasonable guesstimate on horsepower........ And if you provide the details of how the car is set up, weight, etc......along with what elevation you race at......... You should get some good feedback on expected ET's.

For comparison:
We had a stock type 440-6bbl on the dyno this past summer.
No block decking, minimum head mill, 2355 pistons, 906 heads with zero porting.
Small Howard's hyd cam, stock valvetrain with a slightly stiffer than OE spring.

It was run with hooker competition 1 7/8" headers........ It was like 495tq/410hp.

I did another 440-6bbl a few years ago, only this one got kb184 pistons set up with decent quench, 9.7cr, very minor blend on some 346 heads with stock type valve(something to the tune of about 45mins per head---250cfm @ .500).
Stock rockers, a slightly stiffer spring, Comp 280h cam......... With the same headers it made 499tq/425hp.

[BSB67]

I know of posted before with my results..440 bored 030 six pack pistons,lunati cam mild 452 heads rpm intake 750 holley dbl pump msd ing. 13/4 headers...rwhp was 327...car feels decent and I know quartermile mph would be true indicator but do you think numbers would show higher without the 4.56  gears & 4200 stall converter ..thx

Do you have the 4.56 and 4200 in there now?  You might not make it to the end of the track.  How big is the cam?  and what size tire?

[PRH]

The owner of the local dynojet had a 66 Coronet with a mild 440 in it.
The basic build was +.030, KB184 pistons set up for good quench(9.7cr), bowl blended 452's with stock size valves, a .483 lift hyd cam, Crane Gold 1.5 rockers, and he used an A&A cross ram for std port heads, 2x500cfm Ede AVS carbs, and magnum ex manifolds.
With an 11" converter and 3.55's it made 340hp at the wheels.

The motor never got tested on an engine dyno, but we were thinking the 340hp at the wheels seemed pretty good for that combo.

As a side note, another friend ran his NHRA stock eliminator car on the chassis dyno several years ago(header collector testing), and that's a motor that had been on the engine dyno many times.
Manual trans combo....... Open headers......... Showed just under 10% loss, engine dyno to chassis dyno.

Of course, I've also heard stories from the chassis dyno owner where the numbers are off by over 20%.......even motors that came of the same engine dyno as that Stocker.
Some people's car are really inefficient.