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It would be nice to see some discussion on alternative firing orders for 4 cylinder engines. For instance, the 2009 Yamaha R1 (Motorcycle) uses a crossplane inline 4 cylinder crankshaft, which does not fire at even 90 degree intervals as is common in 4 cylinder engines. Likewise, MotoGP bikes sometimes use a 'big bang' firing order, which fires all the cylinders within 180 degrees of crank rotation.
Unfortunately, I don't understand the benefits of these firing orders well enough to make an intelligent addition to the wiki article. The best I could do is repeat some of the manufacturers claims.
In a gasoline engine, the correct firing order is obtained by the correct placement of the spark plug wires on the distributor. In a modern engine with an engine management system and direct ignition, the Engine Control Unit (ECU) takes care of the correct firing sequence. Especially on cars with distributors, the firing order is usually cast on engine somewhere, most often on the cylinder head, the intake manifold or the valve cover(s).
This information is incorrect. The firing order is also based on the position of the intake and exhaust lobes on the camshaft, and the position of the crankshaft. For instance, with a 1-3-2-4 firing order, you could swap the ignition leads for cylinders 1 & 4, or 3 & 2. This would cause spark to occur at the end of the exhaust stroke and the beginning of the intake stroke. Likewise, swapping ignition leads for cylinders 1 & 3, or 2 & 4 would cause ignition to occur at the beginning of the exhaust stroke. In either cause, I doubt the engine would run (very well?)
It *may* be possible to change the firing order by rotating the cams and switching the plug leads. I suspect doing so would be possible on an inline 4, but question weather or not it would be possible on a more complex engine, such as a V-12. Doing so would throw off injection timing on an engine with sequential injection. I suspect it would cause other issues as well.
Obviously, these comments do not necessarily apply to diesel engines.
First some basics on orientation. The back of the engine is nearest the flywheel. The right bank is on your right if you're at the back of the engine looking toward the front of the engine. Put another way, for rear wheel drive vehicle in right hand side of road countries, eg. US and Canada, left bank is on the driver's side and the right bank is on the passenger's side.
Ford: Counting from front to back on the engine:
1 2 3 4 on right bank,
5 6 7 8 on left bank.
Chrysler and GM-Except NorthStar(tm): Counting front to back on the engine:
2 4 6 8 on right bank,
1 3 5 7 on left bank.
Northstar (GM): Counting front to back on the engine on the engine:
1 3 5 7 on right bank,
2 4 6 8 on left bank.
In V8 engines there is usually an offset between the front of the right bank compared to the front of the left bank about equal to the width of the lower part of the connecting rod. This is because piston/connecting rods assemblies are identical and share a common journal on the crankshaft between the banks. Hence there are only 4 journals on the crankshaft for connecting rods. In the Chrysler case: "1" and "2" share one journal, "3" and "4" share a journal, etc. Typically the cylinder nearest the front of the engine is numbered cylinder "1".
In the Chrysler case the left bank is nearest the front of the engine. Hence cylinder "1" is on the left side of the engine. When the Northstar engine was designed it was determine that some space would be saved if the right bank was moved ahead of the left bank. Consequently the apparent flip, left to right, of the cylinder numbering.
These differences in numbering conventions gives rise to differences in the "firing order". As expected, the actual design of the crank shaft also affects the firing order.
There was an interesting development in V-8 firing orders in the late '60's. Ford's Windsor class engines--302W and 351W--have different firing orders. Ford reversed the position of the #2 and #3 crankpins location when they built the 351W. Why? They observed that the firing order used on the 302W caused unacceptably high peak stresses at the #3 and #4 crankpins and #4 main bearing when using that sequence. Reversing those two crankpins (and the resulting change in firing order) cured the problem. The two engines appear externally identical to the untrained eye and this has caused lots of camshaft replacement calamities through the years by careless rebuilders. GM subsequently followed this practice on their latest rendition of the "Big Block" Chevrolet-based engine curing a number of problems. The Ford "385" series engines--the "C" or Cleveland, and the "M" or Modified Cleveland, in all displacements (302 Boss, 351M & C and 400M) all used the same firing order as the little 302W. They were structurally much larger, beefier (and heavier) engines. Leading bank issues are design significant. It greatly affects intake manifold flow design. Ford engines traditionally have a right-bank leading setup as do the Buick, Olds, Pontiac and Cadillac engines. The Chevrolet Small Block, and all Chrysler and AMC engines used a left bank leading design. Ford, alone among the above, numbers 1-2-3-4--right bank, and 5-6-7-8--left bank. The others use a 1-3-5-7--left bank (etc.) sequence.
Claude764 ( talk) 02:12, 29 October 2009 (UTC)
If you had a 12 cylinder 4 stroke engine how can you determine how many degrees apart the firing intervals are,
The section on cylinder numbering isn't very clear about its directional relativity. For example, when it says "left", is it left as viewed from standing in front of the car, looking at it, or left from sitting inside the car, looking out straight ahead?
