hpi nitro 3.5 monster truck


New Member
hi there looking for advice pretty new to nitro trucks got a 3.5 nitro savage monster truck with purple head when I bought tuck its got r 5 glow plug its burnt out wondering if that's the best one to get for truck before I order nitro is 20% thanks

Jam Racing 1

Well-Known Member
HPISF Supporter
I use the McCoy MC8 in all my bigblock nitro trucks.... the designation is just there to identify the plug type, The R5 is a racing plug that is medium heat range and is designed to survive in race conditions so if you have spares of those they should be fine for general use also....



Well-Known Member
Dekalb, IL 60115
I like the odonnel purple. It's a medium temp plug and seems to work well with big blocks. Although, all I run is 25% byrons gen2 fuel, so you may want to go with a hot plug on 20%. I'd still try a medium plug though.

Plug temp changes when ignition happens in the stroke. Too hot of a plug and the fuel/air ignite too early in the upstroke and causes the engine to basically fight itself. Too cool of a plug and it fires too late while the piston is at top dead center or later, which causes you to actually lose power.

I ran hot plugs for years until I switch to 25% fuel. I would imagine it would still work well with a medium plug and 20% fuel.