My EGT measurements are the direct result of observing their condition at set breakpoints while adjusting the timing.
I'm not saying that historically, retarded timing doesn't increase EGT. I'm saying that specifically, the Renesis, at torque peak and 11.5:1 A/F does not respond with a substantial increase in EGT corresponding to a reduction of timing from 13° to 9°.

Am I really being that unclear or is everyone just gunning for me today?

As far as EGR effect, are you saying that charge dilution (resulting from increased effective overlap) does NOT correspond to a lower latent heat from combustion?

BTW - EGT is pretty meaningless until you have established the actual EGT reading for a specific motor at LBT. Then, you can go about making comparisons.

 

I hope I didn't sound(uh, read) like I was out to get you with my comment and I apologize if it appeared so. I was more looking for an alternate explanation than trying to discredit anyone. Hope it didn't seem that way to you.

Chris

 

No, Chris. I just thought you missed my point. I wasn't saying retard doesn't cause an elevation in EGTs (it can), I'm just saying in that particular example, it does not.

Yes. Even for a piston motor, 1600°F at the torque peak is not horrible. On a rotary, 1800° is typical. Even 2000° is not unheard of, but it would scare me pretty good.

Pre-ignition is one of the forms of detonation. Detonation simply means uncontrolled combustion. Do you really do this for a living?

 

Pre-ignition and detonation are two totally different things. They are similar and often confused with each other though.

Jeff, Brian is one of the smartest rotary tuners and builders around. He knows his ****. I wouldn't be so quick to discredit him. He is one of the few and I do mean few people I'd trust to work on a rotary and also one of the few that I'd ask advice to or for his opinion when it comes to rotaries. He's got more experience tuning rotaries than most do.

 

I'm not trying to discredit him (though he is working pretty hard on me, which I don't mind). I hope and believe he has a ton of experience.

Detonation is the blanket term for any abnormal (uncontrolled) combustion.
Pre-ignition is something lighting off the charge ahead of the plug, which is a form of detonation.
Detonation is a reconstruct of the word "detune".
Knock is detonation, as is ping, but the mechanical nature of each is different.
It all comes down to when the charge lights and, more importantly, how fast and evenly the flame propagates.

 

Pre-ignition is as you said igniting of the mixture BEFORE the spark plug fires. Detonation happens AFTER the plug fires. This is spontaneous and uncontrolled flame propagation resulting in several flame fronts colliding. They are not the same thing.

 

Yes. So, if you get pre-ignition followed by "proper" ignition, it isn't detonation?
ANY abnormal burn is detonation. If it too high of a flame speed, resulting in high pressure, it is detonation.
If it is multiple flame fronts colliding, its detonation.
ANYTHING that results in the maximum combustion pressure before 15° or so ATDC is detonation.
Once again - the verb "detonation" is a derivation of the word "detune".
"Detunation" is just not proper English. lol.
It doesn't mean the same thing as the noun "detonation".

 

Fortunately you can't have pre-ignition and proper ignition at the same time. You have either pre-ignition or detonation. Both are dangerous. The difference is when it occurs, either before or after normal spark ignition.

 

Wrong again. This is only true if your sparkplug fires before ATDC. Detonation isn't necessarily an uncontrolled flame only after TDC. It's only after the spark plug fires. If the plug fires before TDC, the of course detonation will also occur before TDC. Pre-ignition is only the lighting of the mixture before the spark plug does it. It is nothing else and is considered nothing else by anyone but you.

 

Not true. If a "hot spot" lights off the charge at one corner of the combustion chamber before the plug, it doesn't mean the flame front will pass the plug before it fires.
Remember how impossibly long the Wankel's combustion chamber is. This is why it has two plugs.
If the leading apex seal area fires off the charge as it is rolling forward, after it has passed the plug, then the leading fires and then the trailing lights off early because of insufficient split, you have three flame fronts!
In fact, you have two controlled flame fronts due to the double plug when it is working optimally! The idea is to have the pressure rise occur in sync with the increase in combustion chamber volume.
At the torque peak , you have 9ms or so for all kinds of mayhem and that is FOREVER in combustion terms.

Re-read that. Its not just the timing. Its the pressure.
I don't care what people "consider". Just what is correct.
Plenty of people consider a lot of incorrect things to be acceptable.

 

where is the popcorn when you need it !!!!!

 

Yeah mon..................my neighbor gave me one of those big tins with two different types in it. If this continues much longer, I might have to crack it open!

 

This stuff goes on ad-infinitum. Ultimately, the goal gets displaced.
Whatever etymology and semantics to which you subscribe, the goal remains the same.

 

Detonation and pre-ignition are absolutely positively not the same thing. You can't argue it into fact. It doesn't work that way. Detonation is commonly misused to mean either/or by the misinformed/confused. This is not correct.

 

Wiki it!

The problem here, I think, lies with the "noun-ification" of "detonation".
I don't doubt that this is how people talk about abnormal post-ignition pressure rise.

Ultimately, whatever words you are going to use, ANYTHING that causes the pressure to rise faster than it can make torque is bad.

BTW - I never said "either/or". Chinese is Asian. Asian is not necessarily Chinese.
We need a Venn diagram!

 

man, you got shafted! Most of them come with THREE flavors. Normal, cheesey, and Caramel.
Back to our regularly scheduled programming...

 

Cheap *** neighbor!

Well.........I got a friggin plant from the same one as well.....does that count?

 

Nope.

 

Depends on what type of plant it was...

 

I'm partial to the Venus Fly-Trap myself, but no one gives those as gifts anymore.

 

Not since they saw the movie Little Shop of Horrors.

 

sheesh! I'm not posting another thing in the same thread as anyone on this page for the rest of the year. Let things cool off a little bit.

 

Why do people confuse a lively discussion around here with "heat" and "hate" and any range of emotions?
Just like I've posted elsewhere on this forum - you are all just a bunch of electrons to me. All I have is the "idea" of you and all I can discuss are the ideas that the "idea" of you puts forth. I hope I'm held in the same light.
None of us actually exist here.

When we get together, face-to-face, you get to be people again.
When we were discussing this around the table at Gordon Biersch at SSX, I don't think anyone had the thought to leave until it "cooled down". The discussion was just as interesting, but I don't think anyone was having their ire raised by it.
Why would teh internets make everyone so raw?

Someday soon, we will be face to face again. Until then, you are all just the pixels above my cursor. Let me be the same.

 

Correct! However you are saying that this is always due to detonation. There's a difference. Pre-ignition and detonation are not the same thing. The fact that they are each bad is not what is being debated.

 

No, that's NOT what I'm saying.
What I am saying is that "detonation" is the proper word for all forms of abnormal combustion.
What you are saying is that "detonation" is ONLY the uncontrolled rise in combustion pressure after ignition.
What you are saying is accepted.
What I am saying is correct.

You've seen how I am in person. Does it strike you as any different?