I'm posting this because of some recent things I have found. I have all most always ran 87 octane in my 97 and 01 Z24's. My 96 gets 93 because it is turbo. I have run my best times and my best dyno numbers on 87 Octane on my 01 Z24. I recently got HPT. I have been doing a lot of datalogging. Found I was getting lots of knock retard. Up to 6 degree's. SO I have started running 93 Octane. That has since cut my knock retard in half and even more. I know some might say maybe my motor is getting weak. That could be so. It did just dyno 151whp about 2 months ago. I also realize I live in very hot weather compared to others. I also have all motor and tranny mounts installed. My motor is internally stock (other than 2.3 cams). I think this goes to show that with proper tools (HPT being one) you can get a better idea of what your car needs. Mine needs a good tune. I have made small changes and have gotten rid of the knock. I added small amounts of fuel to do so. I'm interersted to see what my car will put down as is, and then with a good tune. I have also seen that my injectors are running at 83% duty cycle max, which I was expecting to be much higher.
FU Tuning
Thanks for the info. Goes to show that there is some benefit to useing premium gas on a mostly stock NA aplication.
FORGET GIRLS GONE WILD WE HAVE GOVERNMENT SPENDING GONE WILD!
Wade Jarvis wrote:Thanks for the info. Goes to show that there is some benefit to useing premium gas on a mostly stock NA aplication.
Makes me wonder...I have to be honest, I didn't get the manual with my car (bought it used and there wasn't one). Don't they say that 87 octane is all it "should" need? Not trying to say that either of you is wrong, just seems odd to me that with 87 you were getting that much knock. I've heard in the past of older cars sometimes being better off with higher octane even if they weren't originally meant to need it (better off = better mileage, better power, etc.). What's the exact basis for that reasoning (if anyone else has heard that sort of thing)?
FWIW, I've never put anything but 87 octane in my '98 GT, although I've only had it 6 months myself. Seems to run fine and I get pretty decent mileage (actually, I'd have to say something like 25 mpg or so and it's nearly all city driving). Then again, I suppose I wouldn't really know if I was getting knock retard unless I had a way to datalog, huh? Hmm...need a laptop again, definitely need a laptop.
At this point i cannot use 87, i have to use 100 or better, i was getting alot of knock even with 93 pump gas. I make weeky trips to get my gas at $6 a gallon. The dyno guys are happy with 100, maybe ill try 104 next year
-Ben
Overall Best times
60' - 1.857 (6/24/07)-(Drag Radials 205-50-15)
330' - 5.552 (6/24/07)-(Drag Radials 205-50-15)
1/8 - 8.690 (7/22/07)-(Conquesrt Radials 195-70-14)
M.P.H. - 81.87 (7/22/07)-(Conquest Radials 195-79-14)
1000' - 11.274 (7/22/07)-(Conquest Radials 195-70-14)
1/4 - 13.442 (7/22/07)-(Conquest Radials 195-70-14)
M.P.H. - 104.08 (7/22/07)-(Conquest Radials 195-70-14)
** ALL MOTOR **
* 181whp @ 7600rpm *
Website: www.benwenzeljr.com
2007 GM Tuner Bash Runner Up - Broken Pressure Plate
#1 Qualifer 13.857 @ 101.49
Marcus Williams wrote:I've heard in the past of older cars sometimes being better off with higher octane even if they weren't originally meant to need it (better off = better mileage, better power, etc.). What's the exact basis for that reasoning (if anyone else has heard that sort of thing)?
It's due to carbon build up in the cylinder raising compression. Running water injection for just a day would fix that though
fortune cookie say: better a delay than a disaster
Ok, figured it was something to do with some kind of buildup or wear of some kind. That makes sense.
What about SeaFoam engine treatment? Does that get rid of the evil carbon deposits?
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We all drive in a yellow Cavalier...
MadJack wrote:Get a reading of your long term fuel trims and spark curve. Run the Premium gas for atleast a week then do a reading of you long term fuel trims and spark curves again. It should adjust for the octane rating of the fuel. Thats why if you want to run premium at the track you need to fuel up about a week in advance to allow the PCM to compensate, especially at WOT.
I have been running 93 for over a week already now. I can say I saw a difference in knock retard in less than a day. I also ran it very low on gas so when I put the 93 in it would get in faster.
FU Tuning
So, running 93 octane fuel gives the same performance boost (in HP increase) as adding a short ram air intake in this scenario?
P.S. I always wondered about an engine running 87 octane with 10:1 compression...
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We all drive in a yellow Cavalier...
Hmm
***Looking for a BLUE 03+ STOCK cavi wing pm me if ya got one you wanna sell***
Impreza WRX wrote:So, running 93 octane fuel gives the same performance boost (in HP increase) as adding a short ram air intake in this scenario?
P.S. I always wondered about an engine running 87 octane with 10:1 compression...
I'm not saying that, and on a bone stock car I would say no increase in performance. Another factor I have to deal with that others might not is heat. I'm in Florida and it is very hot!!! When the IAT's go up less fuel is added. I have seen this in my injector duty cycle. This is were it shows every car will be different and every set-up will be different based on mods and location.
FU Tuning
Well, I only live in the Florida KEYS, and it is always hot down here!
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We all drive in a yellow Cavalier...
The main reason you saw less knock on the 93 octane is because the higher the octane the more detonation resistant the fuel is. You run 93 in the boosted car because you have been told to, not necessarily that you know why. With the higher octane fuels you should be able to advance the timing slightly to take advantage of the detonation resistance, hence an slight increase in hp, you will not see a hp increase by just putting 93 octane in. It is merely a safety precaution that people that rev hi, have advanced timing, boost, or nitrous applications use to utilize the power that their car might have. Hope this helps explain things a lil bit more as to "why".
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4 Cams...32 Valves...5 Liters...This Could Get Fun!
Lord knows I'm froced to run 93 in my tu-tu, but then I have a heavy vehicle app (S-10 pickup) with no knock sensor, so you can figure the load I have on it just to drive it around unloaded even with 4.10 gears.
Go beyond the "bolt-on".
do you have stock injectors?
If you mean me, then: Yes. It's a '94 nearing 200,000 miles, and the injectors have been cleaned before in case you were wondering.
Go beyond the "bolt-on".
