30% Fuel Question

[NitroEd]

I'm going to the hobby shop tomorrow to pick up an assortment of glow plugs and I am going to try some 30% fuel in my Llumar. Anyone have any experience with this fuel? Pro's, Con's, tuning?

I am also going to buy a radar gun at Radio Shack tonight. They have a clearance sale on them for $75. I figured this may be a good way to see the effects of the different changes will have on my speed.

[engineman351]

NitoEd, It would be nice if the 30% was 'boat' fuel. Boat fuel usually has a more oil in it. Car fuel usually has 10-14% oil depending on the brand/mix. Boat fuel usually fas 18-20% oil. That said the most important thing about upping the 'nitro' is that you have to richen up the mixtue. Nitro is an oxidizer so it is like adding more 'air/oxygen' in the fuel, so if you have more 'air' you need more methanol to go with it. So, open up the needle 'til it's too rich under load (in the water), then lean out for a crisp sound with blue smoke. Also, as you increase the 'nitro' you sometimes have to 'ADD' head shims to lower the compression to help control detonation. After a few runs, check the top of the piston to make sure you are not getting any 'pitting'. Pitting is an indication of detonation. On the radar gun, it helps if you have someone to aim it at the boat. Check out the latest 'R/C Boat Modeler' mag... it has a tip to tape on a reflective plate so the 'gun' has a better target. Good luck. RC

[Old Sloppy]

I am also going to buy a radar gun at Radio Shack tonight. They have a clearance sale on them for $75. I figured this may be a good way to see the effects of the different changes will have on my speed.

My feelings are that you will be better off with an onboard GPS.
for aprox $24 more cost than that radar gun.
The GPS can log other data too, like run time,actual distance traveled.
besides you can test your car's speedo on the way home from the pond.
Remember a GPS can be used in many ways...

Harry S. :)

[NitroEd]

NitoEd, It would be nice if the 30% was 'boat' fuel. Boat fuel usually has a more oil in it. Car fuel usually has 10-14% oil depending on the brand/mix. Boat fuel usually fas 18-20% oil. That said the most important thing about upping the 'nitro' is that you have to richen up the mixtue. Nitro is an oxidizer so it is like adding more 'air/oxygen' in the fuel, so if you have more 'air' you need more methanol to go with it. So, open up the needle 'til it's too rich under load (in the water), then lean out for a crisp sound with blue smoke. Also, as you increase the 'nitro' you sometimes have to 'ADD' head shims to lower the compression to help control detonation. After a few runs, check the top of the piston to make sure you are not getting any 'pitting'. Pitting is an indication of detonation. On the radar gun, it helps if you have someone to aim it at the boat. Check out the latest 'R/C Boat Modeler' mag... it has a tip to tape on a reflective plate so the 'gun' has a better target. Good luck. RC


For some reason I can't get my engine to start with the new fuel. The hobby shop only had 33% Traxxas fuel. Any ideas?

[engineman351]

NitroEd, Check your glo-plug. Make sure it 'lights' up. While you have the plug out, clear the engine of any excess fuel. How many full turns is your needle valve opened?? Usually 3 1/2 to 4 1/2 turns should be enough to get the engine running. How many turns out do you usually run??

Changing the fuel should not make the engine impossible to start. Let me know what you find.

RC

[NitroEd]

I had the engine tuned for 20% so I don't know how many turns out I am at. I backed it out 3/4 of a turn as it stated on the bottle. The glow plug is good. The motor will "pop" like it has combustion but it just won't start. I've tried priming the carb with 20% to get it to fire but that doesn't help.