For example, when standing in front of a car, looking at it, the steering wheel is on the left in Australia, but right in America, while, sitting inside the car, the steering wheel is on the right in Australia, but left in America.
This is where the confusion arises, and I think it should be clarified.
203.122.107.112 ( talk) 14:07, 21 May 2008 (UTC)
hey, i'm really courius about inline 6 firing order, so they would get balance. can someone tell me, please. —Preceding unsigned comment added by 123xyz321 ( talk • contribs) 11:20, 13 June 2008 (UTC)
The section about cylinder numbering talks mainly about V8 engines, and doesn't mention cylinder numbering for V6 and V12 engines. The firing orders are pretty meaningles without cylinder numbering. Could anyone include the cylinder numbering for V6 and V12 engines to improve the quality of the article, so that the firing orders can be "applied". 203.33.160.179 ( talk) 04:06, 10 November 2008 (UTC)
I have removed the firing order 1-2-3-4 assigned to the Proton Wira VDO engine. This car uses the Mitsubishi Orion engine 4G13 or 4G15, which has a standard 180 degrees planar crank. Hence 1-2-3-4 makes no sense. I expect it comes from their V6, which has a firing order 1-2-3-4-5-6. http://www.ben9166.com/2011/08/4g134g15-17l-crank-shaft-stroker-kit.html Mike163 ( talk) 20:25, 19 January 2015 (UTC)
This part of the article would need correction:
Actually a 90° crossplane V8 has even firing interval, it is just within each cylinder bank that it has uneven firing: Crossplane
Cse78 ( talk) 22:56, 10 November 2015 (UTC)
Some of the engines listed in the uneven firing list are even firing or have even firing variants; vice-versa for the even firing list.
I'll link the disputed entries to here.
Identiti crisis (
talk)
23:43, 30 November 2015 (UTC)
Corrected, this was obviously wrong. Dovatf ( talk) 22:06, 25 January 2016 (UTC)
The firing orders 1-3-4-2 and 1-2-4-3 appear to be essentially the same, just in reverse order. If we extend the sequence 1-2-4-3-1-2-4-3, we can extrapolate that 1-2-4-3 is identical to 2-4-3-1. If we reverse 2-4-3-1, we get 1-3-4-2. By extension, and taking into account (as mentioned elsewhere) that there's no clarity on left on right, I suggest that 1-3-4-2 and 1-2-4-3 are exactly the same. InfoPirate ( talk) 20:43, 14 October 2023 (UTC)
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It would be nice to see some discussion on alternative firing orders for 4 cylinder engines. For instance, the 2009 Yamaha R1 (Motorcycle) uses a crossplane inline 4 cylinder crankshaft, which does not fire at even 90 degree intervals as is common in 4 cylinder engines. Likewise, MotoGP bikes sometimes use a 'big bang' firing order, which fires all the cylinders within 180 degrees of crank rotation.
Unfortunately, I don't understand the benefits of these firing orders well enough to make an intelligent addition to the wiki article. The best I could do is repeat some of the manufacturers claims.
In a gasoline engine, the correct firing order is obtained by the correct placement of the spark plug wires on the distributor. In a modern engine with an engine management system and direct ignition, the Engine Control Unit (ECU) takes care of the correct firing sequence. Especially on cars with distributors, the firing order is usually cast on engine somewhere, most often on the cylinder head, the intake manifold or the valve cover(s).
This information is incorrect. The firing order is also based on the position of the intake and exhaust lobes on the camshaft, and the position of the crankshaft. For instance, with a 1-3-2-4 firing order, you could swap the ignition leads for cylinders 1 & 4, or 3 & 2. This would cause spark to occur at the end of the exhaust stroke and the beginning of the intake stroke. Likewise, swapping ignition leads for cylinders 1 & 3, or 2 & 4 would cause ignition to occur at the beginning of the exhaust stroke. In either cause, I doubt the engine would run (very well?)
It *may* be possible to change the firing order by rotating the cams and switching the plug leads. I suspect doing so would be possible on an inline 4, but question weather or not it would be possible on a more complex engine, such as a V-12. Doing so would throw off injection timing on an engine with sequential injection. I suspect it would cause other issues as well.
Obviously, these comments do not necessarily apply to diesel engines.
First some basics on orientation. The back of the engine is nearest the flywheel. The right bank is on your right if you're at the back of the engine looking toward the front of the engine. Put another way, for rear wheel drive vehicle in right hand side of road countries, eg. US and Canada, left bank is on the driver's side and the right bank is on the passenger's side.
Ford: Counting from front to back on the engine:
1 2 3 4 on right bank,
5 6 7 8 on left bank.
Chrysler and GM-Except NorthStar(tm): Counting front to back on the engine:
2 4 6 8 on right bank,
1 3 5 7 on left bank.
Northstar (GM): Counting front to back on the engine on the engine:
1 3 5 7 on right bank,
2 4 6 8 on left bank.
