Mathematics for 0-60, 330, 660, 1320 ft and top speed times

[Anonymous]

That seems a bit optomistic. Redline is 9000 and the best it did from the factory was ~11.4 @ 117 with a 140lb rider. It definately never made it to 5th gear at those speeds. With me on it, heh, i'd be happy with 13's


-=Whittey=-

 

[xctasy]

Is that 108 bhp figure 108 PS in the handbook (based on the JIS standard), or SAE net, the American bhp value? If so, the actual figure is 92 hp.

I'm petty happy. With 92 hp at 669 lbs all up, thats 11.29 at 120.78 mph. I'll go through the Phil Irving book I'll get back to you. He was a good Aussie bloke. Belived in cubic inches, blowers, and feet, inches and pounds. None of the metric crap I have to go through....


Or maybee it's all flawed!!!!

(Don't think so...)

 

[Anonymous]

The guy wrote his 240 km thing because he appeared to be discusted that some think that the ford 250 wont rev. His real point was he reved his very high all the time with no apparent adverse effects.
He is at the other end of the spectrum to me because I have put about 3000 klms on my newly re-built fully balanced 250 2V and still havent reved it more than 4000 rpm. Its just my oppinion but I took it for a good go the other day and I reckon it does 4000rpm no worries at all but starts to sound a bit strained above that (sounds a bit like a strained turbine, that wines).
Im sure it would do more but 7500 seems a little crazy to me.

 

[xctasy]

Sorry Tim, the revs! If the TE had 225.60 13's on the back, and the std:-

*2.77:1 gears, that is 6005 rpm.

*2.92:1 gears, then at 240 km/h (149 MPH) he'd be doing 6330 rpm.

*With a 3.23:1, that would be 7000 rpm.

*With a 3.5:1, it would be reving at 7590 rpm.

*With the stock 3.7:1 4-cyl gears, a mighty 8020 rpm.


I don't doubt a 250 will do 7500 rpm with the right cam and carburation.
The Ford development engineer affirms 7500 rpm as a possible peak rev range. But to make power at that speed, you'd have a engine that would rev to 8250 rpm, and had maximum torque at 5400 rpm or so. :!:

Even silly little 1.587 liter 4AGE Corolla engines reved to 7500 rpm with a poor 1.58:1 rod ratio. ( 4.803" rods, and 3.03" inch stroke).
But peak power was at 6600 rpm, peak torque was 5000 rpm! Imagine trying to cruise at 2500 rpm at 62 mph in your Cortina, knowing that peak torque was still 2500 rpm away? Any time the rev range is raised, low speed torque drops, all else being equal.

The rule is, peak power, plus 10%, gives you the maximum usable rpm range. Divide that peak power level by 1.5 or so, and that's where peak torque should be. On really low reving engines, like the early XD 1-BBL, peak power at 3600 rpm, peak torque was at 1800 rpm, a factor of 2:1.

Bench mark is Chrysler Hemi 265 I6, with 1.56:1 rod ratio, short stroke, bigger bores, bigger valves, Weber triple DCOE 45's, and unable to do more than 6500 rpm reliably. The top speed of a Charger E49 was 132 with a 3.5:1 diff, running 6300 rpm, 1300 rpm into the red line! The engine was rated at 306 hp gross at 5000 rpm, but was less than 250 hp installed.

 

[xctasy]

http://www.hotrod.com/hotrod/featuredvehicles/113_0306_q2_ld_z.jpg

The irrespressible HudsonNut:-

I made a couple of runs on a chassis dyno today. Run number two was the best, with rear wheel results of 185.1 hp at 4300rpm and 276.2 ft/pounds of torque at 2700 rpm.

'41 Hudson coupe
353 cu.in. flathead 6 (3.875 bore/5" stroke)
2" intake 1.681" exhaust valves
.446 lift / 280 duration cam
Clifford aluminum head / 11.25:1 compression
Tubular tunnelram intake with two Rochester 2G carbs
Magnetic trigger dist. and MSD6AL box
727 torqueflyte trans 2800 stall conv.
Dana rear. 410 gears with welded spiders.
9.0 x 28.5 Firestone slicks (really old)

I'm pretty happy with that, but I'm looking forward to getting the fuel injection on it, and a good set of headers.

Running this little racer is going to be fun!

Weight was 2700 lb's. And I think they were a slippery car, with a quite good drag co-effcient.

Top gear speed per 1000 rpm is 20.23 mph.

