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Thoughts on EGR Valves?
- Thread starter Aldwyn
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T
Tinster
Guest
Guest
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Mhen my 1969ish carbs and manifold were sent to
Jeff Paltech in Ohio thay came back to me with
the EGR valve assembly removed.
Jeff Paltech in Ohio thay came back to me with
the EGR valve assembly removed.
vettedog72
Jedi Knight
Offline
It seems that the "hot gases" that recirculate back to the intake would reduce performance, but I have not seen any before and after studies. I removed my '74 EGR and I do not have any problems, runs smoothly.
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Way back when, the EPA decided that Nitrogen oxides were a serious pollutant. Since NO's are generated at high combustion temperatures, they thought that lowering peak combustion temperatures would reduce NO emissions.
The cheapest way to lower peak combustion temperatures, which also reduces power, was to inject an inert gas into the intake mixture to displace some of the combustible mixture. Since already burned exhaust gas is largely inert, (won't burn) they came up with EGR (exhaust gas recirculation) to solve the problem. It is only injected when the engine is off idle, at cruise loading. It accomplishes the objective, along with reduced fuel mileage & power.
It is basically an engine load controlled valve connected between the exhaust & intake. The valve, it's exhaust connection, intake connection, & vacuum control could be removed & plugged. There will be some increase in NO emissions & an increase in gas mileage & power. If you still want it to pass some emission visual inspection checks, leave the parts in place & just lift & plug the vacuum control hose that operates the EGR valve.
"Some" early EGR systems just used internal bypass ports in the intake/exhaust manifold without any external control valve. Not as easy to block. They didn't work very well because they were effective at idle & screwed up the engines idle.
On another note, to reduce unburned fuel passing out the exhaust at idle, due to valve timing overlap, some engines used a two stage vacuum advance which drastically retarded idle timing. It worked, but was a pretty lame way to do it. They also sometimes screwed up the valve timing specs to reduce cam/valve timing overlap, to the detriment of engine power.
Aother stroke of genius was to add air injection to the exhaust ports. Usually in conjunction with cat. converters. The thinking was that unburned fuel in the exhaust system did not have enough oxygen to completely burn, so injecting air would cause more complete burning/cat. reaction, before the gasses exited the tail pipe. The controls for air injection disabled the injection on closed throttle over run to prevent exhaust popping. If emission regulations allow, the air injection pump, it's plumbing, & controls, can be removed & the air injection ports plugged to greatly simplify the engine compartment.
On any engine, exhaust popping on closed throttle over run, usually occurs only if there are leaks in the exhaust plumbing, or a malfunctioning air injection control valve, if so equipped, which allow enough extra air into the system to make the unburned fuel combustible.
All of these changes are prohibited by law, on cars that are new enough to still be subject to emission regulations.
Probably more than you wanted to know. If so, forgive me for rambling.
D
The cheapest way to lower peak combustion temperatures, which also reduces power, was to inject an inert gas into the intake mixture to displace some of the combustible mixture. Since already burned exhaust gas is largely inert, (won't burn) they came up with EGR (exhaust gas recirculation) to solve the problem. It is only injected when the engine is off idle, at cruise loading. It accomplishes the objective, along with reduced fuel mileage & power.
It is basically an engine load controlled valve connected between the exhaust & intake. The valve, it's exhaust connection, intake connection, & vacuum control could be removed & plugged. There will be some increase in NO emissions & an increase in gas mileage & power. If you still want it to pass some emission visual inspection checks, leave the parts in place & just lift & plug the vacuum control hose that operates the EGR valve.
"Some" early EGR systems just used internal bypass ports in the intake/exhaust manifold without any external control valve. Not as easy to block. They didn't work very well because they were effective at idle & screwed up the engines idle.
On another note, to reduce unburned fuel passing out the exhaust at idle, due to valve timing overlap, some engines used a two stage vacuum advance which drastically retarded idle timing. It worked, but was a pretty lame way to do it. They also sometimes screwed up the valve timing specs to reduce cam/valve timing overlap, to the detriment of engine power.
