Removing the EGR consequences
04-08-2004, 05:56 AM
#1
Thread Starter
Join Date: Sep 2003
Posts: 25
Likes: 0
Received 0 Likes
on
0 Posts
Removing the EGR consequences
After installing my Hondata H22 IM gasket without the EGR hole drilled, I noticed an increase in exhaust gas temperature. My SS catback was red hot after cruising and I could hear the noise of it cooling down.
From the lack of information on this subject (AND from Hondata), I decided to double check how the EGR affects the combustion my self. I do have the Internal Combustion Engine Fundamentals bible from John B. Heywood which is a really complete and informative book. It was lying somewhere in the house since school time.
I found out very important things in this book. Here are the principal ones (shorten):
- Prior to early seventies, there was no EGR on engine. The part throttle combustion temperatures were controlled (cool down) by an excess of air (lean a/f). I was very surprised to read this. They say that the excess of air cool down the cylinder walls. Personally, I always thought that a lean mixture was generating more heat than a stoich. Anyway, for sure from this book, old-school engine were running VERY lean at part throttle.
- The EGR really acts as an additional thermal buffer (to nitrogen) to lower the combustion temperature. Exhaust gas is inert and do not react with the oxygen/fuel combustion. It is simply re-heated from around 200-250F. This allow the possibility of running stoich a/f (a stoich combustion generate less NOx from the start). And NOx are also mainly produced at high temperature. The EGR also permits to run more aggressive timing without the risk associated with high temperature detonation ; this help the fuel economy.
For those like me wondering what's the REAL purpose of the EGR and what it REALLY does, I found this very informative link : http://www.asashop.org/autoinc/nov97/gas.htm
From this link, and from my book, it is clearly indicated that without EGR, the combustion temp will raise from several hundreds deg.F.
My conclusions are :
- It is not a good idea to remove the EGR from our Honda engine since the ECU is focusing on maintaining a stoich a/f at part throttle. Removing the EGR will (with the ECU workaround mod) produce an important increase in combustion temperature. SO if the goal was to maintain a colder intake manifold to avoid detonation (like me), the internal cylinder walls are a lot hotter w/o EGR thus increasing the risk of detonation.
- A check engine EGR code (from a not well removed EGR valve) will affect the timing/fuel maps, and greatly affect overall performance.
- It was not a good idea (like I did) to try running an always rich mixture at Part Throttle to lower the combustion temperature (in place of the EGR). At least I think that old-school engine manufacturer would have tried it . If they went the opposite direction there is a reason. I think this would simply quickly ruins the plugs.
- It is a good idea to use a clean Gasoline. Up here is Canada, we do have 94 ((R+M)/2) octane gasoline that has 10% ethanol. This is a cleaner gas that help prevents exhaust gas deposits often seen on engine (that come from the EGR).
Your comments are welcome
.
WHAT I DO NOT HAVE is EGT readings with and without EGR. OMG I would like to have that.
NOTE: Since EGR is only active at part throttle (low load), all my comments are for part throttle considerations.
On my side, I'm serioulsly thinking about removing all my JRSC setup to access the Hondata gasket and drill the EGR passage Or at least to find a way for piercing it in place.
At this point I'm wondering how much I've affected some of the engine components life... 
Modified by SRVMAN at 9:22 PM 4/8/2004
From the lack of information on this subject (AND from Hondata), I decided to double check how the EGR affects the combustion my self. I do have the Internal Combustion Engine Fundamentals bible from John B. Heywood which is a really complete and informative book. It was lying somewhere in the house since school time.
I found out very important things in this book. Here are the principal ones (shorten):
- Prior to early seventies, there was no EGR on engine. The part throttle combustion temperatures were controlled (cool down) by an excess of air (lean a/f). I was very surprised to read this. They say that the excess of air cool down the cylinder walls. Personally, I always thought that a lean mixture was generating more heat than a stoich. Anyway, for sure from this book, old-school engine were running VERY lean at part throttle.
