# Racing Fuel in a Family Car **URL:** \ **Category:** Factual Questions\ **Created:** [October 24, 2002, 11:11am UTC](https://boards.straightdope.com/t/racing-fuel-in-a-family-car/133659 "2002-10-24T11:11:54Z")\ **Posts on this page:** 19\ **Page:** 1
**Author:** ![HeyHomie](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/heyhomie/32/207_2.png) [@HeyHomie](https://boards.straightdope.com/u/HeyHomie)\ **Post date:** [October 24, 2002, 11:11am UTC](https://boards.straightdope.com/t/racing-fuel-in-a-family-car/133659/1 "2002-10-24T11:11:54Z")
I was at a gas station on an end of town that I’m not usually in the other day, and wouldn’t you know it: they had racing fuel! (At $3.59/gallon :eek: ) What would happen if I put that in my POS 1996 Mitsubishi Mirage? Nothing? ---
**Author:** ![Milton\_De\_La\_Warre](https://avatars.discourse-cdn.com/v4/letter/m/e480ec/32.png) [@Milton\_De\_La\_Warre](https://boards.straightdope.com/u/Milton_De_La_Warre)\ **Post date:** [October 24, 2002, 11:37am UTC](https://boards.straightdope.com/t/racing-fuel-in-a-family-car/133659/2 "2002-10-24T11:37:49Z")
At best, it wouldn’t run very well. AFAIK, your car is set to run with fuel of a specific octane that ignites and combusts at a set rate. Racing fuel doens’t meet that specification. OK, so I am no engineer. I don’t know what might be in your station’s racing fuel, but it is possible it is so volitaile that it could actually do serious damage to your engine’s internal parts. Also, I understand that persons who aren’t known operators of racing cars who attempt to buy racing fuels (especially in quantity) arouse the suspicions of the ATF or whoever it is that looks after bomb-type investigations. Mixing this type fuel with othet things can produce a bomb that is considerably more powerful than the similar home-made bomb used by McVeigh in Oklahoma City. ---
**Author:** ![Frank\_2](https://avatars.discourse-cdn.com/v4/letter/f/8c91f0/32.png) [@Frank\_2](https://boards.straightdope.com/u/Frank_2)\ **Post date:** [October 24, 2002, 12:42pm UTC](https://boards.straightdope.com/t/racing-fuel-in-a-family-car/133659/3 "2002-10-24T12:42:04Z")
It depends on whether it was racing fuel or high octane gas (like 110). I’m not too informed about the racing fuel though. The high octane gas would go through your system like normal gas until it got to the cylinders. The gas would burn too slow and not complete, causing your engine to spit out raw fuel through your exhaust system. This would be a bad thing over time but once or twice won’t do alot of damage. ---
**Author:** ![Una\_Persson](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/una_persson/32/346_2.png) [@Una\_Persson](https://boards.straightdope.com/u/Una_Persson)\ **Post date:** [October 24, 2002, 12:57pm UTC](https://boards.straightdope.com/t/racing-fuel-in-a-family-car/133659/4 "2002-10-24T12:57:24Z")
Would people please not answer the question if they don’t know the answer? I don’t think I’ve seen so much disinformation in such a small amount of responses. Especially when it was so easy to just look in the Gasoline FAQ? > [@](#): > > 6.16 What happens if I use the wrong octane fuel? > > If you use a fuel with an octane rating below the requirement of the engine, the management system may move the engine settings into an area of less efficient combustion, resulting in reduced power and reduced fuel economy. > You will be losing both money and driveability. If you use a fuel with an octane rating higher than what the engine can use, you are just wasting money by paying for octane that you can not utilise. This applies so long as the fuel was actually gasoline, and not some exotic methanol-nitromethane blend. I demand a cite on the ATF investigating people who aren’t “known operators of racing cars”. ---
