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Engine size comparison (SPE26 & G20EI)

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Engine size comparison (SPE26 & G20EI)

Old 11-23-2007, 01:33 PM
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rlemaster
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Default Engine size comparison (SPE26 & G20EI)


I currently have an SPE 26 I was hoping to put in a TF Cessna 182. The engine is a bit large for this plane but I thought it would be a good way to get started with Gas engines. I've recently seen the Zenoah 20EI and am curious to see if anyone owns both and can give me some info about the size differences. From the specs, it appears the Zenoah is actually larger than the SPE26 but seeing is believing. I'm trying to determine whether I would have to cut away as much of the cowling with the Zenoah engine as with the SPE.

Thanks,
Russ
Old 11-23-2007, 09:41 PM
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Default RE: Engine size comparison (SPE26 & G20EI)

The G20EI is smaller than the SPE.The cylinder is smaller so theres not much to cut. You need to purchase standoffs as its not provided to equal the distance of the spe.The carb sticks out about the same distance and supplied welded muffler is bigger and heavier so you might need to make adjustments. You can use the spe muffler by drilling out the holes so that it fits the G20 or the scott ellingson version.Its supposed to increase rpm by a bit and you lose over 2oz in weight.The main bulk of the G20 is at the back so it should'nt matter.It has better performance than the spe!!
Old 11-23-2007, 11:17 PM
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Default RE: Engine size comparison (SPE26 & G20EI)


I thought as you do too but then I went out and looked at the drawings and noticed the following:

Width (from outside of muffler to outside of carb): SPE26 = 144mm, 20EI = 183
The 20 does have a velocity stack on it, but I doubt it is ~= 40mm long

Height (from bottom of engine to top of spark plug - sorta): SPE26 = 125mm, 20EI = 160
The drawing for the SPE doesn't measure to the exact tip of the plug, but it appears to be only 5 - 10 mm below

Length (from back of engine to rear of prop): SPE26 = 110mm, 20EI = 120mm
For the SPE another 10mm or so has to be accounted for due to the threaded shaft

The SPE info was taken from : http://speengines.com/spe26.php
And the Zenoah 20EI was taken from the user manual on horizon.com

I must be missing something here since logic would suggest that the 20 would be smaller, but it looks like the spe26 is. The muffler doesn't appear to be that much thicker than the spe (certainly not enough to account for the difference mentioned above) but maybe the drawing isn't to scale.

Thanks,
Russ
Old 11-24-2007, 09:17 AM
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Default RE: Engine size comparison (SPE26 & G20EI)

My G23 is just about the same physical size as a SPE 26, and though it's been given the Ralph Cunningham (RC Ignitions) diet treatment, it is still quite a bit bigger than my G20.

The standard Zenoah muffler cannot compete in both weight, size and performance with the lightweight Scott Ellington unit offered on some SPE engines, and using one of these will significantly increase the G20's performance.

Also using one of Ralph's thinner and stronger carb rotator blocks which is 3/8" thk. significantly reduces the amount the carb sticks out from the engine while allowing for a straight forward throttle setup.

Karol
Old 11-24-2007, 10:11 AM
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Default RE: Engine size comparison (SPE26 & G20EI)

OK, these are the dimensions that I've taken. The width from muffler to carb excluding velocity stack is 158mm for the G20 and 155mm for the SPE using the spe muffler for both( bolt head included) and about the same if the standard muffler is used for the G20. Height from shaft centre to plug is 130mm for the SPE and about 128mm for the G20. The SPE has a slanted plug so there might be more to cut. Cylinder head dimensions 55mmx70mm for the G20 and 50x60mm for the SPE but then again allowance musrt be given for the slanted plug.The velocity stack measures 25mm tall.
Hope this helps
Old 11-24-2007, 10:20 AM
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Default RE: Engine size comparison (SPE26 & G20EI)

Length from prop drive to rear without standoffs but including rear shaft protrusion is about 120mm for the G20 and 125mm without standoffs and 130mm with the standoffs for the SPE.
Old 11-24-2007, 03:30 PM
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Default RE: Engine size comparison (SPE26 & G20EI)


Thanks for all the info on this. Though the 20 does appear to be a bit smaller (especially when using the alternate muffler), the difference isn't all that extreme. This basically boils down to whether I want to spend money on the 20 or just use the SPE that I already own. For now I think I'm going to go with the SPE. If it turns out to be too much I can always change out to something else later.

Thanks again.

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