The Gen3 manual says

“Best Quality “Premium Unleaded Pump Fuel” you can purchase. If in doubt of the quality of
fuel in your area, a 20 to 40 % mix of 100 OCT unleaded with 93 / 91 OCT unleaded should be
safe.

Does this mean we're tuned to run on 91 Oct fuel? So if we're somewhere 93 isn't available and the track doesn't have unleaded 100 we're ok?

Recommendation is for fuel at 93 Octane (or above). The point being made is that if all you have is a lower grade (or you're uncertain) that a mix of higher octane with lower octane is adviseable to get at or above 93. Here in California (and I expect as well in other areas at altitude and with high ethanol content) the highest grade of premium is 91 (with rare exceptions.) All the tracks I've visited out here have both 91 and 100/101, so I expect most Gen 3'ers are doing some level of "blending". I noticed that the spec fuel at the Runoffs is 100 octane...

Thanks for clearing that up!

I have access to 93 octane with 10% ethanol or 91 octane non-ethanol. Which would be preferable? I've been running the 91 this year.

I seldom use fuel with ethanol. I have a fuel cell that is 15 years old and still looked like new when I did the Gen3 fuel pump conversion. I blend 100 octane track gas with 91 octane non-oxygenated fuel. It is my understanding that ethanol can be hard on fuel cell rubber and foam, your mileage may vary.

It's pretty much impossible to find non-ethanol fuel in California (even the unleaded race gas has ethanol.) One approach to fuel cell preservation, easier with the Gen 3's push-button fuel-pump switch, is to pump out the fuel cell at the end of the weekend.

All this comes with a "your mileage may vary."

I've found that our cells can tolerate typical levels of pump ethanol for at least six months or so. I've been completely draining my cell at the end of the season and so far, so good.

If you do discover some weeping from ethanol softening the cell panel seams' adhesive, try this. IN A WELL VENTILATED AREA (like outside) remove the fuel fill cap and let the empty cell air out for five days or so. This allows the alcohol to evaporate out of the adhesive and it should seal up again. This worked for me several years ago before I started draining my tank in the off-season.

Bill, most track fuel has ethanol, so are you pumping it out after each weekend when you blend it? For example the track fuel for the runoffs is Sunoco 100 octane Gt which has 9% ethanol.

I have been pumping out all the fuel after each weekend with good results. I can get 93 Octane BP with 10% ethanol. If I store the car between race weekends I pump it out and put in a gallon of non ethanol fuel, so I can run it for maintenance purposes. Bill are you going to BIR?

On another subject if anyone is willing to give their opinion. We will be going to the dyno to get a base line prior to full break in of the engine. Is anyone willing to save me some time and comment on any performance difference of using higher Octane fuel and or adjusting fuel pressure with the gen 3 ?

It was nice that Mike allowed us to use the adjustable fuel regulator for the gen 2 to get the most out of our dyno time. Now with the gen 3 it would be nice to know what effect, if any Octane and or fuel pressure has on HP.

Pat









Pat

A little off topic but... What is the best way to drain the fuel cell on a Gen 2 engine? Can you pump it out the schrader valve on the fuel rail? Or, is there a good line to disconnect and pump it out?

Jim

Use a fuel line disconnect tool (available at NAPA/Autozone/....) to remove the fuel line fitting from the fuel rail inlet. The tool retracts the spring and allows the fitting to be pulled out. A plastic hose will fit over the fitting and you can pump back into a fuel can. Be sure to clean the o-ring and use a little WD40 to lube it up for re-assembly.