GT4094R Dyno chart
I do! Higher octane fuel has shown to be less explosive and need more spark to ignite. It's harder to ignite/pre-ignite. Dumping in extra fuel when using a lower octane virtually duplicates running a higher octane gas. Everyone always talks about how dumping in extra fuel provides a cooling effect. Well I always saw it as the extra fuel not burning fully which in itself, helps eiliminate detonation.
BDC Motorsports
Joined: Jun 2002
Posts: 3,667
Likes: 6
From: Grand Prairie, TX
Brian, we have a "lease" option available as well. Would you like to mull it over with a free test drive of idea?? 
Standard IGL, starting low and ramping up and through the torque peak (well it's supposed to when you spin it that high). Ambient air temps were 90F with no "chilling" in between runs other than running the car for 10-15 minutes with industrial fans blowing on the coolers. Did 14 back-to-back runs, not all of them full pulls (as evidenced in the chart). I think I can find my chit for that morning's purchase of gas. Not sure if it details what was purchased or not. I will say that lamda was in piggie range. When you coming out this way? I offered to buy you a beer and a steak.
Tony
Edit: Also, at least 40 nostrils were in attendance...someone would have smelled race gas, I am sure...those that could still smell.
Edit: Perhaps like "peer/pair-programming" we should start a "peer/pair-tuning" program where are tuning is certified by the buy standing behind...with or without a shotgun involved.
Standard IGL, starting low and ramping up and through the torque peak (well it's supposed to when you spin it that high). Ambient air temps were 90F with no "chilling" in between runs other than running the car for 10-15 minutes with industrial fans blowing on the coolers. Did 14 back-to-back runs, not all of them full pulls (as evidenced in the chart). I think I can find my chit for that morning's purchase of gas. Not sure if it details what was purchased or not. I will say that lamda was in piggie range. When you coming out this way? I offered to buy you a beer and a steak.Tony
Edit: Also, at least 40 nostrils were in attendance...someone would have smelled race gas, I am sure...those that could still smell.
Edit: Perhaps like "peer/pair-programming" we should start a "peer/pair-tuning" program where are tuning is certified by the buy standing behind...with or without a shotgun involved.
I appreciate the polite offer, but I still don't buy it. There's something else up here; something you're not telling us. Straight 91 is very volatile up at high loads like that. We've seen it for years and years on much less boost and considerably less engine loads, assuming the figures posted are correct.
What's "standard IGL"? That doesn't say anything as to what the spark advance is at x load and y RPM, but honestly the amount of advance makes no difference when you out-load too low a performance octane fuel. The failure mode of too low an effective octane of fuel in the charge is pre-ignition (caused by auto-ignition) which occurs prior to firing the plug(s) during the compression stroke anyways.
Nonetheless, if the numbers are accurate, they're good and it'll be reflected by how well the car runs.
B
BDC Motorsports
Joined: Jun 2002
Posts: 3,667
Likes: 6
From: Grand Prairie, TX
I do! Higher octane fuel has shown to be less explosive and need more spark to ignite. It's harder to ignite/pre-ignite. Dumping in extra fuel when using a lower octane virtually duplicates running a higher octane gas. Everyone always talks about how dumping in extra fuel provides a cooling effect. Well I always saw it as the extra fuel not burning fully which in itself, helps eiliminate detonation.
You can dump as much fuel at an already low-octane fuel problem you can, but you can never, ever change the physical properties of that fuel on-the-fly by just tossing more at it. Not only does it challenge the ignition system's ability to light it (due to increasing saturation of the charge) as well as the overall capacity of the fuel system, it does a ****-poor job of cooling a chamber during any stroke compared to that of many other fluids (water, alcohols, etc). The whole running a near spark-blowing out mixture vs. that of one that yields the best combustion, torque, and power output comes from choosing to not use the proper fuel for the projected load in the motor -- it has a marginal effect. You could hold a bucket of pump fuel and pour it into the intake manifold; it will still only be pump fuel.On the detonation comment... throwing more and more fuel at a charge creates less and less efficient combustion; more and more fuel will be left unburnt and unused during and post-power stroke, which is what increases the likelihood of real and true detonation. Detonation is not a general term; that's knock. Knock describes a myriad of conditions that can have their roots in tuner mistakes, too-low octane fuel, or goofs in the EFI/ignition system that cause a 'hiccup' in the motor while running. Detonation is a second stage of combustion that occurs post power stroke (after the initial spark-induced power stroke has fired) due to having too rich a mixture (unburnt fuel in this case) along with sky-high chamber temperatures that cause auto-ignition.
