I decided to post this because it came to mind last night while knocking octanes on some MMT dosed gasoline we got in. Just because something has elemental octane additives (note: not chemical) in it doesn't mean it is good. However, before I continue, i'll list the three most common ones... and by chemical additives, I mean like xylene, toluene, benzene, methanol, diisopropyl ether, methyl-t-butyl ether (MTBE)... etc.
elemental additives:
MMT - manganese: turns gas a weird yellow/orange color, not as good as lead, but it can add 5 octane (R+M)/2 at about 200 ppm
Tetreethyllead - lead: turns gas blue, and a brilliant blue at that; strongest of the three in total amount of octane points earned per ppm of TEL in solution, but can cause bad health side effects and does amazing things to catalytic convertors and valve seats (amazing is used in a good way for the later)
Ferrocene - iron: turns gas red, does add some of the same benefits as lead, but does increase the spark plug life of your car by a little bit due to iron build up being conductive
Now, additives work in one real way... the fat ass non-organic molecules get in the way of the random explosions in the combustion chamber known as detonation, keeping the small explosions from spreading to quickly, allowing the flame travel of the explosion caused by the spark plug to engulf the remainder of the gasoline before you knock the motor to death. Thats it. Besides acting as a free radical receptor, the only real purpose for using them is the fact that the elements inside of the compound are just so fat they block pre-ignition detonation. As well, they offer a retarding effect on the fuel's ability to burn, so they have a couple of effects. Now, the reasion I am posting this: you need to be very careful when using fuels with this kind of additive... tonight while running octanes on a sample that got a 97.0 on the Ron/R, the MMT reached the limits of its ability to prevent this detonation, and the motor began to knock extremely hard at any compression past the 97.0 correlated compression ratio. So what does this mean to you? To high of compression, and even in low hp applications, dosed gasolines will still detonate... even harder then anticipated, because the additive loses its effect and the fuel begins to explode on its own worse then an equally rated non-lead/mmt/ferocene gasolines.
Oxygenated fuels (those that contain high levels of oxygenated compounds like MTBE, ETBE, DIPE, Ethanol, Methanol, etc) suffer from one major issue: they make a huge spread between the ron and mon. A normal gasoline with no oxygenates typically has a spread of about 8 (at most approxiamtly 10) between the two numbers: 83 M + 91 R = 87, 89 M + 97 R = 93, etc. Oxygenated fuels can see all the way up to a 12/13 spread, making the mon score (which simulates high rpm and timing) lower: 100 = 94 M + 106 R, 93 = 87 M + 99 R, etc. However, the best type is saturated fuel (this group does technically include oxygenates, but that should be considered as its own entity due to different properties; isooctane is the perfect example of a saturate), which typically contains TEL, will have a very tight spread of at most 2.5: 116 = 114.9 M + 117.4 R. If you can use leaded fuel and you race, it really is the best choice, as the fuel decreases wear and it would be better gasoline for the top end, high boost runs.
Now, this is just what I see in my lab... and I felt like passing it on as I have seen a couple of threads on different forums pop up regarding this topic, and wanted to pass on what I know about it. I hope this helps, and if you have any specific questions, just ask
I just got done running this sample... 14.1 spread between the motors on something with 2.6 weight % oxygen inside of the fuel (about 15 to 20% overall oxygenates, including methanol, tame, mtbe, etbe, n-butanol, etc). So the detonation you have high hp people might be experiencing on oxygenated fuel might not be because of lack of fuel, but because of the oxygenates. Things to keep in mind when running a performance vehicle... (R+M)/2 isn't everything.
I've been playing with home-brews for as long as I've been driving & worked in a few chem labs as a technician then a crew lead / trainer around the Houston area for ~10 years. Went through Waukesha's CFR training program back in the day (operation, maintenance & overhaul) though I'm sure I'd need a refresher if I ever get in front of a knock engine again.
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Last edited by CaptainInsane-O : 07-14-2008 at 01:56 PM.
What effect does Meth have on the octane? Let's say an M5 nozzle at 150 psi.
Methanol (RON of 107 and MON of 92, but only ~1/2 the BTU content of gasoline) IS a decent octane booster, but qualifying exactly what "blend" number you're getting would have to take more factors into account than the nozzle size & alky pump pressure...
As demens mentioned above, methanol is an oxygenate and with the associated wide spread between the RON & MON once the ragged edge of it's anti-knock ability is passed you're going to come into detonation HARD. Being run in an alky injection system has a buffering effect on this problem which also ties into the biggest benefit of running said system.. the dramatic cooling of the intake charge alky injection provides.
Last edited by CaptainInsane-O : 07-14-2008 at 03:26 PM.
I've been playing with home-brews for as long as I've been driving & worked in a few chem labs as a technician then a crew lead / trainer around the Houston area for ~10 years. Went through Waukesha's CFR training program back in the day (operation, maintenance & overhaul) though I'm sure I'd need a refresher if I ever get in front of a knock engine again.
Yea, i'm being sent there at a random time sometime in the near future, because we need another person who can do the maintenance and overhaul. Right now i'm a team lead in a lab, but I deal with everything from crude to the nastiest of black oils, jet fuels, and all of the gasoline spectrum (including knocking stuff like C5... it was fun to watch that stuff boil inside the bowl ).
Right now, my personal home-brew is based off of some 114 I bought and ran through a D5443... 69% Isooctane, 29% Toluene, 12% other (I substitute in Conventional 93 mixed with some MTBE), and about 200 to 250 mics of MMT.
On the non-dosed gas, I get about 104 to 106 R+M depending on the MTBE-conv ratio, but with MMT... sky is the limit. Only problem is, I hate to dose to much, because once you hit that edge, your motor is done.
