EGR upgrades, intercooler?
 

I was cleaning the egr ports on my honda crx hf, a common procedure unfortunately, and thought upon how the system as a whole could be improved after noticing some things about it.

I noticed there is a coolant that runs along side the egr valve ports to cool the manifold, now I don't know if that is to cool the hot gasses from the egr system or if it is just to keep the intake manifold from getting too hot. IF there is a major advantage to cooling recirculated exhaust gas (to prevent engine knock) could you recirculate MORE exhaust gas if you hooked a turbo intercooler/radiator or perhaps water injection to the egr system?

I would be very interested in the math involved in finding out how much gas savings could be gained from these and I suppose leaning it out further and advancing the timing as well. And the nox emissions too, as that tends to go hand in hand with leaning mixture. we can all agree Nitric oxide is bad I'm sure...

Also the possibly less hair brained idea... what if you hooked up a bubbler like filter box before the egr valve to the system that you could just put clean water in every oil change or something instead of ripping apart the entire intake manifold every 80,000 miles. I think that it would be something like a downsized "scrubber" used at coal fire power plants and the like.

oil - heater -
 

hmm cheap sludgy oil could easily contribute to carbon build up, I never considered that as a factor. The motor has gone a couple hundred thousand miles since the last rebuild, there could be a fair amount of blow-by.

I think I'll switch the car over to a decent synthetic and take the egr off in a year or so and see if it changes, maybe I'll even remember to report my findings here.

Slugbeast, it is possible that you have an EGR cooler. The general idea is that more EGR should lower fuel consumption, in a petrol engine of course. Cooling EGR gasses reduces their volume, allowing more to be packed into the cylinder. Here is a discussion:
Increasing EGR flow for better mileage

Excellent! Good thread, I'm going to read through all of it. I'm happy other people have had the same idea as me, now maybe I can actually do some sort of project since I have something to go on. thanks for finding it for me.

Why not just buy an EGR cooler?

Image Search Results for EGR cooler

I see them all the time when digging around the stainless steel pile at the scrap yard.
On diesels EGR hurts milage under most conditions. So the EGR system gets tossed a lot of times.

One of the features of an EGR cooler (will coolant connected) is the exhaust gas will help warm the coolant.

Unfortunately, in most (if not all) cases the EGR valve doesn't open until the engine has slightly warmed up. It may have to do with the gasses condensing:confused:

Adding cooler to existing gasoline egr system - valid idea?
 

Ok, I have gm lx9 v6, 3.5 liter, gasoline, regular egr (not cooled). Decent amount of room near heater hoses to add a small egr cooler from perhaps a 1.9 VW tdi? I can use SS corrugated line from home depot to splice into current egr Pipe, and splice into heater hose for coolant.

Question is not can it be done. eBay has lots of these VW assemblies for 50 to 75$. I have seen Mazda owners on their forums use the small diameter Natural Gas lines as flexible egr pipes. so given the time and funds, I see it as doable.

So, with no ECM mods, does cooling EGR have mpg, emissions, or engine durability benefits? I know Ford EcoBoost and Mazda SkyActiv use cooled EGR in their systems. They would have the ECM programmed with cooled egr assumed, unlike my stock ECM.

So my question to other ecomodders is a one of benefits to adding a cooler to a car and ecm that was designed with a non cooled condition on the inert gas coming in and displacing the A/F mix? I have MAF and air temp sensor just after air filter, and MAP in intake manifold. So how does ECM know the combined charge air temp inside IM once egr is mixed in? Or does it not matter?

I know the general benefits of EGR for gasoline engines, after reading much. So I am glad I have the system. Just trying to see if it can be improved, ah, Wolfsburg style...
:D

The ECM would have a base formula of some kind to know when the egr is opened, how much recirculated gas to expect. It can't correct on its own, the egr gas is released post maf sensor. If someone could expand on what I think I know that might be helpful though... Perhaps the 02 sensor plays a role.

If I'm theorizing right, simply adding a cooler would increase the volume of recirculated exhaust gas. Since the gas is cooled and not heated It would lean out the mixture slightly, but then again the gas is cooled I don't think it would increase risk of detonation.

I can see it having emissions benefits, lowering the combustion temperature could be good for engine durability but then it would take a little longer to reach peak operating temperature... all negligible. To get the MPG benefits I was going for you would have to increase the volume of gas more significantly than just an egr cooler, like a bigger egr valve and a control unit to tell it to open it more and then trick the ecm to tell the car to lean it out even further. Or maybe release the exhaust gas pre-MAF? It would get fouled up pretty quick, maybe even add an in line filter in there like off of a snorkeled jeep type deal.

The O2 sensor will keep the AFR steady as it always does.


Increasing EGR flow doesn't lean anything because all you're adding is inert gas, not oxygen. Dillute is a more applicable word I suppose.


As more EGR is added you can also optimize ignition timing which will increase efficiency.

Since all the OEM diesels have had EGR coolers for many years now I would think so.
But one of the first things diesel owners do is delete the EGR, se we don't dwell on it much. We do this because EGR does not increse MPG unless in cold climates on vehicles that are not worked very hard, even then it more of a function of the EGR cooler warming coolant than the EGR its self.

EGR reduces combustion pressure
 

thanks!
 