Regarding making "virtually duplicated race gas", if what you say is true, then there'd never be a reason to run any AI, let alone any kind of race fuel, ever, but the fact that so much of it exists and is well proliferated, not to mention used pretty well exclusively in race-type circuits, suggests that your argument is incorrect. That good-quality fuel is designed for high load and used for a very good reason.
B
Edit: to insert detonation comment
Last edited by BDC; Jul 19, 2007 at 10:45 AM.
Thread Starter
7 Rx-7s since 1980
Joined: Mar 2004
Posts: 438
Likes: 1
From: oHIo
Not a problem, Brian. Appreciate your questioning. I will offer a correction, the octane level was 92, not 91 as I mentioned earlier. Not that is makes a hill of beans difference. The Sunoco I go to sells 92 and 94, but no 91.
The last 30 days of operation the car has been tapered off of 94 and to 92 octanes, as I drive and tune the car back and forth to work. The motivation here was to never claim a certain performance level at a low octane of gas, but rather to try and save a little bit of money while I drive the car back-and-forth to work. I will also tell you that I have managed to calculate "very good" MPG for a couple of longer trips that would raise some eyebrows. That is noise to the points you raise.
In reverence to scientific method I will offer you an opportunity to come out here, partake in a free beer and a steak, and fill my tank up with 92 (that might a wash with the beer and the steak) and let's out it on the Rx7Store dyno. Be an opportunity for you meet some people and apply observable and empirical evidence to your (and other established) hypotheses and results of formal experimental studies. If I am wrong, I'll honestly admit it, if you are....you can promise to do the intake porting on a HB for my next project.
There is nothing that I am pitching or that I am gaining from posting this information. I no longer actively tune other people’s car for money (few expectations for friends or family.) My goal was to fill a void of performance information around the GT40 family of turbos (and cars running them.) Believe it or question it, it is your prerogative.
To break done our discussion:
Me: I made XXX power with RRR octane fuel.
You: No way you can make XXX power with RRR octane fuel.
I'll be glad to talk you about this on the phone about it if you would like. I have free long distance. PM me your number.
When I add the AlkyControl or Aquamist HS1 systems I hope for future stimulating threads.
Tony
Edit: spelling pwns me
The last 30 days of operation the car has been tapered off of 94 and to 92 octanes, as I drive and tune the car back and forth to work. The motivation here was to never claim a certain performance level at a low octane of gas, but rather to try and save a little bit of money while I drive the car back-and-forth to work. I will also tell you that I have managed to calculate "very good" MPG for a couple of longer trips that would raise some eyebrows. That is noise to the points you raise.
In reverence to scientific method I will offer you an opportunity to come out here, partake in a free beer and a steak, and fill my tank up with 92 (that might a wash with the beer and the steak) and let's out it on the Rx7Store dyno. Be an opportunity for you meet some people and apply observable and empirical evidence to your (and other established) hypotheses and results of formal experimental studies. If I am wrong, I'll honestly admit it, if you are....you can promise to do the intake porting on a HB for my next project.
There is nothing that I am pitching or that I am gaining from posting this information. I no longer actively tune other people’s car for money (few expectations for friends or family.) My goal was to fill a void of performance information around the GT40 family of turbos (and cars running them.) Believe it or question it, it is your prerogative.
To break done our discussion:
Me: I made XXX power with RRR octane fuel.
You: No way you can make XXX power with RRR octane fuel.
I'll be glad to talk you about this on the phone about it if you would like. I have free long distance. PM me your number.
When I add the AlkyControl or Aquamist HS1 systems I hope for future stimulating threads.
Tony
Edit: spelling pwns me
Last edited by Asleep; Jul 19, 2007 at 11:40 AM.
Thread Starter
7 Rx-7s since 1980
Joined: Mar 2004
Posts: 438
Likes: 1
From: oHIo
Hmm. I assume when I purchase 92 Octane from my local Sunoco, I am getting that octane level. I never even throught that I could be getting MORE than I am paying for. That is a variable. The dyno is a variable as well. So is every aspect of my car that contributes to the XXX at YYY equation.
