# Can you reverse the turn of a Car Engine **URL:** \ **Category:** Factual Questions\ **Created:** [July 28, 2009, 12:36pm UTC](https://boards.straightdope.com/t/can-you-reverse-the-turn-of-a-car-engine/504537 "2009-07-28T12:36:19Z")\ **Posts on this page:** 12\ **Page:** 2
**Author:** ![WarmNPrickly](https://avatars.discourse-cdn.com/v4/letter/w/d78d45/32.png) [@WarmNPrickly](https://boards.straightdope.com/u/WarmNPrickly)\ **Post date:** [July 29, 2009, 5:19am UTC](https://boards.straightdope.com/t/can-you-reverse-the-turn-of-a-car-engine/504537/21 "2009-07-29T05:19:48Z")
> [@Malacandra](#): > > /aside > I just figured out your username. 😃 Magnetite nail? ---
**Author:** ![Malacandra](https://avatars.discourse-cdn.com/v4/letter/m/45deac/32.png) [@Malacandra](https://boards.straightdope.com/u/Malacandra)\ **Post date:** [July 29, 2009, 7:46am UTC](https://boards.straightdope.com/t/can-you-reverse-the-turn-of-a-car-engine/504537/22 "2009-07-29T07:46:19Z")
> [@WarmNPrickly](#): > > Magnetite nail? I was guessing “Rusty nail”… ---
**Author:** ![racer72](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/racer72/32/3075_2.png) [@racer72](https://boards.straightdope.com/u/racer72)\ **Post date:** [July 29, 2009, 11:26am UTC](https://boards.straightdope.com/t/can-you-reverse-the-turn-of-a-car-engine/504537/23 "2009-07-29T11:26:23Z")
Running engines backwards was done back in the 40’s and 50’s on Ford flathead V-8’s. It was done so the torque of the engine would keep the left front tire on the track. ---
**Author:** ![WarmNPrickly](https://avatars.discourse-cdn.com/v4/letter/w/d78d45/32.png) [@WarmNPrickly](https://boards.straightdope.com/u/WarmNPrickly)\ **Post date:** [July 29, 2009, 2:59pm UTC](https://boards.straightdope.com/t/can-you-reverse-the-turn-of-a-car-engine/504537/24 "2009-07-29T14:59:35Z")
> [@Malacandra](#): > > I was guessing “Rusty nail”… That’s what I figured, but the nominal formula for rust is Fe[sub]2[/sub]O[sub]3[/sub]. I know it’s a bit of a nitpick, and the oxygen content of rust can vary to lower levels like Fe[sub]3[/sub]O[sub]4[/sub], but fully oxidized iron is Fe[sub]2[/sub]O[sub]3[/sub] so when you want a simple chemical formula for rust, that’s what it is. The way an english major would get a tic from superflous semicolons, his name has kinda been irritating me for some time. I would love for him to correct it. Carry on. ---
**Author:** ![stanger](https://avatars.discourse-cdn.com/v4/letter/s/7ba0ec/32.png) [@stanger](https://boards.straightdope.com/u/stanger)\ **Post date:** [July 29, 2009, 5:28pm UTC](https://boards.straightdope.com/t/can-you-reverse-the-turn-of-a-car-engine/504537/25 "2009-07-29T17:28:11Z")
I remember back in the early 1970’s, one of the Japanese mpotorcycles was known for occasionally running backwards. I believe it was a 200cc twin street bike, maybe a Yamaha. Apparently, you could hit the electric starter just right, the engine would spin over, it would come up on the compression stroke of one cylinder, then, if the starter had disengaged, the engine would kick back in reverse and then fire up. A couple of different cycle magazines noticed this during road testing of the bike. They always let the clutch out slow starting off to be sure whether the bike would move forward or reverse. ---
**Author:** ![Dog80](https://avatars.discourse-cdn.com/v4/letter/d/6bbea6/32.png) [@Dog80](https://boards.straightdope.com/u/Dog80)\ **Post date:** [July 29, 2009, 6:26pm UTC](https://boards.straightdope.com/t/can-you-reverse-the-turn-of-a-car-engine/504537/26 "2009-07-29T18:26:24Z")
As FE3O4ENAIL mentioned the teeth of the gear are hardened, but the rest of it is untreated. This is done intentionally, bacause some elasticity is desired. If the whole gear was treated then it would be more prone to cracking. Same thing with camshafts, only the surfaces of the lobes are hardened, the rest is untreated. ---
