How fast in 2nd gear?

[J Franklin]

Russ you must have been doing something else wrong 'cause I don't think there is a law against driving to slow except on the freeway!

[jhowes]

Lines 10, 11, and 12 are somehow off as the
rpm does not get to 2000 until after the 378 ratio with the same tire size etc.. The 411 ratio should wind out far sooner than the other ratios, as I understand it these were for the hilly country where climbing was the object not speed. Also the 327 ratio is not shown, I would be curious as to how much that drops the RPM at say 40 or 45 MPH. Jack

[jhowes]

In the above post I am referring to the chart in post 20. Thanks Jack

[Big hammer]

Originally Posted by Art Newland

My car has some vibrations here and there but at higher revs it's quite smooth. It will easily attain 50+ mph on the flats, but can't say that I feel comfortable at that speed... 45 seems happier. There is talk of a drive being put together by some local clubs beginning in Blaine, WA and traveling to Mt. Baker. It's a bout a 70 mile trip but the last 20 miles climbs 4000+ feet in elevation, and the last 8 miles has a lot of switchbacks as it climbs even more steeply. Sounds like maybe some sustained 25mph in second gear is doable?

Art did you go on the trip? What did you use for the hill climb? My car in second gear, the gear make more noise the faster I go, so I only use second gear when third gear is lugging the engine.

[Synchro909]

My shift points vary depending on the terrain mostly but I also take other traffic into account. The standard Model A gearbox has a big gap between 2nd and 3 rd (typical of the era) which means on an uphill, I feel I need to rev it a bit higher before I change into top.
In one of my cars, I have the Mitchell synchro G/box in which 1st and 2nd are 15% higher than standard. This closes that big gap and makes driving sooo much easier and cuts down on lugging. The other two cars have standard gearbox and the Mitchell O/D. High 2nd is a very handy ratio on those and I've mastered the art of shifting both at once.
It is a whole different scenario when towing though. Shift points are higher.

[Bob Johnson]

Sponsored Links (Register now to hide all advertisements)

Here is what I calculate for the options in chart.

[BILL WILLIAMSON]

However you drive your car, if you've been doing it for a LOOOONG time & it sounds OK & nothing has come apart, DON'T WORRY ABOUT IT!
Bill Nonworrier

[steve s]

Originally Posted by ryanheacox

With everything stock, 30 in 2nd is about 2500rpm which is the same engine speed as 55 in high gear. With everything stock I probably wouldn't push it any further or hold it at that speed for a long time but for short bursts I don't think there would be any issue.

Remember, Ford rated these cars at 65mph when they were new, not that I would ever want to try it

Originally Posted by BILL WILLIAMSON

I've run Minerva up to 45 MPH, in second---VROOOOM!--Helps keep the plugs burning CLEAN! I ran my Autolite plugs for 12,000 miles & never even looked at them. Chief always said, "If something works GOOD, leave it ALONE"!!
Bill Fast

I've seen claims such as Bill's before (perhaps by someone else--I don't remember). I'm sorry but it's always seemed just impossible to me. For example, if 30 mph in 2nd gear is about 2500 rpm, 45 mph is about 3750 rpm. The horsepower vs. rpm graph available in the Model A books shows that at 70 mph is 3000 rpm in high gear, suggesting that 3000 rpm is close to the maximum possible. When I get my A over 25 mph in 2nd, the sound is almost painful; I can't imagine that it would let me wind it out for 15 more mph. (This is with 3.78 rear end, 21" tires, and a few motors and transmissions.)

Which leads me to ask, what is the highest rpm you've run your motor up to? And, can anyone else get their stock drivetrains up to 45 mph in 2nd gear?

[bnchief]

That is true Steve but your other car probably turns 9000 and does not have a tranny. Love the sprint car picture.

[Terry, NJ]

My Father went to Newark College of Engineering in the late twenties, and he was told in a civil engineering class the NJ DOT purposely REVERSE BANKED highways to make people drive slower. It wasn't until the 60s when they started building interstates that they changed that, and not very much at that. Case in point, there was a section of rt 571in Jackson that went through both the Francis Mills bridge and a swamp that was part of the upper Toms River. It would get foggy with the right weather and you might be headed into the curve and suddenly discover that you were in fog. Not only fog , but a curve with a reverse bank. Life got exciting for a lot of folks. some didn't make it and there were more than a few fatalities at that spot. They've rebuilt it now and no one has died there in at least twenty years.
Terry

[Special Coupe Frank]

Society of Automotive Engineers defined "overspeeding an engine" as operating it beyond the rpm at which maximum HP is developed.

I believe they developed this standard in the mid to late 1930's.

Model A is rated at max HP at 2,200 RPM, so I consider that its red-line.


I would be cautious about deriving a red-line spec based on "modern" (post-1970) vehicles.

With the exception of the Ford 300 and GM 292 inline sixes, no one has built a mass-produced "under-square" long-stroke engine in 50 years. (Edit: Referring to American gasoline engines for passenger car or light-trucks.)


Most engines designed after 1960 are short-stroke / over-square designs that can tolerate revs a lot better than long-stroke / under-square designs.

The issue is piston speed and the fact that the reciprocating mass has to change direction twice for each crankshaft revolution. This mass is larger for long-stroke engine ( longer rod ), so there is more stress on the wrist-pin and the rod bearing end.

As far as what the "factory spec. Ford engine was capable of", how many of our engines are still "to spec", and how many are "unknown" ?

If "unknown", treat it conservatively.

My unrestored 88,000 mile Special Coupe sounded REALLY unhappy above 10 MPH in first, and 20 MPH in 2nd. I do not think it would do 30 in 2nd.