Aother stroke of genius was to add air injection to the exhaust ports. Usually in conjunction with cat. converters. The thinking was that unburned fuel in the exhaust system did not have enough oxygen to completely burn, so injecting air would cause more complete burning/cat. reaction, before the gasses exited the tail pipe. The controls for air injection disabled the injection on closed throttle over run to prevent exhaust popping. If emission regulations allow, the air injection pump, it's plumbing, & controls, can be removed & the air injection ports plugged to greatly simplify the engine compartment.
On any engine, exhaust popping on closed throttle over run, usually occurs only if there are leaks in the exhaust plumbing, or a malfunctioning air injection control valve, if so equipped, which allow enough extra air into the system to make the unburned fuel combustible.
All of these changes are prohibited by law, on cars that are new enough to still be subject to emission regulations.
Probably more than you wanted to know. If so, forgive me for rambling.
D
swift6
Yoda
Offline
[ QUOTE ]
Way back when, the EPA decided that Nitrogen oxides were a serious pollutant.
All of these changes are prohibited by law, on cars that are new enough to still be subject to emission regulations.
[/ QUOTE ]
Which can date back to cars in the 1960's and technically altering ANY emissions device is a federal offense, not just local emissions violations. Though on older cars there is no federal enforcement (they leave it up to local jurisdictions). Though most every regions no longer 'visually inspects for equipment' prior to 1974-5 which was the major introduction of catalytic converters (air pumps were used before this without catalytic converters), they still do a tailpipe emissions level and visual check for 'smoke'.
On a side not. By the end of this year Colorado is ending its emissions program in the majority of counties and by the end of next year the entire program is due to be phased out. The current emissions program in Colorado is a CO based program. Currently the state govt is looking into a NOx based program to replace the CO based program because as CO is dropping, NOx is on the rise. California's program is NOx based.
Way back when, the EPA decided that Nitrogen oxides were a serious pollutant.
All of these changes are prohibited by law, on cars that are new enough to still be subject to emission regulations.
[/ QUOTE ]
Which can date back to cars in the 1960's and technically altering ANY emissions device is a federal offense, not just local emissions violations. Though on older cars there is no federal enforcement (they leave it up to local jurisdictions). Though most every regions no longer 'visually inspects for equipment' prior to 1974-5 which was the major introduction of catalytic converters (air pumps were used before this without catalytic converters), they still do a tailpipe emissions level and visual check for 'smoke'.
On a side not. By the end of this year Colorado is ending its emissions program in the majority of counties and by the end of next year the entire program is due to be phased out. The current emissions program in Colorado is a CO based program. Currently the state govt is looking into a NOx based program to replace the CO based program because as CO is dropping, NOx is on the rise. California's program is NOx based.
wedgehammer
Freshman Member
Offline
I can't speak to the specifics of Triumphs implimentation, but in general, EGR reduces combustion temps which would allow for the use of lower octane fuel, increased ignition timing or a combination of both. EGR can also reduce pumping losses at part throttle (cruise) which should provide better fuel mileage, not worse.
bobh
Jedi Warrior
Offline
Dave,
Emmission controls, 5 mph bumpers, unleaded gas... were all invented in the minds of government officials. No need to take it out on the designers tasked with meeting these requirements. EGR valves were still in use well into the '90s and may still be in use, I'm not sure. It takes time for technology to catch up with government demands. Today you can buy a 200 hp 122 cid aluminum engine that will last for 200,000 miles at 30+mpg with less emmissions that you or I exhale before brushing out teeth in the morning. It's all part of the evolution of the automobile. Some ideas survive, others do not.
Leaky tops, lever shocks, non syncro gears, bias ply tires, generators, untreated sheet metal and negative earth are hallmarks of your Healey. All of these are obsolete yet the car was revolutionary in it's day.
