Fine tuneing ( EGT vs WB A/R )
 

What is better to fine tune a car with ?

EGT ?

WB A/R ?

WB measure air fuel... egt will also kinda do that... since the leaner you run the higher the EGT.

But when u play around with timing the WB AR ratio stays the same. but the EGT goes up or down. The more retarded the timing the hotter the EGT (if i remember correctly), i don't play with timing on a stock ECU

I have a turbo project coming up .....

Mazda BPT ( 1.8L DOHC Turbo, 210hp stock )

I am getting a Haltec soon after i get the engine in and running ... and i got to find out a good tuner and get this thing running at it's optimum.

What happens when you get to a dyno to get your car tuned ? The tuner ... does he use

A) both an A/R and EGT guage to fine tune it
B) do different people preffer different ones
C) does it depend what application is getting tuned

???

Hopefully A.
Use the WB the get your AFR down to 12.5, then adjust the timing based on egt, desired power, and the engines propensity to knock.
Good luck

For a Normally aspirated car, i think the desired AFR under 100% throttle and high load is around 13.0

for a turbo car i saw my friend run his audi with the tech wideband i lent him... they are around 10.7 to 11.0 under full throttle in high gear.

Tune fuel with a WB, Tune timing for max torque on the dyno............. EGT is Ok as a problem indicator while cruising, that's about it.
FWIW, 11.0:1 is good for WOT in 4th, I would not recomend leaner, although there are people who run 11.5-12.0 for a while ;)

I'm going to have to disagree with some of you guys AFRs.
12.5:1 is a calculated number to achieve maximum energy released from the charge. There is a very specific amount of air required to burn a specific amount of gas. Any more fuel than that and you are wasting gas.
If the engine is knocking at 12.5:1 then there is too much timing. You are not making any more power by adding more fuel.

With all do respect, I think running a Turbo Rotary at 12.5:1 is "asking for it" That said, my Supra is tuned for ~12:1, but it will aggressively pull timing upo any knock. as for 12.5:1, why wouldn't you run 14.5:1 to get that max energy you're talking about ;) Do you have a turbo rotary with a stand alone? if so, what afr do you see on a 4th gear pull on the freeway( not the dyno)? If you are at 12.5:1 at the top of 4th, how often do you run your car WOT at high rpm, in 4th or 5th gear? Also, how long has your car been run at these levels? Last I'd like to see your timing maps that you run with the 12.5:1 to educate myself. Thanks in advance, Carl

hmmmmmmm

Sorry I had some of my terms wrong. 14.5:1 is "chemically correct".
And I didn't mean to sound so hard nosed about the numbers. Anything from about 12.0-12.5 is what you should be shooting for. Once you get into the 11's... yes I suppose it's "safer", but you still aren't making any more power.
Good luck

nough said;)

i think he was referring to a piston engine with the 12s number.

Unless you're burning nitro-methane, low to mid 12's should work for any 4 cycle engine.

My NA 13BPP was tune for 12:1 A/R. if I get leaner than that I start loose power. since roatry burn so hot . a lot of fuel is to add to cool down the engine?
about the EGT and WB O2. I personaly like EGT better since acces of TRUE WB O2 is very hard and experience.
so is easier to get EGT gague and have shop tune with TRUE WB and mark the desire A/R and EGT all togeter
what I mean is depend on the location of EGT probe the EGT will change too. so you have to tune with A/R to know what temp is ur "ZONE". and one + site of EGT you can alway got two probe, so you can check F/R rotors EGT