72 3.0 CS 2240344 Restoration

[ScottAndrews]

Scott, I presume that you have already revised the intake to comply with the porting Don would have done on the head of your new m90. the beauty of 3d printing is the ability to 'tune' the trumpet to match the head to avoid turbulence / eddies in the air flow. the more precise of a match the better the flow.

Yeah, I did the original design to the B30 head, so I’ll need to modify it for the M90’s wider and flatter shape. Was waiting until I got the engine, so I can measure it carefully. And yes, being able to iterate quickly and cheaply is wonderful. Unfortunately the intake area is pretty constrained, so not too many options on trumpet length when using an air filter. After some research I settled on a simple bell mouth design. Apparently other tapered trumpets don’t work well because they do too good of a job matching the acoustic impedance, so you lose the reflected wave. So you want a low turbulence inlet but not a smooth or exponential taper to the trumpet

 

[ScottAndrews]

Flywheel Question:

The M90 engine I just got has no flywheel. Can I use any M30 flywheel (like the one on my 3.0 engine, or do I need something different?

I looked at lightweight flywheels, but while these do allow faster spin up, they also apparently negatively affect drivability and shifting.