J&S/PRE IGNITION INFO
10-09-2006, 03:36 PM
#1
Senior Member
Thread Starter
Join Date: May 2002
Location: California
Posts: 22,465
from http://www.rx7club.com/showthread.php?t=47...age=2&pp=15
Anyhow I've been using John's products since the beginning on both piston and rotaries and have always got good results. Every rx-7 I build and tune must have one. The idea of using the output of the J&S to a stand alone have been done before. Some people even got little boxes made to trigger relays,circuits etc. based on knock. I've seen one that cut power to the boost controller in the event of knock.
Most people still believe that ignition retard on a rotary is going to stop knock. It's not!
Here's a little clue to what helps a lot. The first thing the human mind does after hearing knock is to lift the right foot. Why not use the power and speed of the ECU to do the same. It's much faster than the brain most of the times
With that said figure out which program or programs in your stand alone ECU best suit the need. I have!
__________________
The difference between the Honda unit and the RX7 unit is primarily in software, relating to the engine cycle.
The RX7 version was always single channel, retarding only the leading plug, unless you ran zero split with a distributor. I have a three channel version in the works, but can't say when it will be finished. I'm in the process of switching all my designs to a newer Motorola processor, so it will be a while.
The cycle for a piston engine is two revolutions, compared to three revolutions for a rotary. To keep track of the knock in each rotor face, I programmed the knock detector as a six "cylinder", that fires every 180°.
I don't know why the engine blew on the dyno. It may have gone lean, and went into pre-ignition. Pre-ignition means the mixture went off before the spark, so retarding the timing further won't help.
Normal detonation happens at about 45° ATDC on a Rotary, so we have a knock "window" set up in software to listen at that crank angle. Pre-ignition happens at a different crank angle, before the spark event. Since spark retard cannot stop pre-ignition, we don't listen for it.
Bob Norwood called me a couple of years ago. He said, (paraphrasing) "I don't know you and have never bought anything from you, but I've had some high horsepower RX7's come through my shop, and we're talking 600hp, and the ones that live on the dyno have one of your units installed." Then he went on to tell me that he was tuning a Motec for a Honda race team, and thought it might be a good idea to get one and play with it.
Anyhow I've been using John's products since the beginning on both piston and rotaries and have always got good results. Every rx-7 I build and tune must have one. The idea of using the output of the J&S to a stand alone have been done before. Some people even got little boxes made to trigger relays,circuits etc. based on knock. I've seen one that cut power to the boost controller in the event of knock.
Most people still believe that ignition retard on a rotary is going to stop knock. It's not!
Here's a little clue to what helps a lot. The first thing the human mind does after hearing knock is to lift the right foot. Why not use the power and speed of the ECU to do the same. It's much faster than the brain most of the times
With that said figure out which program or programs in your stand alone ECU best suit the need. I have!
__________________
The difference between the Honda unit and the RX7 unit is primarily in software, relating to the engine cycle.
The RX7 version was always single channel, retarding only the leading plug, unless you ran zero split with a distributor. I have a three channel version in the works, but can't say when it will be finished. I'm in the process of switching all my designs to a newer Motorola processor, so it will be a while.
The cycle for a piston engine is two revolutions, compared to three revolutions for a rotary. To keep track of the knock in each rotor face, I programmed the knock detector as a six "cylinder", that fires every 180°.
I don't know why the engine blew on the dyno. It may have gone lean, and went into pre-ignition. Pre-ignition means the mixture went off before the spark, so retarding the timing further won't help.
Normal detonation happens at about 45° ATDC on a Rotary, so we have a knock "window" set up in software to listen at that crank angle. Pre-ignition happens at a different crank angle, before the spark event. Since spark retard cannot stop pre-ignition, we don't listen for it.
Bob Norwood called me a couple of years ago. He said, (paraphrasing) "I don't know you and have never bought anything from you, but I've had some high horsepower RX7's come through my shop, and we're talking 600hp, and the ones that live on the dyno have one of your units installed." Then he went on to tell me that he was tuning a Motec for a Honda race team, and thought it might be a good idea to get one and play with it.
Thread
Thread Starter
Forum
Replies
Last Post
2Lucky2tha7
Performance Mods
2
02-12-2004 09:34 PM
Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)