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Discussion Starter · #1 · (Edited)
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Thread Objective:

To find sufficient octane that supports full timing at relatively high boost pressures.

Thread Summary:

Several fuels were used including a toluene mix, Trac Tek 105 unleaded, Trac Tek 114 leaded, and a Trac Tek 114 leaded/pump gas mix. They were tested at various boost pressures to find when knock and timing retard would occur.

AFR and timing were logged and presented in graphical form.

Octane that is typically considered safe was proven to be insufficient causing knock and timing retard.

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Someone posted some data about the OBDII meter software a while back, but nobody ever posted the user interface. Thought I'd share some data from a pull I just made.

T78 @ 1.6kg/cm2 ~22.7psi
~100 octane from 33% toluene/93 pump
Ambient temp mid/upper 50's
RPM and Timing sampled at 1 sample every .66 seconds (ideally).
AFR 11.2:1-11.4:1 (bit rich)

I suppose this looks about right. I'm going to turn the EBC off and run off wastegate after resetting the ECU. I'll post back the results as I expect a little more timing advance. Around max torque the timing gets very conservative and increases as torque drops off. Looks like maybe the toluene isn't quite enough octane for 23psi.

Pull made starting in third and shifting to fourth. Not a real aggressive pull in the high rpms. Since the sample is every .66 seconds, the rpms may have been a bit higher.



The software is quite nice, but does have a couple nuances. First, as far as I'm aware, you can't overlay the different parameters being recorded on the same graph. You have to open the application twice and line the individual graphs up with each other. Secondly, the parameters being recorded aren't scaled to each other on the timeline. The timing graph starts @.61 seconds and the [email protected] seconds, thus the reason for the shift when aligning them.

The software is very easy to use. I was using two PDA's at the time...one for AFR and one for the OBDII software. A little busy in the cockpit :eek: Overall highly recommended, but the software only supports OBDII cars. Software also diganosis codes, clear's them, and will measure 0-60mph times
 

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You guys might want to check out www.pocketlogger.com It's what I use for my DSM and it has all the datalogging features plus you can use a palm pilot for the datalogging. Also you can overlay the graphs like you want to be able to do.
 

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Bad Karma Supra
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stoker6 said:
Someone posted some data about the OBDII meter software a while back, but nobody ever posted the user interface. Thought I'd share some data from a pull I just made.

T78 @ 1.6kg/cm2 ~22.7psi
~100 octane from 33% toluene/93 pump
Ambient temp mid/upper 50's
RPM and Timing sampled at 1 sample every .66 seconds (ideally).
AFR 11.2:1-11.4:1 (bit rich)

I suppose this looks about right. I'm going to turn the EBC off and run off wastegate after resetting the ECU. I'll post back the results as I expect a little more timing advance. Around max torque the timing gets very conservative and increases as torque drops off. Looks like maybe the toluene isn't quite enough octane for 23psi.
I'd agree with that, more octane seems to be required....looks like mid teens under WOT there eh? By all means post some more results - if you log again with higher octane.

Jay
 

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I inquired about the pocketlogger last year. I got a short reply saying that they didn't have applications for the Supra and that they weren't thinking of making one either.
 

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I'm willing to bet if you had some real 100 MON fuel in there you wouldent see major timing retard like you are now. From what i can tell it dosent look like your fuel will not support boost levels over ~18 psi.
 
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Discussion Starter · #6 · (Edited)
This is a run I just now made after re-setting the ECU. I had planned on running only off wastegate (1.2kg/cm2) but I ran into a big BMW sport bike on an open road and turned it back up :cool: The peak hold on boost was at 1.65kg/cm2. AFR's were in the high 11's low 12's after 4.5kprm. The logging starts in second gear and goes through 4 th at ~6.7krpm.

Ambient temps must be playing a huge role (low to mid 50's). Before re-setting the ECU I'd been running around in some mid 80 degree temps....maybe that's where the timing was pulled? Or maybe the stock ECU hasn't had enough time to learn yet? I dunno :) I can't hear audible knock, but the open wastegate is loud as hell.



The software is definitely telling me what I want to know.

