PDA

View Full Version : Octane testing?



time2burn
06-07-2001, 07:19 AM
All of us hopped up engine owners are quite concerned with the quality of pump gas. Anyone out there know if there is a gadget i.e. hand held tester that can check the octane of gasolene. I sure would be grateful for that info.

boatnam1
06-07-2001, 06:50 PM
hey time to burn.i work in gasoline refinery and to my knowledge the only way to check it is with a knock engine.i can tell you though gas stations are checked and dont want to get caught.gas does loose octane after awhile.so put in what your going to use.

froggystyle
06-08-2001, 10:39 PM
Boatnam1,
Since we have an expert among us... What constitutes "AV Gas". I have been around airplanes for my whole life, my brother is an A&P Mechanic, and three different pilots who were at the river on Memorial Day all took turns poking fun at the "AV Gas" I bought at the gas station on the river. Alledgedly, it did not look or smell anything like any AV Gas they had collectively seen, and my boat did not appear to run too great on it. It was VERY clear with a blue tint to it. No hint of yellow whatsoever. It smelled like car unleaded, lacking whatever it is that makes it smell like Av gas. I drained my tanks into a friends boat with a stocker, and went to the airport and bought some real AV gas and I have to agree with them, it smelled nothing like it, and was a completely different color. It even smelled different burning. I would imagine that they are tested regularly for octane in car gas, but do you think that this "AV Gas" for only $2.09 a gallon comes under the same quality control parameters? I'm not really bitching, I am curious as to what the distinction is, as I'm sure a plane is not about to pull up to the I-95 quickie mart and fill up, so they would not be inclined to have a liability towards aircraft usage and subsequent failure. Anyone? Bueller, Bueller?
[This message has been edited by froggystyle (edited June 08, 2001).]

RiverDave
06-11-2001, 07:50 AM
I'm not an expert here but my father had a few planes, and I grew up around the airport so I'll give it a shot. AV Gas or Aviation fuel is different from regular auto fuel becuase it is altitude sensitive. I believe that the higher you go (the Thinner the air gets) the higher the octane of the fuel gets to prevent detonation. The lower you go or the more dense the air is the lower the octane gets with a baseline of 115. Please keep in mind that this is based off of a conversation that I had with my father about 10 years ago. The 115 might be wrong but for some reason that # is sticking in my mind. See you at the River, RiverDave.

mister460
06-11-2001, 11:13 AM
Av gas(aviation fuel) is about the best quality gas on the planet! Think about it:contamination clogging up a car means you may have to walk a few miles. In a plane it means you have to FALL a few miles! Av gas comes in different colors. Pink and blue are the only ones I know about. These fuels are in the 115-140 octane range. I've seen lots of guys fill up at airports. I can't remember if it's leaded or not but I think it is. Don't hold me to that, though. I do know it is clean and very high quality. One thing to take into consideration, though, higher the octane, more resistant to burning. Only use Av gas in something that has high compression or burns real hot(under a lot of load.) Otherwise you may actually harm performance. But the only way to find out is to try it out and see how you like it. Oh yeah, don't ever use JP 5(common jet fuel) in a piston motor, unless it's a diesel! Jet fuel is kerosene! Just telling you becuase I knew a guy that tried it!
"When in doubt, nitrous the *@#% outta that big block!!"

froggystyle
06-11-2001, 11:49 AM
Boatnam1 You out there? This question should be right up your alley.

dcraig
06-11-2001, 02:28 PM
Hey Mister460. I am thinking about adding a 125hp NOS kit to my 454 mag (carb) engine. Do I need to upgrade my ignition system or any other parts? My experience with NOS is limited. Thanks!

Nivels
06-11-2001, 03:44 PM
Originally posted by time2burn:
All of us hopped up engine owners are quite concerned with the quality of pump gas. Anyone out there know if there is a gadget i.e. hand held tester that can check the octane of gasolene. I sure would be grateful for that info.
Don't use Av gas the octain vares to much, if you live in southern Ca use 76 gas and add a 104 octain buster. If your motor has more then 12.5 compreson then pull the pistons and put in 10.5 or less. The motor will live a lot longer and save you a lot of bucks. Also check you jets in your carbs a little fat is better then to lean. The same thing with the timing.

