I have a MS and a LC-1 wideband and i am wondering what AFR or Lambda values to put in the table for autotune. My idle is pretty much tuned and i'm using an AFR of 14.7 for low rpm & low map. Its mostly WOT that I am unsure of.

Also, how can i get the gauges to show Lambda vaues instead of AFR values. I changed the settings.ini file but they still show AFR.

Thanks
-ian

 

At the track I have run at speeds of 140 plus MPH at 8700 RPM. I have not hurt the engine with oil temps at 260 DEG coming out of the oil pan and 195 to 200 Deg water temp. With my street port I run 13.2 to 13.7 ratio and had no problems at WOT 100 MAP. At the moment I am trying to clean up my throttle coming out of the corners. It runs at 11.8 t0 12.8 and I can feel it trying to clear it,s self. Once she hits 5500 to 6000 then it runs 13.3 to 13.7 all the way to 8700 RPM. I know it's right because at the top end I catch all the big BMWs and other RX7 with larger Bridge ports. Others at the track say the same thing for the rotary do push pass 13.7 to 1 or you might pop a apex seal. Hope this information helps you. Happy Tuning.

 

You mean 13.7 to 1 AFR at WOT? Isn't it too lean? From what i know 14.6 to 1 is an optimal ratio for cruise, and offcourse for full acceleration it should be much more... Surely these numbers are for piston engines, but i can't see a reason why they shouldn't be optimal for a rotary...

 

rotaries actually like to run leaner than piston engines for max power when naturally aspirated. 13.2:1 seems ok to me, 13.7:1 seems a bit lean, but if it works then that's proof enough for me!

 

on cruise you can go as lean as you want really, as long as the engine runs smoothly. i do not have my MegaSquirt in the car yet, but using the stock ECU and an SAFC (with a wideband), i have my cruise at 16:1 to 17:1 at times. for WOT i'm going to aim for around 13:1. this is on a stockport NA. of course, it's hard to fine tune with just AFR, since you need a dyno to really optimize your power curve, but 13:1 is a good ratio on an NA. i would not run much leaner than that.

 

Thanks for the info, i'm dying waiting for next batch of ZEMS hopefully it will be soon enough.

 

BTW, what is the cheapest wide band available? And how long it lasts? I've heard from HiGGY that wideband's lifespan is much shorter.

 

if you are using a standalone, like the MegaSquirt, the cheapest way to go is to get the Innovate LC-1. www.innovatemotorsports.com

i got the Zeitronix ZT-2, www.zeitronix.com, which is a little more pricey, but it allows you to hook up to a laptop to datalog (afr, rpm, tps, boost, etc.). i'm happy with it so far.
the wideband sensors can get damaged if a certain temperature is exceded. so you shouldn't keep it as close to the engine in the exhaust system as the stock sensor.
they will still last a decent amount of time as long as you have it further down the exhaust system.

 

the LC-1 also allows you to hook up a laptop and datalog straight from the sensor. The MS also datalogs wideband data along with all the other engine parameters.

 

yeah, i should have been more specific.
what i meant to say, is that if you are using the LC-1 by itself, you will only be able to log AFR, and not any other engine parameters...which is kind of useless for tuning. but, if you have the MS you can log everything you need with the MS.

 

I went from 12.5ish at WOT to 13.5 today, and I noticed a LOT more power. I was a bit rich when I ran VIR last weekend, but was also under the assumption that lean == rotary death. Time to tune a bit more Thanks for the insight!

 

check out the PLX M-300

 

Mine still needs tuning, especially for low air temps, I was running of the lean side of a narrow band for about 10 miles no matter the throttle input, some lean surging, but nothing bad. I really need to get a new sensor for the LC-1 though, I fried the old one after 500 miles or so.

 

make sure you get the heatsink extender bung... otherwise the sensor will die

 

Here's a thread addressing this question. You may need to log in to read it:

http://forum.teamfc3s.org/showthread.php?t=38317

 

That assumption is true with boosted rotarys (not NA). The internal loads and pressures during knock in a NA rotary are know where near as violent as compared to when the engine is boosted.

