EGR and fuel economy.
- Thread starter SuperMag
- Start date
I think it could ,but it would have to controlled as to how much EGR gasses get passed by the egr valve and into the engine.
MarkP wrote a post sometime back with a suggestion of using the EGR valve to introduce fresh air into the manifold at cruise. Connect the tube to the clean side of the air cleaner, control the EGR vacuum with a thermal vacuum switch connected to ported vacuum and you have a semi-controlled vacuum leak to lean out the mixture. I would want an air-fuel ratio meter to monitor this.
I have been keeping this idea stored away in the dark recesses of my brain housing group for future reference
Joe
I have been keeping this idea stored away in the dark recesses of my brain housing group for future reference
Joe
An EGR valve controlled fresh air inlet wouldn't be practical in this situation because...
(1) I jet & adjust my engines to run as lean as ragged edge possible to begin with. Any leaner and the buggers wouldn't run.
(You can get away with that at high altitude.)
(2) This is on a Ford 335 motor --a 400 specifically-- and 335 motors have the EGR plumbing integrated into the head and manifold castings. Very neat and tidy that, but very difficult to modify for use as a fresh air inlet.
The thought here with implementing EGR at high vacuum conditions was to further reduce fuel consumption; its effect on emissions quality is not even a consideration in this exercise.
I've got the Bronco on blocks at the moment, replacing the 3.54 axle sets with 3.00s (the Bronco is shod with 31x10.50 tires). So between that, EGR, and having Reed cams grind me an advanced timing "tractor" cam, I'm hoping to extract 300/4.9 type mileage figures out of the pig without actually going through the expense and aggravation of actually doing a 300 transplant.
That's my dream, anyway.
(1) I jet & adjust my engines to run as lean as ragged edge possible to begin with. Any leaner and the buggers wouldn't run.
(You can get away with that at high altitude.)(2) This is on a Ford 335 motor --a 400 specifically-- and 335 motors have the EGR plumbing integrated into the head and manifold castings. Very neat and tidy that, but very difficult to modify for use as a fresh air inlet.
The thought here with implementing EGR at high vacuum conditions was to further reduce fuel consumption; its effect on emissions quality is not even a consideration in this exercise.
I've got the Bronco on blocks at the moment, replacing the 3.54 axle sets with 3.00s (the Bronco is shod with 31x10.50 tires). So between that, EGR, and having Reed cams grind me an advanced timing "tractor" cam, I'm hoping to extract 300/4.9 type mileage figures out of the pig without actually going through the expense and aggravation of actually doing a 300 transplant.
That's my dream, anyway.
I thought it would be very helpful during warmup as the engine is runing a richer mix and not burning it as complete.
Titleist16
Well-known member
you can't really let a lot of exhaust gas into the intake at high vacuum situations like idle or the motor will die. I played around with elctronically controlled EGR at my school and controlled how much it would open with the scan tool. The more you open it up at idle and low RPM the rougher the motor ran and it would eventually die. They only really use EGR to reduce NOx gas at cruise, not idle.
On my trip to work it takes a full 10% of the distance (2 miles) for my vehicle to warm up.
I wasn't thinking of the idle.... I know better than that :roll:
I wasn't thinking of the idle.... I know better than that :roll:
That is consistent with what I have observed... On a mechanically actuated system, vacuum controls when the EGR valve opens, but it's exhaust system back pressure that determines how much. But at idle, vacuum alone is not sufficient to open the valve. To overcome the EGR valve spring, it needs a 'push' from the other side as well, in the form of back pressure, which there isn't much at idle, and the valve stays closed.Titleist16":1r63rguh said:
The stock EGR setup on my 81 uses a thermostatic vacuum switch located above the engine thermostat. This doesn't allow any vacuum to the EGR until the coolant temp reaches something around 120º. Furthermore, the vacuum source is ported vacuum at the carb which pevents any vacuum at idle, and WOT has too low vacuum to activate the EGR. Therefore, part-throttle cruise on a warm engine is when you get EGR.
Joe
Joe
Lazy JW":2gj36r63 said:
I still think it might for econmy reasons at ported vac and a cold engine.