**Author:** ![FE3O4ENAIL](https://avatars.discourse-cdn.com/v4/letter/f/ba9def/32.png) [@FE3O4ENAIL](https://boards.straightdope.com/u/FE3O4ENAIL)\ **Post date:** [July 30, 2009, 10:37pm UTC](https://boards.straightdope.com/t/can-you-reverse-the-turn-of-a-car-engine/504537/27 "2009-07-30T22:37:31Z")
> [@WarmNPrickly](#): > > That’s what I figured, but the nominal formula for rust is Fe[sub]2[/sub]O[sub]3[/sub]. I know it’s a bit of a nitpick, and the oxygen content of rust can vary to lower levels like Fe[sub]3[/sub]O[sub]4[/sub], but fully oxidized iron is Fe[sub]2[/sub]O[sub]3[/sub] so when you want a simple chemical formula for rust, that’s what it is. > > The way an english major would get a tic from superflous semicolons, his name has kinda been irritating me for some time. I would love for him to correct it. Carry on. Damn, you know, I can screw up anything. The devil is in the details Chem 110 was a long time ago. To bad I dropped out. I actually did well the first year. I raced through the final, went back over it, nope , nothing to change, and turned the paper in. I can still picture the jaw-dropped looks of some of the other students as I walked away from the desk with only half the time gone. ---
**Author:** ![FE3O4ENAIL](https://avatars.discourse-cdn.com/v4/letter/f/ba9def/32.png) [@FE3O4ENAIL](https://boards.straightdope.com/u/FE3O4ENAIL)\ **Post date:** [July 30, 2009, 10:45pm UTC](https://boards.straightdope.com/t/can-you-reverse-the-turn-of-a-car-engine/504537/28 "2009-07-30T22:45:42Z")
> [@Dag\_Otto](#): > > Ah, that makes sense. Thanks. Whoosh? Induction hardening is a neat way to heat treat steel. A coil near the work piece induces a magnetic field in the steel, but due to hysteresis, heat is generated that makes the steel glow red hot. The field is removed and the unheated steel quenches the hot steel and locks in the changes to the microstructure. Hard shell, gooey center. ---
**Author:** ![Magiver](https://avatars.discourse-cdn.com/v4/letter/m/4491bb/32.png) [@Magiver](https://boards.straightdope.com/u/Magiver)\ **Post date:** [July 30, 2009, 11:28pm UTC](https://boards.straightdope.com/t/can-you-reverse-the-turn-of-a-car-engine/504537/29 "2009-07-30T23:28:34Z")
You could modify an automobile engine to run backwards by regrinding the camshafts if it uses a timing chain without a tensioner system. Otherwise you would have to reverse the tensioning system to accommodate a timing belt. ---
**Author:** ![j\_sum1](https://avatars.discourse-cdn.com/v4/letter/j/8baadc/32.png) [@j\_sum1](https://boards.straightdope.com/u/j_sum1)\ **Post date:** [July 31, 2009, 1:22am UTC](https://boards.straightdope.com/t/can-you-reverse-the-turn-of-a-car-engine/504537/30 "2009-07-31T01:22:52Z")
I recall a tv newsclip about a bizarre and rather substandard car produced for a short period of time by an Australian washing machine manufacturer – the Washburn Zeta. They said the only two advantages of owning such a machine was that it was light to push when it didn’t go. It also had a party trick – turning the key backwards would cause the starter motor to run backwards. This in turn would make the motor run backwards. (Presumably two stroke.) Voila – three reverse gears and one forwards! ---
**Author:** ![Dag\_Otto](https://avatars.discourse-cdn.com/v4/letter/d/439d5e/32.png) [@Dag\_Otto](https://boards.straightdope.com/u/Dag_Otto)\ **Post date:** [July 31, 2009, 3:56am UTC](https://boards.straightdope.com/t/can-you-reverse-the-turn-of-a-car-engine/504537/31 "2009-07-31T03:56:53Z")
> [@FE3O4ENAIL](#): > > Whoosh? No, I was just trying to figure out how to heat treat a specific region on a relatively small part. I understand the process involved, but not the mechanics (until you explained it). ---
**Author:** ![Kevbo](https://avatars.discourse-cdn.com/v4/letter/k/e47774/32.png) [@Kevbo](https://boards.straightdope.com/u/Kevbo)\ **Post date:** [July 31, 2009, 2:39pm UTC](https://boards.straightdope.com/t/can-you-reverse-the-turn-of-a-car-engine/504537/32 "2009-07-31T14:39:45Z")
> [@Dag\_Otto](#): > > No, I was just trying to figure out how to heat treat a specific region on a relatively small part. I understand the process involved, but not the mechanics (until you explained it). Case hardening is another option. Low carbon (“mild”) steel doesn’t harden when quinched. If you raise the carbon content at the surface (heat soaking with the part packed in bone meal is the traditional way) then when you quinch it, only the high carbon steel at and near the surface hardens. Casonite is a proprietary mixture for case hardening, often used by machine shops doing prototype work. [Previous page](https://boards.straightdope.com/t/can-you-reverse-the-turn-of-a-car-engine/504537.md?page=1)