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 Post subject: 1902 Steam Car Engine vs Mike Brown Engine - HP disparity
PostPosted: Wed Apr 01, 2015 3:41 am 
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Preface/Bias Disclosure: I don't know Mike Brown, I have not seen his engines in person, but I am skeptical about some of his claims. I consider him somewhat on the fringe. I am not trying to upset anyone who knows him or his work.

That being said, I would also like to limit the discussion to the technical aspects of my question.

I could have posted this on the Engine/Boiler forum - because both steam engines could certainly be used for a steamboat - but I thought given my bias this might be a more appropriate forum.

----
To keep it simple I'm just going to use the name 'Toledo' for the 1902 Toledo Steam Carriage(Car) engine, and 'Brown' for Mike Brown's engine.

The basic specs are the same for both engines:
1) 2 cylinder (not a compound)
2) Both cylinders: 3" bore x 4" stroke
3) Piston valves
4) Both cylinders double acting
5) Aprox Engine Weight is very similar despite different materials, design, construction 123 lbs vs 150 lbs.
6) Enclosed oil filled crank case

Brown is rated at 20HP.
Toledo is rated at 6 to 6.25HP depending on the source.

So my question is - why is there such a HP disparity between these two steam engines? - Almost a factor of 4

Differences:
1) Brown is a 90degree V arrangement. The Toledo is inline.
2) Brown does not appear to have a reversing linkage - Toledo has a Stephenson type linkage.
3) They were designed and built 100+ years apart from each other. There appears to be 2 castings on the brown engine, but the rest looks machined from billet. The Toledo is much more casting.

Unknowns:
Brown develops 20HP at 200PSI steam at 700RPM - claimed.

Toledo original boiler and modern replacement boilers don't say the boiler pressure - but being a steamcar - I would be fairly surprised if it wasn't near or above 200PSI.

Stanley operated at 600PSI. DetruiTug can chime in about Locomobile pressure if he likes.
[Addendum - look at the steamcar.net link below - the dash steam gauge reads up to 400 PSI - If it's correct 200 PSI wouldn't be out of the realm of truth for operating pressure]


Brown Links:
http://www.mikebrownsolutions.com/20hpengine.htm
Two short videos of his engine running under steam on a ASME Vertical Fire Tube(VFT) boiler.
https://www.youtube.com/watch?v=6MQKc1GYWr0
https://www.youtube.com/watch?v=bxv6uT6AGxM

Toledo Links:
http://www.virtualsteamcarmuseum.org/im ... ochure.pdf
http://www.steamcar.net/hyman-2.html
http://media.aeoned.org/portal/members/ ... 1_5950.pdf

Videos from me and my Toledo engine - Sorry for the poor sound and video.
Running on a small dry leg VFT between 50-100PSI.
https://www.youtube.com/watch?v=GT8Hnqo3TOU
https://www.youtube.com/watch?v=nGcS03Shzo8

---

It could be because I know this has changed over time the definition of Horsepower, and the various other variations brake horsepower, etc. - But almost 4 times?

-CB


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 Post subject: Re: 1902 Steam Car Engine vs Mike Brown Engine - HP disparit
PostPosted: Wed Apr 01, 2015 10:44 pm 
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Though the definition of HP has been standard since it was standardized at 33000 ft * lbft / min in 1783, all horsepower measurements are not the same. Since either engine doesn't give the method of HP measurement (or calculation) was used you can't assume that it's an apples-apples comparison. Also, depending how the HP number was derived (calculated or measured) they can not be necessarily compared or may possibly may not even be accurate. The PLAN formula is the most common method used to calculate nominal horsepower but as with any calculation it is only as good as the numbers being input. The incorrect pressure is often used, boiler pressure not average cylinder pressure, and a way too high HP number results. The only way to get an "real" HP number is to put the vehicle on a dynamometer or brake. So take the numbers with a grain of salt unless it's given as shaft or brake HP. (indicated should be close as well).

The Brown number is not unreasonable to have been derived from the PLAN formula.

Edit.... PLAN calculates to 19.97 using 100psi, 700 rpm, double acting, two cylinders. 100psi mean effective pressure is probably about right for a 55% cutoff at 200 psi boiler pressure but terribly inefficient

If you mess with the PLAN formula you can see that changing the numbers can have a huge effect on the HP result. My guess is that your engine HP is real (measured) or calculated using a way more efficient cutoff, hence lower MEP and probably lower RPM as well.



