5% increased gas mileage

[RETed]

Originally Posted by Pete_89T2

Interesting thread... I'm currently running the stock ECU with the Rtek v2.x mod, and was toying with the idea of leaning out the off-boost/cruise part of the map a little bit to improve highway cruise MPGs. Basically looking to play with only those cells in the RPM range of 2000 - 3200, at MAPs deep in vacuum below 10 inHg (i.e., steady cruise, light load conditions). Unfortunately, I don't have anything to monitor AFRs or EGTs, so I'm a bit hesitant to screw with this. Is there any real danger here, presuming I do this intelligently, i.e., small adjustment increments followed by road testing to assess results?

No, you don't *need* to monitor AFR or EGT if you know what to look for...
It will help to have an EGT gauge though - you want everything to be burning at it's hottest temps - misfires will cause the EGT to drop.
No need for a wideband - I hate those things.
A narrow-band AFR gauge is "good enough" in my book, as it will tell you that you're at least LEAN and not RICH - it's cheap enough that it's no excuse not to have one, unless you already threw away your stock O2 sensor?

The idea is to lean the fuel out and advance as much as possible.
Realistically, you can usually only advance the timing up to 50 - 60 degrees of total advance.
Lean out the fuel up to the point where you can tolerate the "lean surge".

There is no danger in doing the above if you do go beyond the "ideal" range.
If you do lean it too much, the lean surge will get annoying - the car will buck noticably.
If you keep leaning past that point, the engine will stop firing.
It is a trick for emission to run ultra advance ignition timing to burn as much as the combustion as possible.
Just don't run more than 60-degrees, as this is the point where you start to fire into the other rotor - which is not that big of a deal since the prior rotor face is going into the exhaust cycle, but it's still not recommended.

This all should work if you're keeping to legal speeds.
This means that for most FC's, this should be under 3k - 3.5k RPM's.
Don't try to do this over 4kRPM's - we're talking about speeds approaching triple digits at this point for most FC's.
At this point, the engine is running fast enough to negate effects of early lean surge.
The engine is so smooth, you don't feel the typical lean surge, and the EGT's start to climb dangerously.
I guess a "disadvantage" of the rotary engine?
I've seen temps hitting 1050C and climbing...this is getting close to 2000F.
Sustained EGT's at this level will cause damage to the engine.


-Ted