Can 2V original spec comparisons equal rear wheel HP???

[Anonymous]

Just thinking is it possible for one of you with some mathematical skills to work out the actual diffence from standard the 2V head makes and its rear wheel HP from these specs.

In front of me is an origin copy of a road test conducted by Australian Wheels Magazine in 1971 on the 2V 250 compared with the standard integral manifold Aussie six 250.
Ford rated these at 155hp and 170 hp respectively

The actual performance figures after numerous re-runs in two identical cars (250 and 250 2v). both were four speed manual Falcons with a weight of 1373.3 kg
Average of the standing Quarter mile was 17.0 seconds with an average of 18.2 for the standard 250.
But from 0-60 mph the 2v did it in 10.7 and the other in 14.0.
Im not sure but I think part of the fact that this was done in a suprising 3.3 seconds quicker than the standard was that the 2v 250 was able to rev out to 60mph in second gear at 4800 rpm. The standard 250 would not have been able to prevent a gear change from occuring before 60 mph was reached without considerable power loss.
Just the same someone should be able to work out the difference and actual power estimates for both based on the figures and settle some of the arguments Ive seen on the HP benefit of a 2V head

 

[xctasy]

Answer is 26 hp extra flywheel power with a 2V head over a stock IV log head. And 20 hp extra at the rear wheels.


Sorry fans, this is metrics. Can't be biffed working it out in imperial, even though imperial rules, metrics blow... :splat: (at least on this good ole US-based forum, ye-hooo!)

*For you guys and gals out there who want to know, you just divide the loaded drag race weight with driver and fuel in kilograms by the flywheel net figure in Kilowatts, and then pump it up by 325 to get the standard performance curve of power to acceleration, then take the 1/3 rd power.


Well, here goes... a 18.2 second quarter with 1373 kg [3027lb] (not including wheels standard two-up 200 kg [441lb] load including a half tank of gas) would yield the need for 85 kw [114hp SAEnet] at the flywheel, based on a 29% power train loss, and that lines up pretty well with a 94 kw [126hp DIN net ] XDFairmont Ghia which would do 18.3 seconds, from memory, with 1450 kg [3197 lb], which would have had over 3638 pounds to haul at the Wheels figures getting session.

So the 155 hp gross maps to 114 hp net for the single 1V carb 250.

The 17.0 second quarter should be the same power requirement as an 83 XE Falcon EFI S-pack, which weighed 1435 kg, and had 111 kw to haul around to do a 16.9 second quarter. So lets calculate!

(1573 kg/111 KW)*325 = 4605.63, which you take the 3 rd surd of to get 16.63 second quarter mile...a little too quick. So try values that solve the equation to equal 17 seconds. ie 17*17*17= 4913, which gives you 104 kw [140 hp SAE or DIN net]

So 170 hp gross maps to 140 hp net for the 2V 250.

Hence 140-114 =26 flywheel ponies gained, and likey to be about 20 rwhp gained.

 

[Anlushac11]

8)

Didnt Mustangaroo's dyno at 67rwhp before and 105rwhp after?

And it went up slightly when he switched from the Holley 5200 to the Holley 350cfm 2300 style 2bbl.

 

[Anonymous]

Hi Anlushac11,

The 67 RWHP number is a value obtained by AK Miller, on a dyno, with a stock 67 200 I6 in the late 1960's. Mustangaroo's car was not stock B4 the head. Actually, his car was equiped exactly like mine. As a matter of fact, if you look at a Mustagaroo initiated topic related to the value vs. cost of the 250 - 2V you will find general agreement that the WRHP of a 200 I6 equipped as below would be approx 85. So, the value of the 250-2V as a bolt on is approx 20 RWHP. To be fair, however, the nod would have to go the the 250-2V with respect to the "bolt-on" potential to make significant amounts of RWHP with the addition of cams, carb mods, etc. On the other hand, for those with the necessary training, and access to required tools, a multicarb log head could be created that would perform at least as well.

As for the data supporting various HP assumptions, there is some interesting dialog in a topic titled "Horsepower" started by KickinSixer on 4/9/03.

One of these days I'll have to dyno my car. I think there are several out there set-up this way, so the bench mark would be useful. Actually, the only reason I haven't is that I am so comfortable with the data supporting the 85 RWHP value. That is to say, any variation would be insignificant. The value of the exercise would be the opportunity to max tune what I already have. Example, while spark plug inspection and performance say my mixture is good, I suspect it is too lean for max HP.

Throught provoking stuff. To bad I don't have an unlimited R&D budget.

Steve

 

[65coupei6]

The AK Miller dyno of the stock 67 200 was actually 65 rwhp and that was with a standard tranny and 3.20 gears. In the end after changing carbs, adding headers and raising compression he got 100 hp and a 0-60 time of 10.2 seconds. In another article he goes on to do other modifications.

A stock 200 according to a road test I have has a 0-60 time of 15.1 seconds. So basically there is a 5 second change.