Ken


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 Post subject: Re: 1902 Steam Car Engine vs Mike Brown Engine - HP disparit
PostPosted: Thu Apr 02, 2015 4:28 am 
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marinesteam wrote:
Edit.... PLAN calculates to 19.97 using 100psi, 700 rpm, double acting, two cylinders. 100psi mean effective pressure is probably about right for a 55% cutoff at 200 psi boiler pressure but terribly inefficient

If you mess with the PLAN formula you can see that changing the numbers can have a huge effect on the HP result. My guess is that your engine HP is real (measured) or calculated using a way more efficient cutoff, hence lower MEP and probably lower RPM as well.


marinesteam/Ken,

I won't put my Toledo on a dyno - in my mind - It's a strong gentleman well over a hundred years old who managed to survive somehow and shouldn't be put to that sort of test but may enjoy his respite from storage to enjoy steam once again in a gentler way powering my steam launch. :)

If you read the http://media.aeoned.org/portal/members/ ... 1_5950.pdf
link - some of my strong gentleman's brothers were put to a test in Madison Square Garden Auto Show in 1901 - "Revved up to a screaming 2200 rpm's and then the reverse gear would be suddenly engaged." :shock: I know when you engage a reversing gear on a steam engine the steam will cushion it - but you have to agree that's pretty extreme.

Going by PLAN alone the only two variables are P and N are variable between these engines.

I don't know the N for the Toledo for this calculation. I don't think my Toledo would have any trouble doing 500. But I don't want to push it much past that for an old guy

The P - well if assume the boiler pressure is 200PSI equal for the Both the Toledo and Brown:

It's hard to calculate for the Toledo. I won't tear mine apart.

In defense of the Brown engine there are more details:
http://www.mikebrownsolutions.com/techinfo.htm

--- Added ---
You are probably right that the Brown HP was calculated by PLAN, and Toledo by testing.

There is a difference that I didn't stress - the Brown HP was meant to be continuous duty. The Toledo was probably like most other steam car engines of the day - they would only be used to accelerate/climb the vehicle - but on straights or downhill sparingly used.

-CB


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 Post subject: Re: 1902 Steam Car Engine vs Mike Brown Engine - HP disparit
PostPosted: Thu Apr 02, 2015 3:37 pm 
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I think the Locomobile started out in 1899 with 150 psi then went to 250 psi in 1900. That is why the 1900ish and up engines have the center bands on the cylinders, to take the higher pressure. It's been suggested they are also a heat sink to sustain cylinder temperature. Two people started Locomobile Amzi Barber and John Walker, Walker did not want to make changes to the design and Barber did. So Walker left in 1900 er so and started the Mobile steam car company which was identical to the 1899 Locomobile. Barber made many changes to the Locomobile steam carriage in 1900 like the higher boiler pressure, wider wheelstance (tread) and side tiller steering. That is why many Mobile steamers are confused with being 1899 Locomobiles which of only a few hundred were actually built.

Regarding the Mike Brown engine, many are confused by the ratings. They are not consistent with other known engines and horsepower ratings. As Ken said it may be how the rating was arrived at. These little cars were typically rated about 6-8 horsepower. However I think that is a continual sustained horsepower rating. Opening the throttle on a full head of steam exerts much more than 6 horsepower I would say. On mine it will quickly accelerate two adults to up close to 40 mph. Seems like much more than 6hp at work, comparing to it's 6 I/C hp counterpart.

Someone was talking about this the other day regarding a 20 hp Stanley. Crunching the numbers - acceleration over time etc, it was more like 90 hp, but only for a short distance. That was where the White and Doble with their coiled steam generators had it way over the Stanley and it's firetube boiler. Much harder to control, but higher stable output. The Stanley could take off like a bullet and set many speed, short distance, hill-climbing etc records as a result, but the White will pass it within a mile at it's steady steam output and 40 mph. The Stanley driver relied on stopping a lot.

