I hope this isnt a repost or rehash of previously posted info, but if it is it's news to me, since all Ive ever seen are theories and conjecture with actual facts being few and far between. This post is being made for informational purposes only, and to help others make their own, more educated decisions and conclusions about this mod and it's effectiveness or lack thereof. IT is not meant to be a negative or positive recommendation. Hopefully this doesnt step on anyone's toes, or **** anyone off, but if it does, **** 'em, I don't play politics anyway.

Background: a past engine customer of mine called me to see if I were interested in buying a blown core out of his FD. Said it was installed when he got the car, a recent KD rebuild with around 5k miles, 3mm seals and streetport. IT blew running a gt35 turbo around 13psi according to him. Eventually we struck a deal where he traded for a newly built block of mine. These pics document teardown of that block.

The anti det. "device" is just an aluminum plug inserted behind the trailing plugs preventing spark from getting into the engine...this we knew already. One side is machined and actually fits onto the sparkplug electrode, while the other side has a protrusion that attempts to fill the void hole left in the rotorhousing leading to the combustion chamber, which would normally be open for spark to travel through.










Here's how it looks from inside the rotorhousing, first a shot without the plug, then with. There is still about a 1-2mm gap (necessary) between the edge of the housing and the end of the plugs.

 

Here's a shot of the plug in the rotorhousing after sparkplug removal. I wasnt sure how they were inserted at first, but it was obvious they werent threaded as there was no "head" or method to install or remove them.



Since the engine was apart, I just took a little punch and pushed them out from inside. The question was posted recently by someone on this forum about how to get them out of a running engine. IN this case, I would remove my EGI fuse to disable fuel and spark, and remove one trailing plug. Have someone crank the car with the throttle open, and the compression will shoot the plug out of the hole. You need to have your hand over the open hole during this, to catch the piece as it falls out. Repeat for the other. I think this would work. Otherwise, something very sticky or tacky on the end of a junk sparkplug would probably pull them back out, too.

 

pretty neat!

 

Here's some other pics of the teardown to help you decide how effective these are at doing their job. Remember, these were new 3mm seals, so this was not a wear breakage. Milling seems to have been done properly, so I see no reason for the failure, other than...well, you know.






Proof that heavy detonation occured....








Discuss, mock, flame, etc....

 

damn i was hoping for soem dyno comparisons.

 

I will be running trailing spark on the new engine. Glad I wasn't the one that shelled out $500 for that mod

 

It is my understanding that the device does not stop detonation. It merely move the spot at which the detonation occurs with the rotor to a place at which it's far less likely to hurt the seals.
It allows you to actually have a ping or two on the dyno without instantly blowing your motor.

 

my understanding is that its all about the tuning you do after the device is installed. The actually plug itself is only half the product

my buddy with identical mods to me plus the anti det claims 373 rwhp @ 16 psi and more turque. I will race him as soon as he gets it back.

 

I find that a difficult concept to believe. The shock wave of the detonation will always reach the apex seals (the weakest component in the combustion chamber), and I seriously doubt that 12 inches or whatever of distance will make any difference.

 

Yeah, I don't know that for a fact. I'm just telling you how I heard it explained to me. Maybe someone's witnessed some pinging during tuning........
Other than that, it would be hard to attain hardcore evidence.

 

Obviously it did not work. So what's the theory again?

 

You being smart?

 

Not at all. Seeking a more through explanation.

 

Well, i've said all I know. We'll need someone with some more experience to come forth with more.
It's terrible that this happened within 5,000 miles.
I have heard that this thing is alot less effective at higher power levels. Although, 13 psi does not seem unreasonable.

 

Cool - thanks, Kevin!

Can you tell what they're made of - stainless, aluminum, etc.? If they were ferrous, you could use a magnet to extract them. I would guess aluminum, as that's the same as the rotor housing and would have the same coefficient of expansion.

IMHO, there isn't and will never be a "fix" for detonation. It's simple - tune the motor properly or get too greedy for power, and the motor WILL go. Horsepower is unfortunately inversely proportional to engine life. Not to mention I've seen a LOT of motors go from stupid stuff - big favorite is the vacuum line to the MAP sensor for a Haltech resting on the turbine housing, burning a hole - the ECU sees less boost, injects less fuel, and kablow. TWO motors locally have gone due to that simple oversight.

Personally, I've overcome the desire for huge amounts of power. I plan on refinining the stock setup, and having a lot of fun driving my FD instead of watching it sit in the garage. If insane power and straight-line acceleration is all you want, the FD isn't the car for you. If you want a balanced package that can handle, brake, and accelerate well and look phenomenal while doing it, that's the FD.

Dale

 

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The "theory"? Leave more fuel unburned in the combustion chamber by removing half the spark and you'll run far less chance of running lean and detonating.

The end result is roughly the same as running richer fuel maps The downside (to either) is a decrease in power, and decreased gas mileage. You can tune some of that out by leaning out the fuel, but not all of it, according to Roger Mandeville.

In other words, anyone who says they picked up power because of the anti-det "device" is full of ****. To make more power, you need to burn more fuel... not less.

 

Well said.

 

$500 for that? I've known several people that have blown motors with this modification. Some of them more than once. So really what's the point?

 

nevermind...

 

Why not just remove the trailing coil all together and put a dead plug in? Same thing and the added benefit of weight savings.

 

Beautifully put! If you want 550hp then sell the FD and buy a poopra! Quit trying to bandaid thru the powerband. You don't need 550hp to have a fast FD. Someone is always going to have more money/time/shop sponsorship/etc. I love driving my FD, not looking at it on the jack stands with busted ****!

 

Apparently there is no point.

 

This is probably one of the best phrases I've read yet. I've got a novel idea! Lets enjoy our cars!

If you want to sink an assload of money into a street car, where you can go maybe 100mph on the streets for a very minimal amount of time, maybe you should think about building a race car. Then you can go as fast as you want and not worry about tickets, someone changing lanes unexpectedly, someone pulling out in front of you....... For those of you that have not experienced it, Spec Miatas are a blast, and not too much money

 

I found my anti-det. I run 22PSI all day, take her to 7800RPM, I run Turbo Blue. There is a guy a mile down the road from me that has it in a standard pump. You pull up and he fills her up. Imagine that, in York PA.

I also have a 94 Octane 15 PSI setting too for those mellow days...

18 months, same engine. My days are numbered.