Isn't there a law of diminishing returns with higher octane? I mean a stock IS-F is tuned for a certain octane range from what, 91-93? So why would bumping it up to let's say 95 increase performance? Wouldn't 93 be optimal?
Isnt there something in the owners manual about this? If i wasnt so lazy i would go downstairs and look
__________________
08 Is-F Obsidian Neiman Marcus388whp
09 IS-C 350 Starfire Pearl
08 Ls 460-Smoky Granite Mica(Gone)
08 Rx 350-Smoky Granite Mica My Youtube Channel
It does say minimum 91, but I have personal experience with CA 91. It behaves like 89, not 91. Adding some race gas will likely make a difference, but only some. There is no "diminishing return." If the fuel has adequate octane for the engine and load, more octane will not improve things (I've actually seen very high octane fuel dyno worse because the energy in it was less than a lower octane fuel). All octane tells you is how much compression and how much load the fuel will tolerate before it auto-ignites and causes either pre-ignition (not desperately bad) or detonation (death to the engine in seconds - AMHIK.)
Octane is load dependent, so in theory you could run regular in the IS-F and it would tolerate it as long as you don't put a big load on the engine. Of course the likelihood an F owner ISN'T going to step on the gas hard is pretty small, so we need at least 91 octane to ensure the engine management isn't working overtime to try and minimize the bad effects of pinging or detonation.
Again, if its California 91, I'd add about 20% 100 octane to ensure there is enough detonation resistance to prevent the ECM from backing off the ignition timing and losing power. This is readily apparent at the track where you're at WOT for the whole quarter mile.
Most performance mods need a watch and timed course to demonstrate actual improvement. Few deliver the advertised claims. Many are actually worse than stock. The best performance mods are made to the driver.
Emotional arguments - They're not just for chicks anymore.
It does say minimum 91, but I have personal experience with CA 91. It behaves like 89, not 91. Adding some race gas will likely make a difference, but only some. There is no "diminishing return." If the fuel has adequate octane for the engine and load, more octane will not improve things (I've actually seen very high octane fuel dyno worse because the energy in it was less than a lower octane fuel).
.
Isn't that the definition of diminishing returns Going up in octane as you stated past the level of peak performance can actually diminish performance hence the law of diminishing returns!
The tendency for a continuing application of effort or skill toward a particular project or goal to decline in effectiveness after a certain level of result has been achieved.
Isn't that the definition of diminishing returns Going up in octane as you stated past the level of peak performance can actually diminish performance hence the law of diminishing returns!
The tendency for a continuing application of effort or skill toward a particular project or goal to decline in effectiveness after a certain level of result has been achieved.
Ummm. No. Different concepts and different problems. The thing you are describing would have a bell curve shape. Octane does not. It plateaus and stays there. Just because power drops with certain very high octane fuels does not mean there is a problem with detonation resistance. The sole reason for measuring octane is detonation resistance and engine output is unrelated - IOW, higher octane will not detonate if octane is too high. You'll just waste a lot of money on exotic fuel that doesn't provide any more detonation resistance than a lower octane fuel.
Producing power is completely independent of octane, and not all very high octane fuels will reduce output, only certain blends in specific applications.
Most performance mods need a watch and timed course to demonstrate actual improvement. Few deliver the advertised claims. Many are actually worse than stock. The best performance mods are made to the driver.
Emotional arguments - They're not just for chicks anymore.
I'm in the Viper club here in Kansas City and they do a free dyno day every year for paid members. Took the Viper and the ISF since I plan on ordering the Joe Z intake and exhaust. (Want to hear the exhaust in person before ordering). Any way during the day there were about 20 Vipers so I was definately the runt but did get 3 pulls in. All stock with half tank of 91 and half tank of 93.
The STD correction factor is an inflated correction factor. How much rwhp did your car make SAE with smoothing set to 5? I think the adopted norm (especially here on CL) is SAE and smoothing to 5.
Peter
Yeah thats what Joe Z mentioned on a different board. This week I'll see if they saved the run and can reprint it using SAE, cause i'm curious how it did with other stock ISF's. All the cars were dyno'd using the same factors all day, as the Viper Club gives out trophies for the biggest number and also the Viper runt of the day I found my Dyno sheet from the same place 3 years ago and then they used CF: SAE and Smoothing 3. Back then I did 447rwhp and 491rwt. This year using CF: STD the same car did 463rwhp and 503rwt so that explains the difference. (bout 3.5%)
Here's a video a guy made of the dyno day. Video doesnt show the winning supercharged GTS, putting down 1050rwhp and 1050rwt.
Very nice...any idea how the car picked up 10 rwhp and 11 rwtq?
Peter
Hey Peter,
If I had to take a guess based on what I see; I would say between run 2 & 3 there was an approx 11 minute cool down period...
I would also guess the car was turned off for most of that time period.
The 352 rwhp run, would seem to be the most accurate...
Sungkyo -> Thanks for getting your Dyno runs re-graphed
Joe Z
__________________
2008 IS-F ~ Smoky Granite Mica ~ Black Leather ~ NAV ~ ML
Joe Z Intake - Designed by an Enthusiast for Enthusiasts
Performance Tube Systems Full True Dual 304 SS Exhaust
Five Axis S5:F 19x8.5 & 19x9.5 ~ Yokohama Advan Sport 235-35 & 265-30
D2 Racing Sport Coils ~ Optic Blue AeroTect ~ JDM Fogs ~ JDM Visors
Race Ready......
Baseline stock Dynorun 356rwhp and 332ft lbs tq on Dyno Dynamics and corrected too Now I really wanna see what I can hit on a DynoJet? Do I have a factory freak?
Going to dyno again soon on this same dyno since I have my intake and exhaust already. Just breaking it in before dynoing again.
2008 Honda CrV awd(sold)
2003 Honda S2000 heavily modified by J's racing/Spoon/Mugen/Bride/T1R(sold)
2003 Audi A4 1.8T Quattro Modified by Oettinger/Brullen/I-Forged/FK motorsports(sold)
2004 Acura 1.6l EL(sold)
and many more, too many to list
I found my Dyno sheet from the same place 3 years ago and then they used CF: SAE and Smoothing 3. Back then I did 447rwhp and 491rwt. This year using CF: STD the same car did 463rwhp and 503rwt so that explains the difference. (bout 3.5%) 
Now I really wanna see what I can hit on a DynoJet? Do I have a factory freak? 
Linear Mode
