Testing Lean Burn on my RX8.

[Harlan]

I'm currently working on tuning for lean burn on my Rx8 with the end goal of 40+ MPG from a stock MPG of around 20. Here is a video on why I believe lean burn will work well on the rotary engine, and how you gain efficiency as you go lean.

Yes I could start with a different engine, but where is the fun in that! I'll post more as I get more data.

I done a few different tests so far and I will be posting video and results as I get it edited. So far I've seen a 20% reduction in indicated fuel consumption in idle, but I have not run the test long enough for solid data, nor is data at idle that meaningful anyway. I will be live tuning in cruise when I can get everything set up and recruit a helper.

https://www.youtube.com/watch?v=FnXWxXKPnH4

[oil pan 4]

Those things like to run rich at least under boost.

[pgfpro]

Great vid!!!

Looking forward to your findings. I have been running lean burn for about the last 10 years on a few of my cars. My most recent is my highly modified Talon. Check it out some time.

[Daschicken]

Do these things inject oil with the fuel, like a two stroke engine? If that is the case, make sure to modify the oil supply to get the same amount of oil as before lean burn.

[oil pan 4]

No they would never meet emissions even in china if they injected 2 stroke oil into the combustion process.
I have seen RX7 engines that were modified for racing to use 2 stroke oil, they smoked like a gigantic 2 stroke chain saw or weedeater.

[Harlan]

Originally Posted by oil pan 4

Those things like to run rich at least under boost.

They do, but a lot is unknown about tuning. I plan on finding out if there is a range of timing where they like to run lean as well

Originally Posted by Daschicken

Do these things inject oil with the fuel, like a two stroke engine? If that is the case, make sure to modify the oil supply to get the same amount of oil as before lean burn.

They don't inject the oil with the fuel, but they do inject it directly into the combustion chamber. In fact some people modify the oiling system to use two stroke (as it burns cleaner).

I have complete control of oil injection with my tuning setup, so it's not a worry.

[Hersbird]

Do any of these words embarrass you... Wankel Rotary Engine?

[oil pan 4]

Just be carefull these engines don't seem like they stand up to detonation and pre-ignition as well as piston engines.

[Harlan]

Rotary engines don't like sustained heavy (audible) detonation, but mild detonation at light loads isn't a big issue. At least I haven't found it to be a big issue.

I am running ion sensing for both detonation detection and PPP detection. And it can easily pick up mild detonation. I'm setting it up to both pull timing and reduce boost pressure when detonation begins, I may set it up to add more water as well.

[Harlan]

Here is the actual first lean burn test. As you can see it does reduce fuel consumption at idle, but it does not match up to my mental model. Need more research.

https://www.youtube.com/watch?v=ft2Gn68doRM