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  1. #1
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    Too much fuel octane?? Story inside....

    My car was tuned on 91/93 and 118 Torco race gas by Lance (an AEM tuner that used to work at AA). I recently installed a methanol kit to run 91/meth and be able to daily drive it with higher boost. The car seemed to respond very well with no revised tuning and I was very happy with it. I tested this setup up to 25psi with no issues.

    Some of my buddies organized a mexico run today and I was planned to run a 996tt making over 700whp. I wasn't too worried about it as I know my car can make 700whp pretty easily and now i had good tires to run. I started off by putting in a 5 gallon jug of Torco 110 leaded fuel. My methanol was still active and i drove up to the meet, the car seemed to run pretty damn well. I also tested a higher boost run and it ran very solid. Nevertheless i was excited. Got to the meet and i decided to poor in 5 gallons of C16 VP race fuel, keep in mind again i have not turned off my meth.

    The 996tt and I lined up and took off at 40mph, 2nd gear. Since my turbo is large and i have turbo lag (i did not brake boost this run) i fell behind 2-3 cars initially, i reeled the Porsche in and the race ended with the 996tt ahead 1 car. I was pulling but something was wrong with my shifts, enough to prevent me from passing the Porsche in time. Im used to my car playing catch up and reeling cars in pretty easily, this time i was dumbfounded. I realized my car was stuttering getting into boost and as soon as i shifted, the car would literally freeze at 6000 rpm for 1-2 seconds and stutter to get boost eventually getting into boost while stuttering frequently. Im running 30-31psi here and the 700-750whp 996tt should stand no chance in a highway race.

    We finally ran a 2nd time, this time I hoped boost would act normally. Again same stuttering, this time a little worse. I brake boosted which worked well but the stuttering made me short shift into 3rd, the 996tt got 2-3 cars and stayed there while i tried to stay into any boost I could. Im actually surprised i hung in there while this was happening. This race i filmed and I will have the video up soon. You will be able to see and hear the boost stuttering all throughout the rpm as well as seeing my shift delay.

    Initially i thought my spark plugs might be bad (which im going to change now anyways) but after researching I have found out that C16 race fuel and straight methanol injection is a horrible combination for street cars. Apparently its very hard to burn those 2 together and I believe my motor was having trouble igniting the fuel. This explains the stuttering and why I did not have this issue before today. On the way home i realized I had my vbox and I could try a 60-130 time. I tried doing a run with high boost and the car ran a 7.6, 60-130! This is slower then my low boost 91 octane, street tires 6.8 time!! I was amazed, 30psi vs 20psi and my car was slower with higher boost!

    Unfortunately I figured this out before it was too late and we could not run again. We also happened to stop at a gas station on the way home and I put 5 gallons of 91 octane in. Got on the freeway drove alittle and tried a high boost run and all of a sudden i lose traction shooting my rpm to redline! My intercooler hose pops off at the same time. I could feel the car come alive but i did realize it still did stutter slightly initially.

    Hopefully we will setup another run with this fast 996tt so I can see what really happened.
    Last edited by TaZaM3; 08-21-2010 at 08:36 PM.

  2. #2
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    Went to far with that C16.
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    Just spoke to Drew who was also there today and he experienced the same thing but with the problems less obvious.

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    Click here to enlarge Originally Posted by DBFIU Click here to enlarge
    Went to far with that C16.
    I think it was the C16 with the Meth, if he'd ran just the C16 I think he'd ran great. My buddies 810 whp Protomotive 996tt, dynoed with C16 & Meth, and made 710 whp, when they turned the Meth off, it made the 810, a 100whp difference, too much octane Vik, that 7.6 is slower than my best 60-130, NO WAY my car runs with yours, next time just go with C16 or 110.

    This is a good lesson, as I did something similiar today. I ran Water Meth, and 104 octane fuel, the car did not like it, felt sluggish, and according to my Vbox times I was .5 to 1 second slower, even on a 3.x% decline! If I ever decide to turn up the boost more, than race gas will be needed, until then 91+ Meth seems to work best for my setup.

    We'll setup some more runs with those cars Vik, regardless it was a good time, great guys, glad you made it out Brotha!
    08 E92 M3 - DCT
    Bolt Ons - Best ET 11.88 Best Trap Speed 119.8 MPH
    60-130 MPH (3 shifts) 10.71s
    Gintani Stage 2+ Supercharger 60-130MPH (3 shifts) 7.06s
    11.45 @ 131.6 MPH
    579WHP @9.3psi

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    Click here to enlarge Originally Posted by DLSJ5 Click here to enlarge
    I think it was the C16 with the Meth, if he'd ran just the C16 I think he'd ran great. My buddies 810 whp Protomotive 996tt, dynoed with C16 & Meth, and made 710 whp, when they turned the Meth off, it made the 810, a 100whp difference, too much octane Vik, that 7.6 is slower than my best 60-130, NO WAY my car runs with yours, next time just go with C16 or 110.

