Increasing EGR flow for better mileage

[pgfpro]

Originally Posted by Daox

Yeah, I think that does sound more efficient/better/less prone to failure due to clogging etc.


Back to the PWM controller, I tried it out last night and... well there was a fairly violent electrical explosion, the biggest one I've seen from a simple 12V circuit anyway. So, I need to get a replacement mosfet and check what the heck I soldered in wrong. Powering the EGR valve up manually it doens't pull more than 1.3A, so the controller is plenty capable of handling the power requirements. I must have done something wrong at assembly.

Very cool project! Keep up the good work and hang in there.

I'm looking at doing a home built design unit for my car also. My thoughts are to run two 38mm waste gates. One to control boost, the other to act like a EGR valve. This one will be ran off my electric boost controller in my efi software. I already have a AEM electronic boost solenoid. I will have to run CO2 to use as a media to open this waste-gate under low to no boost. The other waste-gate will be activated by my manual boost controller.

[silverinsight2]

Gentlemen, for your amusement:

Tweaking the EGR, Part 1

Tweaking the EGR, Part 2

[Daox]

Thanks, but those were posted a while back in this thread.

[drbobwoolery]

I sure managed to miss them!
The Aussie mag has some remarkable articles on water injection also. Studies of using up to 1.5 times as much water as gas to operate on low octane fuel are detailed. The string of URL's is lost, but searching Autospeed will show them.

[silverinsight2]

Originally Posted by Daox

Thanks, but those were posted a while back in this thread.

Dang! busted. Guess I'll start have'n to read the whole thread.

[markweatherill]

I wonder if it would be beneficial to have EGR active on the overrun, that is, when deceleration fuel cut is happening.
I could expect it to increase coasting distances a bit by reducing engine braking.
Would that work?

[Daox]

Very interesting idea Mark! Assuming you stay in gear I'd imagine it would reduce pumping losses. I have no idea how much. You are still compressing the intake charge... I'll have to keep that in mind as I go forward.

[Christ]

I don't think EGR reduces pumping losses, because you've already pumped the exhaust out, and you're sucking in the EGR's recirculated gasses through the intake, just the same as you would be normally. It's a nice thought, I just don't feel like it's going to work that way.

Even if it did, it would be approximately in line with opening the throttle with the engine off and using the compression for braking. The difference isn't there on all vehicles, and even if it is, it's only a few feet one way or the other.

[Daox]

EGR is routed back to the intake behind the throttle butterfly. So, you are right, it would be like opening the throttle.

[Andy0x1]

Just thought I would chime in on this thread;

I have a Positive displacement Supercharged vehicle and disabled the EGR system after installing an AIR-WATER intercooler between the Supercharger and the intake manifold.

My reasoning was to keep the intercooler and valves cleaner.

I did this over 4 years ago, amung many other modifications.

I feel that this did result in a slight reduction in fuel economy however it may all be in my head as I can't quite explain why it would matter much when accounted for.

....

My understanding as to why:

1) Pumping loses. (minor)

Why? With the throttle at at whatever position, lets call it closed, x amount of air is metered and allowed into the intake manifold. this minor amount of air only slightly reduces the vacuum the pistons have to work against.

A functioning EGR would further reduce back-pressure, without introducing addtional oxygen effectively maintaining the air/fuel ratio and injector flow rates.

On the flip side, the reduction in vacuum also leads to increased 'windage' however minor.

2) Ignition spark / Timing Advance / Retard (moderate)

Without EGR the fresh air entering the combustion chamber when mixed with fuel will burn faster, because it is burning faster this could lead to knock / detonation. Assuming the timing is corrected for this condition (reduced) the mixture will ignite later and possibly result in more burn occuring after the power stroke and during the exhaust stroke effectively adding heat to the valves / ehaust / heads that would otherwise be.. wasted due to poor burn? (less power) but that would mean better fuel economy.

...

Will you see more power (WOT) with EGR disabled? I don't think so, because the EGR closes during WOT anyway.

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