Jay and AZ,

I agree, the toluene isn't cutting it overall. In the warmer weather I need more octane. I need to get another drum of GT 104 and do some logging...
 

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Grumpy said:
I inquired about the pocketlogger last year. I got a short reply saying that they didn't have applications for the Supra and that they weren't thinking of making one either.
Their website says the OBDII logger will work for 96-98 Supras.
 

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I need to get another drum of GT 104 and do some logging...
Don't waste your money with that stuff. Get some C16 and mix it to the octane that you need.

For example, you could make GT104 with a 1 part C16 to 2 parts 93 pump mix, and that would cost you around $3.60 a gallon(i'm sure GT104 costs much more).
 

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Chicago///M3 said:
Their website says the OBDII logger will work for 96-98 Supras.
I forgot to mention for OBDI cars. My car is OBDI. I think I will try and plug a DSM datalogger on my car to see if it's compatible.

Thanks for sharing the info guys.
 

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Lets go Nets
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badass, didu h ave nay kock with a full tank of 100? nothing else in the tank, like no 93?

-Brett
 

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Xylene and Toluene appear to have very attractive octane ratings with PONs of 117 and 114 from what I remember. However according to the gasoline FAQ, the blending octane of Toluene when mixed with modern gasoline is a LOT less.

The Gasoline FAQ lists the "Blending Octane Numbers currently used for modern fuels" for Toluene as 111 RON and 94 MON. The blending octane values indicate the actual effective octane when mixed with gasoline.

This topic just came up on the MKIV mailing list. Here's part of it for those interested. The posting sequence is from the bottom up.

Mike

MKIV mailing list thread;
Thanks for the links Lance!
Two of the three links appear to agree reasonably well with the gasoline FAQ values for the blending octane of toluene which are 94 MON, 111 RON, 102.5 PON.

The first link lists a PON of 106 and the third lists a PON of 103. Both of these are in pretty close agreement with the info in the gasoline FAQ for the blending octane with "modern fuels". Only the second link lists a much higher PON value of 112-115. That value is in line with the 114 PON that I generally see quoted for Toluene on the "mix your own race gas" web sites and the blending octane for Toluene in the gasoline FAQ "by API Project 45 using 60 octane base fuel". In summary, three out of four of these references are quoted a much lower PON.

Based on the gasoline FAQ and Lance's additional references, it still seems wise to use some caution and not accept some of the "popular wisdom" that claims a 30% toluene mix is as effective as unleaded race gas. For BPU cars whose alternative is 91 PON with about an 87 MON, it still seems a viable choice. For singles trying to run 25+ psi, IMHO, you should move the boost up slowly monitoring timing along the way. If you don't have a way of monitoring timing and have an EGT probe in the manifold, looking for signs of elevated EGTs as a sign of timing getting pulled might be an acceptable alternative but I'd advise being even more careful turning up the boost and stopping as soon as the EGTs start rising.

Again, it's just my opinion...I was initially VERY interested in toluene and picked up a 5 gal can. After I found the gasoline FAQ blending octane info, I put off trying it. I'm still running 100% 99 MON unleaded with a max boost of 24-25 psi.

If anybody experiments with toluene and monitors timing, I'd be VERY interested in the results. Full WOT timing should be about 22.5 deg at redline on a stock ECU. It will be less at the torque peak (~4.5k rpm) but I don't remember the value and my Techtom MD100 updates so slowly (function of OBDI ECU) that it's hard to check it there.

Comments appreciated.

