Stalker

is there any advantage in doing this ??

IanS

iTrader: (4)

No, cant remember why exactly. I asked about this also.

fastcarfreak

disabling your trailing plugs reduces detonation greatly. I guess if you wanted you could run 87 octane with the disabled sparkplugs. Save on gas. Skip Gorman developed something to get rid of his trailing spark and drove his Turbo II around with 87 octane and 12 pounds of boost on stock computer, no tuning, just to prove that it works. He had absolutely no harm done to his car. I believe he did this for quite a long time.

IanS

iTrader: (4)

thats pretty sweet. I was thinking that with all the work involved to seal the hole, it wasnt really worth any performance gains that there may be. I guess on a forced setup it would be substantially better to have the option of removing the trailing plug.

Edit - So, with the trailing gone, you could run higher boost using 93 octane (for example) than an engine with the trailing still connected and operating right?

nevarmore

You could just leave the old sparkplug in.

Jeff20B

iTrader: (13)

Guys, that's exactly what I'm doing on my MegaSquirted 20B. I couldn't justify the extra work involved in keeping trailing and its required three extra coils and ignitors just for a measley 2 extra HP (which wouldn't even be noticed on a chassis dyno). Besides, I'm trying an experimental ignition system which outputs an ignition event once every 60° of eccentric shaft rotation which just so happens to work great with the 20B's 120° rotor phasing by sending a spark to each leading plug when it would normally fire, and then another one 180° later. It's just like an FC or FD leading ignition system, but since none of my rotors are phased 180° apart, I couldn't simply spark any of them together; I had to get creative. Anyway, from the plug's perspective, it wouldn't know whether it's in a 13B or a 20B.

I'm running NA for now but may go turbo some day. It's nice to know that I'm not the only person here who thinks trailing isn't worth much.

RETed

It actually make more than 2hp.
Try it on a dyno, and you'll see the difference.

That anti-detonation device was exactly this.
You reduce the risk of detonation, but you lose significant power.
Go figure...
To me it's like taking a step backwards cause you can't tune the car right.



-Ted

Jeff20B

iTrader: (13)

I will see if I can hook an extra three ignitors and coils to my engine and run leading and trailing with no split in order to do some side by side dyno pulls and see of there is any difference in power.

fastcarfreak

Your right on your assumption that it loses more then 2 hp. But it all depends on how much power your making originally. Example, A 400 horsepower car is going to lose more then a 300 horsepower car.

I made 435 rwhp and 360 ftlb on pump gas (93 octane) and 20 psi with my t78 with the trailing disabled.

The way i feel, with this anti detonation device, and water injection, i should never blow another motor due to detonation (knock on wood)

Adam

Stalker

is the trailing plug for better emission??

RX-Midget

I'm just trying to figure out why disabling the trailing ignition reduces the chance of detonation. In my mind, the trailing spark happens AFTER the leading plugs firing event that starts the flame front. Since the trailing fires after the leading, how could it possibly cause detonation (pre-firing of the mixture)?

meddle

This is going to get heated.

Jeff20B

iTrader: (13)

Nah, just pre-fired. Joke.

I wired up a switch to turn trailing on and off in my REPU. I could NOT feel a difference in every driving condition I could think of to try. I thought I felt a difference once, but it was most likely something in the road because on numurous later attempts, it didn't make a difference. I even had my friend switch it for me so the slight movement of my finger wouldn't color the results. The result; no difference. The engine was NA and had a direct fired leading ignition system firing both leading plugs simultaneously from two ignitors and two coils.

Another guy did some dyno runs (yeah, real numbers) with a fully stock 1st gen cap and rotor ignition system and tried various variations. The power difference with trailing disabled was so small it was within the margin of error for the chassis dyno. We're talking +/- of 2 hp here. His engine was also NA.

When I went from a stock 1st gen cap and rotor ignition system to a directly fired leading ignition system, I noticed a very nice improvement in driveability, more power, easier starts, less smelly exhaust, and even the exhaust note changed to a smoother, more FC-like sound. All this just from the addition of an extra spark on the leading plug occouring 180° late. I'd venture a guess that trailing becomes optional at that point since it's firing into the trailing edge of the air fuel mixture (at idle or several degrees earlier depending on advance) just like trailing does; except the leading plug doesn't have a tiny hole between it and the rotor face. Of course it's just a guess, but the real world results speak for themselves. These results compelled me to make it work on my 20B. It's NA as well.

RETed, what ever became of Sky's NA 20B project? It had three FC leading coils firing both plugs of each rotor housing. I now know that's not a good idea. Are they still there, or have you switched to six individual coils? I remember the engine sounded different from other 20Bs I've heard—more like a V6. At first I figured it was due to the header keeping the exhaust pulses seperated for a bit longer than a typical turbo manifold would, but then I test fired my engine with its header and could hear the 20B note coming through (just barely without a smooth idle, but it was there). Thoughts?