In V8 engines there is usually an offset between the front of the right bank compared to the front of the left bank about equal to the width of the lower part of the connecting rod. This is because piston/connecting rods assemblies are identical and share a common journal on the crankshaft between the banks. Hence there are only 4 journals on the crankshaft for connecting rods. In the Chrysler case: "1" and "2" share one journal, "3" and "4" share a journal, etc. Typically the cylinder nearest the front of the engine is numbered cylinder "1".
In the Chrysler case the left bank is nearest the front of the engine. Hence cylinder "1" is on the left side of the engine. When the Northstar engine was designed it was determine that some space would be saved if the right bank was moved ahead of the left bank. Consequently the apparent flip, left to right, of the cylinder numbering.
These differences in numbering conventions gives rise to differences in the "firing order". As expected, the actual design of the crank shaft also affects the firing order.
There was an interesting development in V-8 firing orders in the late '60's. Ford's Windsor class engines--302W and 351W--have different firing orders. Ford reversed the position of the #2 and #3 crankpins location when they built the 351W. Why? They observed that the firing order used on the 302W caused unacceptably high peak stresses at the #3 and #4 crankpins and #4 main bearing when using that sequence. Reversing those two crankpins (and the resulting change in firing order) cured the problem. The two engines appear externally identical to the untrained eye and this has caused lots of camshaft replacement calamities through the years by careless rebuilders. GM subsequently followed this practice on their latest rendition of the "Big Block" Chevrolet-based engine curing a number of problems. The Ford "385" series engines--the "C" or Cleveland, and the "M" or Modified Cleveland, in all displacements (302 Boss, 351M & C and 400M) all used the same firing order as the little 302W. They were structurally much larger, beefier (and heavier) engines. Leading bank issues are design significant. It greatly affects intake manifold flow design. Ford engines traditionally have a right-bank leading setup as do the Buick, Olds, Pontiac and Cadillac engines. The Chevrolet Small Block, and all Chrysler and AMC engines used a left bank leading design. Ford, alone among the above, numbers 1-2-3-4--right bank, and 5-6-7-8--left bank. The others use a 1-3-5-7--left bank (etc.) sequence.
Claude764 ( talk) 02:12, 29 October 2009 (UTC)
If you had a 12 cylinder 4 stroke engine how can you determine how many degrees apart the firing intervals are,
The section on cylinder numbering isn't very clear about its directional relativity. For example, when it says "left", is it left as viewed from standing in front of the car, looking at it, or left from sitting inside the car, looking out straight ahead?
For example, when standing in front of a car, looking at it, the steering wheel is on the left in Australia, but right in America, while, sitting inside the car, the steering wheel is on the right in Australia, but left in America.
This is where the confusion arises, and I think it should be clarified.
203.122.107.112 ( talk) 14:07, 21 May 2008 (UTC)
hey, i'm really courius about inline 6 firing order, so they would get balance. can someone tell me, please. —Preceding unsigned comment added by 123xyz321 ( talk • contribs) 11:20, 13 June 2008 (UTC)
The section about cylinder numbering talks mainly about V8 engines, and doesn't mention cylinder numbering for V6 and V12 engines. The firing orders are pretty meaningles without cylinder numbering. Could anyone include the cylinder numbering for V6 and V12 engines to improve the quality of the article, so that the firing orders can be "applied". 203.33.160.179 ( talk) 04:06, 10 November 2008 (UTC)
I have removed the firing order 1-2-3-4 assigned to the Proton Wira VDO engine. This car uses the Mitsubishi Orion engine 4G13 or 4G15, which has a standard 180 degrees planar crank. Hence 1-2-3-4 makes no sense. I expect it comes from their V6, which has a firing order 1-2-3-4-5-6. http://www.ben9166.com/2011/08/4g134g15-17l-crank-shaft-stroker-kit.html Mike163 ( talk) 20:25, 19 January 2015 (UTC)
This part of the article would need correction:
Actually a 90° crossplane V8 has even firing interval, it is just within each cylinder bank that it has uneven firing: Crossplane
Cse78 ( talk) 22:56, 10 November 2015 (UTC)
Some of the engines listed in the uneven firing list are even firing or have even firing variants; vice-versa for the even firing list.
I'll link the disputed entries to here.
Identiti crisis (
talk)
23:43, 30 November 2015 (UTC)
Corrected, this was obviously wrong. Dovatf ( talk) 22:06, 25 January 2016 (UTC)
The firing orders 1-3-4-2 and 1-2-4-3 appear to be essentially the same, just in reverse order. If we extend the sequence 1-2-4-3-1-2-4-3, we can extrapolate that 1-2-4-3 is identical to 2-4-3-1. If we reverse 2-4-3-1, we get 1-3-4-2. By extension, and taking into account (as mentioned elsewhere) that there's no clarity on left on right, I suggest that 1-3-4-2 and 1-2-4-3 are exactly the same. InfoPirate ( talk) 20:43, 14 October 2023 (UTC)