yea that's why i wasn't sure if that's exactly what they are talking about.

 

Just fixed my dyslexic typing...R7420

 

Lol--bad as I am Dan!

Just to update--someone that is much more knowledgeable than me is looking at this.

 

Dan are you (or were you) running those in the leading position on your renny?

 

looking for a tenth of a mile per gallon, but using cheap plugs that don't fit properly -

 

Running those in L at 10.5 heat range and 11 in trailing..but only track I don't really drive the car on the street much anymore. I think they would be a bit cold for daily driving in a NA car.. The T ones need another shim

I also ran some of the double plat ones ( R67255 I think? ) in 10.5 in both L and T..

 

get the R7440, iridium race plug version with dedicated L/T lengths

 

^i have seen those ones before, available only in 9 and 10 in the leading, 10 and 11 trailing.

they are also like 60 bucks per plug lulz

 

apparently I lucked out because they jacked up the price after my purchase, wish I had ordered the entire qty in stock at the time - basically paid the typical going price for OE plugs

https://www.rx8club.com/major-horsep...2/#post4408374

 

Found this, dunno if the guy is onto something with the plug holes, but seems likely. I don't agree with changing the shape of the bathtub (since its a pneumatic system pressure is the same on all sides regardless of where you put combustion), but the slotted plugs holes look interesting.
Rotary Engine Breakthrough? | MazdaMovement

Here is a comparison between the BUE and stock, and stock leading washer removed. I had pictures of the plugs in the housing, but they weren't very informative and didn't come out well. Also here is a picture of the BUE in the housing from the outside, gonna take some machining or a very thin wall socket to get those to work.

When (if) I get around to actually trying some of this I'm gonna machine some spark plug adapters to go right up to the housing (leaving a small amount of clearance for the apex) then use plugs like these:
http://www.ebay.com/itm/4X-CHAMPION-...21049962613%26

 

that is exactly what the rotary motorcycle owners do.
Make the insert with a hex nut attached to it so if it ever needs to be removed--it is not a problem.
Speaking with Paul/Rick E in detail about this on march 2 at Mazmart.

 

yeah, nobody has ever done that before ...

that rotor welding job was absolutely epic ...

 

Its funny because K.Yamamoto mentions most of what that guy was saying, but he never addressed it in the book, especially the compression leakage to the exhaust phase. I am just trying to picture what the spark looks like during ignition, just doesn't seem that efficient.

 

While I wait for a delivery to continue my build... I have had time to make a mock up plug adapter. Cut up a used Saturn Vue plug and here's what I have. I did not machine it with precision, nor is it tapped, but this is kinda what I'm thinking of.

 

bingo --there it is. Just get the details done and you have it.
I wish I had the tools/place/people locally that could help me pursue some of my ideas.
But--then again they may not really hang around long.......

 

the leakage will be a lot worse when it takes out the apex seal

maybe the shadetree experts can explain to us how it's leaking compression when the exhaust port is not open on the prior chamber yet as the apex crosses the leading plug hole?


.

 

I was wondering the same thing. Wouldn't compression leak only if there was a draw from the exhaust cycle, which there isn't until just before "TDC" on the ignition cycle? Not to mention the forces within the exhaust cycle would surpass those of the ignition cycle so i would think that alone would help prevent 'leakage'.

I am really wondering if his "600 degree" cooler EGT is actually due to a less complete burn of the fuel. I just cannot picture exactly how the spark in that guy's design can be in any way efficient.

 

Good point. (Though there's no shade under trees up here in winter ...). I've wondered before why there's on EGR on the renny when most modern piston engines have it. Perhaps a little free EGR courtesy of the spark plug hole?

 

the zero overlap results in internal EGR from the chamber volume that can't be fully evacuated

which is also why the common header theories don't apply

 

Yes the egr is because of the no overlap. Most of the gases that remain do so in the tub according to the experts I know. I have heard estimates of 10%?
I think we all here realize that the face to face pressure deta is less at the lead plug location versus the trailing. After all that is the reason a bigger hole can be used at the leading plug site, but that doesnt mean that there is NO leakage. There is leakage--how much? IDNK. But, reducing any leakage has to have some benefit.
I also believe in moving the spark closer to the combustion chamber.
The above is even more pertinent when boost is applied.
I will be speaking with Rick E and Paul on Saturday about these things.

 

First off, if it doesn't protrude into the housing how can it take out a apex seal? I know my quick and dirty mock up wasn't perfect, but I'M NOT USING IT IN AN ENGINE.

Secondly, chamber to chamber leakage has nothing to do with the ports being open or closed because there is a differential pressure between chambers. We're not talking about compression leaking out of the engine, but instead it leaking into the chamber ahead of it. I can't find it offhand, but I saw a very interesting graph of total seal leakage vs position in rotation. The leading and trailing spark plug holes had huge (although short lasting) spikes. Trailing we are kinda stuck with, but if we can minimize the gaping hole that occurs when the apex is over the leading plug it can't hurt!

 

the whole design of the side port is to REDUCE the "internal EGR", the whole problem with the older engines is that they have too much internal EGR, and then they need to be run richer, which makes them dirtier.

 

so you guys didn't read the SAE papers yet?

 

maybe you didnt fully comprehend what you posted and what we are talking about?
EGR per the sideport engine is reduced ( not eliminated) in the low load/idle range when compared to the non side ported engine.
In high load situations and especially after you boost this engine the face to face leakage increases.
Now if this face to face leakage can be reduced further by modifying the lead sparkplug opening then that is a good thing.
Now if we can get a more complete combustion by moving the sparkplug closer to the combustion front too--then the combination of these {increasing sealing and better combustion} could have a
very worthwhile effect.
It does remain to be seen.

 

chamber to chamber leakage is one of the problems with the rotary in general. the NSU spider SAE paper has a comparison of seal lengths with the rotary vs piston engine, and the Rotary has a lot longer seal length than a comparable piston engine

it becomes important in a boosted engine because sometimes the leakage can cause detonation. its why you really should start a high hp build with new housings, and rotors, the Japanese even like to have date matched parts, so they want 2 rotors from the same batch.

as for the size of the leading spark plug hole, it moves around a little thru the years, and there are tradeoffs. i forget where the most current info is, but even if you look at the kenichi yamamoto book, you can see that the stock plug location is about the same one you would choose.

incidentally, for the 81 model year, Mazda moved the spark plug closer to the chamber, by 3mm, and the supplied graph is attached.