A
Anonymous
Guest
The engine makes power from heat, the more the better, short of seizing, etc.. To reduce emissions of nitrogen oxides, the heat has to be reduced, which the factories do by introducing exhaust gases into the intake charge. This is cut off if you are temporarily (we hope) using lots of power, but at normal cruise you have to use a little higher throttle setting to compensate for the "polluted" mixture you get with EGR. One measure of the relative inefficiency of the polluted mixture is that an EGR distributor has been recalibrated for more spark advance. If you disable an EGR system, you want to get the springs, weights, etc., from a pre-EGR distributor; if you try to fix the pinging by merely backing down on initial timing, you'll lose fuel efficiency and power.
Now, since you all undoubtedly knew all of that already, I don't get why you want EGR . . . unless what I said is all wrong??
Now, since you all undoubtedly knew all of that already, I don't get why you want EGR . . . unless what I said is all wrong??
I don't know that I do. That's why I'm getting input here.Seattle Smitty":38j39js4 said:
What I do know is this: My 300 equipped truck fully loaded with tools of the trade gets about 1/3 more mileage from a gallon of gasoline than the 400 equipped Bronco does empty. (The EGR has been disabled on both.)
Logically speaking, it takes X amount of HP to push either of these sheets of plywood into the wind, so one would think that the ultimate determiner of mileage would be at the bottom of my right foot. But my wallet tells me it ain't so.
Now I lack the engineering expertise to say this with certainty, but it seems to me that it takes a minimum amount of gasoline and air to usefully push a 4" diameter piston down a 4" deep bore. (The 300 & 400 are the same in that respect.) And that some of this mileage disparity is due to the fact that I'm firing 1/3 more cylinders with the 400 with every revolution, and that regardless of how light I am with the foot, I'm going to burn more gas.
Am I mistaken in that supposition? I hope so. I would like nothing more than to duplicate the 300's HP curve in the 400, hence equalling its mileage. But I'm thinking the only way I can do that is to "neutralize" two cylinders with a little introduced exhaust gas...
A
Anonymous
Guest
If by 'neutralize" you mean, "make even less efficient," you'll succeed. Yes, you have to feed those cubic inches. The trick is to make the engine get the better power at a given throttle setting, or the same power with a lower throttle setting, and how you do that with EGR is beyond me, but maybe the gurus will clue us both in.
Meanwhile, since you have disabled the EGR, have you rebuilt the distributors with the non-EGR parts? I turned a 318 Mopar into a pinging SOB until I did that. As has been said here many times, after you set initial timing with a blinklight, you fine-tune it with a road-test.
Meanwhile, since you have disabled the EGR, have you rebuilt the distributors with the non-EGR parts? I turned a 318 Mopar into a pinging SOB until I did that. As has been said here many times, after you set initial timing with a blinklight, you fine-tune it with a road-test.
hey
well to awnser your question.
on desiel truck engines to meet emssion's and fuel econ expected and engine life cat spent 1 billion us to make the engine's non egr.
egr was the easy route for emssions but
they couldent get the fuel and engine life from the engine they wanted so they have essientaly created a miller cicle engine for desiel where they have the hugh overlap due to a electronic over hydrolic system to hold it open and then have air forced in at 60psi to in effect make a scavanged engine (2stroke) out of a 4stroke.
so ifa company just spent 1billion making an engine non egr for emssion and fuel i dont think egr will help your cause.
i take it you hae a v8 comparing to a 6 losing battle 6 has less moving parts less friction less heat less drag less fuel to run it.
you might find a set of extractors and nice open exhaust help sometimes.
drift
well to awnser your question.
on desiel truck engines to meet emssion's and fuel econ expected and engine life cat spent 1 billion us to make the engine's non egr.
egr was the easy route for emssions but
they couldent get the fuel and engine life from the engine they wanted so they have essientaly created a miller cicle engine for desiel where they have the hugh overlap due to a electronic over hydrolic system to hold it open and then have air forced in at 60psi to in effect make a scavanged engine (2stroke) out of a 4stroke.
so ifa company just spent 1billion making an engine non egr for emssion and fuel i dont think egr will help your cause.
i take it you hae a v8 comparing to a 6 losing battle 6 has less moving parts less friction less heat less drag less fuel to run it.
you might find a set of extractors and nice open exhaust help sometimes.
drift
If you tune the engine to the ragged edge, I don't think you will benefit from egr. The egr would only help if there is some energy to be extracted from it. The better the tune the less to gain.
