any one know torque curve of 0540 and super charged 0540

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airboat_Mike
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any one know torque curve of 0540 and super charged 0540

Post by airboat_Mike » Thu Dec 21, 2006 9:05 am

looking for torque curve of 0540 and various other a/c engines
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Post by Waterthunder » Thu Dec 21, 2006 9:23 am

If you have accurate Horsepower numbers at an RPM you can back calculate how much peak torque it makes. I have never really heard of an airboater ever dynoing an A/C motor! Roughly and this is a fair number most A/C motors make around a 1/2 HP per cubic inch some make more some make less but a 1/2 HP per cubic inch is a good average. Like a 180 HP Lycoming it is 360 cubic inches.
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Post by Waterthunder » Thu Dec 21, 2006 9:32 am

Here is the formula Torque = 5252XHP divided by RPM. I don't know the rated HP and RPM's for a 180 so let's just do a rough guess. Let's say a 180 is rated for 180HP at 3,000RPM this means 5252X180 divided by 3,000RPM so theoretically a 180 makes 315 foot pounds of torque. This is one reason I laugh when people say oh you want a motor that makes torque not a motor that makes horsepower. See you measure one to get the other.
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Post by jim » Thu Dec 21, 2006 10:27 am

These engines are rated at 2700 I believe.

Using that formula the O360 angle valve (200hp) produces 389 ft-lb of torque at 2700.

The O540 angle valve (300hp) produces 583 ft-lb at 2700.

If your supercharged 540 produces 400 hp at 2700, then the torque would be 778 ft-lb at 2700. The hp number is a guess.

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Post by jim » Thu Dec 21, 2006 11:01 am

Here is some food for thought:

The Russian Vedeneyev M-14PF radial engine weighs 485 dry. It is a supercharged, geared, 621 cu in radial that produces 400 hp.

Since it is geared, the propshaft turns only 1941 rpm at max power. The torque at the prop shaft would be 1082 ft-lb at 1941 rpm.

They produce 1800+ pounds of static thrust on an airplane.

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Post by Waterthunder » Thu Dec 21, 2006 11:08 am

What ratio reduction does it use remember you need to multiply the torque times the ratio then subtract the inefficiency of a gearbox. Like this say a SBC makes 500 ft pound of torque so with a 2to1 gearbox it should produce 1,000ft pounds of torque however any time you reduce something you loose efficiency so lets say a gearbox is only 80% efficient that would leave a 500ft pound SBC with a 2to1 gearbox producing 1,800 foot pounds of torque at the prop.
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Post by cowboy » Thu Dec 21, 2006 11:24 am

Nice posting to you both.
Very nice.
Here's a link to the only published A/C dyno numbers I could find.
It's from an aircraft custom exhaust website, but you can read through it, and find some stock dyno numbers.

For what it's worth.
I thought it was interesting anyhow.

http://www.wemakeyoufly.com/main_whats_news.htm#story007

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Post by jim » Thu Dec 21, 2006 11:26 am

None of that applies because it is rated at the propshaft as all airboat motors should be.

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Post by jim » Thu Dec 21, 2006 11:35 am

Cowboy,

Lycon builds my son's engines. I have seen the dyno sheets for one they built several years ago, but I don't recall the numbers.

There are at least two performance aircraft engine builders that dyno their engines that I know of. That would be Lycon and Barrett I am sure there are more, I don't keep up with that stuff any more.

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Post by cowboy » Thu Dec 21, 2006 11:47 am

Hey,
I gotcha Jim.
I think this is a very good discussion y'all are having.
I probably should'nt have interrupted it.

Here's another interesting link guy's. It's just one page from a very intersting site.
It might be just light reading for you both.
For me, it's very interesting.



http://www.epi-eng.com/ET-Eng-LS.htm

Perhaps these are the folks Waterthunder mentioned sometime back that were trying aluminum v-8's in aircraft applications.