boatnam2
06-11-2001, 03:46 PM
hey froggstyle, congrats on the new boat ultra is a sweet ride.i ordered one in 93 before john took over acually i think he was just coming into the picture i think he handled the regatta that year for jerry.im seriously thinking about getting there new cat.but i have to try and get rid of mine. goodluck on the new boat boatnam2 formally boatnam1

skijake
06-12-2001, 09:43 AM
I also work in a refinery, Sorry to say there is not any testers that the normal person can use to run octane. The equipment that is used is very expenseve and hard to maintain.
One more sad note is that starting in August the octane on premium fuel in California will be dropped from 92 octane to 91 octane due to a pantent that is restricting the manufactuing of 92 octane fuel.
Some fuels that you buy at service stations that are listed as Av Gas is not pure Av Gas but a mixture of gasoline and Av Gas. some of these fuels are very good and have a high octane rating but you must be careful.
Most Av Gas (put not all) have lead added and can not be dispenced like unleaded fuel.

boatnam1
06-12-2001, 11:58 AM
skijake is right,most refinery's wiil be going to 91 octane soon,to try and get around a patent that shell tosco has a strangle hold on everyone with.but i think tosco will stll be making 92.good luck to the boys running on the ragged edge of detionation.

Jeff
06-13-2001, 03:07 AM
This is an article I found on the net about fuel The person that wrote it is heavely into jetboat racing.
FUEL: THE BURNING QUESTION?
Some history of fuel in America:
*** Back in the 60’s the fuel was plentiful, cheap and of high quality.* But in 1972 we had the first fuel crisis which caused two things to happen to the fuel. First, the price rose from the standing price per gallon of about 30 cents a gallon, to the much higher price of 50 cents a gallon. At the same time the government was forcing the fuel manufacturers to reduce the Lead content of the fuel.
*** In 1976, the second fuel crisis struck, crippling most fuel based industries, ie. engine manufacturers, boat builders, anyone who had a high demand for fuel. This also raised the cost to the now excepted price of around a dollar per gallon. To worsen the situation, the Lead was further reduced, causing allot of engine damage, and the quest for engine development to combat the problems associated with poor burning qualities.
*** In 1990’s, the Lead in all motor fuels was eliminated completely. This lead the engine manufacturers and fuel manufacturers to develop the additives we have presently, and the engines suffered a serious drop in compression in order to survive the poor fuel burning characteristics. Development of computer controls and fuel injection has partly resolved the problems in autos, but has not done much for the aging motors of yesteryear.
*** In what has been called the Muscle Era, we had motors that came from the factory with up to 12 1/4:1 compression ratios. These engines made serious power but had to have the high lead, high octane fuel to run correctly. High performance requires high quality fuel. It must contain enough Octane to eliminate detonation, the primary cause of engine damage, some lead will extend the valve life also. The introduction of hardened valve seats has helped somewhat, as well as stainless steel valves to withstand high combustion temperatures. There are some changes that can be made to the tune-up of a high compression motor to combat the problem of detonation. Retarding the timing will help to some extent, as would reducing the top RPM under load of the operating engine. But it comes back to fuel quality(Octane) to get the most out of a high compression, high performance engine.
*
*** What can be done?
In a nut shell, only a few of things. These are the options available:
*
1. 1. Reduce compression in the engine, and reduce overall output.
2. 2. Use extra fuel to cool the cylinder before ignition takes place.
3. 3. Use cold spark plugs to lower cylinder temperature.
4. 4. Reduce the timing of the ignition spark.
5. 5. Computerized fuel and spark management (high cost and expensive set up).
6. 6. Lastly, burn Racing fuel.
********** What fuels are available today?
*** There are the fuels that we all are familiar with at the gas station. 87, 89, 92 octane, nonleaded gas. This fuel burns acceptably in most newer cars, and causes a few problems with older cars. As far as a late 60’s, early 70’s big cube, high compression engines are concerned, it is a sure death if run hard on available pump gas without extensive detuning acrobatics. And the question remains, what is the purpose of having a big engine if it can’t run?
*** Fuel octane is what allows engines to produce the biggest bang with the highest compression. Cut the octane and you will have a big bang as the rods smash the bearings from between the rods and crank. PREDETONATION!
Octane keeps the fuel from igniting until it is lit by the spark plug as determined by the ignition timing. High octane gas and racing gas is actually cold fuel. It must be lit with some source. On the other hand, low octane can be ignited by over compression in the cylinder, or ignited by a glowing piece of carbon on the head, valves, or piston top.
