Mixing fuels

[2Z's4me]

Originally Posted by Sven59

In Arizona we basically have 91 octane, but there are a few places that sell "racing fuel" which is 100 octane. My question is can you mix the two and at what ratio? Also once mixed, can you just reset the tables or would a tune be required? I would like to be able to boost the octane this way without buying octane booster. Anyone done this?

We have the same problem in California. I can currently get 100 octane at the pump and I mix the fuel in the tank of the car with this simple formula;

2013 ZL1
15 gal x 91 octane = 1365 gal/octane
4.02 gal x 100 octane = 402 gal/octane
1365 gal/octane + 402 gal/octane =1767.0 gal/octane
1767.0 gal/octane/19 gal tank = 93.01 octane

[ZO6 Bryan]

Originally Posted by jessrayo

Octane prevents knock. If you don't have knock you don't need more octane. If you have more octane you can get more timing advance and more power, but you have to have the octane to support the timing advance without knock. True 93 octane should never knock in a stock. Adding octane won't hurt but without advancing timing you are kind of wasting the benefits of more expensive fuel.

I have this on my car.

I disagree, the knock sensors still work if you don't have 2 tables. You just need to be more aware of the fuel you put in the car and if you periodically look at the tune and see KLF is getting higher you probably need to adjust the tune somewhere. I always have 10 gallons of 100 octane in the trunk in case I'm stuck buying low grade fuel. No fuel or knock related problems in my car with one table.

Agreed.

This is all correct but I have to say if you significantly upgrade the car and make a lot of changes to the tune, then any pulling into the stock low octane table robs a lot of power. Hell the stock high octane table would rob a ton of power on my car. Knock is bad, so is losing races because your car is pulling timing because it sensed some knock sometime in the past. KLF is good to know and a good back-up. If it is not close to 0.00 you're running bad gas or your tune is wrong. Then upgrade your gas or adjust your tune.

If properly tuned the the low octane table is a non-issue. And though you keep an eye on it most people won't. Lots of supercharged engines have been blown because someone leaves their tuner and assumes everything is perfect.

[jessrayo]

Originally Posted by ZO6 Bryan

If properly tuned the the low octane table is a non-issue. And though you keep an eye on it most people won't. Lots of supercharged engines have been blown because someone leaves their tuner and assumes everything is perfect.

Yeah, I have learned a lot on this car. I think everyone that mods the car and takes it to HPDE or drag racing should at a minimum get the dashlogic device and take a look at what is going on. I always get a little frustrated when I read the posts about people taking the car to a road racing event in 80 degree weather and saying it runs like a champ. Either they are not driving the car hard or they just do not realize how much power they are losing to intake temps. It keeps running fine but could be losing more than 100 hp.

Thanks for putting all of this up. Great information.

[Sven59]

Do you have default displays for the strip and track? I would be interested in your setup.

[jessrayo]

My aeroforce gauges are realitively new, I was using an OBD blutooth app and my phone and was just watching IAT2 and KR. When IAT2 comes up around 200 on my car it will start to knock anyway. KR is a real time reading of knock retard and not an average like KLF so if you show anything on KR it kind of tells me to back off a little and let it cool down. I was having trouble with real time display delays and losing sync with the torque app, that's why I went to areoforce gauges. I plan to display IAT2, KR, and water temp, since these are the main things that affect real time power and timing retard on my car.

When I was drag racing I would stare at the tach to time the shifts at redline and then when I banged it into 4th I would quickly take a peek at IAT2 and KR as it crossed the line to see if I was losing any power to heat and the corresponding timing retard. 1/4 happens so fast you just check it at the end. I never see KR drag racing but if I hot lap 1/4's it will start to pull timing from high IAT2.

[Sven59]

Thanks, is there a delay on the dash logic?

[jessrayo]

Originally Posted by Sven59

Thanks, is there a delay on the dash logic?

No dashlogic is real time displayed on your cars stock information areas, HUD, the screen between the gauges and the mylink screen. Plus it has an exhaust controller built in.

[Sven59]

That's what I thought, I had the torque app before.