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Post by jim » Thu Dec 21, 2006 12:16 pm

Cowboy,

Feel free, as far as I am concerned. That stuff was interesting. The bottom line with these engines is how they perform on the boat. Dave and I have fun with these little conversations.

However, I have seen gearbox friction loss numbers that are all over the map. It would be very informative to see them dynoed at the prop shaft, as well as thrust numbers. It take some fairly sophisticated equipment to do that, so don't hold your breath.

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Post by Waterthunder » Thu Dec 21, 2006 12:30 pm

Your right Jim they are different that's why you cant compare engine torque to prop torque. Because you can change ratios and the engine torque stay's the same but the prop torque can change hundreds of foot pounds.
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Post by Waterthunder » Thu Dec 21, 2006 12:37 pm

I looked into that and wow what a can of worm's I opened. The efficiency of a gearbox can change 10% in 15 minutes alone due to heat the hotter the box get's the less efficient it becomes. I spoke to a gear reduction engineer about testing my gearbox he told me it's a complex process and they cost around 30K per test. These company test's all the gearbox's for machinery and all the auto manufactures. He knew his stuff and defiantly educated me on reduction efficiency and parasitic drag coefficients changing with heat and horsepower changes. When he was done educating me I realized there can not be a good average number for gearbox efficiency percentages
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Post by jim » Thu Dec 21, 2006 12:54 pm

Why not just hook it up to the dyno a the prop flange, and let it get warm?

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Post by Geneva0550 » Thu Dec 21, 2006 1:00 pm

Here is a link for a company in california that has their own line of performance parts for lycoming and continental engines.They have forged pistons, cams, titanium rods,roller rockers,etc. There were some flow charts but I didn't see any dyno sheets. Still a cool site though.

http://www.performanceengines.com

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Post by airboat_Mike » Thu Dec 21, 2006 1:21 pm

Thanks you have all given me tons of stuff to think about I had forgot how to figure out torque with that formula.
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Post by Waterthunder » Thu Dec 21, 2006 1:23 pm

That would work but I'm not gonna do it. I was thinking of dynoing a motor then install a gearbox, get it hot an make a pull. Then take the gearbox ratio times the motor alone torque then divide that by the out put of the gearboxed dyno pull and then you would have a confirmed efficiency rating at wide open throttle. Remember this will be slightly different at different RPM's and power levels. It just didn't seam worth it. Hopefully some one else will pay for it and educate us all.
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Post by jim » Thu Dec 21, 2006 1:43 pm

Now I understand why some race cars use coolers on the differential. There is power to be regained there.

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Post by Waterthunder » Thu Dec 21, 2006 2:18 pm

The more heat something generates the less efficient it becomes. Simply stated think of electricity as the resistance goes up in a wire the more heat is generated and the more amps are required to do the same amount of work.
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Post by hmgm123 » Thu Dec 21, 2006 4:51 pm

A supercharge 0540 Is rated at take off 3500rpm with 380 hp and 900 ft/lb of torque.

A normally aspirated 0540 has number of hp 260-310hp.

http://www.aviator.cc/weights.txt

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Post by Converted » Thu Dec 21, 2006 5:00 pm

Very interesting. I remember from the Georgia Tech days that the perfect machine would require absolute zero for a heat sink. I always applied the theory to motors but obviously the same conditions exist in gear boxes. Thanks for posting that.

So is it safe to assume that a belt drive like the Blue Lightning is going to be more efficient than a typical gear drive? I'm assuming they run quite a bit cooler.
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Post by Olf Art » Thu Dec 21, 2006 5:13 pm

They will be more efficient in that there won't be any mechanical loss due to gear clash or the resulting heat, and they're quieter, but the big drawback to them right now is that they're limited to only a 2.3:1 reduction ratio.

I run a 2:1 belt now and like the concept, so it looks like I'll be saving-up for one of the Lightning units just so I can drop a lot of weight and at the same time get a little more 'gear' also.

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