I never tried race gas in any cars before that didn't have a standalone fuel cell. What is the recommended way to use race gas on a 2004 EVO? Do you just run on empty up to the track...and then throw in a few gallons?

I run Sunoco 94 Octane, so I would try and find 116 race gas somewhere near the track.

What happens when you mix 94 with 116? Does that harm the engine in anyway?

Suggestions...?

Thanks.

 

It's really simple, so no worries. First of all, do you have a test pipe? If so, then we can continue. If not, and you have the stock cat or HFC, then only use UNLEADED gas (104 or lower usually) to keep from destroying your cat.

Ok, you can mix the octanes no problem, but what happens is it's a linear calculation in determining your overall octane depending on how many gallons of each that you use. If you could get your tank 100% empty, then add 116oct, you'd have straight up 116oct. If you get to the track with the gauge at 1/8th of a tank, then that's about 4 gallons of 94. If you add 4 gallons of 116, then you'd have effectively 8gals of 108oct, which is still great. I almost ALWAYS have a mix. Here's my experience:

With cat-back/mbc/safc, I ran 12.6 at 106.00 on 93oct.
That same night, I threw in 3 gals of 104 unleaded on top of about 3gals of 93oct and ran 12.34 at 110.7 on a bad 60'. My effective octane was only 98-99oct, but it allowed me to run 22-23psi and lean out my S-AFC settings dramatically while experiencing 0 knock and great timing advance. The next day, I went to a different track and tossed in 4 more gals of 104 unleaded on top of a nearly empty tank and ran 12.22/12.24 at just under 111mph, but this time on good 60' times even though it was 20 degrees hotter than the previous night.

Just last week, I went back after adding a 3" DP and TP, so that I could run fully-leaded race gas (116oct). It was 95 degrees, but I was still able to run 23-24psi (added fuel pump for this high boost) with no knock en route to 12.1s at just under 111. Remember that I'm relegated to 110.7mph in 4th, so I can't get higher right now, even though I'm making more power.

So, at the very least, try to show up at the track near empty, but don't hesitate to mix in higher octane. You then need to be able to raise your boost AND tune for it, otherwise you're mostly wasting your money. Just throwing in the higher octane will eliminate any potential knock without additional tuning, but you won't see the true gains without a significant boost increase and removal of fuel + additional timing.

 

Thanks for the info! good stuff!

 

Thanks. I completely forgot about the cat issue and leaded gas. I have a test pipe on order. I have to email Shiv and get a race gas map from him. I have the V3 Xede and I only have a pump gas map from him. I am hoping he will post all of the V3 maps for the Xede stages on his website. It would make it much easier ....and probably easier for Shiv having to deal with people asking him for maps all the time.

Thanks again. I am going to the track this Friday....looking to get those sixty's down a few....

 

Oh...I see...well, you should have a self-tuning device if you plan on changing boost, octane, and AFR/timing. I'm sure you can get a race gas map, but that will still make it static. You'll have to pick ONE exact boost setting and have the EXACT octane level for it to be optimum. That's still not how you want to do it, because the best settings will depend on exactly where your boost is, exactly what octane you have (mix of 94/116, 94/104, straight 116, 108, 112, etc etc), your altitude, the temps, the humidity, etc etc etc.

 

As I understand the Xede piggyback chip, I can self tune it by editing the maps. Once I have a race gas map, I am sure I can find out from Shiv how to adjust the various columns to coincide with the octane levels.

As for climate issues....I'll just have to wing it...

.....I still have to get my boost gauge installed...

 

And if its not tuned for it make sure you raise the fpr 1psi for every pound of boost you raise
it.

Warrtalon another great write up. And one ? for you how can i disarm the 5k rev limter when i try to launch the car.

Thanks
Chris

 

I thought using leaded race gas ruined your o2 sensors.

 

Wears them out much faster

 

okay I'm heading down to the track in a couple weeks and want to order some vp unleaded fuel because I'm running the stock cat. I have a works P2R reflash and the gas down here on pump is 91 so that's what I'm tuned for. What I want to know is if I throw in some street blaze 100 will it help or hurt? I know it won't be optimized but any little thing helps u know. any advice?

 

anyone?

 

If you are not knocking on the 91, you will not benefit from the higher octane just by putting it in and doing nothing else. Actually, it can make you slower since it has a slower burn. Do a light mix. Say 80% pump and the rest 100. See what the car does. It's all about experimenting.

 

works told me otherwise . . .
they told me to reset the battery right before I race and there can be no negative effects like diambo4life says.

 

MrMejia,

I had almost this same question a couple of weeks ago. What Diambo is saying is true, from what I learned from Warr and Trina. Just adding race gas to the same boost won't do anything unless you have knock, like diambo said. So if you don't have knock and you want to run race gas and get the most out of it, turn up the boost some. I was running a 50/50 at around 102 oct. and raised the boost to 24lbs. ran great. The link to my post is here if you want to read up on it, https://www.evolutionm.net/forums/sh...d.php?t=194796

 

Ok, well, then don't bother us with your inquiries if you don't believe the answer. This is pretty common knowledge as far as race gas goes. I don't know what resetting the battery would do. Your ECU won't suddenly retune itself just because you have race gas in there.