Since compression of the air/fuel mixture is what produces the power, it makes sense to go as high as possible to produce the most power.
*** The limiting factor is usually not fuel but DOLLARS!! Fuel dollars and parts dollars must be considered foremost.
*** Let’s* look at Racing Gas to see the benefits. First is the octane rating. Many makers of fuel have differing octane levels of gas they produce. Each fuel has a top level of compression it can stand before going onto predetonation. The higher the octane level, the higher compression before detonation occurs. Once the compression reaches a limit that gas can not stand, alcohol must be used due to its cold combustion properties. But there is a drawback with alcohol, it takes up to 3 times the amount of alcohol* to equal what high octane gasoline delivers. Then to increase the power of alcohol, nitromethane is added to produce one of the most powerful fuels known to man. Nitromethane is 52% oxygen by content and explodes violently in the cylinder!
*
*** The following statement is my opinion on manufacturers of racing gasoline!
*** I have tried most of them. Unocal 76, Sunoco/CamII, Trick, Sports are the brands I have used in the past. All will work once the tune-up is set for each.* The major difference between all the fuels mentioned is the cost per gallon.
I sell Unocal 76 Racing Gasoline for two reasons. First it is a high quality leaded gas that offers 110, 114, 118, 126 octane levels. Second and most importantly, if you use any quantity of it, is the PRICE! For the price, it is my opinion, you can’t buy a better fuel than 76! And it is the CHEAPEST!!
*** Octane is reached by two factors, research octane, and mechanical octane.* The research octane is a theoretical value of compounds burning under certain conditions before predetonation occurs. Mechanical octane is the real world test that runs an engine at a specific temperature and has a variable compression cylinder that is adjusted until the compression causes the predetonation condition to occur. Take the two results from testing, add them together, and divide by 2, gives the octane rating of the fuel. R+M/2.* Each manufacturer determines the octane in the same manner. However, not all advertise the fuel the same. Some use the research number, and some use the R+M/2 number. The misleading thing about the form of advertising is that you might be convinced by the dealer that the cost is justified by the octane level of the fuel. This is not always the case. The most important value is the mechanical octane number. This is what is going to be tested inside your engine!! Always look at the R+M/2 average octane on any fuel you might be considering. It will pay off in the long run!** The use of race gas can be straight, or a mix of race gas and pump gas to get a level of octane required for your specific engine compression.
*** The following is what I recommend to my customers from real world testing on different compression engines that I have worked on over the years.* It must be noted, any engine can be run for a little while on anything, but the destruction of the engine is what is to be avoided, that’s the point!!
*** The recommendations are my opinion for SAFE operation under heavy load and stress conditions:
* ? Below 9:1 compression- 92 octane pump gas. 9.5:1 can run short bursts also.
* ? 10:1 compression requires 96 light load and 98 heavy load octane. 50/50 110.
* ? 10.5:1 compression needs 89 to 100 octane 60/40 race/pump mix
* ? 11:1 compression needs 102 to 110 octane 70 to 100% race gas.
* ? 12:1 to 13.5:1 can run 110 straight with jetting adjustments to put extra fuel in the cylinder to help prevent detonation in the higher compression engines.
* ? 13:1 to 15:1 compression with Nitrous oxide injection or straight compression will require 114 octane to run safely. always look for detonation signs!!
*** These are the regular compressions that I deal with in boats, and drag car engines. Your engine may require more or less depending on how you run your engine. I have determined these SAFE formulas that have run strong, and lived long lives for my customers engines.
*** The reason for examining race gas as a fuel is the fact that, YOU CAN BUY ALOT OF RACE GAS FOR THE PRICE OF AN ENGINE REBUILD JOB!!!
*** Lastly, the fuel that pops up most frequently when determining cost* for consumption and use is 100LL aviation gas. Some people swear by the stuff, and it will work. But after contacting Unocal 76* and inquiring about AVGAS, I was sent three pages of information which changed my mind about recommending the fuel for off-road uses, boats or cars.
First it is 100 octane, which contains 2.5 grams of lead per gallon. Race gas contains 4.5 to 5.5 grams per gallon.*** Second, it has fewer hydrocarbons and must be jetted for due to the lesser amounts of hydrocarbons. (the molecules that burn in fuel).
Third, The EPA has a mandate on the books that prohibits the purchase and sale and use of AVGAS for any motor vehicle except airplanes.
Fourth, the fine is $25,000.00 for the violation of the mandate, on the purchaser and the seller, PER DAY!!
Fifth, the enforcement of the law was lax in the past, but is being looked at more and more, and is being levied increasingly.