**Author:** ![Booker57](https://avatars.discourse-cdn.com/v4/letter/b/b9e5f3/32.png) [@Booker57](https://boards.straightdope.com/u/Booker57)\ **Post date:** [October 24, 2002, 1:00pm UTC](https://boards.straightdope.com/t/racing-fuel-in-a-family-car/133659/5 "2002-10-24T13:00:09Z")
Just another reason to love you coal babe. Save your money people, listen to Anthracite. ---
**Author:** ![scotth](https://avatars.discourse-cdn.com/v4/letter/s/b9e5f3/32.png) [@scotth](https://boards.straightdope.com/u/scotth)\ **Post date:** [October 24, 2002, 1:10pm UTC](https://boards.straightdope.com/t/racing-fuel-in-a-family-car/133659/6 "2002-10-24T13:10:31Z")
Presuming they are selling racing “gasoline”… It would just be high octane gasoline. Octane rating is simply a measure of the fuels resistance to detonation. High resistance to detenation allows higher compression and/or higher total spark advance. High octane does not cause the fuel to burn so much slower that unburnt fuel would be coming out the exhaust. The straight dope on the results: 1. If the car does not have computer controlled ignition timing, you would detect no difference in the way your car runs unless you manually advance the timing to take advantage of the extra octane. If you did advance the timing, you would notice a modest performance and milage increase. 2. The car has computer controlled ignition timing and the computer can adjust the timing enough for that octane level, you would notice a modest increase in performance and fuel economy. 3. (Rare, but some cars are this way) The car has computer controlled ignition timing, but is confused by octane that high, the car would run crappy. I would not hesitate to run racing fuel in my car as long as it was specified as nothing other than high octane “gasoline”. ---
**Author:** ![Boobka](https://avatars.discourse-cdn.com/v4/letter/b/c6cbf5/32.png) [@Boobka](https://boards.straightdope.com/u/Boobka)\ **Post date:** [October 24, 2002, 2:17pm UTC](https://boards.straightdope.com/t/racing-fuel-in-a-family-car/133659/7 "2002-10-24T14:17:00Z")
Actually if it is Unleaded Race gas then nothing, your car would run normal. It may run a bit worse but most likely not. If it is Leaded Race gas (most likely) then your catalytic conveter would get messed up. ---
**Author:** ![scotth](https://avatars.discourse-cdn.com/v4/letter/s/b9e5f3/32.png) [@scotth](https://boards.straightdope.com/u/scotth)\ **Post date:** [October 24, 2002, 2:19pm UTC](https://boards.straightdope.com/t/racing-fuel-in-a-family-car/133659/8 "2002-10-24T14:19:35Z")
If the fuel is sold at the pump as legal for motor vehicles (not off road use only), it may not contain lead anymore. ---
**Author:** ![cornflakes](https://avatars.discourse-cdn.com/v4/letter/c/9d8465/32.png) [@cornflakes](https://boards.straightdope.com/u/cornflakes)\ **Post date:** [October 24, 2002, 2:29pm UTC](https://boards.straightdope.com/t/racing-fuel-in-a-family-car/133659/9 "2002-10-24T14:29:49Z")
After a while, the lead in the racing gasoline would contaminate your car’s oxygen sensor and catalytic convertor. Without feedback from the O[sub]2[/sub] sensor, the engine control system would go into “limp home” mode and performance and emissions would suffer. ---
