What's the combustion sequence of the ej series engines?

The Enemy · 02-01-2003, 11:44 PM

Discussing it with a friend of mine. Basically I'm wanting to find out if the cylinders fire one at a time or two at a time?

Full_Clip · 02-02-2003, 01:09 AM

It would be easy to assume that cylinders would fire in a diagonal pattern to cancel vibration, but he could be wrong.

Full_Clip is a single stroke guy.

US2JDM · 02-02-2003, 01:16 AM

Firing order: 1-3-2-4

HndaTch627 · 02-02-2003, 05:14 AM

you can't fire 2 cylinders at a time. that's why they have a firing order.

jeremy

US2JDM · 02-02-2003, 06:43 AM

Quote:

Originally posted by HndaTch627
you can't fire 2 cylinders at a time. that's why they have a firing order.

jeremy

Actually I believe Subarus fire the plugs of the paired cylinders on the ignition block simultaneously (one on the compression stroke, the other on the exhaust stroke).

The Enemy · 02-02-2003, 09:03 AM

Quote:

Originally posted by HndaTch627
you can't fire 2 cylinders at a time. that's why they have a firing order.

jeremy

So why couldn't they fire in pairs? Is there a reason why it couldn't be done?

is2scooby · 02-02-2003, 09:27 AM

The motor would shake the car apart. Ever ride a Harley?

WRX Harvey · 02-02-2003, 07:18 PM

USJDM, According to my understanding of the 4 stroke cycle. Internal Combustion Engines never fire during the exhaust stroke. They just push spent gas out in preparation for the intake stroke so they can close the valves and compress the new mixture and THEN fire, starting the power stroke. Which brings us back to the Exhaust stroke, ad infinitum. Or till you turn the key off. The pistons probably move in opposition diagonally to cancel vibration but while two pistons are extended at the same time one would be at the end of Compression while the other would be at the end of the Exhaust stroke.

Disclaimer: I could be wrong!!! Just thinking.

paultg · 02-02-2003, 07:47 PM

I've actually heard of what US2jdm is talking about, but I don't know first hand, and am still new to the "boxer" engines.

These Subaru engines sure are stange. When I found out you could drive around with blown head gaskets as long as you didn't run the car hard, I new something was up.

Paul G.

Jude DeMeis · 02-02-2003, 08:37 PM

US2JDM is correct: On the 2.5RS Subaru used only two ignition coils and alternates firing them. One coil serves the front two cylinders and the other fires the rear two. With this pattern a useless spark gets fired on the exhaust cycle of the opposite cylinder. This ignition strategy is used by many manufacturers and is commonly known as a "waste spark" system.

A "waste spark" ignition system has no benefit other than lower cost and simplicity. The layout allows Subaru to use 2 coils instead of 4 (cheaper) and a two-channel control circuit (simpler) from the ECU.

This of course only applies to Subarus with the coil pack mounted on the intake. The newest Subaru engines (like the WRX) have four individual coils, one mounted on each spark plug and controlled individually by the ECU.

The Enemy · 02-02-2003, 08:42 PM

So the EJ's don't have 2 chambers explode instead they have a waste spark.

Has there been an engine before that has 2 chambers fire at once? It would seem to be an advantage...

Jude DeMeis · 02-02-2003, 08:47 PM

Four cylinder four stroke engines never have two cylinders firing at once. The engine runs the same with a waste-spark, the only difference is that some electricity is wasted by firing an extra spark plug with no benefit.

paultg · 02-02-2003, 08:54 PM

Thanks Jude. I didn't realize my WRX was different than my pervious car (2.5RS).

Paul G.

The Enemy · 02-02-2003, 08:59 PM

Quote:

Originally posted by Jude DeMeis
Four cylinder four stroke engines never have two cylinders firing at once. The engine runs the same with a waste-spark, the only difference is that some electricity is wasted by firing an extra spark plug with no benefit.

Someone should do this, would be cool to see if it worked. Could be hella power too. Thanks for the info

is2scooby · 02-03-2003, 01:33 AM

Honda used that dual-firing theory on it's "Big Bang" series of engines. I believe they were used in motorcycle racing. I bet Google would have something to say about it.

jackansi · 02-03-2003, 01:38 AM

What is the location of cyl 1 and 3?

US2JDM · 02-03-2003, 02:56 AM

Quote:

Originally posted by WRX Harvey
USJDM, According to my understanding of the 4 stroke cycle. Internal Combustion Engines never fire during the exhaust stroke. They just push spent gas out in preparation for the intake stroke so they can close the valves and compress the new mixture and THEN fire, starting the power stroke. Which brings us back to the Exhaust stroke, ad infinitum. Or till you turn the key off. The pistons probably move in opposition diagonally to cancel vibration but while two pistons are extended at the same time one would be at the end of Compression while the other would be at the end of the Exhaust stroke.

Disclaimer: I could be wrong!!! Just thinking.

Don't worry, I know all about the 4-stroke cycle

As Jude pointed out, I was talking about the 'waste spark' system. Other cars use this, I believe the Mazda wankels did this (keeps things cheap and easy).