 

I agree that the forces are not as strong, and the engines can take some weak pings and keep going, but still, don't knock at all on rotaries, I've even seen N/A engines toss apex seals :P

. . . .

Though I've seen my share of DENTED TII rotors. (A force strong enough to put a huge dent into an iron rotor, what makes people think 1mm of extra apex seal will matter at all?)

 

Let me guess, these NA engines that tossed the seals where probably the older engines with the older shitty 3 piece apex seals that would get so brittle they would even break if you dropped a used one on the shop floor? I would love to see a NA engine break a 2 piece 2mm or even a 3mm.

 

14.7:1 is the stoichometric mixture ratio for gasoline and air. in english that means that a reaction takes place best at that ratio.

in reality, 14.7 is only good for light load applications, because at higher loads, the fuel and air dont mix as well, so you waste some fuel, and therefore need a little bit richer ratio. in an NA car, you should never need to go below 13.0. in a boosted car, you throw in extra fuel to safeguard against detonation (although this isnt really the best way to do it, it is the easiest, and safer is better) so ratios can go as rich as 10 or 11 :1

basically, you want a relatively smooth fuel curve from about 14.7 or maybe even slightly leaner at full vacuum to about 13.5 at ambient. on an NA car thats it. boosted, you have another fuel curve for positive pressure, which for a beginner you would want to go from 13.5 at ambient to around 11 at 10+ psi.

tofuball a 3mm apex seal is 1.5 times stronger than a 2mm, which is a pretty decent upgrade. also, a rotor face is only about 2-3mm thick, and is made of softer material than the seals, not to mention the force here is actually a pressure, which means that there is much more force on the rotor face, since it has more area.

that said, i have abused the **** out of 2mm seals and not broken them, and in my personal opinion, 3mm seals are overkill. if you tune right, you shouldnt need them, and if you dont, you will just break something else.

pat

 

I think moderators should archive this thread...

 

thats was pretty good. I feel like building my, test dummy, 12a i have sitting around. Tune it to 13.2-13.5 , see what happens=)

 

I alway tune for 13.4 at 100 MAP with WOT. In my earlier message I said the range of 13.2 to 13.7. In some areas of my data logs I hit 13.7 with no problems. I found that any thing below 13 seam to be sluggish. It is a fact that at 13.4 it is the best ratio for power in a NA rotaries. This fact is based on racing data and dyno pulls. I have hit 14.2 under full load(Short test) and no major motor damage. But after a engine cut and then pulling all four plugs they were showing too lean. I feel that if it were to be held there I would melt plugs and hurt the engine.

Note any thing in the range of 13.5 to 13.8 will not repeat WILL NOT give you more power. This is just a cushion area before going to lean under load. Stick to 13.2 to 13.4. Below 13 you will use to much fuel and the engine will run lazy. Plus below 13 will build carbon on your apex seals and apex springs. I have pounded my NA 13 b four 3 years an at the end of each season I open it up. My main problem is carbon build up from warm up and at idle.

Timing at this load range is 26 Deg. total advance. You will never gain any more power repeat WILL NEVER GAIN with more advance than this just problems. Stick to the numbers and it will work I am fortunate to have a friendship with a fellow race car driver that has been building race motor (two, three and four rotor engines) for over 30 years. Street ports, PP ports, Bridge ports all NA engines no turbos or nitris.

Have fun tuning
RX7 RACER

 

Whats the highest egt i should be seeing on an n/a and a turbo that indicates lean conditions.

 

does anyone have the ranges for a stock turbo 13b ?
im about to do some tuning with a friend of mine and hes not to sure on turboed cars air/fuel ranges.. my guesses are: idel 800 rpm 16-17 / mid range rpm 2500(preping turbo) 13-14 /WOT rpm 7000-7500 12.8-13???
let me know if im close or need to make some adjustments thanks guys.

 

i dont think you will be able to get your car to idle at 16-17 afr. probably 12.5- 13.5 for a strong idle and no more then 14ish on the lean side. During cruise above 40mph tune for around 16. even leaner if the car doesnt buck. for boost to about 6 psi you should be around 12 on the safe side. and then higher boost should be in the upper 11's tapering off to low 11's at around 15 psi.

13 is too lean for a turbo car on pump gas in boost.