I have searched and searched and I have many gaps in my understanding of engine tunning. I can put together and disassmble cars with the best of them but I am totally lost when it come to tunning. I mean some **** seems to be be so basic and yet I don't know it so please help me understand some simple concepts. I want to understand so i may learn it for myself.



Ok 11:1, 11 is fuel and the 1 is air?

What is the significance of knowing what the a/f is as exactly.

Is 11:1 universally the standard for all engines?

What would be the diffenrec between 11:1 and 10:1?

Pretend I don't know **** for a second. https://www.nopistons.com/forums/pub...IR#>/smile.png



Ok next the basic theory to tunning a rotary is....



advancing the timing and subtracting fuel till you detect detonation.

Then retarding the timing a few degrees and adding fuel in 2% incraments until detonation is no longer present correct?



Also when adjust maps, What exactky is the procedure?

Do all rpm ranges need to be adjusted?

Are the adjustments made only in idle/part throttle and WOT?

Does the fuel curve have a set guide line that needs to be followed?

If so please explain.



Does anyone understand what the hell i am trying to say?

Where the hell is Steve Kan when you need him https://www.nopistons.com/forums/pub...O_DIR#>/11.gif

Please help me not feel like such a dumbass.. https://www.nopistons.com/forums/pub...#>/biggrin.png



-D.

I'll start .





11 is the air and 1 is the fuel .



Tom

I think Tony ( Badog ) would be a great wealth of info, it he were willing to post here.





Tony ?





Tom

11:1 is the ratio of air to fuel. so its 11lbs of air to 1 lbs of fuel. this is measured by the oxygen sensor in the exhaust. although there are other ways to measure it.



the afr number by itself doesnt mean a lot, basically on a motor with no detonation you want the mixture to give either the best power or economy, on an rx7 we also have to think about safety.

different motors will want a different afr. the nice thing about afr's though is that it gives you a number to compare lean vs rich vs something in the middle.





when you play with maps if you have all the tools you wanna tune the fuel first and then tune the ignition with an egt.



the fuel and ingnition does not have a set curve to follow, it will depends on the power curve of the motor. vosko was telling me about that the other day, his car wants a ton more fuel over 6k than it does under it. you just want to give the engine the afr that its happiest at



the idea behind ignition timing is to get the biggest part of the pressure rise in the chamber to happen right after the piston/rotor passes tdc. if the timing is retarded you loose efficency because the chamber volume goes up and you dont get as big of a "push". too much timing and the piston will have to push against the pressure in the chamber.



if you can, play with this stuff at idle and light load see what it does, if youre not under boost its hard to do any damage



mike

So mike is TDC, exactly that?

Top dead center of the apex seal straight up at 90degrees?

If not then how does one determine top dead center?

How is an EGT used to tune ignition specifically?

And am I to understand that 11:1 is a more lean condition than 10:1?

And how do you determine afr's?





Also,



Thanks for helping. I'm gonna be asking alot of retorihcal questions so bear with me. https://www.nopistons.com/forums/pub...IR#>/smile.png

yes, 11:1 is more lean then 10:1

tdc is the point where the face of the rotor is closest to the spark plugs.



if the timing is too retarded combustion happens too late, thus its still burning in the manifold = higher egts.

if its too advanced you get hight egts too but i dont know why, i'm gonna tyr and dig up a couple of articles, i dont know everything either



yes 11:1 is leaner than 10:1



you can determine afrs at least 3 ways



1. with an oxygen sensor in the exhaust. this picks up oxygen in the exhaust gas and generates a voltage. it can be fooled by misfires, a misfire looks like full lean to an 02 sensor.



2. on an engine dyno they can measure the air and the amount of fuel going into the engine. i dont know a lot about how this is done but it strikes me as better bcause o2 is not the only thing coming out of the tailpipe.