Rating a steam engine by horsepower is a bit of a misnomer and maybe simply misunderstood. The engine will do as much work as the boiler can deliver in steam - that's it. A buddy of mine uses a Strelinger PM Research coke bottle engine on a steambike. That engine is rated at 1/4 hp. With the pressures and RPM he's running it (with modifications) we ran the PLAN formula and it is actually putting out over 3hp. Quite a difference from it's ratings.

It's much more logical to look at the rated horsepower of a steam engine to intend that it is the maximum horsepower rating per it's designers suggestion. A crane is rated for 10 ton and in reality it will lift 20, for safety's sake it is underrated. However for longevity in service with the Steam engine per it's mechanical strength, area of bearing contact on surfaces that is as much work as suggested be performed. The little Strelinger engine mentioned above has broken many times as a result of trying to get that much work out of it.

-Ron


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 Post subject: Re: 1902 Steam Car Engine vs Mike Brown Engine - HP disparit
PostPosted: Thu Apr 02, 2015 6:28 pm 
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According to the "PLAN" formula, the Mike Brown V-Twin can easily make 20+ horsepower at 700 RPM. Having a boiler that can supply this much steam is another piece of the pie, and the boiler may well limit output.

The Mike Brown V-Twin is about 110 cubic inches displacement, at 700 RPM with 200 PSI steam.

Compare this to my 23 cubic inch single acting uniflow engine is about 1/4 the size of the Mike Brown V-Twin. The uniflow made 4.6 BHP at 1040 RPM with 135 PSI steam, not an estimate, but with a real prony brake.
Roughly speaking, the V-Twin is about 4x larger, and say the lower RPM is cancelled out by the higher steam pressure, compared to my uniflow. So both engines are very similar in output potential per cubic inch displacement.


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 Post subject: Re: 1902 Steam Car Engine vs Mike Brown Engine - HP disparit
PostPosted: Thu Apr 02, 2015 7:38 pm 
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Horsepower is a unit of power (work over a period of time). It's clearly defined as 550 ft*lbs / sec. Any engine with the same HP rating will output the same amount of work. Where the waters are muddied is that not all vehicles have the HP measured at the same place or in the same manner. Locomotives HP is given as drawbar HP, which is calculated by measuring the pull of the loco against a load. Autos are put on the dyno which measures the HP output at the wheels. Both of these methods figure in the losses through the drive system which can be significant. This is a bit more difficult to do with ships, so they are measured by placing the load at the shaft or by calculating, either from a formula or by indicating the engine. All of the methods are designed to give the HP as the maximum work an engine can produce. Don't confuse this with the capability of doing work over an extended period of time. IE: a boiler only needs to produce enough to allow the engine to output for a period long enough to allow the measurement, not necessarily over a sustained period.

Where the waters are even further muddied is where Ron has gone. IC engines have a very different torque profile than that of a steam engine. Acceleration is driven by torque. Steam engines are quite good at delivering high torque at low speeds hence the delivery of great acceleration. IC engines are best at lower torque but higher RPMs so acceleration suffers and necessitating the need for a transmission . The HP output is the same but your swapping lbs for ft. This is why you'll see both HP and torque specs given with autos as they are show different parts of overall performance profile.

I'm curious to see if Jack chimes in. He has put the EB triple on a prony brake and I am curious to see if the measured power is equivalent to the calculated. My guess is that it would be as the formula should be a pretty accurate method of determining shaft HP and has historically been used (so it must work). But of course, the numbers input must be accurate.

With the PLAN formula the number input can have a big effect on the calculated HP. The (P) mean effective cylinder pressure is particularly important and was intended to be calculated using indicated pressure, not just guessing. The use of an indicator is key in getting this number right as the cutoff and exhaust opening points have a huge effect on the average pressure in the cylinder over the stroke. The RPM (N) number used will also have an great effect on the HP. It seems that often this is just an arbitrary choice. Since the bore and stroke are the same, both engines will have the same HP at the same MEP and RPM. Look at what happens when you leave the MEP number constant and plot over a range of RPMs (and vice-versa), you'll see a point where the HP is equal to the given number of the Toledo engine.

Cheers

Ken


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 Post subject: Re: 1902 Steam Car Engine vs Mike Brown Engine - HP disparit
PostPosted: Thu Apr 02, 2015 10:38 pm 
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I do know that the Steam Traction Community shows will some times have a Prony Brake - they do it by belt from the flywheel/pulley.