The egr came about for emmisions. At the same time Ford lowered the pistons in the cylinders, retarded cam timing, added a full open chamber(no quench). I may be grouping egr in with these terrible things wrongly. I have seen 240 engines in half ton trucks get 20mpg and smog engines like the 300 get 10mpg. The 352 engines were better than the 330, 360, 390. The pre 70 429 and 460 were better than the smog version 460. I haven't had a lot of comparisons with the 351 cleavland versus 351m/400, but I would suspect similar results. It seems like in 1970 Ford adopted a policy of 10mpg straight across the board. It took them about three years to perfect this policy but they were suscessful for the most part.
Having spent years building engines and trying to find pistons to get a tight deck clearence and trying to get a cam dialed in with crazy results might have biased my opinion. I know Ford had to fight emmisions laws, but they chose areas that decreased efficiencies.
At one time, I was under the impression that the egr did alot on deceleration. Manifold vac goes real high and the mixture is real rich. This is the condition where the exhaust flamer works best. If you open the egr and circulate exhaust gasses, reducing manifold vac and rich condition. It would seem that you might create a safe lean condition without cooling the chambers. This would reduce emmisions and possibly save some gas on deceleration. Not much use on the highway but good in town. There would be some power loss when reapplying the accelerator pedal from the comtaminated cyls but it should be minimal. This is just spectulation and theory and it seems like it might help.
The egr came about for emmisions. At the same time Ford lowered the pistons in the cylinders, retarded cam timing, added a full open chamber(no quench). I may be grouping egr in with these terrible things wrongly. I have seen 240 engines in half ton trucks get 20mpg and smog engines like the 300 get 10mpg. The 352 engines were better than the 330, 360, 390. The pre 70 429 and 460 were better than the smog version 460. I haven't had a lot of comparisons with the 351 cleavland versus 351m/400, but I would suspect similar results. It seems like in 1970 Ford adopted a policy of 10mpg straight across the board. It took them about three years to perfect this policy but they were suscessful for the most part.
Having spent years building engines and trying to find pistons to get a tight deck clearence and trying to get a cam dialed in with crazy results might have biased my opinion.
I know Ford had to fight emmisions laws, but they chose areas that decreased efficiencies. At one time, I was under the impression that the egr did alot on deceleration. Manifold vac goes real high and the mixture is real rich. This is the condition where the exhaust flamer works best. If you open the egr and circulate exhaust gasses, reducing manifold vac and rich condition. It would seem that you might create a safe lean condition without cooling the chambers. This would reduce emmisions and possibly save some gas on deceleration. Not much use on the highway but good in town. There would be some power loss when reapplying the accelerator pedal from the comtaminated cyls but it should be minimal. This is just spectulation and theory and it seems like it might help.
A
Anonymous
Guest
As far as altering an EGR system to add air and lean out the mixture, that looks to me like a real clunky way to try to meter air. There was a device marketed to Mercury outboard racers forty-five years ago that attempted the same thing, with a reed-valve over an air hole, fitted right above the intake ports. The idea was to richen the carburetor to compensate, but while you might get lucky and get a useable mixture at some particular rpm, outside of that band the engine would go either rich or lean. The few guys who tried it seized a lot of pistons. The fast guys used bigger, or more, carburetors to accomplish the same thing. Of course, you're after economy rather than power, but it seems to me there are more precise methods of getting there.
