jimlab

Let's discuss that.

Normal combustion starts from the point of ignition (spark plug) and the flame front spreads in an even and controlled manner throughout the rest of the combustion chamber.

Detonation, on the other hand, is a rapid and uncontrolled burn of the air fuel mixture caused by pre-ignition of the charge (due to heat, pressure, or both), resulting in colliding flame fronts. The shock wave(s) produced generate an extreme pressure increase in the combustion chamber, which is what breaks apex seals and "collapses" (dents) the rotor's combustion face.

If they're saying that it moves the "location" of detonation, what they're really saying is that the rotor is farther along its path of travel before the one remaining spark plug is fired. However, that doesn't mean that detonation is prevented, nor does it mean that there will be any less damage as a result. All they're doing is limiting normal combustion to a single ignition point (one spark plug), and eliminating dealing with the split between firing both plugs.

Bottom line, detonation is bad no matter where (when is more accurate) it happens in relation to rotor travel. There is no "ideal" position of the rotor that will allow the apex seals and rotor to survive repeated detonation.

mad_7tist

look i will but the idea that the trailing plugs contribute little in the way of peak hp, and also that the trailing plug is also a hot spot in the combustion chamber. much the same way that you want all shap edges out of the combustion chamber in a piston engine removing these may help some if it helps out in the long run. i doubt it. especialy if like jim said, say this does give you less chance of detonation if you tune right up to the new threshold the second anything goes amiss you are still toast. the more hp you make the worse detonation is when it does happen. ever seen a stock honda blow a hole through a piston?

Kento

Untrue. I'm open to listening to any product claims, as long as there's some sound engineering principles to back up those claims. Unfortunately, there hasn't exactly been a whole lot of that brought to the table recently for this device.

By eliminating the trailing plug and altering the a/f ratios and ignition to compensate, there were supposedly several benefits, including the ability to run regular unleaded fuel instead of premium, increased power, and better fuel economy. By leaning out the a/f ratios, they were able to increase combustion efficiency at lower rpm, which is where I assume the improved torque figures and better fuel efficiency claims came from.

The problem is that the rotary is like a two-stroke engine in that its power strokes occur much more frequently than a comparative piston engine, so there's far less time to allow internal components to leech off some of that absorbed combustion heat. The rotary partially depends on the incoming fresh intake charge to help keep those combustion chamber temps under control. I'm sure this is where the "melted" engines, "350 hp limit", and talk of major oil cooling upgrades comes from. I have yet to see evidence of a tremendous increase in torque and/or horsepower as opposed to a comparative trailing plug-equipped engine that would cause temp increases simply from the increased power to warrant cooling upgrades. Actually, the power increases I've seen posted have been a bit underwhelming.

The only way you can "prevent" detonation is precisely control a/f ratios and ignition timing via some sort of sensing method in the combustion chamber. Without that controlling feature, there's no way you can completely stop detonation from occurring. This talk of "moving" the detonation location to a "less harmful" spot is somewhat incredulous.

Basically, I haven't yet seen any power figures-- torque or hp-- that are enough of an improvement to warrant spending the $500 or whatever cost of the device, plus the additional costs of a standalone and tuning to make it work.

FDNewbie

iTrader: (10)

Kento, can you give an example of a controlling feature that senses the combustion as you spoke of? Would that be a knock sensor?

mad_7tist

ion sensing ignition systems. sabb and gm are using them in some newer car lines

Kento

^Yep, Saab, Volvo, GM, Mercedes, and BMW all have some ionization-sensing detonation controllers in some ECM systems in their lineup. Instead of using a knock sensor that "listens" or some sort of pressure sensor in the combustion chamber, the ion-sensing unit works by sending a specified AC voltage through the spark plug during the combustion phase. Since combustion gases change their electrical resistance, by precisely measuring and comparing the current flow across the plug gap, the ECU is able to determine whether detonation is imminent, and is able to pull back timing in time.

mad_7tist

It's All Ball Bearings These Days.......

Jim Calandrella

I totally agree with the not alot of info and/or product backup from them. I think they did that on purpose though.......
Again, I never said that I thought it prevented det., I just said that it moved where(or when as Jimlab said) it happened. Jim put up a nice explanation of his thoughts on that. I'm actually reading up right now
I have not seen any dyno charts either. I would like to. I haven't heard of horsepower increases..............just torque. The 350 rwhp is something that i've heard tossed around alot in reference to when people start having cooling issues.

jimlab

Now, you prepare that Fetzer valve with some, uh, 3-in-1 oil and some gauze pads. And I'm gonna need about 10 quarts of antifreeze... preferably Prestone... No... No, make that Quaker State...

turbojeff

iTrader: (30)

Jim C,

Horsepower levels do not cause cooling issues by themselves. It is the frequency in which the HP is used.

