General Motors X-250 Radial

Reluctant Poster · Jul 11, 2022

Does anyone have any info on this engine?

General Motors X-250, Radial 4 (8) Engine

Type: Radial, 4 (8) cylinders, supercharged, liquid-cooledPower rating: 168 kW (225 hp) at 2,500 rpmDisplacement: 4.1 L (252 cu in)Bore and Stroke: 78 mm (3.0625 in.) x 109 mm (4.281 in.)Weight: 125 kg (275 lb)A direct-drive, liquid-cooled, supercharged, two-stroke cycle engine,

airandspace.si.edu

NevadaK · Jul 11, 2022

All googling got me was this

GMRL X-250

The cutaway view is informative

ddwhitney · Jul 17, 2022

Reluctant Poster said:
Does anyone have any info on this engine?

General Motors X-250, Radial 4 (8) Engine

Type: Radial, 4 (8) cylinders, supercharged, liquid-cooledPower rating: 168 kW (225 hp) at 2,500 rpmDisplacement: 4.1 L (252 cu in)Bore and Stroke: 78 mm (3.0625 in.) x 109 mm (4.281 in.)Weight: 125 kg (275 lb)A direct-drive, liquid-cooled, supercharged, two-stroke cycle engine,

airandspace.si.edu

Go to enginehistory.org for information on X-250.

NevadaK · Jul 17, 2022

ddwhitney said:
Go to enginehistory.org for information on X-250.

The link I posted above is to engine history.org. Saves you the searching.

brianwnz · Jul 18, 2022

If you're not already a member of the AEHS, it's worth joining - there is a heap of info on that link once you log in.

Not quite the same engine, but the concept must have some relation to it, but here is an obscure design I grabbed the press photo of a while back..... not what you'd want in your Pontiac I'm picking....

special ed · Jul 18, 2022

It appears to be a 2 cycle engine, air cooled. I can see a model airplane application.

Kilkenny · Dec 26, 2022

What an interesting engine; I'd love to see a schematic of it! Because it has an even number of pistons per row, wouldn't it run roughly? And how about wear and tear on the crankpin assembly? I note that the NASM engine is water cooled with a radiator in the front of the engine; whereas the Pontiac engine is aircooled (which might make it better suited for aircraft). But the overall dimensions and weight (of both versions) would make them well-suited for aircraft.

cammerjeff · Dec 26, 2022

I have read that it is not an issue with a 4 cylinder radial, the firing order is #1, #2, #3, #4 repeat. So I guess it could scale up to a 2 row 8 cylinder, 3 row 12 cylinder.....

But I do not know of any multiple row versions actually being built.

SaparotRob · Dec 26, 2022

Won't be fun changing plugs.

General Motors X-250 Radial

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Reluctant Poster

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