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Which Brand of Pump Gas?

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Posted by: Jim Crenca---------------------

Other than buying pump gas from a station that does a large volume (possibly fresher fuel), does one brand work better than another. Also, does the 94 octane from Sunoco have any advantage over 93 octane? I've checked the threads on DRN but couldn't find brand recomendations?

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Posted by: spanky250---------------------

I have not noticed any difference between brands. I usually use Amoco, but only because they are the closest to my house, and convienient to stop at on the way.

------------------
1992 KDX 250-FMF porting,two-stage power reeds, Fatty pipe, Power Core silencer,titanium rod,Wiseco Ultra-lite, Pro-Action suspension...Oh my Gawd, they killed Kenny!


Posted by: Rich Rohrich---------------------

The brand of pump gas isn't as important as trying to avoid pump gas that contains ethanol. The MTBE based pump fuels will almost always outperform the ethanol based fuels.

------------------
Rich Rohrich
==

"Wisdom is not a product of schooling but of the life-long attempt to acquire it."
- Albert Einstein


Posted by: Buzz Bomb---------------------

Rich, which brands are MTBE-based and which are ethanol-based?

------------------
2001 CR250


Posted by: JTT---------------------

...and is there an easy way to determine if it is MTBE based? (ie; special labeling, etc)

------------------
JTT
"Character is like a tree, and reputation is like it's shadow. The shadow is what we think of it, but the tree...the tree is the real thing."
Abe Lincoln


Posted by: Pekka Hänninen---------------------

Quote:
Originally posted by JTT:
...and is there an easy way to determine if it is MTBE based? (ie; special labeling, etc)

The oil company should have made some kind of data sheet. Like this one... http://www.neste.fi/tuotteet/oljy/futura/FUTURA98ER.doc



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Posted by: HiG4s---------------------

Jim,
In the US there should be a label on the pump if there is ethanol in the gas.

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Posted by: afm_722---------------------

Besides performance and more importantly, Eric has attributed a lot of lower end failures (seals the culprit) to the use of ethanol based fuel.

------------------

Regards,
Ted
'01 KX250


Posted by: KDXN---------------------

Rich,I got Sunoco gas IN SE PA yesterday and I thought it said it had MTBE and Ethanol! Is this possible?

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Posted by: Rich Rohrich---------------------

Sure they can mix combinations of different oxygenates like MTBE, ETBE, TAME, Ethanol etc. In the Midwest they only mark the pumps for Ethanol not MTBE. I'm not sure how it works in other parts of the country. The fuel can change seasonally, as well as with the changes in component pricing. Ethanol is usually the more expensive additive to blend with due to different pipeline requirements. There are shortages of bulk MTBE at the moment and there have been incentives to use Ethanol so even if you are getting MTBE pump fuel now it may change soon. MTBE is currently banned in Minnesota so you'll see a LOT of ethanol there. You can expect to see knee jerk bans in other states as well. You guys who are using pump fuel better say Good bye to throttle response

------------------
Rich Rohrich
==

"Wisdom is not a product of schooling but of the life-long attempt to acquire it."
- Albert Einstein


Posted by: rick#3---------------------

Rich, if ethanol becomes the norm, would aviation gas be a good alternative?


------------------
rick#3


Posted by: Rich Rohrich---------------------

Yep, Avgas is looking better all the time.

Here's my short course take on things based on my experience and personal biases, (keep in mind this is pretty generalized)

- In almost every case 100ll Avgas is a better choice than alcohol pump fuels

- If you don't need the additional octane that 100LL provides, then MTBE based pump premium (especially Amoco) will tend to provide better throttle than Avgas assuming you have any jetting skill. If you can't jet you're just wasting your time worrying about any of this stuff on a stock bike.

- Mixing 100LL Avgas with a good race gas designed for your application and rpm range is a reasonable way to save some money.

- Mixing alcohol based pump fuels with ANYTHING in an attempt to make it BETTER is just a chemical circle jerk, and if you're that cheap or that ignorant you deserve the crummy performance and the insurmountable jetting problems that you will invariably be blessed with.

- Milspec Avgas is a different animal entirely, but isn't readily available so we won't worry about it.

- The correct race fuel for your application will outperform ANY of the above, regardless of whether the engine is stock or modified. The more demon tweaks hiding in your engine, the more you have to gain.