RETed

The claims on the anti-detonation device is that it allows for a slightly richer mixture due to the trailings not firing.
Their claims, not mine...
This does not prevent a nasty ignition problem (i.e. misfiring or base timing not within spec) from killing the motor though.

You'll find that there are people who are totally against it, and there are those who totally support it - there are very few people that are in between.

Hey, when you get charged $600 ($400?) for two machined plugs that block off the trailing spark plugs and disable the trailing ignition spark, I would be rather pissed!


-Ted

RETed

It might be all the NA's you're messing around with.

Mazda claimed like a 10% power gain by the trailing ignition spark.
This was printed in an SAE paper.

The 20B FC is currently changing chassis'.
The old one was just tired, and the owner found a new chassis to swap everything over.
All the hard stuff is done - engine, trans, drivetrain.
Haltech E6K is swapping over as we speak.

We got the original E11V1 exchanged for a new E11V2, but I told the owner I wanted to get the turbos fired on the E6K, since it'll be easier (and cheaper) at this point.
We got *one* turbo in so far - we need two more.
We're going to start mocking up the piping to install the three turbos soon - hopefully in the next couple months.


-Ted

RX-Midget

Wow! What a band-aid to cover up a lean mixture problem, but even that explination doesn't make sense. With the leading plugs lighting off the mixture, when the trailings fire (or don't) has no bearing on the mixture BEFORE the leading spark event.

Sounds like snake oil to me, and at $600 it is not the cheap stuff.

Thanks for the info.

b.

RX-Midget

Wow! What a band-aid to cover up a lean mixture problem, but even that explination doesn't make sense. With the leading plugs lighting off the mixture, when the trailings fire (or don't) has no bearing on the mixture BEFORE the leading spark event.

Sounds like snake oil to me, and at $600 it is not the cheap stuff.

Thanks for the info.

b.

meddle

oh ****, a pun....at least for the guys with trailing.

RETed

I didn't claim that.
That's what that particular shop claimed with this mod.
Go figure...


-Ted

Bond

435 on pump at 20psi no trailing, sounds good to me. Reted, not all of us have access to proffessional tuners like yourself.

RX-Midget

Understood...

fastcarfreak

The claim you got was obviously from no one associated with the device. The direct result of assumptions made by people who are against the device.

Let me try to explain this best i can. I am not sure i can give you the best explaination but I will try.
detonation is caused when your fuel trys to combust too early. With 2 spark plugs per chamber with different firing times (split on our motors), When you get into higher rpms you run a risk of the trailing plug firing on, close to, or even after the apex seal from the very fast speed of the rotor. If this happens you run the risk of igniting the combustion chamber that follows the one that is firing now (hence pre combusted fuel). We all know that when you fire a spark plug to early (too advanced) the piston (or in this case the rotor) trys to essentially reverse direction (which isnt possible) and can cause a ton of damage from the unwanted stresses and break the crack or break the apex seal.

I hope i have this as clear as possible without giving your false info.

Adam

fastcarfreak

Also, there is another problem you can get into with the wasted spark from the leading plugs and how it can cause detonation. Because the leading plugs fire simultaniously and the trailing plugs fire in sequence, it brings you to another cause of detonation with these motors. I dont exactly know all the detail about this, but i also believe KDR has gotten the leading plugs to fire in sequence so there is no more wasted spark.

Adam

Jeff20B

iTrader: (13)

So you're saying they've gone to all this trouble to reduce the number of sparks available to the fuel mixture and that's appearantly a good thing? You're right; you didn't explain it very well. The logic you used doesn't fly. If KDR thinks they've discovered the perfect way to run a rotary, I certainly don't believe it. RETed will probably have a few things to say about this.

RETed, three turbos? Eep!

As for the anti-det devices, what's this about spending over $400 on a couple machined bolts? Just to supposedly prevent carbon build-up inside the trailing holes? What about all those people that have driven for thousands of miles without trailing ignition functioning without a problem? Is this an NA vs turbo thing? Probably not exclusively. Sounds like a scam to me.

fastcarfreak

Ok, if my logic doesnt fly, why dont you correct it. Just because you dont believe it, doesnt mean it isn't true. I am all for the truth in this situation. If you provide facts that my statements are false, i will not argue. But simply saying my logic doesn't fly, doesn't fly with me. Where did my explanation go wrong? I will agree with you on the price issue, it is kinda steep. But then again industry does this all the time. They sell parts that dont cost **** to make, but took a long time to develope for high costs (example: Contact lenses cost a couple a cents a set to make). Skip had a lot of time and money invested in this device/idea, there is no reason, he cant try to recoupe from this.

Im not trying to cause any kind of argument with anybody, just trying to give a valid explanation. I just dont like the fact that too many people have thier assumptions and they try to pawn them off on everyone else as facts.

Adam