There is a comment at the bottom of this page where " interesting observations " this person suggests that more air could be directed to the engine area through the fog light holes if they did not have the fog lights in them. Does anyone know what this is about. Also we have gas stations here in Vegas that sell 100 octane fuel. My fuel meter was down 3 bars so I used some of this fuel in the tank (2.8 gal )then I went for a 80 mile ride, had 91 octane in the tank so I believe that the mix was some where around 95 to 96 in the tank. However I also noticed a dramatic increase in the smoothness of the motor plus I was driving up though a mountain range ( Mt. Charleston ) which is just north of town and is about a 8 degree slope up or greater and around 8500 at top of grade. Had the 3 air mods form spyderpops and never went over 3 bars on the temp meter. And on the freeway on the way back about 49 miles at 75 + MPH never went over 3 but averaged 2 bars most of the time and the outside temp was 100 degrees f. So my question is is this high octane fuel or a fuel octane booster OK for this motor. This was a one time event but I was amazed at the performance and the smooth engine. 2008 roadster right at 5000 miles.
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cool air option
- Thread starter fdunham1
- Start date
Sny
New member
At 2 to 3 bars you're running below the normal operating temp of the engine. The ECU will add additional fuel when running cold which will make it run more smoothly.
We used to use this to trick Japanese engines into adding more fuel by putting a resistor inline with the engine temp sensor so it would think it wasn't warmed up yet. In reality the engine would warm up fine (the thermostat controls that) and the result would be more fuel to compensate for all the extra air it was breathing due to intake modifications and backpressure reduction in the exhaust.
I have thought about trying this on the Spyder to see if the ECU would send more fuel, but my guess is the O2 would detect the resulting A/F and compensate... to a point. Or it would just throw all kinds of errors
So back to your fuel question, Octane is a measurement of detonation resistance. It doesn't mean there's any more energy in the fuel or and difference in the power that it can create. A properly running motor shouldn't be detonating unless there's serious performance modifications (cams, cylinder changes, turbo charging).
That all said, the additives in fuel can effect the energy released in combustion. For example fuel with 10% ethanol in it will burn faster which often results in less power (unless the valve timing is adjusted to account for this. I don't think the Spyder ECU can do that...) The 100 Octane fuels might have less junk additives in them which might result in a slower smoother burn which in turn can yield more power in open loop and a smoother running engine in closed loop.
Another thing I noticed is a fresh tank of gas always seems to make my Spyder happy for a while. Could be cold fuel from the ground or something having to do with the fuel pickup and pump... haven't really figured that out yet. It doesn't like to be run low... maybe all that heat gets soaked into the gas in the tank when there's not a lot in there and causes some vapor lock or something...
the one I was thinking of is the MMG cold air intake off ebay...
http://www.spyderlovers.com/forums/showthread.php?13583-Cool-Air-Intake
We used to use this to trick Japanese engines into adding more fuel by putting a resistor inline with the engine temp sensor so it would think it wasn't warmed up yet. In reality the engine would warm up fine (the thermostat controls that) and the result would be more fuel to compensate for all the extra air it was breathing due to intake modifications and backpressure reduction in the exhaust.
I have thought about trying this on the Spyder to see if the ECU would send more fuel, but my guess is the O2 would detect the resulting A/F and compensate... to a point. Or it would just throw all kinds of errors
So back to your fuel question, Octane is a measurement of detonation resistance. It doesn't mean there's any more energy in the fuel or and difference in the power that it can create. A properly running motor shouldn't be detonating unless there's serious performance modifications (cams, cylinder changes, turbo charging).
That all said, the additives in fuel can effect the energy released in combustion. For example fuel with 10% ethanol in it will burn faster which often results in less power (unless the valve timing is adjusted to account for this. I don't think the Spyder ECU can do that...) The 100 Octane fuels might have less junk additives in them which might result in a slower smoother burn which in turn can yield more power in open loop and a smoother running engine in closed loop.
Another thing I noticed is a fresh tank of gas always seems to make my Spyder happy for a while. Could be cold fuel from the ground or something having to do with the fuel pickup and pump... haven't really figured that out yet. It doesn't like to be run low... maybe all that heat gets soaked into the gas in the tank when there's not a lot in there and causes some vapor lock or something...
the one I was thinking of is the MMG cold air intake off ebay...
http://www.spyderlovers.com/forums/showthread.php?13583-Cool-Air-Intake
Last edited:
ryedoggracing
New member
Been using Star Tron and my Rt has never been happier. I also am getting 32-33 mpg. I in no way am part of star tron. It's just a good product.
Sny
New member
I'm not so sure about these fuel additive products... but 32-33mpg on an RT is better than the 29-30 I get on my RS
Yeah but you don't have to carry trees in the frunk like my wife makes me do... (oh I wish I had a picture...)
BLUEKNIGHT911
Sadly Passed Oct 2024 - RIP
The higher the compression your engine has the higher your octane has to be..... If the manufacturer says it will run on 87 octane , it should without knocking. If it doesn't you have other issues to deal with first. Higher octane doesn't make your motor faster etc. it just makes your wallet lighter. :thumbup:
Sny
New member
Absolutely correct.
Unless you modify your engine with something that changes the compression or increases the volumetric efficiency of the engine such as a Turbocharger, supercharger, changing anything in your exhaust, intake, valve timing, valve diameter, port and polish on the heads and so on.
Doing basic modifications like exhaust pipe and a filter don't change your VE by a whole lot, but if the engine was already near detonation limits stock, you might require a higher octane to increase the detonation resistance (burn slower).
I think if your combustion temps are high that can also cause detonation, this could be due to alcohol in the fuel (ethanol) or very lean conditions? A stock setup will have knock sensors to detect this and retard the timing to keep it from knocking... or something...
I'm far from an expert... tho I do act like a know-it-all sometimes
feel free to add/correct anythingSimilar threads
