# Engines: Cost and weight per HP

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#### Vigilant1

##### Well-Known Member
Has to be typos.
I wish Scott at Hummel would redo his website, its need a lot of help.
Yes, it could use some sprucing up. I get the impression he stays pretty busy just based on his reputation, which is a good thing.

I do like Scott's 2180 cc engine, but I don't know what he is using for dual ignition, there again, I want to be able to hand prop. Not that much infro on his website. I know Scott, and would trust him at his word and he sells a good product. That means a lot to me.
Here's a picture from the website of a Onex builder who bought a Hummel/Casler 2400cc engine. I see a magneto going to the top plugs. The bottom plugs look like they are fired by an ignition system triggered by a unit in the distributor hole--maybe this one from Great Plains ($470, incl plugs). If so, the engine could be hand-propped using the magneto, then turn the secondary ignition on >after< the engine is running. I can't tell much about the heads Scott is using from the photo. There's a lot of other stuff to like about the engine, though. (The oil cooler on top is just the way it is typically set up on the Onex, it could go anywhere). Last edited: #### pictsidhe ##### Well-Known Member The lowest cost per hp is the Briggs 21hp 540cc vertical shaft lawn mower engine.$500 brand new with carb and starter.
Would need significant conversion to horizontal shaft, but could be as light as 50 pounds.
Unless they've changed the design significantly from older versions, the balancer will be a nightmare if you turn this engine horizontal. Be wary of vertical Briggs singles! Out of the box weight is the same as the 627cc vanguard twin, though they cost far more.

#### BBerson

##### Well-Known Member
HBA Supporter
Unless they've changed the design significantly from older versions, the balancer will be a nightmare if you turn this engine horizontal. Be wary of vertical Briggs singles! Out of the box weight is the same as the 627cc vanguard twin, though they cost far more.
The sliding balance weight needs some guides to hold it if converted. Or just remove the balance weight and deduct 6 pounds.

#### Hot Wings

##### Well-Known Member
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Log Member
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:gig:

#### BBerson

##### Well-Known Member
HBA Supporter
The crank is counterweighted. Removing the reciprocating anti vibration weight might not matter much at all on a prop plane. At full power the single cylinders pulses shake the engine from intermittent torque. Can't be eliminated.

#### gtae07

At any rate, an IO-360 for an experimental plane should not be $83,000 (wherever that number came from)!!! I believe that is the factory-new certified engine cost. And that's list price. Few things ever sell at list price. #### Topaz ##### Super Moderator Staff member Log Member ... Hummel (Scott Cassler) sells a "2400cc" engine: (85 HP max, 94mm bore x 86mm stroke, unspecified CR). It looks like the weight is 167 (incl carb?) All Scott's listed weights include everything needed for the engine to run except oil. Weight of the prop and hub are additional, of course. I wrote him one time and asked him this exact question. +1. And among distributors, finding a price online is as likely as finding nuclear missile launch codes. All-up weight data? Notoriously incomplete ("Oh, that weight doesn't include a starter. Or carb. Or pistons.") Actual general arrangement drawings, specs, and a power curve seem to be exponentially harder to get with the inverse of the engine price. Heaven forbid that you ask for reasonably accurate fuel-consumption or even >gasp< SFC. It's as if the manufacturers don't care that someone has to design a firewall-forward installation for their products, and the distributors follow suit. I've asked a few small-engine manufacturers - some of them specifically aircraft engines - for basic data like this and the e-mail response is usually the textual equivalent of looking at me as if I had a third eyeball in the middle of my forehead. #### TFF ##### Well-Known Member I can see why fuel burn is not quoted. How its propped and the airframe it's on will make too much a difference. There is no standard to test to. #### Pops ##### Well-Known Member Log Member Yes, it could use some sprucing up. I get the impression he stays pretty busy just based on his reputation, which is a good thing. Here's a picture from the website of a Onex builder who bought a Hummel/Casler 2400cc engine. I see a magneto going to the top plugs. The bottom plugs look like they are fired by an ignition system triggered by a unit in the distributor hole--maybe this one from Great Plains ($470, incl plugs). If so, the engine could be hand-propped using the magneto, then turn the secondary ignition on >after< the engine is running.

I can't tell much about the heads Scott is using from the photo. There's a lot of other stuff to like about the engine, though. (The oil cooler on top is just the way it is typically set up on the Onex, it could go anywhere).

Good with the mag it can be hand propped. The mag is the new surplus mag, nothing wrong with that. I do not like the oil cooler in that location. Its not a full flow cooler. I think you can get more air through the cooler mounted on the lower firewall in the low pressure area and large scat from the baffling. That is the easiest way. I welded aluminum bosses on to the same cooler that was drilled and tapped for oil lines. Ran the oil from the front oil pump cover for full flow and then back to the block. Just a bypass plate on top of the engine where the oil cooler is mounted.

#### Marc W

##### Well-Known Member
I have a 2180 built by Scott. It has the electronic ignition and surplus magneto like the picture. I believe the electronic ignition is the one sold by Great Plains. The mag only has 15 degrees of lag. People have modified the mags to increase the lag so you can hand prop. 25 degrees of lag is better to hand prop. I bought one of the surplus mags on ebay to experiment with.