Emmission controls, 5 mph bumpers, unleaded gas... were all invented in the minds of government officials. No need to take it out on the designers tasked with meeting these requirements. EGR valves were still in use well into the '90s and may still be in use, I'm not sure. It takes time for technology to catch up with government demands. Today you can buy a 200 hp 122 cid aluminum engine that will last for 200,000 miles at 30+mpg with less emmissions that you or I exhale before brushing out teeth in the morning. It's all part of the evolution of the automobile. Some ideas survive, others do not.
Leaky tops, lever shocks, non syncro gears, bias ply tires, generators, untreated sheet metal and negative earth are hallmarks of your Healey. All of these are obsolete yet the car was revolutionary in it's day.
TR6oldtimer
Darth Vader
Offline
In California, my 73 TR6 is no longer subject to inspection of any kind. Before it became exempt, I had swapped a 250 engine for the original six. Although I had the smog stuff for the 250, I had to make it look like a six.
When the time comes for a rebuild (soon), I plan to mill the head, bore the cylinders, put in a mild street cam, headers, ignition, other stuff, and of course jettison the smog nonsense.
When the time comes for a rebuild (soon), I plan to mill the head, bore the cylinders, put in a mild street cam, headers, ignition, other stuff, and of course jettison the smog nonsense.
Offline
[ QUOTE ]
Dave, no forgiveness needed! /ubbthreads/images/graemlins/smile.gif Thanks for all the info!
In my case, I do not need it to pass any emissions tests, visual or otherwise.
What do you think is the best way to plug everything up if I remove the system?
[/ QUOTE ]
For legal reasons, I would rather not be specific. There is an inlet to the EGR that should be plugged at it's source to prevent an exhaust leak. The outlet of the EGR should be plugged at the intake manifold to prevent an intake air leak. The EGR control line should be plugged to prevent a vacuum leak. Take the stuff loose & see what is required to plug the holes. It might require plugs, or even a block off plate. Maybe someone wants to be more specific. Most professional mechanics won't go near such a project, since it isn't legal.
D
Dave, no forgiveness needed! /ubbthreads/images/graemlins/smile.gif Thanks for all the info!
In my case, I do not need it to pass any emissions tests, visual or otherwise.
What do you think is the best way to plug everything up if I remove the system?
[/ QUOTE ]
For legal reasons, I would rather not be specific. There is an inlet to the EGR that should be plugged at it's source to prevent an exhaust leak. The outlet of the EGR should be plugged at the intake manifold to prevent an intake air leak. The EGR control line should be plugged to prevent a vacuum leak. Take the stuff loose & see what is required to plug the holes. It might require plugs, or even a block off plate. Maybe someone wants to be more specific. Most professional mechanics won't go near such a project, since it isn't legal.
D
Aldwyn - if you were going to race the car you could remove everything legally. Let's assume you are. And assume my '76 is going racing to. You won't need any block off plates anywhere on a '76. The EGR can be plugged by an appropriately threaded plug or bolt, your choice. The threads into the head needn't be more than 3/4". I used a bolt head for mine, cut it down, and it looks like it belongs there. I can't recall the thread size. Ask here, someone will tell you. You'll need to plug the other end of the EGR, that is the steel tube that goes into the intake manifold. I used a steel squared headed NPT plumbers plug 1/2" and it looks factory original. I left the charcol canister and fittings in place. The remaining vacumm openings (on the intake man. and front carb, if you remove the ignition retard) can be nicely plugged by rubber caps. Check a good hardware store. If no luck, seach under "caps" at McMaster-Carr for ideas. You'll need to deal with the air injectors into the exhaust man. and I suspect they will be frozen nicely in place. Tread carefully here so as not to snap one off. I found a '72 manifold, had it ceramic coated and solved the problem that way. It looks original, as it should. You could just cap and leave the one-way valve in place and take everything else off as a last resort. Good luck.