Brewer
06-18-2001, 12:30 PM
A lot of good info there (thx Jeff), I suppose that visiting either Parker or Lake Havasu Airport w/ a boat to fill up is not a viable option. Saying that, does anybody know where to get good high octane fuel in that area? I don't like the idea of carrying fuel jugs across the desert, and am not a fan of the stuff they sell at those couple of gas stations off the 95 in N Parker. Thanks in advance for any tips.

boatnam2
06-18-2001, 04:11 PM
hi brewer,get a cfn account theres a station right after you cross the bridge into parker they carry 110 octane and av gas.

Brewer
06-19-2001, 09:06 AM
Hey boatnam2, thanks for the lead. One question, what is a cfn account?

froggystyle
06-19-2001, 11:37 AM
I'll tell you where not to buy "AV" gas... The market across from Castle Rocks. Not av gas. Not even kind-of. And by the way, you can pull your boat up to the airport and buy gas. I do it all the time.

boatnam2
06-19-2001, 02:22 PM
hey brewer,listen to froggstlye do not buy av gas from the station across from castle rock thats where i bought majority of mine from last year and it tore up my carbs.plus it smells a little funny.a cfn account is a downs fuel card thay have stations all over especially where truckers are.the office is at 91 and the 15 off of magnolia heading towards elsinore go left on magnolia.they have 110 octane at the pump.

Brewer
06-20-2001, 08:33 AM
Hey guys, thanks for the info. I agree the stuff they sell @ the market by Castle Rocks is junk & may have (probably) contributed to the early demise of my last motor. Good gas is cheap insurance! I did some checking around, and found they sell high octane at the 76 station on 95 in Havasu by Queens Bay Resort.

froggystyle
06-20-2001, 09:04 AM
Two words... Air-Port. They don't mind at all. Most of the time they totally dig seeing hot boats come in there.

Timer
06-20-2001, 02:14 PM
Anybody, since the higher octane fuels burn slower does that mean you would need to advance your timing to take advantage of the av gas? Or, can you just leave the engine as is and get a benefit from using it? Thanks.

froggystyle
06-20-2001, 09:25 PM
My impression was that there is two benefits to octane. Ability to run higher compression/boost, and advance your timing to optimum curve. The only way you will get power out of the advanced timing, is if you had it retarded to allow for pump gas. If you are running full advance with no detonation with 92, I don't think that AV gas has any magical properties that would increase power. Could be wrong though. PonPon? You out there???

Boater Bill
06-21-2001, 05:12 PM
Re octane maybe this will help. Quoted from VP Brochure.
Question: How much Octane do I need?
Ans: Only enough to stop preignition and/or detonation. Remember there are other important factors in power output than just octane. Octane is not the measure of the fuel's power output, it is only a measure of its resistance to preignition and detonation in an octane engine.

MrHavasuCat
06-27-2001, 02:10 PM
Av gas at the 76 station by queens bay resort in havasu is $2.25 per gallon. They also sell it for a little cheaper at the "super fuels" up the road, but I have heard bad things about the quality of their fuel. I run a blown 510, 8-71 w/9# boost. The engine builder recomended running straight av-gas, and it runs great.
[This message has been edited by MrHavasuCat (edited June 27, 2001).]

900rats
07-01-2001, 09:52 AM
FYI, The 76 gas stations here in Glendale just lowered their octane points from 92 to 91. Does anyone know where to fill up on 100 octane fuel around Burbank?

boatnam2
07-01-2001, 10:31 AM
hey rats,try calling downs fuel in corona they have stations all over the place the one by my house in corona carries 110 at the pump.the stations are called cfn and a few other names also.there a lot of them around the river area.

Jungle Boy
08-08-2001, 05:10 PM
Why not buy a can of VP C-12 fuel and mix 20% VP with premium fuel (more if needed). It is designed for race motors (lubricants). A/V gas is for planes and burns dry. Nothing beats the smell of burnt VP gas in morning.

racingrascal
08-08-2001, 06:42 PM
What is a good octane additive and how much does it cost?

SUPERCREWJOHN
08-09-2001, 03:29 PM
Originally posted by 900rats:
FYI, The 76 gas stations here in Glendale just lowered their octane points from 92 to 91. Does anyone know where to fill up on 100 octane fuel around Burbank?
Hi 900Rats..I recently purchased 100 Octane at the 76 Station in San Marino( just south of Pasadena for those that dont know he area) off of Huntington Drive-just past Atlantic if youre going east. They get a lot of Super-exotic traffic from San Marino so they need to have some better gas..besides they figure the clients will pay the 2.80/gal..