True horsepower?

[ir3333]

Most performance threads end up in a horsepower discussion.
.. there is a dyno number which means no.. fan,water pump,alternator,
fuel pump,air cleaner or exhaust and usually through open headers.
.. a net rating (with the above accessories)
.. and rear wheel horsepower which would also include with drivetrain losses.
what might these three numbers be for a 350 hp small block?

 

[diymirage]

E/T divided by weight = true horsepower

 

[replicaracer43]

E/T divided by weight = true horsepower

Incorrect.... it's 1/4 mile speed, "MPH" figured in with the vehicle weight, not ET

 

[cannucky]

 

[j par]

Oh yeah this thread is going places! LOL

 

[rumblefish360]

Most performance threads end up in a horsepower discussion.
.. there is a dyno number which means no.. fan,water pump,alternator,
fuel pump,air cleaner or exhaust and usually through open headers.

Not always!

There are several different was as well as several different ways the dyno calculations are done. The American way, the European way, the Japanese way. And I goes on and on.

Let the track be your guide?
That may not even be accurate. Why?
Is your car maxed out for track runs?
If not, then it is not accurate.

Find a rear wheel dyno and run it on that. It will work well enough. Let the shop tell you how much power is lost through the drivetrain.

 

[grean meany]

Most performance threads end up in a horsepower discussion.
.. there is a dyno number which means no.. fan,water pump,alternator,
fuel pump,air cleaner or exhaust and usually through open headers.
.. a net rating (with the above accessories)
.. and rear wheel horsepower which would also include with drivetrain losses.
what might these three numbers be for a 350 hp small block?

 

[fishmens67]

400 is 300 or less at the wheel

 

[ir3333]

400 is 300 or less at the wheel

Tx, this was what i was wondering
....about 100 in total losses

 

[72Dart6pack]

Are you taking in account wind speed & outside air temperature.? Is this with conventional oil or fully synthetic? Oh yeah! I see this thread getting over 75 post. Let the games begin.

 

[72Dart6pack]

Let's throw in E3 Spark plugs into this post also. Good or Bad?

 

[70aarcuda]

Most performance threads end up in a horsepower discussion.
.. there is a dyno number which means no.. fan,water pump,alternator,
fuel pump,air cleaner or exhaust and usually through open headers.
.. a net rating (with the above accessories)
.. and rear wheel horsepower which would also include with drivetrain losses.
what might these three numbers be for a 350 hp small block?

350 hp....... unless you put mothballs in the fuel tank

 

[72Dart6pack]

Heard those increase octan rating.

 

[ir3333]

i guess i wasn't too clear.
for the three numbers would 350 on the dyno, 310 with accessories and 250 at the rear wheels
seem reasonable?

 

[j par]

i guess i wasn't too clear.
for the three numbers would 350 on the dyno, 310 with accessories and 250 at the rear wheels
seem reasonable?

So then this is chassis Dyno versus engine dynos correct? whether you're chassis Dyno is the race track or an actual chassis Dyno that would read what you're asking with the wheels on the ground what it's getting back there as compared to what a motor on a stand would do by itself? So at this point I'll ask everybody's question here, who's Dino? Who's chassis Dyno? who's engine dyno? LOL

 

[ir3333]

i wonder how much the different dyno's differ.
..10%...15%

 

[ir3333]

so a 1969 440 GTX was rated at 375 hp.
Would this be at the crank with accessories operating?

 

[Pascamp]

so a 1969 440 GTX was rated at 375 hp.
Would this be at the crank with accessories operating?

Nope. At the crank, no accessories, open headers, no air cleaner, whatever fuel they wanted, and any tune they liked.

Net for this same basic engine was 280 in 1972. Probably about 230 at the wheels for both cars.

 

[j par]

so a 1969 440 GTX was rated at 375 hp.
Would this be at the crank with accessories operating?

Keep dredging the treble hook along the bottom and you're liable to catch anything! LOL

 

[ir3333]

O.K....a '69 340 at 275 hp was at the crank,no accessories
and a '73 340 was 240 hp at the crank with accessories?

 

[Pascamp]

O.K....a '69 340 at 275 hp was at the crank,no accessories
and a '73 340 was 240 hp at the crank with accessories?

In this particular case...no. The 340 was underrated for various reasons. It was actually around 315hp.

There's a few reasons why net hp was mandated... not voluntarily adopted. Net ratings are real world. An engine is pulled from the line and randomly tested, and independently verified. It is also configured for the application (air box, exhaust, ect for the car to be installed in). This is why an identical engine may be rated differently when installed in different vehicles.

 

[famous bob]

In this particular case...no. The 340 was underrated for various reasons. It was actually around 315hp.

There's a few reasons why net hp was mandated... not voluntarily adopted. Net ratings are real world. An engine is pulled from the line and randomly tested, and independently verified. It is also configured for the application (air box, exhaust, ect for the car to be installed in). This is why an identical engine may be rated differently when installed in different vehicles.

I remember reading that they were in a climate controlled room at the factory when dyno`d, pretty much at ideal temp for a human, they always made more than out in the real world. Unless the factory was under rating it for racing purposes.

 

[MOPAROFFICIAL]

Most performance threads end up in a horsepower discussion.
.. there is a dyno number which means no.. fan,water pump,alternator,
fuel pump,air cleaner or exhaust and usually through open headers.
.. a net rating (with the above accessories)
.. and rear wheel horsepower which would also include with drivetrain losses.
what might these three numbers be for a 350 hp small block?

350 hp small block?
Roughly 262 hp at the wheels.
Thats not sorting out the draw from belt driven accessories though.
If a flex fan,alternator, power steering, fuel pump eat up 50 hp, I wouldn't be surprised ;)

 

[MOPAROFFICIAL]

and a '73 340 was 240 hp at the crank with accessories?

With accessories and with less compression and valve.
If you do the 240 divided by .75 then subtract 50 hp....you're in the ball park, same with the 275 version. Accessories eat it up.
Now figure the motor tested was an actual CORRECT factory blueprint test mule with every spec on the money proto type , meanwhile the mass production were loose **** like what we got.
Again..you're in the ballpark.

 

[Hot Metal]

for reference>
'71 stock 340 Cuda........3600lbs+/-? with me
stock bottom end with .039 fel-pro's so poss/prob 10:1 or under.
add> ally dual plane intake,
add> 750DP Holley
add> .484/284 purple hyd.
add> small tube hdrs.
add> 3500 converter
add> 8x26" M&H slicks, 3.55's
add> MSD6A
best ET/mph = 13.28@101
= 302 fly hp
All runs made at SPR...