**Author:** ![Blown\_Injected](https://avatars.discourse-cdn.com/v4/letter/b/a87d85/32.png) [@Blown\_Injected](https://boards.straightdope.com/u/Blown_Injected)\ **Post date:** [October 24, 2002, 3:38pm UTC](https://boards.straightdope.com/t/racing-fuel-in-a-family-car/133659/10 "2002-10-24T15:38:13Z")
as mentioned, if leaded, it would kill your O2 sensor and catalytic converter. since it is sold at the pump, i’ll bet it is 100 octane unleaded. the only street leagl “race fuel” i know of is GT-100. i believe it must be street legal to sell at the pump. there is a GT+, which is 104 unleaded but contains too much oxygen to be considered street legal. if you use the cheapest low octane fuel available, then you will probably notice a difference. BUT, unless you have a modified engine, 100 octane is overkill and a waste of money. new computer controlled ignitions, found about 20 years ago in GM cars, can hide knock making it difficult to tell if the lower octane fuel is hurting performance. the computer usually will only add so much ingition advance as set in the program. the bomb making fuel is nitromethane, the stuff used in top fuel race cars and remote controlled toy cars and planes. i doubt one would earn a visit from the man from such a purchase. steve ---
**Author:** ![Blown\_Injected](https://avatars.discourse-cdn.com/v4/letter/b/a87d85/32.png) [@Blown\_Injected](https://boards.straightdope.com/u/Blown_Injected)\ **Post date:** [October 24, 2002, 3:48pm UTC](https://boards.straightdope.com/t/racing-fuel-in-a-family-car/133659/11 "2002-10-24T15:48:24Z")
BTW, race gas smells very good!!! higher than 104 octane (R+M/2), the average of the two measurement techniques, will contain lead. ---
**Author:** ![Frank\_2](https://avatars.discourse-cdn.com/v4/letter/f/8c91f0/32.png) [@Frank\_2](https://boards.straightdope.com/u/Frank_2)\ **Post date:** [October 24, 2002, 6:21pm UTC](https://boards.straightdope.com/t/racing-fuel-in-a-family-car/133659/12 "2002-10-24T18:21:08Z")
**Blown & Injected** , since you seem to know about race fuel do you by chance ever go the Cecil County Raceway? ---
**Author:** ![lieu](https://avatars.discourse-cdn.com/v4/letter/l/c2a13f/32.png) [@lieu](https://boards.straightdope.com/u/lieu)\ **Post date:** [October 24, 2002, 7:06pm UTC](https://boards.straightdope.com/t/racing-fuel-in-a-family-car/133659/13 "2002-10-24T19:06:36Z")
I’d track down the high octane stuff to run in my '69 Corvette. You could audibly hear the engine smooth out when the old stuff was replaced by the new as you pulled away from the station and it would run like a bat out of Gotham. However, the '69 engine was much better suited to that kind of fuel that your newer one will be. Basically, what Anthri **cite** said. ---
**Author:** ![DougC](https://avatars.discourse-cdn.com/v4/letter/d/7feea3/32.png) [@DougC](https://boards.straightdope.com/u/DougC)\ **Post date:** [October 25, 2002, 1:12am UTC](https://boards.straightdope.com/t/racing-fuel-in-a-family-car/133659/14 "2002-10-25T01:12:29Z")
> [@](#): > > I demand a cite on the ATF investigating people who aren’t “known operators of racing cars”. - - Uh, not exactly what he said, but sort of. Maybe. When production of crystal meth surged, many national/state police depts sugested that local depts identify businesses that sell materials used to make meth, and request that people (the businesses as well as ordinary folks) report to the police any “suspicious purchases”, such as, someone buying a whole lot of certain products, that they have no regular justification to buy. Methanol fuel was among the list, as were lithium batteries and several types of cold/allergy medicine. It was only a suggestion on the police’s part, and many didn’t even bother. But the idea was that if somebody bought suspiciously large amounts of any of this stuff, the police would hear about it and do… uh… something. Maybe they just come to your house and sniff and arrest you if it’s stinky. - I myself read this in the St Louis Post-Dispatch, but it was long enough ago that any story is well into the (pay-to-view) archives by now. I had always read methanol fuel to be the RC-car/plane nitromethanol fuel sold at hobby shops. I’ve been told that you can buy straight nitromethane to mix your own fuel, but I didn’t find any right off…35% was the highest nitromethanol I could find, at about $25/gal. That’s _real_ racing fuel. Put a gallon of that in yer stud-mobile, I dare ya! 😃 ~ ---
