switching form odonals 20% to 30%
 

I plan on using 30% fuel in my truck this summer considering it is ony $3 more. What am i going to have to do to my engine in order for it to use 30%

Shouldn't need to do anything, except maybe re-tune it.

I figured a re-tune. I read somewhere that I should add a head shim because compression increases. I am running the original Dynamite Mach 26 Engine that came in the original Losi LST.

It wouldn't hurt to pick up some extra shims but I don't think they will be needed.

Compression does not increase per say, you will just get a bigger explosion and if it's not shimmed right or running the right plug heat it will pre-det. IMO on that engine there is really no point going to 30% unless that's all you can get. There are a bunch of things that can change going to 30%. Fuel milage changes, higher % means you need to run a richer tune. Depending on what Od's you want to run, all Od blends have different oil content. Example, If you run Speed Blend, that has low oil% and your tune needs to be on key but your engine will also run cooler.. Just be sure to read up.

You will be re-tuning for sure. You will also be shortening the engines life.