I believe some radial airplane engines do fire multiple cylinders simultaneously.

As for the cylinder numbering:

3 - 4
1 - 2
____

(as seen from above w/ the line being the front of the car)

Word.™

-Milan

P.S. don't blow up your motors experimenting

HndaTch627 · 02-03-2003, 03:04 AM

theres a difference between a wasted spark on and exhaust stroke and firing 2 cylinders at the same time.

is2scooby · 02-03-2003, 04:07 AM

Those motors may fire 2 SPARK PLUGS at the same time, but they're not firing 2 cylinders containing ready-to-combust a/f mixture at the same time...

NavyBlueSubaru · 02-03-2003, 07:42 AM

I believe that in the manual for the wrx, the firing order is simply 1-2-3-4. May sound strange, but the boxer arrangement makes this possible. Check your manual, its in there i promise

US2JDM · 02-03-2003, 10:00 AM

Quote:

Originally posted by HndaTch627
theres a difference between a wasted spark on and exhaust stroke and firing 2 cylinders at the same time.

Quote:

Originally posted by is2scooby
Those motors may fire 2 SPARK PLUGS at the same time, but they're not firing 2 cylinders containing ready-to-combust a/f mixture at the same time...

Quote:

Originally posted by US2JDM
Actually I believe Subarus fire the plugs of the paired cylinders on the ignition block simultaneously (one on the compression stroke, the other on the exhaust stroke).

Perhaps I wasn't clear enough?

TheMadScientist · 02-03-2003, 11:19 AM

Quote:

Originally posted by The Enemy

Someone should do this, would be cool to see if it worked. Could be hella power too. Thanks for the info

I belive that some F1 cars either did or do fire two cylinders at the same time.

is2scooby · 02-03-2003, 02:26 PM

Quote:

Originally posted by The Enemy

Someone should do this, would be cool to see if it worked. Could be hella power too. Thanks for the info

My post was in response to this. US2JDM your post was clear.

HndaTch627 · 02-03-2003, 02:30 PM

Quote:

Originally posted by NavyBlueSubaru
I believe that in the manual for the wrx, the firing order is simply 1-2-3-4. May sound strange, but the boxer arrangement makes this possible. Check your manual, its in there i promise

try 1, 3, 2, 4 it's been that way for years they cranks are almost identical.

jeremy

Jude DeMeis · 02-04-2003, 09:57 AM

Quote:

Originally posted by mmurray75

I belive that some F1 cars either did or do fire two cylinders at the same time.

Yes, but only on 8 cylinders and up. If you did this on a 4 cylinder engine like the Subaru it would run about as smooth as an old tractor or a Harley.

Lotus and Ferrari do this on some of their 8 cylinder street cars as well. It's called a "flat plane crankshaft" and unlike a normal V8 is more like having two four cylinder cranks in a row. The "flat" design can take advantage of the exhaust pulse to extract more air from the engine. Flat plane motors make better power but are rougher than a traditional V8 with "cross plane" crank. They also don't sound the same as a normal V8- the exhaust note is more like an inline four cylinder.

02-01-2003, 11:44 PM	#1
The Enemy Scooby Specialist Member#: 12851 Join Date: Nov 2001 Chapter/Region: South East Location: Loitering Outlaw	What's the combustion sequence of the ej series engines? Discussing it with a friend of mine. Basically I'm wanting to find out if the cylinders fire one at a time or two at a time?

02-02-2003, 08:37 PM	#10
Jude DeMeis Scooby Newbie Member#: 491 Join Date: Nov 1999 Chapter/Region: NESIC Location: Boston, Ma, USA Vehicle: 1995 Legacy race car Pan Am Blue	US2JDM is correct: On the 2.5RS Subaru used only two ignition coils and alternates firing them. One coil serves the front two cylinders and the other fires the rear two. With this pattern a useless spark gets fired on the exhaust cycle of the opposite cylinder. This ignition strategy is used by many manufacturers and is commonly known as a "waste spark" system. A "waste spark" ignition system has no benefit other than lower cost and simplicity. The layout allows Subaru to use 2 coils instead of 4 (cheaper) and a two-channel control circuit (simpler) from the ECU. This of course only applies to Subarus with the coil pack mounted on the intake. The newest Subaru engines (like the WRX) have four individual coils, one mounted on each spark plug and controlled individually by the ECU. Last edited by Jude DeMeis; 02-02-2003 at 08:43 PM.

02-03-2003, 07:42 AM	#20
NavyBlueSubaru Scooby Specialist Member#: 22127 Join Date: Jul 2002 Chapter/Region: South East Location: Jacksonville, FL Vehicle: 2002 WRB WRX 12.5:1 @ 24psi w/ W.I.	Firing Order I believe that in the manual for the wrx, the firing order is simply 1-2-3-4. May sound strange, but the boxer arrangement makes this possible. Check your manual, its in there i promise

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02-02-2003, 01:09 AM	#2
Full_Clip Scooby Specialist Member#: 22218 Join Date: Jul 2002 Chapter/Region: South East Location: University of Florida	It would be easy to assume that cylinders would fire in a diagonal pattern to cancel vibration, but he could be wrong. Full_Clip is a single stroke guy.

