Building a smarter air compressor-- my Champion Project compressor

[oil pan 4]

That's a clever approach but I'm pretty sure, not readily done on the R15b, I think it's more common on even larger pumps that generally need a least 7.5hp.

If there's no intercooling between the stages that seems like it would lose a lot of the advantages in efficiency that a 2 stage would offer. Assuming you need to have well above 100psi.
For me more tank capacity and more single stage compressors does the job.

 

[Hohn]

If there's no intercooling between the stages that seems like it would lose a lot of the advantages in efficiency that a 2 stage would offer. Assuming you need to have well above 100psi.
For me more tank capacity and more single stage compressors does the job.

Indeed, for most people, more tank is sufficient.

But I got basically the useful bones of a $4000 compressor for $200, so I think it’s worth it to try to get it into service. A VFD is a reasonable price to pay for making the whole package functional.