Increasing EGR flow for better mileage

[cfg83]

Daox -

Is that a Saturn S-Series EGR?

CarloSW2

[Daox]

Nope, its off a 4.6L chevy blazer engine.

[Daox]

Originally Posted by born2pdl

How do you determine which burn rate your specific engine uses (moderate -vs- fast)?

Unfortunately, I won't be able to do that.

In the absence of that info, what I want to do is find some way of gradually opening up the EGR valve while monitoring mileage. Do a run @ 25% open, check mpg over that run, do another run @ 50% open and check mileage, rinse & repeat. I'll create some sort of load vs valve opening map and hopefully find some way of controlling the valve with it.

[Christ]

Tim -
It's a solenoid, so if you vary the voltage to the input coil, it will probably only open so far.

Also, I think 10% exhaust flow is going to be 10% exhaust flow, no matter what engine it's on. I don't think displacement really makes a difference, because many auto makers are famous for using the same EGR's and associated parts on many engines.

I believe the actual flowrate is relative to the size of the opening, not the displacement of the engine.

[bgd73]

I was thinking of routing the cars exhaust into the house, to save on petro.

and then sticking my tongue in a 120 volt outlet.

I want to mimick radon. I want to feel like an egr user....


I am an ecomod winner, I can feel it...


overabundance of oxygen is for airplane cabins.

Starve an intentional burn, you ask for trouble.

I hope this adds to the list for world war 3 reasons...

[Christ]

Originally Posted by bgd73

I was thinking of routing the cars exhaust into the house, to save on petro.

and then sticking my tongue in a 120 volt outlet.

I want to mimick radon. I want to feel like an egr user....


I am an ecomod winner, I can feel it...


overabundance of oxygen is for airplane cabins.

Starve an intentional burn, you ask for trouble.

I hope this adds to the list for world war 3 reasons...

You realize that the point of EGR is to reroute unburned HC's back into the combustion chamber, right? So they don't get into the cat, being burned off and doing no work as a result of it.

So basically, you're advocating waste.

[pstrbrc]

Came acrosss this thread for the first time today-waiting for a server to finish doing its updating stuff, so just killing time.
EGR dilution as a way to increase FE at part-throttle on an ignition-type ICE has fascinated me for a long time. Some work I did as an engineering student way back in the late 70's was working towards that. Problem was, we didn't have anything close to the electronic controls that are available today.
OK. Some of the control problem you're going to encounter has to do with the contradiction that your intake will draw through whichever has the least restriction. You experience this when a car with an intake gasket leak runs like cr@$ with the throttle closed, but can run just fine at quarter throttle or more. That's becase when the throttle plate is closed, you are developing high intake vacuum, which can suck a lot of air through a little gascket leak, but when you open the throttle, lowering the vacuum, the amount of air drawn through the gasket leak is much less, AND the metered air flowing past the throttle plate is much greater, and the cpu/metering valve puts in fuel to match this air across the throttle. So, under high vacuum, if you use a monster egr valve, it will be next to impossible to adjust it in such a way that is meaningful. You see, the point of egr is % dilution, and at small throttle openings, that means very little exhaust recirculation, or the car don't run.
Here's a thought:
Ford used variable cam timing on some of the Zetecs (Contour, Cougar, ZX-2) to advance the exhaust timing in such a way that the exhaust stroke wasn't completely scavenged. They were able to use this instead of egr to meet nitrous standards. So how much the intake charge is diluted has much less to do with intake vacuum. The smaller the throttle opening, the smaller the charge that went in on the previous cycle, and so the easier the subsequent exhaust gasses have of getting out during the exhaust cycle, so the lower the total number of exhaust gas molecules left. Now, this isn't exactly linear, but a whole lot more linear than egr.
So, I'm thinking of putting a Zetec /exhaust VCT in my Escort. MegaSquirt the intake, control the VCT solenoid (it's PWM, and I think 12v, but it might be 5v. Have to play with it, 'cause there is limited info on the solenoid.) with an Arduino board if I can't build a pwm circuit in the prototyping section of a v.3 MS board.
But, for those engines that can't alter the exhaust timing, how about an exhaust throttle? You know, they used to call them heat risers? I think GM used them as late as '81 on their V-8s. They used a vacuum dashpot, but you could hook it up to a manual push cable, hook up a pressure gauge to read exhaust pressure, and experiment away.

[Daox]

I took the EGR valve to the EV build today and talked with some of the guys there. We fiddled with it and found that it is a solenoid valve with position feedback. I'll need to make some sort of PWM controller in order to drive the device to specific positions.

[Tygen1]

Originally Posted by pstrbrc

Here's a thought:
Ford used variable cam timing on some of the Zetecs (Contour, Cougar, ZX-2) to advance the exhaust timing in such a way that the exhaust stroke wasn't completely scavenged. They were able to use this instead of egr to meet nitrous standards. So how much the intake charge is diluted has much less to do with intake vacuum. The smaller the throttle opening, the smaller the charge that went in on the previous cycle, and so the easier the subsequent exhaust gasses have of getting out during the exhaust cycle, so the lower the total number of exhaust gas molecules left. Now, this isn't exactly linear, but a whole lot more linear than egr.
So, I'm thinking of putting a Zetec /exhaust VCT in my Escort. MegaSquirt the intake, control the VCT solenoid (it's PWM, and I think 12v, but it might be 5v. Have to play with it, 'cause there is limited info on the solenoid.) with an Arduino board if I can't build a pwm circuit in the prototyping section of a v.3 MS board.

Sorry to thread jack...
There is a tuner available who can control the VCT on the Zetec: Vit Tunes available yet again! If you go thru him you can get it done cheaper, with less headaches and he can tune the Zetec to run better than anyone. I've been talking with him about options. I'm hoping to go this route soon. I'm definatly not advertising for this dude, just want to see this happen.

[Thymeclock]

I don't know of this will be of any help, but for what it's worth: I used to own an '89 Celica that had an EGR valve that had an air filter on it as part of the valve. I could tell when it needed to be cleaned, because there would be a slight but noticeable lag in acceleration from a dead stop. I got in the habit of checking and cleaning the filter yearly to prevent malfunction.