Most interesting. We'll have to actually monitor the valve rather than seeing it.

 

Well, I just filled up with 93 on an empty tank today. Informal tests (with ScanGauge II) seem to indicate the computer is willing to maintain advance in the 20's up to about 85-89% load at 2000 RPM, which it would not do before. We shall see if any noticeable gains in power or economy come out of this or not.

It cost me around $4.00 more for the 93 octane, by the way.

 

Okay, After 3/4 tank of mixed driving--35% city, 65% hwy--I have noticed that the computer will at times maintain 20 degrees of advance (per SG II) up to 87% load at 1600 RPM. The car does seem a bit more torquey down low, as well, but dyno tests would be needed to quantify the difference.

As for economy, I'm not entirely sure whether I'm getting more or not, but I certainly am not doing worse for the 93 octane.

Whether it's worth the extra $4.00 or so per tank, though, is going to be up to the buyer. I think I like it enough to fill up with 93 every time.

 

If you feel like carrying this a little further, why not see what adding a quality name brand octane booster in addition to premium fuel to see if there is a further increase in timing advance and seat of the pants performance increase.

 

Well the difference ''milleage wise'' is unsignificant with the IK22 spark plugs. I feel the car is a little torquier in the midrange but it didn't do squat milleage wise...

We'll see once i get my Fujita Short Ram intake i just ordered to replace my worn out Factory air filter if that one mod will help... If i had a lot of cash i would compare the short ram to a new air filter but why should i buy a part i wouldn't use later...

My milleage is excellent but note that these are highway milleage (Record is 832km for 44l of Premium fuel from Irving!) I will rarely go beyond 650km in city... Quebec city + rush hours = PITA!

As for AMSoil ATF fluid i planned to use it as my ATF is beginning to look brownish but i will wait another 8000km (i'm gonna reach 50 000km) before i put the good stuff in! Once i'm gonna change it, i'll let you know about it!

Marko!

 

Well, I filled up 10 miles early, but I got 450 miles out of that tank of 93. 460 miles is about 20 more than normal for me, but I have been doing a bit more highway driving.

I filled up with 89, and could tell the difference right away. Almost like 87, torque-wise. Spark advance on the ScanGauge is anywhere from 3 to 10 degrees less than on 93 octane at RPM below 2000 at high load. At or above 2000 RPM, the advance seems about the same as with 93. Fuel economy is about the same so far.

Oh, and to make the math harder, I changed my oil to M1 0w20, with the M1 filter, and added the last 4 fluid ounces of a can of Sea-Foam to the fuel tank.

 

DOHCtor and Scratch&Dent..... Great information and mileage figures..... It amazes me that you guys are producing such great mileage figures with cars equipped wit automatic transmissions..... It is so hot down here that I would be jumping up and down if I could get 38 MPG. The KWSC isn't helping and is making a fraction of the power in 95 to 103 heat.... A lot of the problem is caused by my lack of discipline on winding hilly back roads.

 

Okay, almost done with a tank of 89. Looks like I'll get 460-470 out of this one. Keeping in mind that I changed to 0W20 oil, it looks like 89 is about the same as 93 for fuel economy.

Also, I went to a meet in Atlanta, so I removed the silencer, and I and a friend washed and waxed up the Fit. I was not sure, but acceleration actually seemed to be a little better without the silencer. I don't remember that making a difference before switching to a higher octane fuel. Of course, it could be my imagination.

 

I just returned from my hometown wich is at 320km from where i currently live and my fuel gauge is a little upper then ¾ of a tank... that time the needle did started to go down at approx. 200km instead of the usual 220 230km, but i had 3 passengers in the 200 pounds range plus luggage in the car and you know that if you add 700 pounds in a car that is powered by a tiny 1.5l engine performance and fuel economy will suffer.....

Also when i did get there 3 days ago, i followed a friend that just bought a brand new Evo X so i had a hard time keeping up with him.... it also impaired fuel economy to drive at 100+ Mph for 200+km and then 80+ for the other 100+km.... Yet, still managed to drive 430km instead of the usual 450km to reach exact half a tank (Combined Highway and city!) so i figure the Fujita must have somewhat helped!!

-AMSoil 0w20
-Denso IK22
-Fujita SRI
-Vogtland Drop (Front is more droped then rear so maybe it help..?)
-Alignment was just done!
-Tires are at 40Psi
-92 Octane Irving fuel

Marko!

 

I finished that tank the other day. I got 469.6 miles (minus 4% for the odometer, of course). I then proceeded to fill up with 93. Better spark advance. At 2500 RPM and light load, I was seeing advance in the 30's. I really don't want to go back if I don't have to.

 

Whenever I put premium fuel in I get an extra 3 MPG, however the extra cost of the premium makes it an even trade off in the end. Not worth it really.

 

I haven't yet figured the cost/benefit for me, but if it's an even trade-off, I'll take 93 simply for the performance.

 

I'll admit, it does seem to run a bit smoother on premium.

 

I was getting 33 mpg on regular fuel and consistently over 38 to 39 mpg with premium, generally driving faster than most people do.... There is only a twenty cent difference in price here so it certainly isn't going to break me and there is a noticeable in performance..... My mileage figures aren't what the were when my car was stock and it now requires premium fuel since adding the KWSC kit.... I have been adding an octane booster at times now and there is a positive change in performance when I do....... Than you Scratch&Dent for providing so much information. I appreciate the time and effort that you have invested in researching this.....