A 350rwhp car shouldn't run any hotter driving down the road than a 215rwhp car. Likely the higher HP will run cooler since it won't have any cats and may have other mods on it to increase airflow through the engine bay.

On the track the 350rwhp will put more heat into the cooling system.

My point being you can't name a HP level that the cooling system is starting to become too small, you have to also consider the useage.

As far as the rotor getting so hot that the dents were caused by material softening, not likely (hope someone didn't already mention this, too lazy to read everything). Aluminum in the rotor housings melts around 1100F, the rotors are cast iron and melt around 2700F. If the rotors were begining to soften from the high temperature the oil in the engine would be on fire and the aluminum housings would be melted...

FDNewbie

iTrader: (10)

Now THIS sounds like an anti-det device... Why it's sensing ions is a bit beyond my understanding, but I'm sure it works. Here's my newb question...is there any way you can integrate such a system into an RX7 engine? The way you're describing it sounds like the sensor is very close to/in the plug gap. Granted, it's an integrated function of the respective car's ECU, I'm sure if you can mount such a sensor, you can have a separate device to piggy back on whatever existing ECU you're running, and function as a fuel cut or override the current timing map? (Sorry if this is so theoretical, but that's all I am at this point lol). And depending on HOW the program for such a sensor is, maybe one of the current ECUs has the ability to integrate such a function? PFC, Haltech, or even a blank ECU such as an HKS FCon, etc?

Jim Calandrella

Yeah, I understand. I didn't think just driving the car normal would be any diffirent. I'm just talking under full load, or aggressive driving(I probably didn't express that well enough). After all, I didn't buy this car just to pimp around town. I want to autocross it and eventually track it.

Kento

I never said you did; I was only pointing out that despite any claims made, it's impossible to do without some sort of outside control.
That's why I mentioned the fact that running the rotary at such lean a/f ratios robs it of one of its primary cooling functions.

Jim Calandrella

I read your post fast. I'm at work, so it's tough for me to sit and ponder alot. Sorry.

Kento

Nope.

FDNewbie

iTrader: (10)

LOL care to elaborate Kento?

artguy

water injection vs no water injection is a difference of 20 points of knock on my car. running no plugs in the trailing made my car run slower and rougher (even after being tuned by steve kan). So...my vote goes to water injection. the data on my guages is proof enough for me to believe in it. The lower temps are a nice benefit too.

proper tuning will solve your problem to a greater degree than pulling your plugs and relying on mediocre tuning. those devices sound like the last gasp solution to a tuner with limited ability, frusterated with blowing up peoples motors and having to rebuild them. probably got some gripes from the wife when she had to re-port the rebuilds after he destroyed the housings she just finished. if that was happening to me id be pulling plugs too.

FDNewbie

iTrader: (10)

Artguy, that's a bit low/personal, dontcha think?

Kento

In a nutshell, far too complicated a system to be simply piggybacked onto an existing EFI unit. Reread my post about how the ion-sensing system works and you'll hopefully understand.

Conv.WS6

Tidbits of worthless knowledge, because I'm WAY over this subject, and therefore I will not be debating this. BTW, good luck with the V8 conversion Jim.

The anti det device plugs the hole to prevent blow by.
If you pull the anti det device you will need a retune.
Conversion from 1 firing plug to 2 firing plugs was an emission related change.
You see more heat issues from the anti det device because of the leaner A/F ratios, and not because of the torque.

Does this make me a skeptic or a supporter, I don't really care. I'll have another FD to toy with, but it will be slightly different of a setup than my previous one, if it remains a rotary.
later guys.

FDNewbie

iTrader: (10)

Fair enough. It's my lack of understanding of how complex the system is (and of such systems in general) that makes me wonder. I saw it as a program/table (much like the ones that exist in our ECUs) that has a readout of voltages and the timing associated w/ it, then integrating the sensors to whatever unit would be reading them and correlating it w/ the existing table. Then it would have to be able to execute the new timing map.
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Okay...so it's pretty complex lol. Nuff said. But it's a nice idea, huh?

artguy

whats low is kdr selling those stupid plugs and hyping up this forum for a year before hand. thats low.

but my points sound accurate....dont know if they were..but i would be that was the case.

j

jimlab

Not to mention the ******* who was trying to sell the knock-off anti-det plugs for $500 a pair...

Kento

So how much is KDR charging for the actual anti-det mod?

Hyperite

One engine