Extra weight on full bodied cars & the effect on performance

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Model T Ford Forum: Forum 2017: Extra weight on full bodied cars & the effect on performance
Top of pagePrevious messageNext messageBottom of page Link to this message  By Kevin Weeds on Thursday, May 18, 2017 - 11:34 pm:

If I wanted a car for open road touring what would I lose in performance if I chose a Full body v runabout.
How much is the extra weight?

So here is the scenario -Take two cars of the same year, a full body v a runabout. Both cars with same modifications if any like Z head, Ruckstell etc.
Two adults with one suitcase (back seat or running board.
1. Open road cruise speed on flat ground no wind.
2. Same with strong head wind
3. Hill climb where runabout stays in top gear just

I guess downhill braking would be harder with more weight and perhaps more chance of running hot in extreme conditions.

Be interested in your feedback

Thanks


Top of pagePrevious messageNext messageBottom of page Link to this message  By steven miller on Friday, May 19, 2017 - 12:01 am:

I would consider aerodynamics first. With both cars having a vertical windshield they are shaped like a brick. Slant or lose the windscreen on the runabout would be a good first choice.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Kevin Weeds on Friday, May 19, 2017 - 03:31 am:

I'm not interested in making one faster Steven just what effect the extra weight has in general i.e. if thinking of buying a T


Top of pagePrevious messageNext messageBottom of page Link to this message  By Roger Karlsson, southern Sweden on Friday, May 19, 2017 - 03:53 am:

One indication is that nearly all the participants in Montana 500 uses runabouts, but the difference isn't really as noticeable until you fill the back seat with people..
See for example the weights listed for 1924 in the encyclopedia: http://www.mtfca.com/encyclo/1924.htm

Touring ** 1650
Runabout ** 1540

Only 110 lbs difference with the same equipment = starter/battery and demountables.

I have a foldable rear seat on my light (1300 lb) pickup and it zooms up any hill with two persons in it, but when I fill the rear seat with people it's much harder getting it in high when starting uphill.

So a rear seat is perfect for luggage, the runabouts pre 1926 really doesn't have much space in the trunk, and it's only when you fill it with people you'll notice the weight difference.

Much more flexible use with a car where you can bring some friends, so I would still recommend a Touring. And lighter children in the back seat isn't as noticeable at all when pulling hills or braking.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Kevin Weeds on Friday, May 19, 2017 - 04:37 am:

Great info Roger. I was expecting the difference to be more although it full body v runabout not touring.
Hence according to your link its 335 lb which is 152 kg difference. That's about 8 suitcases, I guess there might be a slight saving in drag from a clear running board but from your experience that extra weight would make a noticeable difference.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Roger Karlsson, southern Sweden on Friday, May 19, 2017 - 05:08 am:

Ok, so full body = Tudor or Fordor, then. It depends on the gear ratio also - I have 3:1 in the rear end and it's great for speed, not so great for heavy pulling uphill. The std ratio 3.64:1 is a very good all around ratio, but Ford also offered 4:1 for Fordors in mountainous regions. Don't be afraid of a full bodied T - but there's a reason Ruckstells are so popular. They give you an intermediate gear between low and high that would help a lot in hilly terrain with a car full of people and stuff.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Kevin Weeds on Friday, May 19, 2017 - 05:58 am:

Yeah sorry, i knew what I meant by full body lol.

All mine are 3.64 but a friend has a 13 runabout with a 3.1 and it struggles to get into top but then ticks along good,
A see a Fordor is heavier again than a Tudor, almost 20 suitcases more than a runabout, that would make a difference.
Ruckstell 3.64 would be good and even better would be a 4.1 rear with a Warford.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Tom Carnegie Spokane, WA on Friday, May 19, 2017 - 08:15 am:

The weight of the car makes little difference on the top end on the flat. More weight just means that any given hill that can't be taken on high will require low pedal sooner. Also, it will take a heavy car a bit longer to reach its top speed. My gut reaction - no empirical proof - is that closed cars, at any rate 26-7 coupes, have better aerodynamics than a roadster with top and side curtains. Therefore, all else being equal, a coupe would have better top end than a roadster, on the flat. A roadster with top and side curtains has better aerodynamics than one without side curtains, and much better than one without a top entirely. One of our local Montana 500 guys actually did wind tunnel tests to prove this.


I drove a coupe one year in the Montana 500. Came in third. It was a rather hilly course that year and I got killed on the hills, but did ok on the flat.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Dennis Seth - Jefferson, Ohio on Friday, May 19, 2017 - 08:43 am:

Well the one flaw I see in your question is two adults and one suitcase. That would never happen with my wife!


