What is average highway speed for the model a?

As a technician, I say it's not about how fast the car can go, but how much rpm the engine can handle.


We're talking about the average piston speed plus any vibrations that occur. The Ford engine is a long-stroke engine that can't handle high rpm. It should top out at 2200 rpm.
 
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"Sweet Spot" for my 1930 Cabriolet is 45-50 when factoring in motor and brakes. I have a Snyders 6.1 head, and a Borg Warner T5 transmission. On a flat stretch in 5th gear you hardly notice the engine running; rpm's at 1900.
 
Werner, can you give more information on piston speed and long stroke engines?
What about a Jaguar 3.8L XK-E engine, thought that was a long stroke engine.
Thanks
 
Funny story. I was going out west on Rt 78 near Clinton, NJ a few weekends ago. Three lanes of traffic were going 75-80. All of the sudden, huge bottle neck appeared seemingly out of nowhere.

After a while, realized it was caused by a beautiful '30-'31 Sedan doing 45 in the right lane. Let's say that drive must of heard numerous Bronx cheers and other NJ niceties as people passed him.

When I drive my '28 roadster on public highways, I find I'll get one of two responses: A thumbs up or the middle finger.
 
Herb Concord Ca said:
Werner, can you give more information on piston speed and long stroke engines?
What about a Jaguar 3.8L XK-E engine, thought that was a long stroke engine.
Thanks
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Herb,


On a long stroke engine, the stroke is greater than the bore.
The greater the stroke, the greater the piston speed. 18 m/s was considered the critical speed for engine designs from the 1970-tis.
Today, nearly all short-stroke engines are built. That can easily handle high speeds a. s. o.


This Jaguar engine is a long-stroke engine that can only sustain its maximum speed for a short time.
 
My A cruises well at 45 and I always wondered why other owners could get better speed than I. So it is good to see many drivers don’t and my old quote comes to mind. Here it is.

There are more lies told about the size of fish caught and especially the ones that got away.

There are more lies told about the yields of crops and the more beer that goes down a growers neck the more the yield becomes embellished.

There are more lies told about the speed of Model A’s.
 
woofa.express said:
My A cruises well at 45 and I always wondered why other owners could get better speed than I. So it is good to see many drivers don’t and my old quote comes to mind. Here it is.

There are more lies told about the size of fish caught and especially the ones that got away.

There are more lies told about the yields of crops and the more beer that goes down a growers neck the more the yield becomes embellished.

There are more lies told about the speed of Model A’s.
Click to expand...

Something like you wrote in post #85... :p
 
woofa.express said:
My A cruises well at 45 and I always wondered why other owners could get better speed than I. So it is good to see many drivers don’t and my old quote comes to mind. Here it is.

There are more lies told about the speed of Model A’s.
Click to expand...

Well believe what you want but I have been messing with Model-As for pretty much all of my life, and what I can say from years of experience is the worn, used, sub-standard Model-As are the ones that struggle to maintain 45 mph. These vehicles generally struggle with Braking (-which is another reason why Model-As have a bad rap when people are discussing brakes). The same applies for safe Steering. Alternatively, when someone has the opportunity to drive a low-mileage, unmolested Model-A, -or one that is truly restored with everything brought back to at least a minimum level of the factory specifications, these vehicles have no issue whatsoever stopping, steering, and driving 60 mph. This is no BS or some Fish tale.
 
My Model A will certainly do 60 mph, but I certainly don't want to run the engine at 2500 rpm for very long.
 
Werner said:
Herb,


On a long stroke engine, the stroke is greater than the bore.
The greater the stroke, the greater the piston speed. 18 m/s was considered the critical speed for engine designs from the 1970-tis.
Today, nearly all short-stroke engines are built. That can easily handle high speeds a. s. o.


This Jaguar engine is a long-stroke engine that can only sustain its maximum speed for a short time.
Click to expand...

Jaguar 3.8L engines lasted 24 hours at high speed at Le Mans.
 
hi Blockhead-y.

I checked and yes you are correct. Must be that aging ailment starting with letter "D" when memory retention is comparable to that of a gold fish. Do read the third line in my signature below which hopefully will clarify. cheers, gary.
 
