ENG: EGR removable plugs :)

[reklipz]

In the last pic, you can see that I started drilling into the top of the runners. I didn't take off too much material, so I think it's still usable.

[wildBill83]

In the last pic, you can see that I started drilling into the top of the runners. I didn't take off too much material, so I think it's still usable.

Did it actually breach the chamber? If it did you may not want to use it. It will bypass the EGR valve in a bad way.

[reklipz]

I didn't enlarge the EGR ports at all, I just kind of chamfered it a little. There is already a hole between the EGR "runner" and the runners themselves, that's the EGR port that gets plugged, and the reason for this mod. So, as you can see from the photo, I didn't make the existing breach any larger in principle. In fact, it's possible the chamfer will help prevent clogging because there is slightly less surface area at the wall of the egr hole, who knows.

The only thing I'm worried about is structural integrity of the hole. Its not much material removed, but depending on how hot the EGR gas is, it could be issue. I don't think it will appreciably affect flow dynamics of the EGR "runner" either. Finally, I think the EGR "runner" is at a higher pressure than the intake runners, so there are no issues with flow of the EGR port.

[wildBill83]

Install it and run it with new plugs, then after 500 miles can you tell us if there is extra carbon on that plug related to that port? I'm curious to see if the exhaust gasses will flow more to that one cylinder now.

[reklipz]

Can do, I'm curious as well.

While the topic is hot: if the chamfer is a problem and does affect something like EGR flow rate ratios between runners or is structurally compromising, is there any suggestions to fix it? The easiest way I can think is to just weld on some more material, level it back out and clean it up, and then run a drill through the port to clean it up; good as new. Welding through that 1/2" opening might take some concentration, but that'd be the hardest part.

If it turns out that EGR flow ratios are different, but structurally things are fine, I could simply chamfer the other ports as well.

Unless the chamfering is somehow affecting exhaust gas pressure locally at the hole, the flow rate should be the same because the area of the opening didn't change (diameter didn't change). Science!

Anyway, I can check for consistent carbon folking/deposit on fresh spark plugs, no problem. I don't know how much of an indicator that will be of flow rate though.

[reklipz]

Wait... you do mean spark plugs, right?

[wildBill83]

Yes, spark plugs. My mistake for not clearing the air there.

That end of the EGR should be under a vacuum to pull the exhaust gasses into the intake. I doubt heat will be an issue.

The chamfer will affect flow. Gasses are compressable and funneling gas increases compression and the amount of compressed gas is what your flow is based on. If it was a liquid your logic would be sound. Easiest fix if it does drop more carbon in one cylinder would be to chamfer the other holes as well and even out the draw of vacuum.

Initially I thought you drilled plumb through the intake runner itself. Realistically this is not a big deal.

The only real scientific way to test if it makes a difference is to install A/F meters in each runner and O2 sensors on each exhaust port, but this is not feasible.

[reklipz]

Yes, spark plugs. My mistake for not clearing the air there.

No worries. I actually saw your first post before you edited it, and I rightly assumed you meant spark plugs. Then you edited it, and I typed my reply, and then I wanted to make sure we were on the same page, .

If it was a liquid your logic would be sound.

Hmm... I thought we had the same logic here. I read our statements as the same, except you confirmed that chamfer/funnel will compress the gas, whereas I was unsure but said that compression of the gas is the only variable that could change, as the area of the opening is the same. I think we're on the same page, I'm just curious by nature; don't take this as me calling you out or anything like that.

The chamfer will affect flow. Gasses are compressable and funneling gas increases compression and the amount of compressed gas is what your flow is based on.

Unless the chamfering is somehow affecting exhaust gas pressure locally at the hole, the flow rate should be the same because the area of the opening didn't change (diameter didn't change).

----

The only real scientific way to test if it makes a difference is to install A/F meters in each runner and O2 sensors on each exhaust port, but this is not feasible.

