You're going to have to refresh my memory a bit. I've had alot of info pass through my head this week and my brain went on vacation for a while. I'll help out if I can though.

 

check out this thread, and let me know what you think

https://www.rx8club.com/series-i-tech-garage-22/getttin-dynod-today-69209/

 

negative split for dummies :D

As the rotor turns the air-gas mixture gets squeezed to the trailing corner of the chamber so firing the trailing sparkplug first will ignite this richer area of the intake charge.

This allows tuning for a leaner overall mixture than with positive split because it will still be rich enough at the trailing area to be able to ignite.

 

Thanks for the info RG! I knew about the flow velocity's importance in maximizing charge volume. What you said about the port's timing and shapes acting in concert with each other (and about cross-flow not being important with the intake ports) makes a lot of sense. I wonder if extending the closing of the center exhaust port to overlap with the primary intake would yield any benefits, esp. in terms of cross-flow? (Note: I'm not sure its even possible to do this without major surgery, just curious).

Regarding the exhaust, I'm confused by the relationship of each of the exhaust ports to each other, and how the pulses interact. It seems weird that the although the center exhaust port is divided, the header isn't (right?). I've never seen a header that joined two cylinders' exhaust so quickly, so I would think dividing the center tube to the collector would yield gains.

Also we don't have anything variable on the exhaust side. On motorcycles, I've seen butterflies placed in the exhaust to create variable backpressure (really to maximize exhaust velocity at all rpms). Would something like that work on the Renesis? What about blocking off the center exhaust ports until a certain rpm?

Regarding fueling, I don't see why not to run the engine in closed-loop all the time. Get a couple good WBO2 sensors and put one in each outer exhaust tube. This would allow the ECU to simply shoot for a target AFR at various rpm/load sites, and would allow for individual rotor trim (and maybe, for the creative, individual FACE trim). The only issue might be heat on the sensors.

I know some of the things I've mentioned can't really be quantified without testing, but I'm just curious if there is any theory or experiences that go against them.

Finally, thanks RG, for all the great info you provide on this forum. A lot of this stuff is NOT easy to find online or in texts. Some of us really appreciate it! You rock dude.

 

How did the weekend go guys? I am not in town so I dont know if the weather cooperated with you or not. Make any progress with the fuel maps?

 

I am having to redo our wiring harness. This is taking some time. The one we were using has been beat up pretty good already so I am just going to be safe and redo the whole thing. Go look at how many wires it has and then image what it much be like to solder every single connection. We usually only have a chance to try anything on the weekends anyways.

 

That's cool RG, was just wondering how things went. Good luck with the continued work.

 

Thanks RG ---sorry to get off thread. RX 8 guys are learning a lot and learning is good. We take advantage when we can! This is an interesting project. I have often wondered if an expansion chamber on the exhaust would help this car but I understand now how it would not.
Again thanks
Olddragger

 

Grassroots Motorsports writeup of Megasquirt in the October issue.

http://www.edgesavvy.com/megasquirt/

 

It seems like you guys have really lost all you momentum. You were making tons of progress, and now nothing new for two weeks. Have you been discouraged by the Interceptor being released?

 

Nope.

Just been working through some issues with my wiring harness and trying to fit the testing into some busy schedules. This isn't a Interceptor vs Megasquirt race. We aren't trying to compete with them. I for one think their system is a nice product, and offers people a fairly simple, reliable plug and play setup.

Not to mention, its August in Houston, and its pretty hard to work outside in 101 degree heat with 100% humidity. Not that the weather is totally holding us back, but I don't find myself wanting to spend hours tuning in the heat. We are going to get there, just have patience and keep showing support on the MS forum.

Thats a nice writeup on the MS. I highly recommend you guys read it.

 

Since we are waiting on the code to get written for the ignition, there isn't a whole lot to do right now. The code is almost done that will allow us to at least use the stock RX-8 ignition coils. We were facing the possibility that we would have to upgrade them but that will soon be solved. A very helpful MS coder is helping use out. Ken also has the trigger wheel worked out in pseudo code on paper right now. Hopefully he'll get to that after he gets us the code for the coils. Hopefully we should have that within the week although that is just a guess.