Top of pagePrevious messageNext messageBottom of page Link to this message  By Paul Vitko on Friday, May 19, 2017 - 09:52 am:

Agree Tom-----My 22 touring will drop a few mph lifting the top fabric clear up from the wood cross supports.
A few years past I noticed Mr Green had the rear of his touring top missing after winning the 500.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Val Soupios on Friday, May 19, 2017 - 12:06 pm:

I have a speedster, runabout, touring and sedan. They are all stock. They perform in the order I listed them with just the driver. I do agree that once you reach desired speed on a flat there is no difference but acceleration and hill climbing really separate them and added passengers and luggage just make the difference that much more dramatic. A couple of hundred pounds may not sound like a lot but when you consider the percentage increase in the overall weight of the car and relate that to a scant 20 hp you have to expect performance to suffer.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Andy Clary on Friday, May 19, 2017 - 12:29 pm:

As everyone agrees, the weight makes the biggest difference on the hills. Note that the bulk of all the accessories for a T were to improve hill climbing more than speed.

Andy


Top of pagePrevious messageNext messageBottom of page Link to this message  By Kevin Weeds on Friday, May 19, 2017 - 07:06 pm:

Thanks people,
Tom that's very interesting I would have thought a top down runabout would have been better than top up!
The trouble is most open road driving involves inclines, sometimes only slight and isn't noticeable in most cars but a heavy T would probably be effected a fair bit of the time. If buying for a very long road trip I think its relevant.

p.s its approx 9 suitcases extra for a Fordor over a runabout not 20 as listed, I forgot to convert the weight back to KG's

Thanks for your feedback guys


Top of pagePrevious messageNext messageBottom of page Link to this message  By Hap Tucker in Sumter SC on Saturday, May 20, 2017 - 05:43 pm:

Kevin,

The Tulsa Model T Ford club has some excellent documented research on your question. Their conclusion agrees with the observations I skimmed above (so I may have missed one that has a counter conclusion). Their tech page site with the information is located at: http://mtfctulsa.com/Tech/power_and_torque.htm

Their summary:

What have we learned by combining the engine power and torque curves with the calculations for power requirements? In summary, the calculations show that if you are interested primarily in top speed then you should concentrate on peak horsepower. If you are more interested in being able to pull the hills in high gear, then you should look at peak engine torque, gearing and weight.

Here are some guidelines based on the information presented here and other calculations with the spreadsheet. Obviously, a good cam and high compression head will help your carís performance. Either a new Stipe cam or an original stock cam with good lift will do nicely. In the case of our Tudor, the cam and head accounts for most of the increase in maximum grade from about 7% to more than 11%, a huge improvement.

Use gears that are appropriate for your car. As a rule of thumb, for every 10 percent you increase or decrease the rear axle ratio, the maximum percent grade will change by about one percentage point. For the example presented the maximum grade with gears of 4:1, 3:64:1 and 3:1 was 9%, 8% and 6%, respectively. Consequently, a 3:1 rear axle is not recommended unless you have a lightweight speedster with a good strong engine and a Ruckstell rear axle or other auxiliary transmission.

Weight is very important. We estimate that for every 150 to 200 pounds the weight is reduced, the maximum percent grade will increase by about one percentage point. It doesnít matter where the weight reduction comes from. Reduced passenger weight, less luggage, fewer spare parts all work just as well as removing weight from the car. Ruckstell axles and auxiliary gearboxes are heavy. A car with a good strong engine should not need one. Since a new billet cam and Z head costs about half as much as a Ruckstell axle, this approach is also cost effective.

Many Model T owners use distributors instead of the original vibrator coils. We have only limited and not very systematic data concerning this modification. In one test, we found that a distributor may give an 8 to 10 percent increase with peak torque improved more than peak horsepower. We have not considered alternate carburetion either. Since we can achieve very good performance without this modification, we see no need for it. Unlike the cam and head, changes to the ignition and carburetion will alter some of the unique features and the original appearance of the engine.

Thanks to the Tulsa club for making their information easy to get to. They also have other pages on heads etc.

Respectfully submitted,

Hap l9l5 cut off


Top of pagePrevious messageNext messageBottom of page Link to this message  By Kevin Weeds on Saturday, May 20, 2017 - 05:52 pm:

Thanks Hap,
brilliant info


Top of pagePrevious messageNext messageBottom of page Link to this message  By Richard E Moore Jr. Pickwick lake Tenn. on Saturday, May 20, 2017 - 07:30 pm:

I have a 11 open runabout and with a head wind I can tell with the windshield standing straight up. With as much as I can load and 2 people it will g t it. It dose have a ruxtell.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Hap Tucker in Sumter SC on Saturday, May 20, 2017 - 07:33 pm:

Kevin,

You are welcome! In addition to Henry Ford providing us some fun cars, a lot of great folks over the years have shared their time, talents, and lessons learned to help the rest of us have more fun and less frustration.

Oh, and don't forget ... if you spend time & money to make your T go faster don't forget to spend time & money to make it stop better also.

Respectfully submitted,

Hap l9l5 cut off


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