Agreed. If it turns out there is no extra carbon on the plugs, then either a) carbon on the plugs is not a good indicator of EGR flow, b) the flow is not appreciably changed by the chamfer. I'm going to put my money on c) both a and b are the case. Unless we have that scientific setup, we'll never know! I'd be more than willing to do the work if someone wants to fund this...

So long as we can ensure that there are no negative side effects of the chamfering (like extra carbon fowling, the extra gas affecting/disturbing normal intake gas flow, etc.), the extra gas provided by the chamfering could be seen as a benefit, no? The only other complication I'd be worried about is the extra EGR affecting air-to-fuel ratio / stoich. The CPU can compensate by means of the O2 sensor, but if it's compensation is static (i.e. (there's no strike-through here, apparently; this is the half thought that spawned the next paragraph)

I did some research, and the purpose of EGR is to reduce NOX emissions, not to increase fuel economy or performance. Discussing "benefits" of "extra EGR" is pretty much pointless. What does matter though is that the flow rates are relatively the same between cylinders, because this could/will affect O2 readings, and could create oscillations in the readings and affect the ECUs compensation algorithm, which probably is static and assumes a certain lab-determined/tested amount of EGR flow. That said, I would have a hard time believing that the O2 sensor reacts on the time scale of individual cylinder firings, or even that the ECU reacts to O2 readings at that rate, which would mean that all of this discussion is pretty much moot anyway. Do you agree? Perhaps someone (perhaps you) knows more about these systems in the CB (or in general, if applicable) and can chime in.

Anyway, great discussion! I don't know when I'm going to be installing this intake; I am installing it on my F22A1 w/ an H22/H23 TB + Plenum (both from wed3k, ironically, ), and I have to clean up the TB and source the appropriate sensors (I don't want to sabotage my current intake setup to do so). But, I'm hoping to do it in the near future, and I'll be sure to share the results when I do.

[wildBill83]

I was also concerned about leaning out the mixture, being that more combusted material will be injected on that one port possibly.

[reklipz]

What does matter though is that the flow rates are relatively the same between cylinders, because this could/will affect O₂ readings, and could create oscillations in the readings and affect the ECUs compensation algorithm, which probably is static and assumes a certain lab-determined/tested amount of EGR flow. That said, I would have a hard time believing that the O₂ sensor reacts on the time scale of individual cylinder firings, or even that the ECU reacts to O₂ readings at that rate, which would mean that all of this discussion is pretty much moot anyway. Do you agree? Perhaps someone (perhaps you) knows more about these systems in the CB (or in general, if applicable) and can chime in.

I was also concerned about leaning out the mixture, being that more combusted material will be injected on that one port possibly.

I found this interesting paper from 1999:
http://96.0.50.31/files/Individual_C...el_Control.pdf

I haven't read the whole thing yet, but it gets pretty technical and talks about bandwidth (1/reaction time!) of the O₂ sensor. It fills in a bunch of the voids and questions in our discussion, .

[reklipz]

I found this interesting paper from 1999:
http://96.0.50.31/files/Individual_C...el_Control.pdf

I haven't read the whole thing yet, but it gets pretty technical and talks about bandwidth (1/reaction time!) of the O₂ sensor. It fills in a bunch of the voids and questions in our discussion, .

Holy crap... has anyone actually read that paper? It's gets pretty ridiculous! It's from 1999, almost a decade after our engines were designed, so the research from the paper is probably not used in our engine. But that said, it's still pretty awesome. It talks about using a single O2 sensor to estimate the stoich of individual cylinders, and it discusses variances in fuel-injectors, intake air distribution, EGR distribution, and even gets down to discussing the effects of wetting the intake walls and valves. Wow.

Anyway, an update on the intake: I won't be installing it until spring rolls around. It's currently too cold outside for my liking, and I don't want to hassle with finding a garage to work in. I need to finish cleaning and painting the parts to my liking as well, and that also requires better weather. I haven't forgotten! Though I will probably wind up chamfering all of the holes straight off, because I don't want to have to take the intake back off to do so afterward.