Thank you all for thinking about this as well. :thumbup:

But since I am NOT adding more EGR, just cooling it, and not adjusting ECM programming / timing, it may be a "can't hurt, not sure if it will help" scenario?

Since the ONLY thing in my case would be the adding of a cooler to an already functioning, GASOLINE egr system, then the inert charge taking up space in the cylinder will be denser as compared to a non cooled EGR.

So perhaps some even less sensitivity to knock? Even less chance of NOx?

If O2 sees sees a bit less NOx, due to results of a cooler & denser EGR inert volume, then (perhaps) it knows it can advance timing more (more MPG)?

But, if there is no ECM software logic designed to lean it out and / or advance timing more to increase efficiency, while still keeping NOx low, then there may not be any MPG advantage?

I suppose that is where Mazda and Ford are taking advantage of cooled EGR with SkyActiv and EcoBoost. Their computer actually will know it is cooled, and take full advantage of it to increase MPG.

So many variables, so few sensors, so little control over our ECMs...

02 sensors do not measure or see 02
 

...."
If O2 sensor ?sees sees a bit less NOx, due to results of a cooler & denser EGR inert volume, then (perhaps) it knows it can advance timing more (more MPG)?...."

the 02 sensor does not / can not see 02
the 02 sensor measures presence of combustibles

despite the name

the 02 sensor has no (direct) authority over ignition timing
the 02 sensor does have authority over Air Fuel Ratio and has authority over weather or not the system will be in
"closed Loop" as with no input from the 02 sensor
(or the AFR sensor in later systems )
the feedback needed to confirm actual AFR is not present .

a better name for an 02 sensor is
Lambda sensor
since 02 sensors change state at Lambda ,
they either report leaner than lambda or richer then lambda
so the system will always be in flux , slightly lean to slightly rich of Lambda
never stopping at Lambda
Lambda = AFR of 13.64 to 1
---------------------------------------------
NOX sensors are used in later Diesel systems
______________________________
EGR improves FE by reducing combustion chamber volume
by diluting incoming air fuel mixture with INert gas
while EGR is active
effectively reducing engine size and suction throttling loss because throttle must be opened more to provide the same amount of
go

the gas pedal is really an
air pedal

The reduction of combustion temperature and pressure in a diesel reduces power and fuel economy.
Need to keep the gas/diesel seperation clear, we have people trying to run warm air intakes and more EGR trying to increase diesel fuel milage because they read stuff the gas guys are doing and have had sucess with.

Agreed!!! Lets be clear for everyone else...

In general, a well running EGR system in a GASOLINE engine can have secondary positive impact on fuel economy, in addition to its primary job of reduced emissions.

Also, in general, a well running EGR system in a DIESEL engine can have secondary negative impact to fuel econnomy, while perfroming its primary job of reduced emissions.

Hence, diesel owners that may do an EGR delete to improve FE and performance (at a cost in emissions), and gasoline owners (and Ford and Mazda) looking to do an EGR add to improve FE on gasoline engines.

The EGR on a diesel tends to reduce NOx but increases soot.

fuel saving that works and simple - EGR
 

Cooled EGR system works:

Basically, if it's not cooled you loose compression power by its volume in the cylinders.

If it's cooled, you bring back up compression. A simple intercooler should do it.

After that, you may even increase the factory compression ratio of your engine if you have the money to do that, to level up the horse power of your original engine.

Adding more EGR makes this possible. There is less nox, the engine runs more cool and less knocking. Actually, you can see this kind of systems in newer eco but powerfull cars.

See it here:

http://docs.google.com/viewer?a=v&q=...Ca_N3pn0Jqz_pw

Your link do not work. Login window appears.
Can you add link without login?

All the best.

try right click on mouse and then "copy shortcut". then paste on browser. Thanks!
 

try right click on mouse and then "copy shortcut". then paste on browser. Thanks!

or...
 

go to google and search:
"clean_and_cool.pdf"

it should be the first link.

Regards.

You could have posted the link. ;)

Click me

I was thinking about the heat exchangers which cool down EGR gasses with coolant (like in most new turbodiesels): We ecomodders want to run our engines hotter than normal, but then the coolant is also hotter, so there is less EGR cooling. So in a gasser, why not use intake air for cooling? It is almost always colder than coolant, it works like a WAI, and if the HX gets a leak, then there is not too much wrong with some exhaust gasses seeping into the intake.

You don't want to cool the EGR gas down too much so that it condenses. If it does you now have to worry about water in the EGR system.

I think that water is not a problem, but different impurities that accumulate to cooler with moisture and eventually block it.

There you go:
http://home.comcast.net/~junk9989/pw...(1024x768).jpg

EGR gases cleaning
 

Maybe a "water bubbling filter" like the guys that run the wood gasifyers have should prevent that...

I'd like to dabble with EGR mods first beginning with EGR cooling. For the sake that i have an archaic 80 car and no cooler. Rather than complicate my cooling system i'd rather have an air cooled heat exchanger by means of tapping the exhaust pipe further down stream.

Should get my egr source at a medium temp in front of the cat or after the cat at the coldest point. I plan to return it to the engine with 5 - 10 feet of copper tubing. I understand it should not be cooled too much.

My main question is should I take advantage of unburned combustibles before the cat or go for max cooling and keep the intake charge dense???

Thanks!