Evo 8, 91 octane: Should I worry about knock?

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Jun 4, 2003 | 02:29 AM

#16

02MaximizedVQ

Evolving Member

Joined: May 2003

Posts: 218

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From: Jackson, MS

Quote:

Originally posted by Claudius
The ECU should normally pull the timing when the car isnt run on the 93 octane gas it is intended to run on. I'm not sure if there's a limit to how much timing the ECU can pull, but if there is, there may be some knock left. This is of course bad and shouldnt happen. Either you run 93 octane like you are supposed to or you have the ECU reprogrammed by your tuning shop in order to accomodate the lower octane gas.

I know in the 2nd generation Eclipses the ECU was very quick to pull ALOT of timing. With upgraded sidemount intercooler and 40 degree temps I was only getting about 11 degrees of timing at 6k rpm. With the proper ECU adjustments you can see over 20 degrees. The 1st gens weren't as bad. But I would suspect the EVO's are timing ***** as well for that nice, fat safety margin for the California folk

Jun 5, 2003 | 11:14 AM

#17

BLKEVO8

Evolving Member

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Joined: Mar 2003

Posts: 283

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From: Seattle

Hey forget the octane boost

Quote:

Originally posted by mayhem
if 93 is unavailable in your area could a mix of octane booster work? Or maybe go out and find some racing fuel and mix your own 93.

OK here in Washington the norm is 92 octane but I lucked out with a Cenex that 94 octane the runs alot better, what I was doinf before I found that Cenex was mixing 101 unleaded race fuel with 92 octane to get 93-94 octane. Don't waste your money on octane booster it will rais your octane .2 at best so you will run 91.2 octane total rip off. The other option is Toluene do a search here there is a whole thread on with links. Or do a search on the web for race fuel there is even mail order for hte stuff or you could find a local distributor. I have spent alot of time researching this topic. The best thing you can do for the Evo is a turbo back high flow panel filter and the highest octane you can get. Then do a ECU flash to lean out the car and lock in the 19.5 psi boost to redline and you will have a reliable rocket car.