Well, so much for this being a nice informative exchange of ideas and not turning into a pissing match! LOL

The key to reducing NOx with efficient combustion is lean burn. It's done all the time with gas fired turbine generators. The oxygen content in the mixture is incresed to the point just before flame out to cool the flame temperatures. That's where the lowest NOx emissions can be found.

With the SI engine it's a little more complicated, you must deal with lean burn misfire limits, this can be corrected by increasing in-cylinder turbulence. When lean burn miss-fire limits are extended and the engine is leaned to the new found limit, the result is reduced NOx and drastically reduced fuel consumption!

I feel confident that I can make this work, but I haven’t tried yet. I have a friend that is doing this in England; he claims to be running leaner than 17:1 air/fuel at steady cruse. I can’t confirm this although I have no reason to not believe him.

I have personally done testing at 13.5:1 compression and 8000RPM with elevated combustion temperatures to monitor stress and hot spots. The groove ends discolored from the heat, it did not affect performance. The heads are still in use, my "fix" was to grind back the sharp tips and add fuel to the tune up.

The actual disadvantages to the grooves are increased surface area exposed to combustion temperatures and increased crevice space (assuming the grooves are narrow enough to hinder combustion).

The advantages are greater than the disadvantages by far. The keys are increased flame intensity to improve crevice burn, wider grooves and faster burn velocities to reduce heat transfer.

You are correct on both points; no completive builder would modify an engine for competition with out having a good idea of the impact. Secondly it's very common for a competitor to claim ignorance to avoid giving the competition details of success.

We've discussed these grooves before and I think that the idea has some merit to it, but it's not a magic bullet.

The real problem to really testing them is that you need to be able to test turbulence at "speed", which is not the same as a typical swirl meter test.


Anyway, let's just say that if you boil it down to gravy, we might not have enough to cover a chicken fried steak.



Does that make sense?

Arguing proves nothing; the results must speak for themselves. The proof I needed was in the performance of the cars I'm involved with. This is not something that will give you tire blazing performance like a hot cam and a good flowing set of heads. Then again it's not something that you need a dyno to determine the value. Over 95% of the people I know around the world that are using this can describe the results in detail.

I don't understand why people are dead set against seeing this idea catch on. Just because these people haven’t seen results presented in the fashion that they consider "proof” doesn’t mean it doesn't work. Regardless of the arguments against the idea the fact remains "it works", this I proved to my self within the comforts of my own environment, I encourage others to do the same.

On the surface this appears to be just as you describe, "not a magic bullet"; to most involved it's just that. In my opinion it's much more

Find someone you consider to be an expert in engine performance; don't mention a specific idea or modification. Ask them seriously: If something was found that would elevate detonation and lean burn miss-fire limits in the internal combustion engine what would it be worth?

Huh? What was that you wanted to know what BVD stood for? Oh yea, back to why these grooves are not finding their way into production engines...

Going along with what you said, an engine is a package of parts that have to work together with each other. Once we start sticking in bigger cams, whats the next logical thing to do, increase compression because our big cam low compression engine is now soggy on the bottom end. Ok, we did all this and now it rattles every time we race it up the hill climb. Now what? You want to be the fastest or quickest up the hill climb so you see this forum and try the grooves. It works and now your the record holder for that hill climb.
I think thats how we are going to prove these grooves. Someone build or go back to the high compression engine that is pinging and then put these heads or pistons in and see if it quits pinging. Its pretty simple if you ask me. By the way, who here races up hills? That could be a better place to test these grooves than on a dyno.

Would you tell anyone your "secret????" If the results were exceptional, would you spread the word in the name of helping engine builders and garage tinkerers everywhere?

I suspect there may be more people using it but not telling anyone because they like their edge. But hey, who knows.

I've got a wrench in one hand and a ratchet in the other - do those heads want to come off and try something new??

This conversation is pretty close to snake oil. That's why some of these guys get a little ruffled about talking up modifications like this. If I remember correctly, Singh's website had pictures of cars doing wheelstands and made some pretty substantial claims that appeared to be unproven.

Again, I think there is some merit to it, but I'd hate to see some young guy ruin his heads by grinding big gouges in them.

If it had that huge of an impact, you would think that this would be implemented on modern cars. I mean, the results that are being touted on this thread are pretty spectacular. High compression, pump gas, under a load, no ping? That's painting a picture with a very, very broad brush.

I'm not knocking the modification, and it is interesting. I would like to see some hard data on it. Hear-say will not quiet the critics.

So, someone build a high compression, street type engine, put some knock sensors on it, and swap some heads.

Let's see a scientific comparison.


nairb has spoken

That is exactly what no one on this forum can do and why I refuse to accept that it might work. I trust my builder, he put's out 1000 engines a year in drag, circle and marine applications for 30 years. When I asked him about it...his reply was, "never heard of it".

Just think of the engine damage that could of been thrwarted with this sooooo easy grooves. I can't believe no one is using this. IT's the new age of engine building.(read sarcasm here)

The mod is so cheap and quickly done, that one should be able to afford the dyno time. Some one did sometime, and it don't work.

I don't think a dyno is a good tool to test this unless you can do accurate and repeated testing in the 1200-2500rpm range. Nearly every dyno test I have seen starts off at 3000rpm and on up. A steep hill would be a better testing grounds than a dyno in my eyes.

Detonaton occurs at any rpm.

True, but detonation wont occur in my engine at the same rpm as your type of engines. And detonation will not occur at any rpm's, it can occur at any certain engine speed. In other words you have an engine that is prone to detonation, but it might only happen between 4000rpm and 5800rpm but not above or below those rpms. Or it can happen in the other rpms and not in that 4000 to 5800rpm range. A lot of variables can cause detonation but it seems like a lot of people want to dismiss things that can help eliminate detonation. Turbulence is one way to combat detonation and higher rpms can create enough turbulence to stop detonation. Perhaps these grooves can cause the turbulence to quell detonation.