Reversing firing order?

[racer_f50]

Hey guys, just changed my spark plug cables the other day, and it got me to thinking...
what if you put the cables on in reverse order? so that you essentially reverse the firing order?

i'm no expert on how engines and drivetrains work, so i'm just curious what would actually happen? would it turn the crank the opposite direction, and if so would i then have 5 reverse gears?

[graywolf624]

First hand guess.... preignition.. it wouldnt match the timing of fuel insertion.

[T-Bird]

well it depends on the car and all the computers

[racer_f50]

okay, graywolf's idea that it just won't run makes sense.
T-bird, do you have any ideas on what would happen in any sort of car? i'm dealing with a toyota celica here, but what about a Ford, which you are familiar with?

i was just hoping that it would turn things the opposite way, would be fun to play around :mrgreen:

[T-Bird]

well in some cars the computer would be able to correct firing order through the plugs but that is on higher end cars I doubt you would see it on a Toyota. Some cars have fuel injection that just dumps fuel into all cylinders in which it would eventually fix itself in a best case scenario but it would run like shit. It would take alot of work to get your car's engine to run reversed. On my car It would be pretty damn difficult to mix the wires because they are all preset lengths so it's kind of obvious and the coils and cylinders are clearly labelled. On my car I doubt it would turn over if they were all wrong and being an interference engine if my timing is off too much my whole engine will have to be rebuilt. Now adays cars are going to coil on plugs so that it would be impossible to mess them up. But there is no way that reversing plugs will change rotational direction of your crank.

[racer_f50]

thanks for the explanation, and for setting my crazy imagination straight :P

guess i'll cancel those plans to drive 110mph in reverse :lol:

[coombsie66]

^^ Yeah, an absolute no go with a 4 stroke, but if youve got a single cylinder 2 stroke moped you can bump start them in reverse. :mrgreen:

[saadie]

thanks for the explanation, and for setting my crazy imagination straight :P

guess i'll cancel those plans to drive 110mph in reverse :lol:
the thingy tht we call reverse is because of the gearbox :P .... run the crank anti clock or clockwise ... there will be only one reverse :P :wink:

and in my openion .... if you switch the plugs and the engine is only 2 or 1 cylindered .. only then it would work .... if you try to do it to something like a 12 cylindered engine ... it wont work untill you also change the firing order ....

and another thing ... imo the crankshaft is made to move in only one direction ... if you reverse the rotation ... i guess it will break up ... not sure though .... cuz i've never heard crankshaft rotating clockwise once and anti clockwise the other ....

[lerex29]

Hey, first of all, I agree with the fact that you can't reverse the firing order by switching around your spark plugs. The point being the engine would be feeding gas onto the pistons which have no way of combusting without the spark being there at the right time. All that compressed gas and air would be wasted and your engine would not run.

However, I heard from a reliable source that Ferrari's V-12 engine fire two pistons at the same time. I failed to find any proof supporting this but was just wondering if anybody else knows whether it's true or not. IMO i beleive it would produce a huge power gain.

[coombsie66]

^^ Firing orders vary hugely between engines. Not all pistons fire individually in the majority of engines.
Inline 4 cylinder bike engines have a 2 up 2 down firing arrangement, v8's adopt similar just in two banks.
Im not sure on any examples, but if you want to know more im guessing it wouldnt take much searching to find more info.

[T-Bird]

thanks for the explanation, and for setting my crazy imagination straight :P

guess i'll cancel those plans to drive 110mph in reverse :lol:
the thingy tht we call reverse is because of the gearbox :P .... run the crank anti clock or clockwise ... there will be only one reverse :P :wink:

and in my openion .... if you switch the plugs and the engine is only 2 or 1 cylindered .. only then it would work .... if you try to do it to something like a 12 cylindered engine ... it wont work untill you also change the firing order ....

and another thing ... imo the crankshaft is made to move in only one direction ... if you reverse the rotation ... i guess it will break up ... not sure though .... cuz i've never heard crankshaft rotating clockwise once and anti clockwise the other ....

You can rotate an assembled engine backwards and have no problem doing it when it is disconnected from the transmission. The Crankshaft itself doesn't control it's rotation. If you take an engine and put it on a stand you can easily rotate it with no problem if you take the plugs out you can do it by hand usually.

The real reason that cars rotate a certain direction came from the older cars when you would have to hand crank them. It was easier and safer to crank them clockwise then counter clockwise.

[3than]

LMAO.. I'm bored so here's some stuff to think about

it wouldnt work .. its possible to rearrange the order of the plug leads if you keep the cylinder pattern the same IF you turn the distributor (or its cap) the correct amount of degrees to correct it... but of course then really you are back where you started.. its not just the plug leads but the camshafts and subsequently the valve opening sequence which control which order the plugs have to fire in - BUT if its a modern engine with management then forget that as the spark timing is most likely controlled by crank position, and then its not uncommon for engines to have 2 cylinders firing at the same time (wasted spark ignition)


IF the crank span the opposite way to which the engine was designed then the engine would be sucking in air through the exhaust and blowing air and fuel out of the carb/plenum LMAO.. except of course before this happened you would probably have thrown the cambelt and smashed the valves into the pistons a few times bending valves and / or putting holes in your pistons

this is why its a bad idea to even turn an engine the wrong way once its fully assembled, as it can cause the cambelt/chain tensioner to loose all tension and then its possible for the belt to jump a few teeth on one of the cam pulleys and cause valve to piston contact - so remember this the next time you park your car on a hill in gear ;)