Here is an experience I would like your thoughts on.
Normally I run a 75/25 meth/water mix & I end up with an A/F starting around mid 10's & slowly running up to 11.5 by redline.
The other day I ran out & filled with straight meth. My A/F's at WOT went down to high 9's til like 4800 rpms, then quickly jumped up to mid 11's. Does the water really make that big of a change? My car didn't feel as angry as usual (angry is good). Felt like I was down on power being that much richer for so many rev's. I have yet to add back the water, but I thought it was interesting.
Here is an experience I would like your thoughts on.
Normally I run a 75/25 meth/water mix & I end up with an A/F starting around mid 10's & slowly running up to 11.5 by redline.
The other day I ran out & filled with straight meth. My A/F's at WOT went down to high 9's til like 4800 rpms, then quickly jumped up to mid 11's. Does the water really make that big of a change? My car didn't feel as angry as usual (angry is good). Felt like I was down on power being that much richer for so many rev's. I have yet to add back the water, but I thought it was interesting.
You have to remember, what makes 0 hydrocarbons and does not compress. So yes, it would make a huge difference depending on how much you put in there.
Personally, if I could do it with 0 rubber fittings, i'd make it acetone + methanol... acetone has a good amount of heat absorbtion, but it would eat all the rubber it found. I'm just VERY leary of water going in my motor. Just me, though... i've seen what happens when water mixes with our ethanol handblends and how much of a change you get in the way the motor acts.
The water mixed with the meth is really undetectable visually. I think of meth as fuel & the water as a cooling agent. Steam. I think when I went to full meth, it is just comprable to adding more fuel. Just didn't expect it to have a full A/F point effect. TIme to experiment to get teh best mix for my car. 100% meth is not it. Lol
Here is an experience I would like your thoughts on.
Normally I run a 75/25 meth/water mix & I end up with an A/F starting around mid 10's & slowly running up to 11.5 by redline.
The other day I ran out & filled with straight meth. My A/F's at WOT went down to high 9's til like 4800 rpms, then quickly jumped up to mid 11's. Does the water really make that big of a change? My car didn't feel as angry as usual (angry is good). Felt like I was down on power being that much richer for so many rev's. I have yet to add back the water, but I thought it was interesting.
Does your system have an adjustable pump or do you have to change the nozzle to alter the flow rate? You were dumping 25% more fuel than normal with straight meth, so of course its not going to perform the same way... spend some time retuning & you might be suprised at how well 100% methanol works.
I know this is apples to oranges, but the Alkyholics among the Turbo Buick tend to run 100% alky when they wanna step it up & blend with water for street fun.
Demens,
You in an inspection lab or a plant? Ahh jet fuel testing... some of it is SOoo complicated; ever run a bucket test?
Does your system have an adjustable pump or do you have to change the nozzle to alter the flow rate? You were dumping 25% more fuel than normal with straight meth, so of course its not going to perform the same way... spend some time retuning & you might be suprised at how well 100% methanol works.
I know this is apples to oranges, but the Alkyholics among the Turbo Buick tend to run 100% alky when they wanna step it up & blend with water for street fun.
Demens,
You in an inspection lab or a plant? Ahh jet fuel testing... some of it is SOoo complicated; ever run a bucket test?
I have a turbo buick and my methanol kit sits on the floor because I never saw the use for it.
Then again, that whole thing isn't applicable since it is a trans am with a buick motor in it... so OBVIOUSLY it doesn't apply to the Buick crowd with their brick on wheels
Anyways, I work for a private inspection company. As far as jet fuel goes... Ministry of Defense Defense Standard 91/91, US American Government JP-5, Colonial 54 and 55... i've seen it all. I don't recognize that acronym, but I absolutely despise the JFTOT... it is like helping a cow give birth, except you're covered in jet instead.
Bucket test... one white bucket, ~1 gallon of jet fuel, one shiny penny: pour jet fuel into bucket, drop penny into bucket, look at penny... any haze or distortion of the penny's image indicates suspended water in the fuel. It's an old-school test, JFTOT is a lot more accurate & yep also a BIG PITA!!! I did some time at a couple of inspection labs, didn't leave on good terms though... my last petrochem gig was at Marathon-Ashland running / maintaining their knock engines.
Looks like that TTA has a good bit of work done to it, I've got a Turbo-T myself.. few mods here & there:
You familiar with The Houston Buick Club? They have a big group heading out to the Kemah cruise-in this Saturday if you're interested.
Yea, I know of the HBC. My dad is a member... you probably met him if you go to the meets... he is on the board or something.
The T/A is down right now... the motor actually destroyed the polylocks on the rocker arms. When we took the valve covers off, one of the rocker arms wasn't even moving due to that fact. So yea, just a little bit of work...
Anyways, they use MSEP for testing the water seperability of jet fuel. It isn't hard, just can't leave it alone for to long... so I normally run smoke point and MSEP at the same time. Then I kinda stare at the freeze point and use our automatic freeze point machine and hope it passes. One thing I hate about working for an inspection company and not a plant is that the customers always think their product is 100% the best there is... not always true. I've seen a lot of off-spec gasoline ... even more off spec diesel.
So yea... i've even had clients try to get me to knock their toluene... I laughed. Then they had me knock some clear liquid that smelt like H2S... on the RON it was < 40... so I didn't even write down the data for the mon's < 40.
thread has gotten pretty far off topic, Demens check yer PM's
BTW, I'm not a fan of MMT... it works well, but the rusty colored residue / goop it leaves behind ain't worth it to me. It not only fouls plugs & O2 sensors, get too much of that in the combustion chamber / on the backside of the valves it acts like a heatsink, driving up temps & lowering the detonation threshold.
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