------------------
Rich Rohrich
==

"Wisdom is not a product of schooling but of the life-long attempt to acquire it."
- Albert Einstein


Posted by: rick#3---------------------

Thanks Rich, but you should learn not to hold back your feeling What would you recommend for a person like myself with both a 2 stroke (ktm 300) and a 4 stroke (yz426)or is their not one fuel for both.

------------------
rick#3


Posted by: Rich Rohrich---------------------

What fuel brands can you consistently get?

------------------
Rich Rohrich
==

"Wisdom is not a product of schooling but of the life-long attempt to acquire it."
- Albert Einstein


Posted by: rick#3---------------------

Rich, usually just Mobil 93 as race gas is not carried by the dealers in my area

------------------
rick#3


Posted by: Rich Rohrich---------------------

Good luck trying to get them jetted clean

------------------
Rich Rohrich
==

"Wisdom is not a product of schooling but of the life-long attempt to acquire it."
- Albert Einstein


Posted by: Strick---------------------

Quote:
Originally posted by Rich Rohrich:
- Mixing alcohol based pump fuels with ANYTHING in an attempt to make it BETTER is just a chemical circle jerk, and if you're that cheap or that ignorant you deserve the crummy performance and the insurmountable jetting problems that you will invariably be blessed with.



I am going to check out the pump at the station where I get my pump gas to mix with the 110 oct Sunoco (purple) race gas. I find what you said interesting, because my bike always seems to perform better when I mix oxygenated fuel (Oct - Feb it is sold here for pollution control - per the verbage at the pump) with the Sunoco. I have now been told by the company that sells the Sunoco race that at the pump a normal 'blend' is sold in the spring and summer here. He went on to say it is not an MTBE or ethanol influenced type of gas in the spring and summer. I always change jetting seasonally, so it's not jetting issues that are affecting my performance.

Rich, if I am off base here let me know.

------------------
Strick '99 KTM 300mxc, AMA & BRC member



[This message has been edited by Strick (edited 04-26-2001).]


Posted by: Rich Rohrich---------------------

Strick - I'm not really clear on exactly what this means:

Quote:
when I mix oxygenated fuel (Oct - Feb it is sold here for pollution control - per the verbage at the pump) with the Sunoco


Oxygenated gas (TAME, ETBE, MTBE) is not the core problem, running up to 10% ethanol is. So it's certainly possible to take a non-alcohol oxygenated pump fuel and improve it somewhat with the addition of race gas.

If you are saying that you are getting better results with a pump/race mix than you are with straight race fuel than I would suggest changing race fuels

If that's the case then I'll be happy to try and explain why Sunoco purple might not be the best choice for your KTM.

------------------
Rich Rohrich
==

"Wisdom is not a product of schooling but of the life-long attempt to acquire it."
- Albert Einstein


Posted by: Strick---------------------

Rich, in all candor, I have never used straight race gas. What I was getting at above is: the winter blend (oxygenated) gas when mixed with the Sunoco (110-purple) race gas seems to perform better than the normal (non-oxygenated pump gas). I mix the two 50/50. The Sunoco is $4.43/gallon, VP (red -106) is $5.75, and C12 (112) is $7.45.

The local bike shop that sells VP, says that Sunoco's 110 rating is bogus, and the VP rating is correct. For what that's worth!

So of course I am curious, what fuel is going to make the 'ole 300 a fire breather??

------------------
Strick '99 KTM 300mxc, AMA & BRC member


Posted by: Rich Rohrich---------------------

Quote:
Originally posted by Strick:
Rich, in all candor, I have never used straight race gas. What I was getting at above is: the winter blend (oxygenated) gas when mixed with the Sunoco (110-purple) race gas seems to perform better than the normal (non-oxygenated pump gas).


That makes sense. Oxy fuels have gotten an undeserved bad rap from people who don't understand how they work and can't jet around the differences.
Ethanol BAD ether based oxygenates GOOD


Quote:
Originally posted by Strick:

The local bike shop that sells VP, says that Sunoco's 110 rating is bogus, and the VP rating is correct. For what that's worth!


Not much in MY book

Quote:
Originally posted by Strick:

So of course I am curious, what fuel is going to make the 'ole 300 a fire breather??