Mike


At 04:09 PM 12/5/2003, you wrote:
>From: "lance"
>Date: Fri Dec 5, 2003 3:32 pm
>Subject: RE: [mkiv] Plugs, bulbs & Toluene
>
>You might want to rethink that blending octane:
>
http://www.ethanol-gec.org/clean/cf04.htm
http://www.ethanol-gec.org/clean/cf04.htm
http://www.acfa.ws/Support\MTBEProdBltn.pdf (see page 4)
http://www.worldfuels.com/sample.phpOCWK>http://www.worldfuels.com/sample.php?OCWK
>(scroll down about 2/3 to the
>tables)
>
>Nobody seems to agree...
>
>Lance
>'93 TT 6 speed Coupe
>
>-----Original Message-----
>>Sent: Friday, December 05, 2003 10:20 AM
>To: [email protected]
>Subject: Re: [mkiv] Plugs, bulbs & Toluene
>
>I'd suggest being cautious and not initially trusting some of the octane ratings attributed to a toluene & pump gas mix. According to the gasoline FAQ, toluene only has a "blending octane" of 94 MON "currently used for modern fuels". The much higher ratings you see are evidently based on "API Project 45 using 60 octane base fuel" (112 MON).
>
>The gasoline FAQ can be found at
http://www.faqs.org/faqs/autos/gasolinefaq/part1
>
>The info I quoted is in section 4.9 of page 1 of the FAQ. I'm not sure if the higher or lower octane #s represent the true effectiveness of toluene but I haven't seen people post results based on actually monitoring the stock ECU timing at elevated boost. BTW, I've seen at least one other reference that was in line with the info in the gasoline FAQ.
>
>Mike
 

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Wow, Toluene is only 94 MON? Basically that tells me that its rather usless and a higher octane number could be had with a 5 gallon of pump to a 1 gallon of C16 mix which would cost about 2.65 a gallon...how much does Toluene cost again?
 

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AZMongoose said:
Wow, Toluene is only 94 MON? Basically that tells me that its rather usless and a higher octane number could be had with a 5 gallon of pump to a 1 gallon of C16 mix which would cost about 2.65 a gallon...how much does Toluene cost again?
Toluene isn't leaded. That can matter a *lot* to folks who run the stock O2 sensor like me. Beyond that and finding a local source for C16, it's no contest.

IMHO, even if the MON for toluene is that low, it can still matter a lot to BPU cars stuck with 91 pump gas that's probably 87 MON. From this thread, I just don't think it's viable for singles wanting much over 18 psi and certainly not the mid 20s I want.

Mike
 

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Great info guys, this is just what I needed because I've heard lots of mixed opinions of the octane with pumpgas + toluene or xylene mix.

Good to know I cant boost over 20psi eventually when I go single. Too bad you cant get "real" racegas from Finland, not anywhere I know atleast.

Krister
 

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BTW: Do you have an EGT gauge? Do you know which EGT's did you hit?

How much boost would you run on straight 93 octane compared to 93 + Toluene?

Is that 14'ish timing (compared to 23deg stock) dangerous to the engine? Id there a risk in destroying the engine with that kind of timing pulled?

Krister
 
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Discussion Starter · #16 · (Edited)
Hey everyone, and happy holidays...

Just got back from Scottsdale AZ on business (very nice place btw) or I would have responded earlier.

Brett,

I had a mix of chevron 93 and the toluene. I mixed them at 2/3 pump 1/3 toluene.


Krister,

No EGT gauge. Just boost and fuel pressure. I would assume that the EGT's were reasonable because the AFR's are good. Correct me if I'm wrong, but high EGT's are due to lean AFR's while knock is due to to low octane. Not sure but that makes sense to me. Knock will pound a hole in a piston, or crack it, while high EGT's will reduce compression. Again, not sure so someone correct me. Changed my plugs and oil a week or so ago and they didn't show any signs of detonation (although from the timing it happened).

It's not bad to run low timing, you'll just lose a lot of power. The ECU did it's job by sensing a bit of knock and pulling timing. Interesting though, at peak torque is when it was being pulled, then it was back on it's way up. If I would have gone to redline (first pull) it may have gone in the low 20's.

If you guys notice the second run, the timing looks very acceptable. The only change was ambient temp. This looks to me as VERY good data to have. I'm going to start off with a few gallons of 104 ( I want to stay unleaded for now) and increase it until I can run low 20's timing and about 23-25psi boost.

Look for me to bump this thread over the weekend, but yes, the toluene doesn't look like it's going to help a whole lot.
 

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Retarding timing will result in increase EGTs because the air/fuel mixture is ignited later in the compression stroke. You can see increased EGT even though AFR remain the same. Peak torque is where the engine is seeing peak cylinder pressures, and is also when the engine is most prone to knock with too much timing advance. That's why timing is always low at peak torque then increases as rpms goes up. Keep up the research. This is good info.
 
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