02-02-2003, 01:16 AM	#3
US2JDM Scooby Guru Member#: 5893 Join Date: Apr 2001 Chapter/Region: E. Canada Location: Fairport, NY Vehicle: 1997 Black GC4 1995 White BK6	Firing order: 1-3-2-4

02-02-2003, 05:14 AM	#4
HndaTch627 Scooby Guru Member#: 6551 Join Date: May 2001 Chapter/Region: MWSOC Location: Carol Stream, IL Vehicle: '01 GC8 Dinged STM '93 GF2 Rust White	you can't fire 2 cylinders at a time. that's why they have a firing order. jeremy

02-02-2003, 09:27 AM	#7
is2scooby Scooby Specialist Member#: 19851 Join Date: Jun 2002 Location: Honolulu, HI Vehicle: 02 WRX Aspen White/12.75@105.67	The motor would shake the car apart. Ever ride a Harley?

02-02-2003, 07:18 PM	#8
WRX Harvey Scooby Specialist Member#: 13025 Join Date: Dec 2001 Chapter/Region: RMIC Location: Longmont, Colorado Vehicle: 1998 RS-T Rally Blue	USJDM, According to my understanding of the 4 stroke cycle. Internal Combustion Engines never fire during the exhaust stroke. They just push spent gas out in preparation for the intake stroke so they can close the valves and compress the new mixture and THEN fire, starting the power stroke. Which brings us back to the Exhaust stroke, ad infinitum. Or till you turn the key off. The pistons probably move in opposition diagonally to cancel vibration but while two pistons are extended at the same time one would be at the end of Compression while the other would be at the end of the Exhaust stroke. Disclaimer: I could be wrong!!! Just thinking.

02-02-2003, 07:47 PM	#9
paultg Scooby Guru Member#: 437 Join Date: Oct 1999 Chapter/Region: NESIC Location: Londonderry, NH Vehicle: '91 Miata MX5 (Red) '09 Impreza OBS (Blk/Gry)	I've actually heard of what US2jdm is talking about, but I don't know first hand, and am still new to the "boxer" engines. These Subaru engines sure are stange. When I found out you could drive around with blown head gaskets as long as you didn't run the car hard, I new something was up. Paul G.

02-02-2003, 08:42 PM	#11
The Enemy Scooby Specialist Member#: 12851 Join Date: Nov 2001 Chapter/Region: South East Location: Loitering Outlaw	So the EJ's don't have 2 chambers explode instead they have a waste spark. Has there been an engine before that has 2 chambers fire at once? It would seem to be an advantage...

02-02-2003, 08:47 PM	#12
Jude DeMeis Scooby Newbie Member#: 491 Join Date: Nov 1999 Chapter/Region: NESIC Location: Boston, Ma, USA Vehicle: 1995 Legacy race car Pan Am Blue	Four cylinder four stroke engines never have two cylinders firing at once. The engine runs the same with a waste-spark, the only difference is that some electricity is wasted by firing an extra spark plug with no benefit.

02-02-2003, 08:54 PM	#13
paultg Scooby Guru Member#: 437 Join Date: Oct 1999 Chapter/Region: NESIC Location: Londonderry, NH Vehicle: '91 Miata MX5 (Red) '09 Impreza OBS (Blk/Gry)	Thanks Jude. I didn't realize my WRX was different than my pervious car (2.5RS). Paul G.

02-03-2003, 01:33 AM	#15
is2scooby Scooby Specialist Member#: 19851 Join Date: Jun 2002 Location: Honolulu, HI Vehicle: 02 WRX Aspen White/12.75@105.67	Honda used that dual-firing theory on it's "Big Bang" series of engines. I believe they were used in motorcycle racing. I bet Google would have something to say about it.

02-03-2003, 01:38 AM	#16
jackansi Scooby Specialist Member#: 23894 Join Date: Sep 2002 Chapter/Region: MAIC Location: Central, PA Vehicle: '02 2.5 WRX WR Blue	What is the location of cyl 1 and 3?

02-03-2003, 03:04 AM	#18
HndaTch627 Scooby Guru Member#: 6551 Join Date: May 2001 Chapter/Region: MWSOC Location: Carol Stream, IL Vehicle: '01 GC8 Dinged STM '93 GF2 Rust White	theres a difference between a wasted spark on and exhaust stroke and firing 2 cylinders at the same time.

02-03-2003, 04:07 AM	#19
is2scooby Scooby Specialist Member#: 19851 Join Date: Jun 2002 Location: Honolulu, HI Vehicle: 02 WRX Aspen White/12.75@105.67	Those motors may fire 2 SPARK PLUGS at the same time, but they're not firing 2 cylinders containing ready-to-combust a/f mixture at the same time...