Increasing EGR flow for better mileage

[Daox]

I have not abandonded the project. However, I no longer drive the Paseo on a daily or even weekly basis. Its now the wife's car and with her whopping 3 mile commute to work, the priority of the project has been greatly reduced.

[mechman600]

I finally read through this whole thing after several attempts.

I wonder if one could try a much simpler/crude attempt at increased EGR. insert a length of 1/4" copper tube into your tail pipe (or drill a hole in your muffler and insert there) and bend it to run it under the car towards the engine. This will serve as your "EGR cooler" as air rushes past the copper tube. At the end of the copper tube install a hose that goes to a ball valve (to adjust/turn on/off) and then to a small vacuum port on the manifold. If it runs ok, advance to larger vacuum ports and adjust the ball valve as required.

No? Just a thought. It might be fun to try. Less investment of time and money.

[Daox]

That might work. I'm not sure how that small line would hold up with carbon build up over time.

I already have the current pieces needed to do this. I just don't see it working at all with my wife's current commute. Vehicles don't use EGR until they are at least somewhat warmed up I believe. In her 3 mile trip I doubt the car gets up to a temperature I could use EGR for any reasonable amount of time.

I'd highly encourage others to try this out though. A lot of the new higher mileage cars are using higher flow and/or cooled EGR to get better mileage.

[mario.silva]

Hello all! I'm currently testing a car with a tweek on the egr. I'll keep you post it soon. Regards!

[euromodder]

Originally Posted by mario.silva

Hello all! I'm currently testing a car with a tweek on the egr. I'll keep you post it soon. Regards!

Welcome to ecomodder.

More EGR, or less ?
Shutting off EGR (or leaving only a small orifice open) is what usually helps the mileage.

[Daox]

Originally Posted by euromodder

Shutting off EGR (or leaving only a small orifice open) is what usually helps the mileage.

On a diesel maybe, but not on a gasser. We have 21 pages here that proves this.

[mario.silva]

Well, actually i'm running with more (full open valve and i do not even cool the gases) but that's not the point because i just want to lower the power output from the engine and use the heat also to help making a good gasoline/air/egr mixture. On my daily needs i do not need to drive like i'm racing. For the "mix" i use 2 stainless steel meshes: after egr/air and after INJECTION. That's why i found myself a mono/single injector car on purpose. When you use more hot egr, you loose power/pressure in the cilinders, not exactly save fuel... that's why you can run it LEANER AND AlSO PUTTING MORE COMPRESSION without pre-ignitions. ONLY then you'll see fuel economy. At least this is what i found from experience... regards!

[mario.silva]

Let me introduce the car in question:
ROVER 111 SLI (1.1)
8 valve
single cam
4 cilynders
Natural Aspirated
aluminium block
Cat
850kg
40.000km
Gasoline
5 speed manual
Only one bosch injector replacing the carb
All the standard sensors and ECU
Year 1995
All original

Belive me when i say that automotive engeniers know what they are "throwing" in when building a car, problem is the economical/financing restrictive budget they must meet.

The best eco-mod you can do for a "standard mass production car" is to change driving habits... works like a charm, it's cheap, reliable, usualy more safe and makes the biggest difference in fuel economy. Other than that you'll find yourself spending more money than the one if you keep your feet light in fuel savings, unless you have a fleet or you're a taxi driver...

Still have no doubt that as a hobby is lots of fun and rewarding, and soon you'll find yourself willing to making your car from scratch, engine and sometimes your own alternative fuel!

Best regards!

[ECONORAM]

Originally Posted by MetroMPG

Well, another option might be feeding the exhaust into the intake tract, upstream of the throttle.

Though that might mess things up because of the intake air temp (IAT) sensor ...

I was starting to think about that as well in an effort to warm up the intake air. Having finally read through the entire thread (whew), some interesting discussion. I just found the wiring diagram for my truck's EGR valve, but haven't examined how it actuates yet. As I mull over what I read here, and the fact more throttle opening would be required, this might actually be useful for me to test. My truck is aerodynamic enough now that I find it hard to feather the throttle without making the fuel flow go wild.
I'm not too worried about the IAT, but am a little hesitant with the plastic air filter box and plastic intake... I guess if one were to use a second EGR valve that routed its exhaust to the intake tract, in the center of the incoming airstream, maybe that would work okay.

@mechman60, interesting idea...

@mario, curious to see how the testing is going.

[RobertISaar]

having cleaned quite a few intakes filled with carbon before, i don't think i would want to introduce EGR upstream of the throttle... it will gut stuck in the worst of places, including but not limited to your IAC system and likely on the throttle shaft itself...

you don't want either of those getting stuck open.



that and consider this: EGR flows largely due to differences in pressure.... pressure in the exhaust will always(with very few exceptions) be higher than pressure in the intake system. now, compare exhaust pressure to atmospheric pressure and while you will still have flow, compare exhaust pressure to manifold pressure... while atmospheric pressure will be around 100kPa at sea level, manifold pressure could be around 50kPa at cruising speeds. with EGR being introduced behind the throttle, the engine will literally be sucking exhaust into the engine, rather than it before before the throttle and the exhaust flowing in.

clear enough?