If you're pulling a hill, and you've got a line behind, find a place to pull-aside and let them pass if possible.

If not, they'll just have to wait. Don't wreck your engine because of some jackwagon in a hurry.

If it's a long, 2nd gear hill, pick a speed that sounds "happy" for your car, and sit back and plug away.

Model A parts, engines, and machine work were cheap and plentiful in the 1930's, so not a big deal if you blew yours up.

Not so in 2016.

SC Frank

[Dick Steinkamp]

Originally Posted by Special Coupe Frank

With the exception of the Ford 300 and GM 292 inline sixes, no one has built a mass-produced "under-square" long-stroke engine in 50 years.

Many modern diesels are. My wife's Jetta is 79.5 mm bore × 95.5 mm stroke

[wmws]

I have a tac in my car and I generally don't rev it past 2000. On a long hill the engine seems happy there and I don't feel anything is going to blow. If you have a balanced blueprinted engine I'm sure it would feel fine well past 2000 but mine is just a stock engine. I do have a Mitchell OD so 2nd OD keeps the people in a big hurry somewhat happy.

[Special Coupe Frank]

Originally Posted by Dick Steinkamp

Many modern diesels are. My wife's Jetta is 79.5 mm bore × 95.5 mm stroke

But most automotive and truck Diesels are built for torque, not to be rev-makers.

I'm curious what the red-line on the tach is ?

If my math is correct, the B & S translate to 3.129" bore x 3.75" stroke, about 5/8" difference. Fairly close to "square", and the stroke is shorter than most engines designed before the OHV V-8 era.


I'll qualify my previous statement, restricting it American gasoline engines...

[Dick Steinkamp]

Red line is 4800. 100 hp 177 ft pounds torque. Certainly built for torque. Surprisingly (at least to me), the torque is only 1.8 X the HP. The ratio would be even less if it was normally aspirated. With a Model A, the torque is over 3X the HP. Our A's are torque monsters!

The Jetta stroke is shorter than most engines designed before the OHV V8 era primarily because total displacement is only 115 cubic inches . I don't think there were many engines that small in 30's-60's.

I agree that if you restrict to gasoline car engines, it would be tough to find one less than 50 years old with a stroke longer than the bore. The closest I can come is a 1964 Studebaker 289 V8 with 3.562 bore x 3.625 stroke.

[Mitch//pa]

I shift by ear and feel, which is sooner rather than later. I strive for no grinding and low R's

[Synchro909]

Originally Posted by Mitch//pa

I shift by ear and feel, which is sooner rather than later. I strive for no grinding and low R's

X2. I can't see any point in flogging the car just to gain a few seconds, minutes at the most then having to spend hours (and lots of $) rebuilding the motor sooner than you would have if you'd been sensible.
I drive with Grace, not pace. (just don't tell my wife about Grace!!)

[Mitch//pa]

Originally Posted by Synchro909

X2. I can't see any point in flogging the car just to gain a few seconds, minutes at the most then having to spend hours (and lots of $) rebuilding the motor sooner than you would have if you'd been sensible.
I drive with Grace, not pace. (just don't tell my wife about Grace!!)

Shifting is kinda like tightening an oil pan or manifold set... the feel

[40 Deluxe]

Originally Posted by Special Coupe Frank

Society of Automotive Engineers defined "overspeeding an engine" as operating it beyond the rpm at which maximum HP is developed.

I believe they developed this standard in the mid to late 1930's.

Model A is rated at max HP at 2,200 RPM, so I consider that its red-line.


I would be cautious about deriving a red-line spec based on "modern" (post-1970) vehicles.

With the exception of the Ford 300 and GM 292 inline sixes, no one has built a mass-produced "under-square" long-stroke engine in 50 years. (Edit: Referring to American gasoline engines for passenger car or light-trucks.)
Most engines designed after 1960 are short-stroke / over-square designs that can tolerate revs a lot better than long-stroke / under-square designs.

SC Frank

Would like to back up the bus a bit here. Ford came out with the 5.4 (330) engine in 1997 with a bore of 3.55" and a stroke of 4.17". Definitely under square! The 6.8 V10 had the same bore and stroke.
Thus stroke is 5/8" larger than bore. By contrast a Model A's stroke is only 3/8" larger than bore. So the A is more nearly "square" than a late model F-150!
A lot of other modern US gasoline engines are also under square, though by not nearly as much.

[Cornishman]

Originally Posted by steve s

The horsepower vs. rpm graph available in the Model A books shows that at 70 mph is 3000 rpm in high gear, suggesting that 3000 rpm is close to the maximum possible.

It's not quite that simple. At 70 mph the Model A, with the aerodynamics of a brick, is having to work hard to push itself through the air. It may be relying on torque more than horsepower to maintain that speed. The same rpm in a lower gear would have much less aero resistance to deal with and might well rev beyond that point. Most modern cars would not be able to reach maximum revs in top gear despite getting to the red line easily in the others.
Practically it's irrelevant. When I'm out on the road driving my 3.3 litre, 86 year old car I do not have a rev counter to watch, I have my senses and the road conditions to work with. I live in a hilly area but at fairly low altitude so the are no very long climbs. When going up a hill I am able to gauge whether the car will pull third gear comfortably or not, if not I cruise up the hill in second as there is no point of revving the guts out of the engine. Last year I sold a small Suzuki motorcycle. Riding that was similar to driving the A, there were a lot of times that a low intermediary gear was the best choice, see-sawing between high revs in one gear and labouring in another solved nothing, much better to adjust the throttle and climb the hill comfortably. Come to think of it it's no different on my mountain bikes either.