The trick is more not wasting the fire you are already producing. Sunoco purple will tend to pass liquid fuel through to the combustion chamber on engines that aren't pushed really hard in a thermal sense. If you are pushing the engine REALLY hard at WOT for extended periods this liquid fuel can have the effect of cooling the piston crown and keeping charge density higher, while keeping detonation at bay. When you are approaching the thermal limits these are positive effects. If you aren't pushing the thermal limits then this liquid fuel just leaches heat( and ultimately pressure) from the chamber and ends up as spooge.

Here are a few numbers to contemplate:
- there is a 5 degree(F) difference between the 90% evaporization point and the end point with C12
- there is a 100 degree(F) difference between the 90% evaporization point and the end point with Sunoco purple
- there is a 88 degree(F) difference between the 90% evaporization point and the end point with VP Red

Once you add in the fact that the 90% temp ranges of Sunoco purple and VP Red are much higher than C12 to start with you are setting yourself up for a lot of fuel passing through the engine unburned, and the need for richer jetting to make up for it. Pump fuel has temp range and vapoization issues that are even worse, so it's not surprising that people find it difficult to stop the spooge when they are using it.

So depending on the type of riding you do, of the 3 you mentioned C12 MAY prove to be the best choice. The average desert racer would likely find VP Red to be a great fuel, while the average MX racer would just blow most of it out the silencer.

It pretty much gets down to matching the fuel to the application, and no matter HOW you do the math pump fuel DOESN'T cut it unless you are willing to leave some performance and response behind

------------------
Rich Rohrich
==

"Wisdom is not a product of schooling but of the life-long attempt to acquire it."
- Albert Einstein


Posted by: NO HAND---------------------

That is such helpful information Rich!!


Posted by: VOR 492---------------------

Rich, My Local Marathon station Sells CAM 2 110 Octane race gas, is this good Gas for my VOR? I pay $3.00 a Gallon.


Thanks
Bill

------------------
1999 VOR 503cc
1999 F-550 4x4


Posted by: Jim Crenca---------------------

So Rich,

Can we make a gross generalization that:
* If you have to use pump gas try non-ethanol laced Amoco premium
* Avgas is better than pump fuel but not as good as race gas
* A good readily available race gas is VP
C-12; the gas at the drag strip is probably not the best choice

One most jet to the fuel type & atmosphere in order to realize maximum gains

Lastly, is it fair to say that plug heat range is decided by riding type & not fuel type? Thanks for sharing all the info.

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Posted by: Strick---------------------

Rich;
Thank you very much for the detailed answer. I do think I will experiment, like I did a few months ago with gear box oils (winding up with Mobil 1 15W-50).

As you mentioned, I am involved in desert racing. It is a strange breed of racing. Sometimes 10-15 miles of sand dunes ,10-15 miles of WFO 2-track, and depending on the club, some races are tight and techical with 6-8' dropoffs and waterfalls to climb. You can't dial it in like you can on some MX tracks.

Once again thank you, and back to testing.

------------------
Strick '99 KTM 300mxc, AMA & BRC member


Posted by: KawieKX125---------------------

Quote:
Good luck trying to get them jetted clean


Rich, does that comment mean that Mobil gas is hard to jet? I run it sometimes with very good results for a pump gas. Rich, can you tell at all if a gas is oxygenated by it's smell? I have noticed that MR2 has a very distanct,pungent odor. This odor also wxists in the exhaust of my fathers car. Does this mean that the gas he uses is oxygenated? If so, it is mobil, so why would you think that mobil is bad in the above stated comment?
Thanks



Posted by: Rich Rohrich---------------------

Quote:
Originally posted by KawieKX125
Rich, does that comment mean that Mobil gas is hard to jet


No it means Rick has two bikes that are know to require jetting out of the box and pump gas will make it difficult to achieve the desired results. Compounds like MTBE have a pretty distinct smell and are usually pretty easy to pick out in a crowd.




Posted by: Rich Rohrich---------------------

Quote:
Originally posted by Jim Crenca
Lastly, is it fair to say that plug heat range is decided by riding type & not fuel type?


When we are talking about gasoline absolutely.


Posted by: Rich Rohrich---------------------

Quote:
Originally posted by Strick
Rich;
Thank you very much for the detailed answer. I do think I will experiment, like I did a few months ago with gear box oils


Ultimately that's the only way to know for sure


Posted by: Rich Rohrich---------------------

Quote:
Originally posted by VOR 492
Rich, My Local Marathon station Sells CAM 2 110 Octane race gas, is this good Gas for my VOR? I pay $3.00 a Gallon.