My oil cooler is mounted on the bottom of the engine. An inlet feeds air to the bottom of the crankcase and the air exits through the oil cooler.

Scott is busy! I called him a month ago about going through my engine since it has been sitting for 4 years. He was backlogged 5 months.

#### Pops

##### Well-Known Member
Log Member
I have a 2180 built by Scott. It has the electronic ignition and surplus magneto like the picture. I believe the electronic ignition is the one sold by Great Plains. The mag only has 15 degrees of lag. People have modified the mags to increase the lag so you can hand prop. 25 degrees of lag is better to hand prop. I bought one of the surplus mags on ebay to experiment with.

My oil cooler is mounted on the bottom of the engine. An inlet feeds air to the bottom of the crankcase and the air exits through the oil cooler.

View attachment 73219

Scott is busy! I called him a month ago about going through my engine since it has been sitting for 4 years. He was backlogged 5 months.
The Slick mag made for the VW has 25 degrees of lag but the cost is like gold.
I see you are using the full oil flow cooling system, great. No oil control piston to stick and take the oil cooler out of the system.

#### Topaz

##### Super Moderator
Staff member
Log Member
I can see why fuel burn is not quoted. How its propped and the airframe it's on will make too much a difference. There is no standard to test to.
Neither SFC, nor fuel consumption at a given power setting, are influenced by the prop, the airframe, or anything else beyond the engine itself. Those things influence power setting for a given performance. SFC is a measure of power output per unit fuel and unit time.

SFC is the standard measurement of fuel consumption by a gasoline engine from an engineering perspective, precisely because it's not influenced by the airframe.

#### blane.c

##### Well-Known Member
HBA Supporter
Couldn't a vibrator/exciter be put on one or the other ignition systems to facilitate easier starting and make hand propping feasible? And would it be less or more expensive than a Slick mag?

#### TFF

##### Well-Known Member
It is and isn't. Without a standard it isn't. An airplane standard. Personally I think people put too much into the HP numbers beimg precise, especially with a low volume product. The problem is with application. Climb prop never develops load on the engine to get to max horsepower and a cruise prop never lets the rpm get to the max HP point. Of course as altitude changes the producible horsepower is changing. True fuel consumption is going to be about application. Add to extremes of clean or draggy airframes and you will probably get 20% true number swings for the same engine.

#### mcrae0104

##### Armchair Mafia Conspirator
HBA Supporter
Log Member
It is and isn't.
BSFC is variable, depending on torque produced and RPM. Selecting a cruise prop vs climb prop would be akin to the 2nd/4th/5th gear points on this chart. I don't think aircraft engine manufacturers produce these charts for public consumption, but it would be helpful in selecting a prop for the intended design point if efficiency is the goal.

A clean or draggy airframe shouldn't change the BSFC (and I'm not even sure how much % difference the prop will make). I presume that higher altitude would simply limit power output without changing the BSFC chart, but the chart probably assumes a particular mixture (stoich? best power? I don't know...).

#### BBerson

##### Well-Known Member
HBA Supporter
The Lycoming operators manual has charts.

#### Vigilant1

##### Well-Known Member
The lowest cost per hp is the Briggs 21hp 540cc vertical shaft lawn mower engine. $500 brand new with carb and starter. Would need significant conversion to horizontal shaft, but could be as light as 50 pounds. Is the 21HP version still available? This retailer says that they have been discontinued, and that the B&S 540cc vertical engine that is currently in production provides 19HP (gross). It sounds like they either changed the compression ratio or they got caught, er, decided to relabel the same product for a lower HP. Hmm--a single-cylnder 19 HP engine that weighs 50 lbs, but may have a bit of a shake if the balancer were removed. If we could Siamese two of them together, we'd be at about 100 lbs, 38 HP, maybe a lot of the shake gone, at a price of about$1000. That would be something, but I'm sure a lot harder to do than to think about.

#### Vigilant1

##### Well-Known Member
My oil cooler is mounted on the bottom of the engine. An inlet feeds air to the bottom of the crankcase and the air exits through the oil cooler.

View attachment 73219
Marc, is that the installation on your Thatcher CX4? My Sonex is setup the same way (I think most Sonexes are like this, though those who have fitted the turbo had to move the cooler to the top of the engine, as it is done on the Onex). It works well, and keeps the air duct and oil lines short. It does make changing the oil a bit of a bother since the oil cooler has to be moved to remove the cover and screen installed on the bottom of the oil pan.

#### pictsidhe

##### Well-Known Member
Is the 21HP version still available? This retailer says that they have been discontinued, and that the B&S 540cc vertical engine that is currently in production provides 19HP (gross). It sounds like they either changed the compression ratio or they got caught, er, decided to relabel the same product for a lower HP.

Hmm--a single-cylnder 19 HP engine that weighs 50 lbs, but may have a bit of a shake if the balancer were removed. If we could Siamese two of them together, we'd be at about 100 lbs, 38 HP, maybe a lot of the shake gone, at a price of about \$1000. That would be something, but I'm sure a lot harder to do than to think about.
Briggs got into legal trouble over their claimed hp a few years ago. Most of the smaller engines are now rated in torque. That way they didn't have to obviously derate them.

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