Ruth said:
My Model A will certainly do 60 mph, but I certainly don't want to run the engine at 2500 rpm for very long.
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Let's chase a Rabbit for a bit and discuss this. Exactly 'why' are we not wanting to sustain 60 mph or 2,500 RPMs?

It definitely is not the piston speed because my calculations are about 1720 feet per minute, ...which is tame when the industry typically wants to see 3500 feet or less.

Is it the Connecting Rod or its lubrication? A properly restored Model-A Rod that was crack checked prior to pouring, and has the proper bearing material will live at rpms twice the 2500 number. The dipper oiling system works well, and great example of this is an air-cooled Briggs & Stratton engine where those run reliably at 3,500 rpm for years & years. So it isn't the Rods.

Is it the Crankshaft? Could it be the rotating mass was not correctly balanced before assembly? Is it torsional harmonics that has you worried? Lightening the Piston and/or the Pin greatly reduces those stresses. Additionally, adding counterweights or replacing with a new SCAT or Burlington type CW Crankshaft even pushes stage 2 harmonics past the 2,500 range, ...but again, having a good crankshaft and a well-balanced rotating assembly goes a long way towards keeping torsional oscillations at bay. So what is it that has us worried?
 
I'd think a person could 'push' the new Burtz engines comfortably at at least 50-55 mph with the new balanced crank, inserts, and five bearing mains:)

I stay at 40 with the original engine that is good enough for me. Those hinky dinky bicycle tires don't have a whole lot of ground contact! I always felt running these cars at 55 or 60 was a suicide threat!
 
My 1928 open cab pickup which is completely stock will easily hit 65 on a level road but its sweet spot does seem to be 50 miles an hour.
 
Direct from Henry late 1927.
 

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Henry said a Model A has actually done 65 mph. That doesn't mean he drove it at 60mph all day as some have claimed they do.
 
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BRENT in 10-uh-C said:
Let's chase a Rabbit for a bit and discuss this. Exactly 'why' are we not wanting to sustain 60 mph or 2,500 RPMs?

It definitely is not the piston speed because my calculations are about 1720 feet per minute, ...which is tame when the industry typically wants to see 3500 feet or less.

Is it the Connecting Rod or its lubrication? A properly restored Model-A Rod that was crack checked prior to pouring, and has the proper bearing material will live at rpms twice the 2500 number. The dipper oiling system works well, and great example of this is an air-cooled Briggs & Stratton engine where those run reliably at 3,500 rpm for years & years. So it isn't the Rods.

Is it the Crankshaft? Could it be the rotating mass was not correctly balanced before assembly? Is it torsional harmonics that has you worried? Lightening the Piston and/or the Pin greatly reduces those stresses. Additionally, adding counterweights or replacing with a new SCAT or Burlington type CW Crankshaft even pushes stage 2 harmonics past the 2,500 range, ...but again, having a good crankshaft and a well-balanced rotating assembly goes a long way towards keeping torsional oscillations at bay. So what is it that has us worried?
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Brent, you can run your engine as high or as long as you wish. What I said was "My Model A will certainly do 60 mph, but I certainly don't want to run the engine at 2500 rpm for very long., for whatever reason you want to come up with.
 
Driving slow won’t save a bad rebuild — from my experiences Mycar had a problem 3000 miles of easy driving broke in at 35,not driven over 52– rear main crumbled.
Driving fast hasn’t given me problems since the mains were repoured— 2 days after assembly I knew it would do 67, drove over 2000 miles at speed over 55, all day down the PA turnpike at 65 and 40 years later still trying to break it(3rd gear starts at full throttle,lugging in 3rd at 5 mph and full advance,riding the clutch pedal for 40 miles trying to loosen a stuck clutch.
I used to work at a high end european shop and many of the older customers had a model A in college and they would drive 60 all the time trying to visit girlfriends stopping every 50 miles to add oil ( stops at friendly gas stations for used oil)— driving tired 30 year old car.
I had to learn to do my own machining due to the poor quality work and to figure if I did a good job I have to try and break it—- what else should I do — I have even tried pedal to the floor in first and second to see how fast I could go.
I think I can make the end of the speedometer (75) if I go through it and get everything to original spec because I know there is a balancing problem that is out of spec
 
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