It's my understanding that Cam 2 110 is the same as Sunoco purple. It's a reasonable starting point especially if the VOR requires more octane than you can find in standard pump fuel.




Posted by: Jeepboy---------------------

Rich,
How does Citgo racing gas compare to VP C12 or Klotz 113. my bike is stock. I can get the citgo for $3/gal.
Thanks


Posted by: KW---------------------

Rich My supplier of c12 is shutting down and the only options I can
find to replae it are Trick 110 octain or 76 114 octain. Are these
fuels fine for 2 stroke MX bikes?
Thanks
KW


Posted by: Rich Rohrich---------------------

KW - I've never used anything from Trick, or the 114 octane version from 76 and I don't have specs on them so I can't really say. If you'd like to post the full specs on the fuels along with the type of bike and riding you'll be doing I'd be happy to try and take a semi-educated guess.


Posted by: Jim Crenca---------------------

Hey Rich,

You never responded regarding my gross generalization statement which was:
* If you have to use pump gas use Amoco premium without ethanol blending agents (although a dealer told me as of June 1 MTBRE won't be allowed in MD)
* Avgas is better than pump fuel
* Race fuel from the dragstrip is probably only good for wide open throttle applications
* A good readily available fuel for general purpose riding is VP C-12 (about $8 per gallon here)
* Any generalizations on jetting from pump to race fuel?
Please comment on the above. Thanks in advance


Posted by: Rich Rohrich---------------------

Quote:
Originally posted by Jim Crenca
Hey Rich,

You never responded regarding my gross generalization statement which was:
* If you have to use pump gas use Amoco premium without ethanol blending agents (although a dealer told me as of June 1 MTBRE won't be allowed in MD)

In the Midwest this would tend to be true, I can't say for sure in other parts of the country. Basic rule, it's worth the effort to find something OTHER than ethanol based pump fuel to use in your bike.

Quote:
Originally posted by Jim Crenca
* Avgas is better than pump fuel

AvGas MAY prove to be the better choice when compared to 10% Ethanol blends, but your statement is a bit to general and broad range for my taste.

Quote:
Originally posted by Jim Crenca

* Race fuel from the dragstrip is probably only good for wide open throttle applications

I don''t know what they sell at "the dragstrip" in your area so I can't comment.

Quote:
Originally posted by Jim Crenca


* A good readily available fuel for general purpose riding is VP C-12 (about $8 per gallon here)

Yes, VP-C12, and Phillips B32 are two very good easy to tune fuels that cover a wide range of applications that we are interested in.

Quote:
Originally posted by Jim Crenca

* Any generalizations on jetting from pump to race fuel?

Good quality non-oxygenated race fuels like VP-C12 and Phillips B32 will USUALLY require leaner jetting due to the improved vaporization characteristics and ignitability of the fuel. Most oxygenated race fuels like VP-MR2, Phillips B35 and P45 will require RICHER jetting when compared to non-oxygenated race fuels, but when you are comparing them to standard oxygenated pump fuels it can go either way.

I hope this helps.


Posted by: Jim Crenca---------------------

Thank you, thank you, thank you; as much as I like R&D as well as documenting test data, I just don't have enough time to finish the current group of projects.


Posted by: JTT---------------------

Rich, what can you tell me about Sunoco "Supreme"? Is this a good choice for use in a stock '01 CR250? or would the next higher level (I think it's "GT plus"?) be a better choice? As I understand it, the supreme is 104 octane, and the GT is like 114?

Thanks


Posted by: Rich Rohrich---------------------

Sunoco Supreme is leaded 112 pump octane (AKI). It will work well with excellent throttle response but it's probably overkill on a stocker, and some people find it difficult to read plugs when there is lead in the fuel.
GT Unleaded Plus is 104 octane, and GT Unleaded is 100 octane. On a stocker both all should work fairly well, but given a choice I would pick the GT Plus unleaded for easy of tuning and response.


Posted by: N.H. Hick---------------------

i was told that leaded gas runs cooler then unleaded, is this true??
and if so would you mind explaining why? thanks


Posted by: Rich Rohrich---------------------

Quote:
Originally posted by new hampshire hick
i was told that leaded gas runs cooler then unleaded, is this true??


It's not true.