    This is a good lesson, as I did something similiar today. I ran Water Meth, and 104 octane fuel, the car did not like it, felt sluggish, and according to my Vbox times I was .5 to 1 second slower, even on a 3.x% decline! If I ever decide to turn up the boost more, than race gas will be needed, until then 91+ Meth seems to work best for my setup.

    We'll setup some more runs with those cars Vik, regardless it was a good time, great guys, glad you made it out Brotha!
    Definitely agree and it makes alot of sense, makes sense i was making around 700whp today on high boost since i stayed right there with the Porsche. I should be doing that on low boost 91 oct! Yet another lesson learned, I will either run 91 meth next time or run 110 and turn the meth off.

    Drew your car still ran great bro! But it definitely looks like you suffered from too much octane as well. These motors are sensitive and they react much differently to different burn rated fuels, add meth to that and the whole thing goes crazy. I feel stupid for making this mistake today and it cost me a race! Oh well, definitely had a blast and everyone there was awesome, great group of guys for sure....

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    Hey I may be preaching to the choir on this, if so please excuse me.

    Running higher octane doesnt always mean more power unless taken advantage of the octane (including but not limited to) via ignition advance. Octane effects the burn rate and the activation energy of combustion. Higher octane slows down the reaction rate + requires more activation energy which = less prone to detonation/pre-igniting the fuel and allows you to run more ignition advance + cylinder pressure.

    Running high octane in a car that wasn't tuned for it will not yield benefit especially when going from 91 to C16; unless.

    Think of it this way, if your car was tuned on a standalone (I dont know Taza, just hypothetically) then the standalone may not know that can bump up ignition advance to take advantage of the octane. If your standalone is monitoring knock sensors (I dont even know if you have knock sensors) and it tips in more ignition than your problem may not have been an octane one.

    That may be what happened, either you were running too much octane to reap it's benefits or there are other problems that were overlooked; I dunno.
    Some people live long, meaningful lives.

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    Great info guys!

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    Click here to enlarge Originally Posted by DBFIU Click here to enlarge
    Hey I may be preaching to the choir on this, if so please excuse me.

    Running higher octane doesnt always mean more power unless taken advantage of the octane (including but not limited to) via ignition advance. Octane effects the burn rate and the activation energy of combustion. Higher octane slows down the reaction rate + requires more activation energy which = less prone to detonation/pre-igniting the fuel and allows you to run more ignition advance + cylinder pressure.

    Running high octane in a car that wasn't tuned for it will not yield benefit especially when going from 91 to C16; unless.

    Think of it this way, if your car was tuned on a standalone (I dont know Taza, just hypothetically) then the standalone may not know that can bump up ignition advance to take advantage of the octane. If your standalone is monitoring knock sensors (I dont even know if you have knock sensors) and it tips in more ignition than your problem may not have been an octane one.

    That may be what happened, either you were running too much octane to reap it's benefits or there are other problems that were overlooked; I dunno.
    Great points all around, I don't think his Stand alone will advance timing to take advantage, but it will pull timing if necessary, but I could be wrong.
    08 E92 M3 - DCT
    Bolt Ons - Best ET 11.88 Best Trap Speed 119.8 MPH
    60-130 MPH (3 shifts) 10.71s
    Gintani Stage 2+ Supercharger 60-130MPH (3 shifts) 7.06s
    11.45 @ 131.6 MPH
    579WHP @9.3psi

  9. #9
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    I don't know the details of the car (ie: tune, EMS etc..).. but leaded fuel will fry your o2 sensors if your using them resulting in poor performance.

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    I was only running leaded fuel for awhile with no issues, then i decided to get meth and drive the car with 91 meth all the time. There was no issues with this. This issue was caused by running high octane leaded fuel and meth. Ive talked to several tuners now who have agreed. Ill be driving the car more this week and reporting what i find.

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    Totally sucks Vik, bad day for us both.

    I'd like to hear from HPF on this subject as their kits do fine with 110+ and 100% meth; but I think they are turning up the timing a lot for this.

    Hopefully we both can get another round of runs with the 996tt's soon and redeem ourselves!

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    Thanks for all the information you sharing. Will be highly valuable to a lot of people.

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    Mike, remember HPF tunes their cars on pump, pump+meth, race gas and race gas+meth. My car was never tuned on meth, it was only tuned on pump and race gas. On pump and meth I've ran it with no issues but when I added the 110 then the c16 with my meth on, the car just didn't like it. I will post the video today, you guys can hear the motor preigniting trying to get into boost, stuttering, etc... My car was severely underpowered because of this, it would have done better on pump meth low boost! On high boost it should have been a complete kill.

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    In the process of ordering an 02 sensor, it seems like that also might be a culprit. Ive noticed some stuttering during low part throttle driving as well.

