Let's talk gas/oil mix...

[Steve White]

^^^ And tons of low end torque.

 

[David Bryant]

Stu Barr mentioned that he runs 110 octane (or 100LL) w/Quicksilver oil (@10%), thru his CMB 27.0cc Alpha-EVO for best results

 

[Wasted wages]

So far.... I've never damaged a gas motor in my boats, but have read up on some threads that do show some carnage pictures...

Where does most of the damage happen on the Zenoah and Quickdraw engines?
Big end of rod, small end ?

I saw a few that had scoring on the piston/ sleeve near the exhaust port. Is this type of damage due to lubrication issues?
High exhaust temperature vaporizing the oil ?
Or just too low of oil content?

 

[John Beardslee]

So far.... I've never damaged a gas motor in my boats, but have read up on some threads that do show some carnage pictures...

Where does most of the damage happen on the Zenoah and Quickdraw engines?
Big end of rod, small end ?

I saw a few that had scoring on the piston/ sleeve near the exhaust port. Is this type of damage due to lubrication issues?
High exhaust temperature vaporizing the oil ?
Or just too low of oil content?

That can also be a symptom of no water or not enough cooling

 

[Wasted wages]

I understand the cooling part, but have seen piston mods / port mods to help with oiling and prevent scoring ??
Or does the ring get pinched in the piston groove, and cause the scoring ?

 

[Daniel's Racing]

Stu Barr mentioned that he runs 110 octane (or 100LL) w/Quicksilver oil (@10%), thru his CMB 27.0cc Alpha-EVO for best results

100 LL is only 95 to 96 octane RM/2

 

[David Bryant]

100 LL is only 95 to 96 octane RM/2

this is from his response (quote):
"I have used Quicksilver, Red Line and Klotz. My motor did not run well with Klotz. Surprising, because it runs great in nitro motors. I have had Redline go bad. After opening jug, oil would turn a dark amber. Probably was absorbing water. Went back to Quicksilver at 10% break in and run.
I would try to run at least 6 bags of fuel thru for break in. Run 100 LL (avation fuel) or 110 octane"

 

[LohringMiller]

Zenoahs in their stock form are as bullet proof as you can get. They stop when you loose cooling, but often will restart without a problem. Water in the cylinder will twist the crankshaft and might bend the rod. Modified engines start to have issues with the rod big end bearing, especially at over 20,000 rpm. Quickdraw and others modify the rod to help. A better solution is explained in my article Big End Blues. The cylinder can crack if the upper edge of the exhaust port gets too thin. Of course, running the engine on the gasoline without oil in it is really bad. Don't ask me how I know.

Lohring Miller