What year is your 400M, Mike? "Hot Rod" did an article three or four years ago in which they got over 400hp and enormous torque out of a smogger 400M without spending much. It might have some useful info even if you don't need 400hp. That engine always looked on paper like an ideal truck/van motor, with 15% less displacement than a 460, but a longer stroke. It wouldn't rev with a 460, but so what? Stubby mentioned that the smog motors had the cam timing retarded, 8 degrees on my 460. I made a new keyway in the sprocket to get "straight up" timing, but maybe a zero-retard sprocket is available. That gets you some low-end torque, therefore a lower throttle setting, etc., etc.. A fresh valve job never hurts, either, esp. since you can grind the unwanted lumps out of the ports at the same time. If a 400M head is like a 460 head, it has big, ugly obstructive lumps in the middle of the exhaust ports for the air injection; grind 'em flat.
My dream truck engine (someday, if I can ever wear out the 460) is a 400M with Aussie closed-chamber heads, the block decked to .040" squish, 9.5:1 compression, water injection, aaannnndd . . . laptop-programmable fuel injection with all of the feedback sensors, which is surely the ultimate in mixture control throughout the whole rpm range. I think once I had built that, I'd start WANTING sky-high gas prices, just so I could brag about my gas mileage!!
What year is your 400M, Mike? "Hot Rod" did an article three or four years ago in which they got over 400hp and enormous torque out of a smogger 400M without spending much. It might have some useful info even if you don't need 400hp. That engine always looked on paper like an ideal truck/van motor, with 15% less displacement than a 460, but a longer stroke. It wouldn't rev with a 460, but so what? Stubby mentioned that the smog motors had the cam timing retarded, 8 degrees on my 460. I made a new keyway in the sprocket to get "straight up" timing, but maybe a zero-retard sprocket is available. That gets you some low-end torque, therefore a lower throttle setting, etc., etc.. A fresh valve job never hurts, either, esp. since you can grind the unwanted lumps out of the ports at the same time. If a 400M head is like a 460 head, it has big, ugly obstructive lumps in the middle of the exhaust ports for the air injection; grind 'em flat.
My dream truck engine (someday, if I can ever wear out the 460) is a 400M with Aussie closed-chamber heads, the block decked to .040" squish, 9.5:1 compression, water injection, aaannnndd . . . laptop-programmable fuel injection with all of the feedback sensors, which is surely the ultimate in mixture control throughout the whole rpm range. I think once I had built that, I'd start WANTING sky-high gas prices, just so I could brag about my gas mileage!!
This would be of major interest to me. Here in the mountains, engine braking/deceleration can account for as much as 25% of total engine operation, particularly on a trail rig such as this. And the ruptured muffler under my work truck is testament to how much raw gas is sucked through on the down hill when the throttle blades are shut... BOOM! But to effectively use EGR in this way would mean I'd have to use straight manifold vacuum, not ported. But then how would the engine know this condition from a standard idle condition? Hrmmm..... Maybe standard port vacuum actuation but add a solenoid that snaps the EGR wide open when I mash a button on the floor board with my free foot?Stubby":7ut1hh03 said:
Smitty":7ut1hh03 said:
It's a '79. And I have that article. It reads like the typical low-buck build up that we've all read a hundred times before. Silvolite flat-tops, Edelbrock intake w/ a Holley 650, Crane Cam, stock rockers, etc...
As for the EGR/non-EGR distributor thing, I'm blessed. At high altitude you need to run quite a bit more advance than one would at sea-level, so an EGR diz performs splendidly on a non-EGR motor....
Be careful with this one. I would worry about possible rapid cooling and cracking of heads. On a long downhill run, this might become an issue.
I was browsing the LM-1 forums yesterday and I read that on some Fords you can calibrate the O2 sensor on deceleration because the computer turns off the fuel on deceleration. So this might just be a safe area to experiment with.
I was browsing the LM-1 forums yesterday and I read that on some Fords you can calibrate the O2 sensor on deceleration because the computer turns off the fuel on deceleration. So this might just be a safe area to experiment with.
Deceleration is where EFI shines. when the TPS shows 0% throttle opening and you are above 20 mph the fuel shuts off completly. ( I can tell my jeep turns the fuel back on at 1k rpm) It would be great if you could make a carb shut the fuel off like that.
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