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400 LP compression??

I

*IHMMJD*

Member
What should the compression be on a 400 lp? I just overhauled mine and I have atleast 200. It takes two batteries to start this tractor and was wondering if I have too much compression.
 
If it takes two batteries, you have something wrong. Our 400LP always started fine with one battery, even in cold weather.
 
200 PSI at sea level is about 13.6:1 compression ratio. Is this too much. It might be at the top limit. 12:1 is more common, and as engine speed is low, the effective detonation tendency is greater (more time to make excess pressure) Jim
 
It is generally safe to run up to 16:1 compression ratio on an engine that runs only propane. Propane is rated at 110 octane.

Before turbo chargers became common on diesel tractors, one of the ways to increase the HP of the engines was to add propane at the intake manifold. The propane would not ignite until the diesel was injected to start the burn.
 
Two different heads were used on 400 LP tractors. Without knowing what pistons are used or head used its hard to say. If its the late LP head and 4-1/8 pistons are used depending on type 200, PSI is close to standard.
 
the compression ratio is 8.35 to 1 for both

C-281 LPG Fire Crater Piston * +197
C-281 LPG Flat Top Piston * +223
Compression Pressure (at cranking speed)
 
Ya, this tractor is a 56 and does have the better head on it and it does have the 4 1/8 bore. Thanks for the info
 
have you ever thought about seeing how many amps your starter is taking while cranking??? your starter could be on its way out and dragging, causing it to require more amps than one battery can properly provide
 
did you actually check and see how many amps it pulling?? just because something is new or rebuilt doesnt mean it works. they are put together by people, and people can make mistakes.

ive got a 450 LP, and one battery zings it over pretty good
 
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