Posted by: rda---------------------

does it make much differance which octane you buy at the pump? all i have availible is 87, 89, or 92 octane shell. i have a stock ktm 300, in the past, i have always bought the 92 octane. is this really neccessary, or am i wasting my money? would i get the same results with the 87 octane?

ps. there are no signs on the pump that say anything about mtbe's or ethanol.

thanks


Posted by: Rich Rohrich---------------------

JEEZ - Don't be such a cheapskate.
If you are going to buy pump gas buy the highest octane available to you.


Posted by: rda---------------------

so, is your answer yes, i will get better performance with premium? i have heard when it comes to most modern cars, that buying the lowest grade is the best way to go, because you won't see any improvement for your money. but, i guess modern cars have computers to compensate for gas, temp, etc.

i have never worried about it in the past, but since the gas prices are so high now, i am looking for any way possible to save money on it. its going to cost enough driving my gas guzzling van to the races!

yes, i have been known to be a cheapskate sometimes!


Posted by: holeshot---------------------

Heck, I'm a cheapskate, but I'd still buy the highest grade of premium pump gas available. Knowing that pump gas quality can vary from day-to-day and location-to-location, buying the highest grade lessens the chance of detonation occuring. Performance is not necessarily an indicator of octane requirements, because our mild little DS80 is more finicky about octane requirements than the 426. 92 octane pump gas is barely enough to stop detonation when the little 80 has to haul me up a hill for any appreciable distance.

This is not for your grocery getter, it's for your high performance hobby toy.


Posted by: rda---------------------

thanks guys,

i guess i'll stick with the premium, i just hate helping to line the pockets of the greedy oil barons.


Posted by: rick#3---------------------

Rich, my local dealer Just started carrying VP-c12. What can I expect Jetting wise running the fuel and do you have any recommendations. I will be running it in both my 426 and 300mxc.


Posted by: Rich Rohrich---------------------

Compared to most pump fuels C-12 will tend to richen the jetting about a full jet size (pilot and main). On the 426 it will tend to cure the lean stumble.


Posted by: rick#3---------------------

Rich, is the C12 a good choice to run in both, or is their another VP fuel that would be a better choice?


Posted by: Rich Rohrich---------------------

If you want to run the same fuel in both bikes C-12 will be an excellent choice.


Posted by: Dirty Dave---------------------

Rich, here in California we are pushing the state gov. to hurry up and remove MTBE as the oxygenate of choice because it is a known carcinogen. According to tests the cancer causing agents are unaffected by the combustion process and come out of the exhaust pipe in the same chemical form as it came out of the pump nozzle. Several lakes have banned jet skis and outboard powered boats because of their less than optimal combustion efficiency. There was almost zero testing done on the stuff prior to authorizing it to be blended in at the refineries to clean our air. Several tests have shown no improvement to air quality with it's use...I suppose when it's gone it's race gas for me...


Posted by: Rich Rohrich---------------------

Quote:
Originally posted by Dirty Dave
Rich, here in California we are pushing the state gov. to hurry up and remove MTBE as the oxygenate of choice because it is a known carcinogen. According to tests the cancer causing agents are unaffected by the combustion process and come out of the exhaust pipe in the same chemical form as it came out of the pump nozzle.


These tests were likely performed by the same people who were surprised to find benzene coming out of the tailpipe when there was no benzene present in the fuel. I'd take their "results" with the appropriate sized grain of salt. The lobbyists from the agriculture states have a major influence on the use of ethanol as the "preferred" oxygenate for pump fuel. Not much we can do about it.


Posted by: motopuffs---------------------

I hear you Rich, I'm from Iowa, and am personally against passing laws mandating the use of ethanol. People should have a choice at the pump.

Talk about having an agenda!

Also, there is a lot of misinformation out there regarding ethanol, some people refuse to use it for applications where it would be perfectly fine, and others unknowingly damage equipment by using it.


Posted by: bwalker---------------------

The corn lobby never talks about the effects of combustion on ethanol. Can you say formaldahyde? The use of alchols in fuel is pretty stupid IMHO. Countries like Brazil tried it and have since returned to standard gas. Why do we think we are special.


Posted by: motopuffs---------------------

Please explain more about formaldehyde. We react methanol in a furnace at work, and I am sure that some of the by-products are released into the air. Maybe at this high temp, it breaks down...