As was mentioned it is not all that hard for a traction engine to significantly exceed it's original as sold HP rating.

However it is considerably harder/impossible for them to actually maintain such a load. The boilers can't keep up with the demand and steam pressure in the boiler drops.

I have certainly noticed this first hand with my Toledo and the non code dry leg VFT in my videos above. I can run for 5-15 minutes, but after that time the boiler pressure has dropped so much that I have to stop the engine and weight for the steam pressure to build up.

The new larger ASME boiler wet leg VFT for my launch shouldn't have this problem.

-CB


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 Post subject: Re: 1902 Steam Car Engine vs Mike Brown Engine - HP disparit
PostPosted: Fri Apr 03, 2015 1:10 am 
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DetroiTug wrote:
A buddy of mine uses a Strelinger PM Research coke bottle engine on a steambike. That engine is rated at 1/4 hp. With the pressures and RPM he's running it (with modifications) we ran the PLAN formula and it is actually putting out over 3hp. Quite a difference from it's ratings.
...
The little Strelinger engine mentioned above has broken many times as a result of trying to get that much work out of it.

That made me chuckle. Not sure if your buddy has the horizontal(#6) or vertical(#4) - They have the same HP rating and bore x stroke. I have a vertical #4.

When I was first learning steam first hand in my driveway I ended up giving my PM #4 the name - "The Ground Pounder".

I over revved the PM 1/4 vertical, It started to jump up and down until a pin came out of the eccentric linkage. (No permanent damage)

I find the Stuart engines much more balanced at higher revs. I have a stuart 4a - I will not sell it. I'd sell my PM Research #4.

-CB


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 Post subject: Re: 1902 Steam Car Engine vs Mike Brown Engine - HP disparit
PostPosted: Fri Apr 03, 2015 4:03 am 
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""Not sure if your buddy has the horizontal(#6) or vertical(#4) - They have the same HP rating and bore x stroke. I have a vertical #4.

When I was first learning steam first hand in my driveway I ended up giving my PM #4 the name - "The Ground Pounder".""

He's made several mods to it. Bronze steel lined cylinder. Balanced crank shaft, it runs quite well. Just doesn't hold up very long putting that much work through it.
Google "Steam Bike" the poster is "AuraEng"

"As was mentioned it is not all that hard for a traction engine to significantly exceed it's original as sold HP rating."

Yes, that is why I think the HP rating is a sustained rate of work. Or what the boiler can put out at a stable level. Rating an engine by horsepower using PLAN is only as realistic and reasonable as the user of the equation. Like a spreadsheet. As mentioned above any numbers can be put in, but how about the boiler to run it? And how many large steam engines run at 700 RPM?

6 hp steam vs 6hp I/C, the steam engine wins easily. Just as they did in the early 1900's. Steam cars would outrun any gas engine car of the day. The Locomobiles were the first police cars and emergency response vehicles for most cities with a top speed of 40 mph plus. The curved dash Olds and similar cars of the same horsepower wouldn't run half the speed of the steam cars. Top speed on the Olds of 5hp was about 16 mph and that was on the level. Up hill was get out and push. YouTube London to Brighton for a good comparison between the two.

The only reasonable explanation is the steam car (at periods of operation) was putting out a lot more hp than it was rated at.

-Ron


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 Post subject: Re: 1902 Steam Car Engine vs Mike Brown Engine - HP disparit
PostPosted: Fri Apr 03, 2015 6:28 am 
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DetroiTug wrote:
Google "Steam Bike" the poster is "AuraEng"

I couldn't find it - link?

This which just happened in the last year is incredible if you are into steam bikes:
http://ecta-lsr.net/?p=2327

DetroiTug wrote:
The only reasonable explanation is the steam car (at periods of operation) was putting out a lot more hp than it was rated at.

I completely agree with that assessment - especially with firetube boilers. The energy has already been made and stored into a form that can be used and pushed to the engines.

The balance is more delicate for continuous duty.

The USS Monitor which played a pivotal role in the American Civil war and also started the era of Ironclad ships for Naval war was a poor steamer. Probably the boiler(s) and fuel couldn't keep up.

-CB


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