I am also redoing the wiring harness right now. It's harder than it seems as I have to personally wire about 100 or so wires. The hard part is that they are in 3 rows on the harness. Soldering the middle ones is a slow process that I can't afford to mess up. It is coming along very nicely though and is going to be a very neat and tidy harness. I also just got in the ignition circuit parts for my MS and will have to build it this week. This is all trying to fit into a very busy work schedule. The reason we were moving along pretty fast before is because we had everything up to that point already waiting for us to just put together. We are waiting for the rest.

EDIT, update! Straight from Ken's (the guy doing the coding) mouth:

"Update on the rx8 wheel decoder. I started writing the rx8 wheel decoder, and I've gotten most of the code written. I just have to add the code for cranking, and it's done. (well that and I have to buy a wheel and sensor, and test with them)."

 

wtf ! you guys havent done a thing for 2 whole weeks. damn get back to work for crying out loud

 

watch it or I strangle that cat of yours

 

Update:

Ken had a little time to code last night, so he went ahead and finished the cranking code, So now all he has to do is fix a bug he found (it would've made trailing ignition have problems).

He needs to add the option to the msns-extra.ini file for megatune so we can have it in the software, and of course test it all.

With any luck, In a couple of weeks we'll have a scope-tested rx8 wheel decoder with coil-on-plug outputs for 4 coils (the way rx8 is set up now).

Good news!

 

Everything is just sounding so great!

I'm vastly tempted to go start piecing together turbo parts!

 

we appreciate the encouragement, but I would hold off until we can show difinitive control of Fuel and SPARK. Spark being the critical part for you turbo guys.

we're working fast to get it up and running.

 

Hey Brillo,

In ABSOLUTELY NO WAY am I trying to hurry you, or pressure you and RG into havingi this thing ready asap. I'd rather it be done correctly than quickly. Hell my 8 barely has 3k miles on it... I was just thinking that the funds needed to turbo one of these the 'right' way in my opinion will take some serious budgeting...

Keep up the good work and try to stay cool down in Houston... its bad enough up here in DFW I can't imagine with Houston humidity....

 

No worries, I wasn't implying that you were trying to hurry us, I just don't want people to go spending what could amount to alot of money until we have something I can feel good about saying is a real soution.

and while I'm thinking about it, hookem

 

There won't be anymore news until next week sometime. Ken is out of town for the weekend and I am sick as a dog right now with the flu. It sucks.

 

Hook'em

Best thing about today...

TCU 17 @OU 10

It 7:00 PM CST and OU still Sucks!

 

Just thought I'd let you guys know about what is in store for the immediate future of the Megasquirt ecu in general. The Megasquirt was designed as a minimum bare bones ecu kit that controlled fuel only. There was no provision built in for added features or ignition. If you wanted these, you needed to find a way to build the needed circuits and then figure out how to add them in. Luckily there are people who are always trying to make life easier and realized this is difficult for the beginner. There is now a solution. The software has been updated nearly constantly to include new ouput features but the board itself has been very far behind. This is about to change. Here is a layout of the daughterboard. The second diagram shows what each section of the board adds. Keep in mind this is an upgrade for the current v2.2 version as well as the new v3.0. You just unplug the old chip and plug this in instead. Couldn't be easier. Everything is built in from the ignition conditioning circuits to many added output features. There is even open board space to experiment with new circuits if you need to. Check out the diagram. I'm sure you guys will be quite excited about what it can do and yes we could apply it to the RX-8 if need be. Total cost for this kit (not built) is around $65.

 

Will this be useful for NA RX-8s or is it really aimed at RX-8s with F/I?

 

Both, I'm going to use it NA for a while, until I decide what to do as far as FI.

 

The whole intent is to make it useful for the car period. It doesn't matter if it's forced induction or not. Any upgrades will always show more potential on forced induction because you have more power to show potential with. Makes sense. Hopefully we'll see a little better economy out of this as well as some power. Don't expect miracles though. You're not going to pick up 40 hp.