Posted by: Jaybird---------------------

Rich,
I raced dirt track cars for years. With my higher compression engines, I always used race gas OR i used 93-94 octane and added nitro-methane with decent results.
When I got into dirt biking, I tried running straight 94 octane pump fuel and found very inconsistant results, especially in throttle response. I'm very sceptical of how fuel suppliers handle their fuels. Dirty tanks, "stale" gas, etc...
I recently started using 100LL in my 125sx. I'm getting it for 2.38 a gal at the local airport. Ive found that it runs more consistant than pump gas, but a slight lack in throttle response.
I'm wondering if maybe I should experiment with running nitro-methane as an additive to the 100LL. I feel it may help with any detonation issues, but would it be correct to think it may help with the throttle reponse? Nitro additives are very expensive and I sure don't want to spend too much for no reason. Should I start concentrating on jetting instead? I'm very ignorant on jetting...is it time to learn?
BTW...I'm mixing the 100LL at 40:1 w/Mobil 1 2stroke. (some spooge)


Posted by: bwalker---------------------

motopuffs, When a fuel is combusted in a IC engine chemicals are found in the exhaust that are not present in the fuel before it combusts. Combustion of ethanol fuels leads to the formation of formaldahyde compounds in the exhaust. I think it could have something to do with all that heat and pressure.

Jaybird, Nitro would do nothing to improve your throttle response.


Posted by: Rich Rohrich---------------------

Quote:
Originally posted by Jaybird
Should I start concentrating on jetting instead? I'm very ignorant on jetting...is it time to learn?


YES For a given engine combination throttle response is a direct result of matching the fuel curve to the engine's requirements. It's silly to dump ANY additives in fuel unless you can optimize the jetting for the changes.

FYI, Nitromethane ( CH3NO2 ) will not mix correctly with gasoline so it's out of the question. Dimethylnitromethane (aka 2-Nitropropane C3H7NO2 ) will mix correctly with gasoline but it alters the fuel distillation curve to the point where throttle response is usually compromised. It's possible to use other additives to readjust the distillation curve and bring the throttle response back, but it's a TON of work, it's easy to break LOTS of engines parts along the way, and it requires some serious jetting to get right. It's impact on power is debatable.

My advice would be to lose the avgas, buy some decent race fuel like Phillips B32, B35, or VP C-12 and jet it sharp. Playing with fuel is lots of fun but I can assure you you'll spend more time wreching then riding.
Good luck


Posted by: motopuffs---------------------

does formaldehyde form with the combustion of methanol as well, or is this limited to ethanol?

My friend's race car uses about 95% nitro and the balance is methanol.

Since nitro makes an engine run rich, isn't there some type of additive you could use to balance out the equation such as a fuel with a higher specific heat (uh, been awhile since thermo class)????


Posted by: RM250Rida---------------------

The motors are designed to burn a certain octane gas. Im not sure exactly what it is but I'm almost positive it is not race gas. The octane rating of gas is measured by its stability. Lower octane gas burns hotter, easier, and faster. So you may wonder, why do they produce higher octane gas, if it causes slower combustion and cooler burning? :think Answer: It is for use in higher compression engines. As the compression rises, it becomes easier for the gas in the cylinder to combust. It can become so easy that it will explode before the spark plug fires. This is known as detonation, which can cause major engine damage. Higher octane gas resists detonation and allows for the use of higher compression ratios while maintaining engine reliability.

Is the compression that high that the use of a high octane gas is needed? I think that a stock motor will have no benefits at all from using a higher octane gas. And with everything thats going on today you cant be certain that you are getting what you are paying for. Maybe the pump says 93 or whatever on it, but do you know for sure that it is actually 93 octane rated gasoline? They know that you probablly will not test the gas so they may just put 87 in all the pumps and label them differently.


Posted by: Rich Rohrich---------------------

Quote:
Originally posted by RM250Rida
Lower octane gas burns hotter, easier, and faster. So you may wonder, why do they produce higher octane gas, if it causes slower combustion and cooler burning.


Hi welcome to DRN.
Because you are new here you might not realize that unlike most internet sites posting incorrect technical info is frowned upon here at DRN especially in THIS forum.
Before you get flamed for what you posted here's a link that might help clear up some of the points on this subject for you. Enjoy.

http://www.ericgorr.com/techarticles/Fuel_Basics.htm


Posted by: Jim Crenca---------------------

Very diplomatic Rich, & to think they say you are mean! Interesting article as well.