3. with a smog machine, it gives you all the data if you know how to read it



dont worry about it, the more you know the better off you are



mike

on an dyno, they use a wideband o2. it's a five wire o2, which is much more accurate than a 2 wire. i believe thats the only difference from a regular o2.

on an dyno, they use a wideband o2. it's a five wire o2, which is much more accurate than a 2 wire. i believe thats the only difference from a regular o2. [/quote]

oh sorry i meant engine dyno, where they can acutally measure the air and fuel as its going in to the engine



mike

ah, i have no idea how those work

What exactly is a wideband and what does it measure?

TDC is when the face of the rotor is closest to the spark plugs meaning parrallel or when the apex seal is on its approach to the plug and just past?

I assume that when the entire face is completely parallel. I just want to clarify so i don't try to learn off wrong assumptions.

And if both conditions (to retarded and/or to advanced) produce high egt's how does one tune the ignition off egt? You lost me on that one. Also when you say "playing" with fuel. How exactly do you mean?

Subtracting fuel at 4% intervals. If not 4% then at what percentage is the standard unit of deduction/addition?



Thanks for hangin in there Mike.



Anyone else care to help Mike explain all this to me?



Oh and great answer Bobby https://www.nopistons.com/forums/pub...IR#>/smile.png



D.

thats tdc

https://www.nopistons.com/~j9fd3s/al...dd1b330ab1.jpg



in regaurds to egt theres a range where they are low, and if you get too advanced or too retarded they go up. or to put it another way theres a happy spot



playing with fuel, ive heard 3%, but 4% is fine, theres no real standard, its just whatever you are most comfortable using. 1-2% is prolly too small to feel/see, and over 5-6 can be dangerous if you dont know what you are doing.



keep asking away, i'd like to learn something too https://www.nopistons.com/forums/pub...#>/biggrin.png



mike

That's a WONDRFUL photo of TDC https://www.nopistons.com/forums/pub...IR#>/bigok.gif



Tom

yah, ive had to use it a few times



mike

A 14.7:1 air-to-fuel ratio is stoichiometric, or a situation where all fuel and all air are being burned in their entirety. Most high performance engines are tuned with a richer a/f ratio in mind to keep, at bay, any detonation that could possibly occur. Rotaries, of course, seem to like an even richer a/f ratio, as the extra fuel aids in cooling I believe. Plus, for the most part, the richer your a/f ratio, the more guarded against detonation you are even though a sacrifice may come in the form of not so optimal power outputs.



Interesting stuff this is.



Not sure if this has been clarified already or not: the higher the EGT temperatures are, the leaner the car is running. On a diesel this is the exact opposite, as higher EGT's dictate excessive fuel.



High EGT's on a gasoline motor = too much air and not enough fuel.



High EGT's on a diesel motor = too much fuel and not enough air.



Of course, timing is also a part of the mix which must be considered.

yeah bascially you're running a turbo rotary rich and using the extra fuel to keep the chambers cool(er)



mike

heres some reading



http://www.misterfixit.com/deton.htm



http://www.oldengine.org/members/diesel/Mi...isc/Ricardo.htm



http://www.howstuffworks.com/question257.htm

http://www.streetrodstuff.com/Articles/Sep...ne_Basics_I.php



http://www.classactt.com/actt/actt_main/do...cal%20Paper.pdf



http://reaflow.iwr.uni-heidelberg.de/~icde...001-050/050.pdf

another



http://yarchive.net/car/knock.html

I now the bit about running lean and det, but the same person told me that if I was running to rich, I could also get det!



Is this correct or are they talking crap?



Dan

they are prolly right, i read a really good article a couple weeks ago, i wish i could find it. bascially detonation is a chemical reaction, that needs lots of heat



mike

Thanks for the info guys.

Mike let me get throuigh all those links and then I'll be back with some more questions Im sure.



Turborotor, can we get a pin please.

D.

So if 14.7:1 is stochiometric then my car being tunned 11:1.