- The EGR really acts as an additional thermal buffer (to nitrogen) to lower the combustion temperature. Exhaust gas is inert and do not react with the oxygen/fuel combustion. It is simply re-heated from around 200-250F. This allow the possibility of running stoich a/f (a stoich combustion generate less NOx from the start). And NOx are also mainly produced at high temperature. The EGR also permits to run more aggressive timing without the risk associated with high temperature detonation ; this help the fuel economy.
For those like me wondering what's the REAL purpose of the EGR and what it REALLY does, I found this very informative link : http://www.asashop.org/autoinc/nov97/gas.htm
From this link, and from my book, it is clearly indicated that without EGR, the combustion temp will raise from several hundreds deg.F.
My conclusions are :
- It is not a good idea to remove the EGR from our Honda engine since the ECU is focusing on maintaining a stoich a/f at part throttle. Removing the EGR will (with the ECU workaround mod) produce an important increase in combustion temperature. SO if the goal was to maintain a colder intake manifold to avoid detonation (like me), the internal cylinder walls are a lot hotter w/o EGR thus increasing the risk of detonation.
- A check engine EGR code (from a not well removed EGR valve) will affect the timing/fuel maps, and greatly affect overall performance.
- It was not a good idea (like I did) to try running an always rich mixture at Part Throttle to lower the combustion temperature (in place of the EGR). At least I think that old-school engine manufacturer would have tried it . If they went the opposite direction there is a reason. I think this would simply quickly ruins the plugs.
- It is a good idea to use a clean Gasoline. Up here is Canada, we do have 94 ((R+M)/2) octane gasoline that has 10% ethanol. This is a cleaner gas that help prevents exhaust gas deposits often seen on engine (that come from the EGR).
Your comments are welcome
. WHAT I DO NOT HAVE is EGT readings with and without EGR. OMG I would like to have that.
NOTE: Since EGR is only active at part throttle (low load), all my comments are for part throttle considerations.
On my side, I'm serioulsly thinking about removing all my JRSC setup to access the Hondata gasket and drill the EGR passage Or at least to find a way for piercing it in place.
At this point I'm wondering how much I've affected some of the engine components life... Modified by SRVMAN at 9:22 PM 4/8/2004
05-20-2004, 10:05 PM
#3
Honda-Tech Member
Join Date: Jan 2002
Location: On., Can.
Posts: 1,349
Likes: 0
Received 0 Likes
on
0 Posts
Re: Removing the EGR consequences (SRVMAN)
well, some good info. But honda doesn't run the egr on all their engines, and apparently dropped it on the g3 integra autos (from using it on g2 autos).
I swapped a b20 into my g2 auto, and now i have no egr valve and the computer is looking for it. I'm planning to just take the valve off the old b18a manifold and plugging it in to the harness, and blocking it off, just to keep the computer happy. You believe the ecu, running a certain mixture, depends on the egr to keep the engine cool and safe?
d
I swapped a b20 into my g2 auto, and now i have no egr valve and the computer is looking for it. I'm planning to just take the valve off the old b18a manifold and plugging it in to the harness, and blocking it off, just to keep the computer happy. You believe the ecu, running a certain mixture, depends on the egr to keep the engine cool and safe?
d
05-20-2004, 10:25 PM
#4
Honda-Tech Member
Join Date: Jan 2002
Location: On., Can.
Posts: 1,349
Likes: 0
Received 0 Likes
on
0 Posts
Re: Removing the EGR consequences (SRVMAN)
maybe i should look into getting a g3 integra obd1 auto ecu, if its true that honda dropped the egr system. don't want to cook my nice b20 engine with incorrect fuel maps.
d
d
05-21-2004, 05:18 AM
#5
Re: Removing the EGR consequences (daver)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by daver »</TD></TR><TR><TD CLASS="quote">... if its true that honda dropped the egr system.</TD></TR></TABLE>My '95 Integra doesn't have EGR. Both Accords ('98 & '03) have it. So Honda didn't drop it across the board. Saab had EGR for a couple years during '80s but not all years. So it just depends on which engines needed it to control NOx. I'm sure the engine-control maps take into account whether it's there or not.