Not to be rude t-von... but baloney. You can dump as much fuel at an already low-octane fuel problem you can, but you can never, ever change the physical properties of that fuel on-the-fly by just tossing more at it. Not only does it challenge the ignition system's ability to light it (due to increasing saturation of the charge) as well as the overall capacity of the fuel system, it does a ****-poor job of cooling a chamber during any stroke compared to that of many other fluids (water, alcohols, etc). The whole running a near spark-blowing out mixture vs. that of one that yields the best combustion, torque, and power output comes from choosing to not use the proper fuel for the projected load in the motor -- it has a marginal effect. You could hold a bucket of pump fuel and pour it into the intake manifold; it will still only be pump fuel.
On the detonation comment... throwing more and more fuel at a charge creates less and less efficient combustion; more and more fuel will be left unburnt and unused during and post-power stroke, which is what increases the likelihood of real and true detonation. Detonation is not a general term; that's knock. Knock describes a myriad of conditions that can have their roots in tuner mistakes, too-low octane fuel, or goofs in the EFI/ignition system that cause a 'hiccup' in the motor while running. Detonation is a second stage of combustion that occurs post power stroke (after the initial spark-induced power stroke has fired) due to having too rich a mixture (unburnt fuel in this case) along with sky-high chamber temperatures that cause auto-ignition.
Regarding making "virtually duplicated race gas", if what you say is true, then there'd never be a reason to run any AI, let alone any kind of race fuel, ever, but the fact that so much of it exists and is well proliferated, not to mention used pretty well exclusively in race-type circuits, suggests that your argument is incorrect. That good-quality fuel is designed for high load and used for a very good reason.
B
Edit: to insert detonation comment
You can dump as much fuel at an already low-octane fuel problem you can, but you can never, ever change the physical properties of that fuel on-the-fly by just tossing more at it. Not only does it challenge the ignition system's ability to light it (due to increasing saturation of the charge) as well as the overall capacity of the fuel system, it does a ****-poor job of cooling a chamber during any stroke compared to that of many other fluids (water, alcohols, etc). The whole running a near spark-blowing out mixture vs. that of one that yields the best combustion, torque, and power output comes from choosing to not use the proper fuel for the projected load in the motor -- it has a marginal effect. You could hold a bucket of pump fuel and pour it into the intake manifold; it will still only be pump fuel.On the detonation comment... throwing more and more fuel at a charge creates less and less efficient combustion; more and more fuel will be left unburnt and unused during and post-power stroke, which is what increases the likelihood of real and true detonation. Detonation is not a general term; that's knock. Knock describes a myriad of conditions that can have their roots in tuner mistakes, too-low octane fuel, or goofs in the EFI/ignition system that cause a 'hiccup' in the motor while running. Detonation is a second stage of combustion that occurs post power stroke (after the initial spark-induced power stroke has fired) due to having too rich a mixture (unburnt fuel in this case) along with sky-high chamber temperatures that cause auto-ignition.
Regarding making "virtually duplicated race gas", if what you say is true, then there'd never be a reason to run any AI, let alone any kind of race fuel, ever, but the fact that so much of it exists and is well proliferated, not to mention used pretty well exclusively in race-type circuits, suggests that your argument is incorrect. That good-quality fuel is designed for high load and used for a very good reason.
B
Edit: to insert detonation comment
Believe me I didn't intend to lead people into thinking that dumping in large quantities of lower octane gas was a replacement for race gas. I know better than that. The whole point of my example was really based on how the stock fd was tuned. It's tuned so pig rich that one can drive the stock car with 87 octane and still be safe. The extra fuel is how mazda compensated for people who would put in 87 octane not knowing that the vehicle was recomended for 91. Asleep stated he was pig rich so I assumed there was a slight comparison. Anyways if he really did use 91 (hell or even 93), then I'm very impressed and surprised at the same time by his numbers.
Last edited by t-von; Jul 19, 2007 at 08:00 PM.
Joined: Feb 2001
Posts: 6,541
Likes: 0
From: Abingdon, Md
Tony,
Congrats on the power. Looks like a nice powerband. Good to see the old school guys keepin up the good work.
Brian....You seem to never have anything to contribute, but snyde, sarcastic comments unless it has to do with your work, which I don't see anything overly impressive that you'd be able to throw your comments around like your a "guru".
Congrats on the power. Looks like a nice powerband. Good to see the old school guys keepin up the good work.
Brian....You seem to never have anything to contribute, but snyde, sarcastic comments unless it has to do with your work, which I don't see anything overly impressive that you'd be able to throw your comments around like your a "guru".
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