It's quite a bit more rich than stock maps.(i assume that stock maps are supposed to be tuned to stochiometric?) I'm starting to make sense of it. https://www.nopistons.com/forums/pub...IR#>/smile.png

I'll throw in a few things i learned



timing should be retarded the most at the peak tourqe and can be raised again after peak torque to keep the egt temps stable.Also find out what the safe egt temps are for a fd...for idle/cruise and wot.



about tuning timing with a egt...lets say at idle your a/f is 13.5-14.7 and your egt temps are a bit high.because the fuel is set at a reasonable mixture at idle,you dont want it any richer,you would keep a eye on knock and raise the timing at that rpm point to lower the egt temps,i dont see someone having a/f of 11.5 at idle..theres only so much fuel you can dump in,into a engine.so set the fuel,then timing and always keep a eye on KNOCK!!



most ppl put egt in the exhaust manifold and if got someone elses map id look it over first and compare it..Also use the powerfc boost controller to raise the boost a few psi at a time to tune and dont just hit it at 15psi or w/e..im learning alot myself because i have noone at all to help me tune my car...



Hope we keep this thread going...

Air:fuel ratios fluctuate depending on load, boost, rpm, tuning, etc. Mazda may have tuned for a near 14.7:1 at idle but I think they are around 9.5:1 or 10.5:1 under full load in stock form.



I've only seen a few runs on the dyno with stock cars and wide band air:fuel meters hooked up.

How does a wide band display info?

Does it tell you the exact afr?

Yes.



Let me re-state. Exact to within whatever margin of error the wide band is calibrated for I would imagine.

It displays voltage correct? i.e. 4volts = 14.7:1 stoch.

You need to know the conversion as I understand it.

Is there a site that has that chart?

Where did everyone go?

heres a map of the stock ecu tuning zones



https://www.nopistons.com/j9fd3s/alb...a5e11_high.jpg



in the light load and idle zones the ecu is gonna run in the 13's as far as afr

in the feed back zone its gonna run off the 02 sensor, so its gonna be 14.7:1 +/- .4



in all the others it runs 9-10's to be safe



mike

Nice find Mike,

Is that from the factory work shop?

If so what section is it under?

its from the 93 rx7 service highlights book, i think you can still get it. it explains how stuff works and why they used it pretty neat. the rx8 service highlights book has a goood section on that too.



the fd book is pn #9999-95-045f-93





mike

Thanks.

I don't have any questions at the moment, but if any one can contribute please do.

lots of good stuff. again i figured out alot and asked tons of questions to all the gurus i know https://www.nopistons.com/forums/pub...IR#>/smile.png

they make kits that convert it for you.



what EMS do you plan on running? Wargasm has a good setup with the PFC, datalogit and wideband.

Not sure yet, But when i get around to doing more with my car next year. I will need more fuel so the purple box i have now isnt gonna cut it. I've been browsing the AEM forum and it looks liek a cool ass unit. Its either that or PFC so far. But I am not serious about buying anything at the moment. I have to learn hoe to go about tunning my car first. My last tuner turned out to big a Big jack ass that I can't stand now so I'm starting the learning process on my own as far as tunning goes. Hopefully my car holds out till i learn. https://www.nopistons.com/forums/pub...IR#>/smile.png

i think what you will find is that all the different systems have their pros ans cons and you need to decide witch one is the best fit for you.



FOR EXAMPLE

the pfc is a super easy install, and runs the stock stuff, but its a little harder to tune cause you need the datalogit



the tec3 is harder to install, its more invasive to the car, you have to mount the coils, and the ecu, the software is intimidating, but it gives you lots of options



the e6k can be easy to install, it will run all of the stock stuff if you want it, its easy to program, the interface is simple. its a little limited to the amount of stuff that it can run (fans/emissions solenoids etc)





mike

The PFC is easy to work with when using the datalogit. Wargasm plugged his datalogit and wideband into my car and we did some tunning a few weeks ago. The software is really simple, and as long as you arent refarted with computers that would be good. I picked it up pretty well after a few hours of tunning, even being the driver https://www.nopistons.com/forums/pub...IR#>/smile.png





aww did you and mr rikki have a fight? j/k https://www.nopistons.com/forums/pub...DIR#>/wink.png

you can down load the manual for the haltech at the haltec site, i think. i read thru that, i understand a bit more about tuning, its haltech specific, but its still helps.....

yeah they just put everything up, go to the downloads section



mike