Two simple technical questions

[jmw]

I have two technical questions that I'm sure are well within the knowledge and skill base of the members of this group:-

1) The hole for the lifting eye bolt on these Changfa type engines goes all the way through the casting (crank case). Would it be possible to use this hole for lubrication oil refilling? I don't like the dip stick hole method.

2) I plan to convert one of these Changfa type engines to run on biogas. One of the challenges I have to beat is to reduce the compression ratio down to around 11:1. What's the most economic way of doing this (I don't wan to have to change the crank shaft or con rod if I can avoid it)?

Thanks,

     Mark

[mobile_bob]

if you have a direct injection engine, you might not have to reduce the compression ratio

as for the hole in the top of the case, you could add oil there, i don't think you can dip stick it there though
iirc the hole is in line with the con rod.

bob g

[jmw]

Bob,

Thanks for this.

I need to reduce the compression ratio to save the exhaust valve and seat (they burn-out if it's too high).
It's also going to be for a CHP build and we don't mind losing rotational efficiency because we need as much heat as we can get.

Mark

[vdubnut62]

Have a 1/4"( or what ever is needed, my math skills are pretty weak!)  steel spacer, water jet or laser cut using a head gasket for  a pattern, then sandwich between 2 gaskets?
Ron.

[Apogee]

Spacer like vdub mentioned.

Mill a bit off the top of the piston.

Depending on how much meat is in the head, you could also enlarge the combustion chamber a bit thereby dropping the compression ratio down.

Finally, don't forget about changing the injection timing as that could also assist with alleviating the pre-detonation issue.

Just my $.02,

Steve

[LincTex]

2) I plan to convert one of these Changfa type engines to run on biogas.

Mark, by biogas, you mean methane from a poop digester, right?

There is no need to lower copression. Just pipe it into the inlet duct, no other mods needed. Lots of diesel guys are running natural gas into the intake pipe, some engines will run with up to 90% of all fuel being burned as natural gas. A friend of mine that gets free natural gas (gas well is on their property) runs about 15-20% natural gas. You still need to have some diesel injected to get the fire started. All of this depends on how responive you governor linkage is. You start the engine on diesel and bring it up to speed, and as you add natural gas the governor slowly starts taking more and more diesel out to maintain the speed setting desired.