Ok let the talk begin. I am relatively new to the FI world. I am running the Pettit kit with their flash. I have been running this car for about 4 yrs---usual mods before now. Many miles on the track
I am learning as this is my 1st rotary car.
So some questions i would like to throw out since i will now be taking my FI rotary onto the track soon.
1- what does detonation sound like in a rotary-- i know pre ignition /detonation in the recip but not the rotary .
2- does the rotary survive episodes of detonation. Or does any mean rebuild time.
3- in recips the higher the rpm the less likely detonation will occur (without some type of malfunction of course)--is this also true for the rotary?
4- Is our knock sensor sensitive enough?
5- what are some of the most common causes of detonation in the rotary? bad coild cause detonation or just misfires?
Easy on me please--I admit i am learning.
oscd

 

Ok good to know
oscd

 

beers

 

anyone got sound clips?

 

I have also had it explained as sounding like sand being shaken in a coffee can.

 

+1..

 

Sand in a can? lol

More like marbles in a can.

Maybe your talking about the "sand in a blender" issue some 8's have at higher RPM's.

http://www.youtube.com/watch?v=bm3NcgTnmRk

 

...hmmm....Well it depends were you got the sand from. It cant be hourglass sand. PR sand is white but the actual grains are pretty big compared to fine sand, this is what I speak off. I guess small marbles in a can or shotgun pellets in a can would work too.

Chris

 

i will say that when you hear it, you will know what it is..

chris some insight on ? 3.

beers

 

sand grows up to be marbles ...

 

Absolutely true on all combustion engines, even turbines. When they are going faster it gets harder to cause detonation. The flame front propagates at a more or less constant speed regardless of rpm(assuming constant AFR) but the rotor's/piston's speed increases with the rpm making the engine less and less prone to detonation. This, of course, assuming constant manifold pressure and intake volume per explosion(not exactly a constant but close enough for it to work similar to theory)

Chris

 

Sounds like about a hand full of grade 6 bolts being dropped on smooth concrete floor. Come down here in the summer and let your car idle at a light and then hit 5000 rpm. Like music to my ears.

 

yup - that will do it alright . Get those intake temps up high enough and wham bam kablamo

 

but in terms of volume, it is hard to miss right? say, if you have the windows down at 50-60mph would you still hear it?

 

fixed

 

^ i realize no one would make clips on purpose, but i figured someone might have dyno / tuning video footage where detonation happened to occur...

jeez, pulling no punches tonight

 

The various descriptions above are very good. It is a relatively loud sound, but so unusual, you will probably not undertand it the first time you hear it until after you think about it.

Very often, yes. Motors that fail immediately usually do not experience a "sustained" period where the "pings" are rapid and multiple as is described above. The kind of detonation that destroys an engine is usually a single, loud "tink" and then conplete loss of power.

Detonation in the Renesis happens in pretty much only one place - 5200 to 6100 RPM. Its possible for it to happen lower, but only a failure of the fuel system (bad injector, bad fuel pump, etc.) may cause it to happen higher.
It does become very hard to cause detonation after 7200 RPM.

The knock sensor is completely ineffective.

If a leading coil is failing and you are only igniting the charge with the trailing coil, you can get some pretty nasty detonation. Fuel quality is your main variable with regards to detonation. Most of the time, we are running around on the ragged edge of detonation because of variable fuel quality.

Really, all you can do is prepare the tune to prevent detonation. Once you experience it, there is nothing you can do about it at that moment. Either you luck out or you don't. Just lift and pray.

 

The main issue I think about all the time is my fuel filter clogging ever since I started to premix. The last thing I need is a blown engine.

I have spent many hours reading about the issue and talked with olddragger on the rotary4life forum. It seems I should never let my fuel tank go bellow 1/2 tank and that I should never mix FP60 with premix at the same time.

I really wish our fuel filters could be replaced easily!

 

That can. You just have to do the pump along with it (unless you are crafty).
Mazda only wants $150 for the pump assembly, so just think of it as insurance against a pump failure.

 

If your coils are bad and one of your leading stops firing while under load, the trailing will fire and you will suffer from a really bad ping(ask me how I know ...). This is the only instance where coils would cause such a thing. Although if this is going to happen you would probably notice the car is misfiring and wouldn't be accelerating it hard anyways....

Chris

 

How do you know?

 

How often do you replace yours?

 

<< nice plug

 

My car is pretty loud with just a midpipe, you can really hear the engine coming from the center column. So detonation would be louder than this? How much louder?

 

When you go FI your car will sound like it still had a Cat on it. The turbo really takes alot of the loudness away. It will turn into a deeper, toned, growl as opposed to a raspy sound like stock. You'll be able to hear it.

Chris