Originally Posted by
Spillertwo
Hello Uriah,
Wanted your opinion on these choices for 1/8th on road:
MM M21 engine full ceramic and normal
MM OS XZ-R
how do these engines compare after your modification ?
What kind of break in procedure on hudy propellor bench would you suggest for the OS engine ?
Similar for the M21 ?
Thanks
The M21, and XZR have similar power bands to each other after they are modified. The M21 has the edge on power over the XZR.
The M21, and XZR don't like to be run on the prop as long as some other engines. Heat the M21 up to 200F cover the head, and let it run on the prop at a low-medium rpm for no more than 500CC. Then put it in the car, gradually reach race tune over 5 to 10 tanks. The M21, and XZR are both much easier to break in than most engines.
A long, cold break in will damage the Picco M21 engine. Picco himself only runs a couple of tanks rich, then gradually reaches race tunes over the next few tanks.
The OS can be done the same way. I would not recommend this with most engine brands. Most engines need up to a .5 to 1 gallon of fuel, before you start leaning on them.