Risks to tuning rich or lean?

[brooke]

Discovered the rich/lean adjustment on my gas 13b rx7 the other night, and found with much amusement that if I richen it by two turns, it
Pours flame down to idle at the traffic lights, fun little feature.

It can also be leaned back by one turn from standard, and runs roughly the same, maybe a smudge less power, but more economical.

Is this doing any more damage/long term wear and tear to the engine compared to leaving it on a standard tuned mix?

[13bwankel]

yes
Lean mixtures = popped motor..
Rich mixtures = less power/higher exhaust gas temps. failures due to damage for extreme temps on seals etc (in extreme cases)

Generalisation, but you get the idea.

[brooke]

Perfect, awnser I was looking for, not good news, but means I'll be leaving it on a tuned setting.

Damn it. I loved the rolling flame look at the traffic lights

[mUnky-matt]

running rich actually lowers engine/exhaust temperatures...

not sure about the specifics for rotors tho...

essentially, the closer to stoich you run (closer to 14:1) the more power you'll make... if you don't run enough fuel (lean) you will run hot and risk detonation... if you run rich you'll run like shit, put tons of carbon on the insides etc etc...

so yeah, tuned is by far the best; you should have no reason to change it (im not sure how much adjustment 'one setting' is, but if two are enough to make flames at idle i'd say there's no need to touch it... if it were more sensitive you could use it to increase fuel efficiency on long trips/careful driving... and run rich on hot days for security etc..

[13bwankel]

well a retarded ignition timing causes the mixtures to go rich and the egt to rise. so I'm assuming that a rich mixture will also do that.

I know that a trick alot of manufacturers run a VERY rich mixture in cold start and increase egt so the cats warm up faster and work more efficently.

[mUnky-matt]

ignition timing is a whole new ball park... but mixtures are very simple... lean is very hot, rich is very cold... the running rich on startup is for different reasons...

a cat doesn't heat up due to the gas temperature but instead heats up due to how much of each reactant is available.. running rich will mean colder gas but it will be much 'richer' with reactive products and hence warm up the cat

[brooke]

Would be useful to lean it off for efficient driving, how much of a difference it will make is the real question?

How does one tune a LPG rotor in terms of rich and lean? With out a dyno or fancy gear

[mUnky-matt]

good questions to ask your tuner... not sure how LPG changes things

at the end of the day, there's no way it's worth the risk :P

[spinergy]

brooke, go see steve at Jazmac he can do a tune on your LPG with the dyno then you know its exactly right, then dont play wid it.

Cheers spin