05-21-2004, 07:21 AM
#6
Honda-Tech Member
Join Date: Jan 2003
Location: Charlotte, NC
Posts: 3,788
Likes: 0
Received 0 Likes
on
0 Posts
Re: Removing the EGR consequences (JimBlake)
The whole purpose of EGR is to cool the combustion chamber to reduce NOX under part throttle conditions. This is where emissions is focused on part throttle conditions. Your car will not run hotter from a rich condition however the excess fuel will heat the cat up but the engine itself should not run any hotter it should run cooler. NOX is created when combustiont emratures reach an excess of 2500 degrees farenheit and pressure is excessivley high
05-21-2004, 11:20 AM
#7
Honda-Tech Member
Join Date: Jan 2002
Location: On., Can.
Posts: 1,349
Likes: 0
Received 0 Likes
on
0 Posts
Re: Removing the EGR consequences (JimBlake)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by JimBlake »</TD></TR><TR><TD CLASS="quote">My '95 Integra doesn't have EGR. Both Accords ('98 & '03) have it. So Honda didn't drop it across the board. Saab had EGR for a couple years during '80s but not all years. So it just depends on which engines needed it to control NOx. I'm sure the engine-control maps take into account whether it's there or not.</TD></TR></TABLE>
i understand it was only auto tegs of certain years that had the egr valves. Someone said that the g3 autos do have them as well (obd1).
I'm just trying to figure out if i need it on my b20 to be safe. I don't want to cook the engine or cat; i'm not too worried about emmisions here. I can throw my b18a manifold on my b20 to have the egr, but it'll rob some power with those smaller ports.
d
i understand it was only auto tegs of certain years that had the egr valves. Someone said that the g3 autos do have them as well (obd1).
I'm just trying to figure out if i need it on my b20 to be safe. I don't want to cook the engine or cat; i'm not too worried about emmisions here. I can throw my b18a manifold on my b20 to have the egr, but it'll rob some power with those smaller ports.
d
Trending Topics
05-21-2004, 11:39 AM
#8
Keyboard Humorist
Join Date: May 2002
Location: Granada Hills, Ca, USA
Posts: 9,814
Likes: 0
Received 9 Likes
on
7 Posts
Re: Removing the EGR consequences (daver)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by daver »</TD></TR><TR><TD CLASS="quote">
I'm just trying to figure out if i need it on my b20 to be safe. I don't want to cook the engine or cat; i'm not too worried about emmisions here.
</TD></TR></TABLE>
If you aren't worried about emmisions then why not gut the cat or use a test pipe? As long as you are defeating some of the emmisions you might as well go all the way!
I'm just trying to figure out if i need it on my b20 to be safe. I don't want to cook the engine or cat; i'm not too worried about emmisions here.
</TD></TR></TABLE>
If you aren't worried about emmisions then why not gut the cat or use a test pipe? As long as you are defeating some of the emmisions you might as well go all the way!
05-23-2004, 01:53 PM
#10
Honda-Tech Member
Join Date: Jan 2002
Location: On., Can.
Posts: 1,349
Likes: 0
Received 0 Likes
on
0 Posts
Re: Removing the EGR consequences (eLusive ek4)
thanks guys, i've just read a few posts which said that an engine will run much hotter with the egr unhooked.
What i meant about not being too worried about emissions here, is that they're quite leniant. If you have an engine swap, they're even more leniant and call it a hot rod. If there is no cat then you'll fail no matter what.
d
What i meant about not being too worried about emissions here, is that they're quite leniant. If you have an engine swap, they're even more leniant and call it a hot rod. If there is no cat then you'll fail no matter what.
d
Thread
Thread Starter
Forum
Replies
Last Post