**Author:** ![clayton\_e](https://avatars.discourse-cdn.com/v4/letter/c/c57346/32.png) [@clayton\_e](https://boards.straightdope.com/u/clayton_e)\ **Post date:** [October 25, 2002, 3:03am UTC](https://boards.straightdope.com/t/racing-fuel-in-a-family-car/133659/15 "2002-10-25T03:03:13Z")
I just wouldn’t do it… Unless you really don’t care about experimenting with your car (with good or bad results). ---
**Author:** ![red\_dragon60](https://avatars.discourse-cdn.com/v4/letter/r/ce73a5/32.png) [@red\_dragon60](https://boards.straightdope.com/u/red_dragon60)\ **Post date:** [October 25, 2002, 3:43am UTC](https://boards.straightdope.com/t/racing-fuel-in-a-family-car/133659/16 "2002-10-25T03:43:55Z")
So what does lead in gasoline do? ---
**Author:** ![Gary\_T](https://avatars.discourse-cdn.com/v4/letter/g/3ec8ea/32.png) [@Gary\_T](https://boards.straightdope.com/u/Gary_T)\ **Post date:** [October 25, 2002, 3:54am UTC](https://boards.straightdope.com/t/racing-fuel-in-a-family-car/133659/17 "2002-10-25T03:54:01Z")
_So what does lead in gasoline do?_ It raises its octane rating, at less cost than additional refining. The additive used is tetraethyl lead, which was also called ethyl years ago. ---
**Author:** ![Milton\_De\_La\_Warre](https://avatars.discourse-cdn.com/v4/letter/m/e480ec/32.png) [@Milton\_De\_La\_Warre](https://boards.straightdope.com/u/Milton_De_La_Warre)\ **Post date:** [October 25, 2002, 11:51am UTC](https://boards.straightdope.com/t/racing-fuel-in-a-family-car/133659/18 "2002-10-25T11:51:25Z")
“I demand a cite on the ATF investigating people who aren’t “known operators of racing cars”.” I didn’t mean to say that the ATF per se would come knocking on your door. Rather, as Doug C said, the purchase of something like drag racing fuel or whatever it is by someone who didn’t seem to be a person who used the stuff as intended. As there’s still no law against being stupid, buying 20 gallons for your Chevy Caprice isn’t illegal, but I would feel comfortable in the belief that buying 20 gallons to put in blue plastic drums in the back of a Ryder van and being evasive about the intended use would arouse the suspicions of the seller and the interests of the police. I have no direct cite, but shortly after the OK city bombings, there was some discussion in the press about home-made truck bombs of the kind McVeigh used (ammonium nitrate fertilizer and diesel, kind of like ANFO). They said that if he’d used “racing fuel”, the bomb would have been many times more powerful, and that therefore the authorities were asking sellers of the stuff to report any suspicous purchases. Given the nature of the times, I would not be surprised if the sellers did indeed report you if they thought you to be suspicous. ---
**Author:** ![cornflakes](https://avatars.discourse-cdn.com/v4/letter/c/9d8465/32.png) [@cornflakes](https://boards.straightdope.com/u/cornflakes)\ **Post date:** [October 25, 2002, 4:45pm UTC](https://boards.straightdope.com/t/racing-fuel-in-a-family-car/133659/19 "2002-10-25T16:45:39Z")
Tetraethyl lead also “cushions” the exhaust valves. With the hot exhaust blowing past, the exhaust valves and valve seats get hot, not hot enough to melt, but hot enough that the parts can begin to stick together and the soft parts can erode away. The lead deposits on the valves and seats. It separates the metals and acts as a sacrificial layer which erodes instead of the metal. Engines made for unleaded gas have valves with treated surfaces to keep this from happening and/or have hardened valve seats. This may not be a perfect explanation of the physics involved, but I think it’s a fairly accurate explanation.