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    I know HPF tunes for their different maps, I'd just like to hear their opinion and insight and what they have gone through in this situation

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    Turns out my 02 sensor is in bad shape and requires a replacement. Ive had the same one on there since the initial build of this car. I would run leaded fuel all the time, eventually it caught up to its life. Running high boost with all that high octane fuel recently just made it more noticeable. I had noticed some very low part throttle, slight stuttering issue as of late but thought it was something else but now it makes sense my 02 sensor was going bad. Ordered a new sensor, will report back in the next few days.

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    Hmmm, I wonder if the high octane and meth really wasn't the culprit then...

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    Click here to enlarge Originally Posted by MSpiredM3 Click here to enlarge
    Hmmm, I wonder if the high octane and meth really wasn't the culprit then...
    I really dont know, some are saying that it is and some are saying its the 02. I will try to test out the 02 with some methods i found online after i take it off this week. I think its a combination of both to be honest. The 02 sensor is failing and all that leaded fuel with meth caused it to really fail this weekend. Also since i dont run high boost all the time, when i ran high boost this weekend the failing 02 sensor could not read accurately enough. I seriously think my car was underpowered 200-300hp no joke!

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    Also im finding out that straight meth is as bad as leaded gas for the 02 sensors.

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    Damn man, we both have our share of problems! I think my diff took it's lat breath last night as I tried some vbox runs Click here to enlarge

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    Click here to enlarge Originally Posted by TaZaM3 Click here to enlarge
    Also im finding out that straight meth is as bad as leaded gas for the 02 sensors.
    who says this and why?

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    Click here to enlarge Originally Posted by MSpiredM3 Click here to enlarge
    Damn man, we both have our share of problems! I think my diff took it's lat breath last night as I tried some vbox runs Click here to enlarge
    Crap, what happened?

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    Click here to enlarge Originally Posted by LostMarine Click here to enlarge
    who says this and why?
    Ive read it at several different sources, i will try to post it up here. But remember it all depends how much meth you spray and alot of guys just do water/meth. I think this applies to the guys that run straight meth and alot of it. I didnt have 02 sensor issues until after i put on the meth on my car.

    Innovative motorsports says, "Many methanol engines run very rich, not only because of the low stoich AFR of methanol (6.4), but also because methanol has a very high latent heat value compared to gasoline. On a cold engine only part of the inducted or injected methanol even vaporizes and takes part in the combustion. The rest runs out of the exh. ports still in liquid droplet form. This can be seen on the exhaust ports that show traces of liquid methanol running out. This liquid methanol can kill the sensor by heat shock (high latent heat, as said), just as water can.

    In addition the EGTs of methanol are typically much lower than on a gasoline engine, while the exhaust gas volume is higher. This causes the sensor heater to not be able to keep the sensor at operating temperature and it will error out. Even higher supply voltage will not help because the sensor heater has a limit to how much wattage can be supplied to it. After all, these sensors are designed for production cars with much lower power than a methanol fueled dragster. Using a double height bung so the sensor is out of the direct exhaust stream will help the sensor heater to keep the sensor in its operating temperature range."

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    Click here to enlarge Originally Posted by TaZaM3 Click here to enlarge
    Ive read it at several different sources, i will try to post it up here. But remember it all depends how much meth you spray and alot of guys just do water/meth. I think this applies to the guys that run straight meth and alot of it. I didnt have 02 sensor issues until after i put on the meth on my car.

    Innovative motorsports says, "Many methanol engines run very rich, not only because of the low stoich AFR of methanol (6.4), but also because methanol has a very high latent heat value compared to gasoline. On a cold engine only part of the inducted or injected methanol even vaporizes and takes part in the combustion. The rest runs out of the exh. ports still in liquid droplet form. This can be seen on the exhaust ports that show traces of liquid methanol running out. This liquid methanol can kill the sensor by heat shock (high latent heat, as said), just as water can.

    In addition the EGTs of methanol are typically much lower than on a gasoline engine, while the exhaust gas volume is higher. This causes the sensor heater to not be able to keep the sensor at operating temperature and it will error out. Even higher supply voltage will not help because the sensor heater has a limit to how much wattage can be supplied to it. After all, these sensors are designed for production cars with much lower power than a methanol fueled dragster. Using a double height bung so the sensor is out of the direct exhaust stream will help the sensor heater to keep the sensor in its operating temperature range."
    Hi Taza.

    I think what Innovate was referring to were motors running on methanol requiring the 6.4:1 AFR. Our motors run on gasoline, and it's safe to say all the methanol is combusted through our injection process. I think if the sensor is assumed to fail due to thermal strain (heat shock) then it wouldnt be the mode of failure for our cars because we are not using nearly enough methanol as a pure alcohol motor would.
    Some people live long, meaningful lives.

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  25. #25
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    Click here to enlarge Originally Posted by TaZaM3 Click here to enlarge
    Mike, remember HPF tunes their cars on pump, pump+meth, race gas and race gas+meth. My car was never tuned on meth, it was only tuned on pump and race gas.
    And this was part of your problem. Why not retune?

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