Posted by: AMinkman---------------------

Rich, I am VERY disappointed:D Do you know him??


Posted by: Rich Rohrich---------------------

If I KNEW him he'd be wearing his butt for a hat I expect far more from my friends than random strangers.


Posted by: Ando---------------------

Sorry to jump on this late, but as long as we are clairifing info, to respond to Dirty Dave's thoughts on MTBE. It is not a known carcinogen, it is classified as a potential carcinogen, with no conclusive studies showing it to be definitively carcinogenic. This is much unlike other known carcinogens such as ethanol. Where does MTBE stand up against ethanol in cancer causing effect? Maybe a little more, maybe a little less, but they are in the same order of magnitude. Oddly enough many Americans (including Californians) actually put additional carcinogenic ethanol in their water supply regardless of the potentially toxic results! As far as straight toxicity (as in causing death when ingested) ethanol is about half as toxic as MTBE in rats, so you can only drink half as much MTBE as you would ethanol.

The reason for the displeasure with MTBE in the Golden State stems more from the amazing motility of MTBE verses other substances. If you have a leaking gas station tank, in the past the leaking fuel slowly permeated and contaminated the surrounding soil, MTBE practically runs unhindered through the surrounding soil straight into ground water. This is combined with an odd characteristic of MTBE; humans can actually taste it at quite low levels, levels far lower than are considered harmful. So water supplies in CA were turning up with a funny taste. Not necessarily harmful, but certainly undesired.

Finally, MTBE is very stabile in water, so unburned MTBE fuel coming out of marine engine exhaust stays in the water for a long time.


Posted by: motopuffs---------------------

wow, great post...thanks for the info!


Posted by: jadair---------------------

Rich tell me if this is true or not. Low pump gas has more of an explosion. And high test gas is an controlled explosion and you should only run high test if you have the compression. Is this true?:think


Posted by: Rich Rohrich---------------------

Nope it's not true Jimmy. Basically high octane gas can handle higher temperatures, higher loads and more pressure before it starts to knock and damages the engine, lower octane gas can't handle the loads or temps as well so it causes problems MUCH sooner.

In most cases there is no difference in performance between high or low octane fuels, but it's really easy to break the motor using the low octane stuff. To be safe run the highest octane gas you can afford.


Posted by: JTT---------------------

Rich, although this is slightly off topic, I wouold like to ask about this....A while back you talked about the idea of race gas causing deterioration of rubber o-rings in 426's. If I remember correctly, this was determined to be hooey. I just got back from visiting a good freind who works for a large Roadracing team. They use VP mr1 and he indicated that it is corrosive enough that they have to replace the gas cap gasket after each weekend. Is this possible?


Posted by: Rich Rohrich---------------------

Just to put this idiotic topic to rest I bought a dozen of the internal o-rings from a 39mm FCR and proceeeded to soak them in various fuels and additives for a few hours followed by letting them sit and air dry for a day or two, and then repeated the cycle 10 times. I tested with Phillips unleaded B35 & P45 (both contain MTBE), pure MTBE, MMT based octane booster, Phillips B37 leaded 118 octane, Amoco Clear Premium, Nitropropane, and NitroMethane. Only the NitroMethane caused some swelling damage to the seals. None ofthe rest had measurable changes.

If they are having problems with the gas cap seal then they need to spec a proper material. I've never had problems with the cap gaskets on OEM Japanese tanks, and I'm pretty sure I run harsher fuels through my tanks.


Posted by: JTT---------------------

Thanks Rich! ...promise "I" won't bring it up again :D


Posted by: Rich Rohrich---------------------

I don't care about it getting brought up here unless it's some nitwit parroting back magazine drivel


Posted by: monkeybutt---------------------

I am in no way a gas god(only when I eat beans).On the sub of avgass, the fuel is made/designed for planes.Designed to burn high,withstand all kinds of diff changes ect(alot of not 2-stroke friendly additives).Also plane motors are slow rpm motors compared to ours(This means a diff flash point the fuel is designed to fire at).No avgas for my machines!


Posted by: Jaybird---------------------

I was using 100LL Avgas because of the price and availability. It's much cheaper than race gas...BUT I couldn't get it to perform. I went to 109.5 octane and new brass and I'm now a happy camper. My main beef with the Avgas was throttle response.
BTW...I'm still hoping for some info on Turbo Blue, if anyone has any.



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