Drivetrain power loss

[FMACHI 10]

How much power does the drivetrain normally loose 20-30%??

My M code Mach I should produce 290hp in factory trim. It currently runs a 600 vacum Holley on a 2bbl inlet manifold with 2V heads. An FMX and I'm not sure on the diff ratio. It was recently on the dyno and held 120kw/160hp at the wheels. This sounds pretty poor to me, but a lot better than the 100kw/130hp it ran recently with the 2bbl carbie the car came with.

 

What power figures have you guys experienced at the wheels, on the stockier models of course.

Thanx, David.

[*JackBurton* 0]

Well an M code Mach1 should be 4bbl carb and 4v heads for 290bhp.

 

1969 M Code 351w

4bbl Carb

4v heads

10.7:1 Compression

290bhp @4,600 rpm but I've seen one mustang site list it at 5,400

 

1969 H Code 351w

2bbl

2v heads

9.5:1 compression

250 bhp @ 4,600 rpm

 

Did someone replace the motor at one point?

 

My understanding is that the FMX loses a lot of power and so does a Ford 9" (don't know what axle you have). My guess is somewhere in the 20-30% loss from the combo of the axle and transmission. Someone on stangnet mentioned that C6 trans +9" = about 100hp loss.

 

Another factor is the car was rated in Gross horsepower back in 1969 and now we rate in SAE net horsepower. http://en.wikipedia.org/wiki/Horsepower . According to the all knowing wiki the difference can be anywhere between 40 and 100 horsepower.

 

So taking 290bhp and subtracting 40(guessing) to convert to SAE = 250. Then a 30% loss puts you at 179hp at the wheels. Basing it off the H code stats 250bhp -40 =210 / 30% = 161.

 

Hope this helps.

Sean

[FMACHI 10]

Someone has replaced either the enigne on put on 2V heads with a 2bbl manifold. This restricts the flow from the 600 Holley vacuum 4 bbl. And I'm getting 160hp at the wheels, which by the calculations is only 20hp of your estimation. Which is not bad for a clapped out restricted motor. I guess if I switch to a mechanical carb and a 4bbl manifold I can recover the lost 10 to 20 hp, if not more.

Thanx that does calm my nerves. The car does chirp into second 8/10 times I flat foor it, and I'm running 235s in the rear. 9" no LSD

 

Thanx again, David

[indianfiremach 170]

2v heads and 4v heads were the same for windsors. It was the cleveland engines that had 2v and 4v versions.

[*JackBurton* 0]

2v heads and 4v heads were the same for windsors. It was the cleveland engines that had 2v and 4v versions.

 

I did not know that.

 

FMACHI

So it comes down to carb and compression ratio. It would seem to me that a good after market intake and the holley 600 CFM and an hi-output ignition and you should be fine. Don't forget that the horsepower conversion is 40-100 and FMX/9" combo might sap more power than you think. I'm guessing on that.

[bnickel 10,004]

i've read that the fmx and c4 both have about the same amount of parasitic drag but the c6 is hungry mother and sucks up alot more power than the others.

 

also, the rear wheel hp is not the more accurate method of determing overall power but can't really be compared to the older gross hp ratings from the 60's. remember the hp rating system was changed in the early 70's and the power figures from the 60's were measured on an engine that had no accessories whatsoever and in a max performance state of tune most often, which was not usually the as delivered tune up. so really, the power figures you got weren't all that bad considering.

 

the way magazines usually test their engine combo's is closer to how it was done back then.

[FMACHI 10]

So if whats a 4V in the Mcode Windsor. Just the valves.

[ForceFed70 14]

So if whats a 4V in the Mcode Windsor. Just the valves.

 

Not the valves. The carb and manifold were the difference along with the compression ratio. The 4V windsors had a higher compression ratio, a 4bbl carb, and a 4bbl intake manifold. I believe that's the only difference.

[bnickel 10,004]

correct, different pistons (flat top for higher compression) 4v carb and intake. the 4v stands for 4 venturi not 4 valve as most people think. 4 venturi meaning 4 venturis in the carburetor as in 4 barrels.