Roelof: Has the European union rules change again for nitro content? I thought the maximum was 16%? If this is the case why has Efra now changed to by weight over volume? Is all very confusing when Energy and Runnertime both have 16% fuels that give performance of a 25% nitro fuel.

It is the European Union who is imposing this rule, they have always said 16% by weight. While the nitro% of the commercial fuels are measured by volume.

Because there is no real affordable(cheap) method of measuring the nitro content of a fuel during a race event. The NITROMAX has been invented which gives a limit to the nitro% used in the fuel by measuring the density.
Some fuel manufacturers have found some solutions to alter this density by changing the type of oil used in the mixture and so they can increase the nitro content, with the result more power. But for me sometimes this also reduces the lifespan of the engine and reliability.

I think these high energy fuels probably also come with some Ethanol mixed that has a higher burning energy. As mentioned only the gravity of weight is checked not the ingredients.

Does anyone know if the sleeve of the r04 is 2103 based or euro spec based?

Hi,

The VSR04 sleeve is the same as the Euro Spec sleeve.

Hello Rody,

With how many shims does the VSR-05 come? Is ot build to run on 16% by weight? Can I run ot on 25% without doing anything to it or should I add shims??

When I ran this motor on 25% I had to run the rp8 plug, to avoid detonation. I changed nothing else. On 16% the rp7 works and the engine runs very well. This was my experience.
the head button on the r05 has a depth of 3mm while the 2104 has a depth of 3.5mm from the squish band to the center where the plug sits.

Thank you Cant drive for to share your experience.
The VSR05 comes with 1 copper shim(0.1mm) and 1 alu shim(0.15mm) the engine can be used like this with 25% nitro. Depending on the track or outside temps. Sometimes a RP8 plug is needed to avoid detonation, or adding another shim of 0.1mm when using 25%

Thank you very much for your quick reply!!
I will try it out and see!!

How can you tell if engine detonation is happening? Is it something you can hear?
or see by checking glowplug or when opening up engine?

thanks

Engine becomes lean easily and very hot. Then it is possible the wire of the glowplug will break and disappear.
Then you need to open the engine at the combustion chamber and if it looks like it is sandblasted then you have had detonation.

The combustion chamber as also the top of the piston must have an equal colored layer with (depending the fuel) some darker edges/lines.
If the colored layer has all over small spots with a lighter color then you are on the edge of detonation, if you are over the edge then it will look like sandblasted as Rody says.

I should add that I run at SCS in Fontana where summer is 90-105f and is at an elevation of 1200ft above sea level

cheers Rody👍

cheers Roelof👍