Hi Stephen,

I think that air intake noise/resonances are also to blame. I believe that
the SA inline 4 has a modified intake elbow assembly that has some sort of
truncated cone in it to reduce the noise.

Exhaust noises can also resonate.

Alistair

>I almost hate to add to the debate, but a question comes to my feeble mind:
>
>One of the problems I recall people talking about re: Eurospec conversions
>was a very irritating resonance or drumming noise from the motor at certain
>rpm's. Many people said it was from the vibrations inherent in an inline
>4cylinder motor. Are these same motors not making drumming noises in the
>TiiCo conversions? Are the motor mounts different, or is this motor
>different, or is something else different?
>