Power available is 247 hp at 4300 rpm (185.1*1.333 for an auto)

Top speed, assuming 0.45 cd, 25 foot front area, and about 11.6 hp of tire drag at 135 mph.

Lets try 135mph

NB// New imperial formula is

target speed 3*drag factor*frontal area(found in books) all over 147773 to get rear wheel horsepower reguired. To that you must add required tire rolling resistance. Target amount is 8 hp for a 195 section tire on a 2000 pound car

(135*135*135*0.45*25)=27679219. Then this gets divided by 147773.

Rear wheel power needed is 187.3 hp, plus 11.6 hp, which is 198.9 hp.

Solve for 185.1 hp, try speed and rolling resistance values until the equation equals 185.1 hp.

*Answer is top speed of just under 131 mph. IF IT WAS GEARED FOR BONNEVILLE...I'd say you'd need 2.75:1 gears to get that at 4300 rpm. An overdrive would be perfect. To get 131 mph, you'd be doing 6475 rpm with 4.10:1 gears

*Standing Quarter Mile 14.23 sec at about 97 mph

*Rpm at end of I/4 mile(1320 ft) = 4800 rpm in top gear

*Standing 1/8 mile (660 ft) = 10.00 sec

*Standing 330 ft = 6.77 sec

*Standing 60 ft = 2.53 sec.

Just my opinion:-Shove some 3.7:1 gears in brother, and I recon flat 14's are possible!


Edited. I made a mistake by putting 247 hp, not 185.1 hp, into the formula. 12.93 at 105.44 mph and 5217 rpm wasn't correct

 

[Hudson Nut]

Well, your calculations are very close to reality. Here are the results of some of my runs the last time out.

1/8 mi. 9.062 sec.
330 ft. 5.920
60 ft. 2.160


1/8 mi. 9.031 sec.
330 ft. 5.882
60 ft. 2.132


I will be changing the rear end in the car, and going to 370 gears... I was thinking along the same lines as you were on gear ratios.

 

[xctasy]

Your car is kick a$$ cool.

I've got it on my wall, along with these ones:-

( from http://www.nhra.com/50th/top50/G_Montgomery28.html , and http://www.gassermadness.com/daveedwards/65detroit/index.html )

I've been reworking my formulas based on what you guys have been finding. The 60 and 330 times are very conservative...I'm sure your gonna cut 2's on the 60 foot launch. Most six cylinder guys keep finding that they make the gearing steeper, and watch the times tumble.

Sorry to keep up with the hero worship, Danny, it's just that real historical 62 year old cars aren't supposed to kick butt like yours!

 

[xctasy]

This ones for hasa68mustang

1968 Mustang 200 notchback

estimated 125hp net at flywheel, up 35 to 40 hp form stock, C4 automatic, 3.55:1 rear, P215/60-15 tires, 0.44cd, 2750lbs.

mph at 1000 rpm is 20.6, so 75 mph is 3640 rpm

frontal area is 2.0592 m2 or 22.06 square feet. Drive train loss with auto is 1.333. Weight is 3200 pounds all up, as I'ved added 450 pounds for the gas and two people.

Tire hp loss is 7.8 kw with 3200 pounds, or about 10.46 hp at 112 mph.

*Top speed 112 mph @ 5435 rpm if it had that estimated 125 hp at that rpm. As it will be, if power is at 4600 rpm, you'd only get about 95 mph or so. At 5400 rpm, all the power would have tailed off long ago.

*20.63 mph @ 1000 rpm in top with C4

*Standing Quarter Mile 17.17 sec ( Haven't calculated mph, but it should be 77 mph with ease)

*Rpm at end of I/4 mile (1320 ft) = 5400 rpm in second gear

For the other 660, 330 and 60 feet accelerations, you calculate them like this :-

Standing 1/8 Mile Formulae (0-660 feet):-

ET=([Weight/hp]*198 )^0.289 , = 11.77 secs

Standing 1/16 Mile Formulae (0-330 feet):-

ET=([Weight/hp]*198 )^0.240, = 7.75 secs

Standing 1/88 Mile Formulae (0-60 feet):-

ET=([Weight/hp]*0.54 )^0.450, = 3.26 secs

Summary

This would be a nicely geared car, with a good balance between 1/4 mile gearing, top speed, and open road cruisin'. Go to 3.08:1 gears, and it'll all be ruined for off line acceleration. Best next diff gear is 3.27/3.25/3.20. If you go to a Ford Overdrive auto gearbox, you can run a set of 4.62/4.30/4.11's and still cruise on the highway.