Mazda3 Forums banner
1 - 3 of 3 Posts

· Registered
Joined
·
5,697 Posts
dang af of 15:1 it seems
you think thats due to the intercooler?
id be a tad nervous that you are running so lean in warm weather. I really wonder if thats somehow a function of the larger diameter cai or the maf sensor getting some bugged readings.
hopefully someone dyno's the mazdaspeed cai to get some comparisons becuase I dont see how the intercooler could make it so lean, but i dont know volumes about intercooler physics to rule it out either.
 

· Registered
Joined
·
5,697 Posts
[quote author=tuckaloe link=topic=71369.msg1255348#msg1255348 date=1173319079]
[quote author=CosmicBlueMS3 link=topic=71369.msg1255278#msg1255278 date=1173317522]
dang af of 15:1 it seems
you think thats due to the intercooler?
id be a tad nervous that you are running so lean in warm weather. I really wonder if thats somehow a function of the larger diameter cai or the maf sensor getting some bugged readings.
hopefully someone dyno's the mazdaspeed cai to get some comparisons becuase I dont see how the intercooler could make it so lean, but i dont know volumes about intercooler physics to rule it out either.
[/quote]

I'm not sure why everyone seems to think he's running "so lean". Must be a Mazda thing where we get comfortable at 10 and 11:1.

He's *crossing* 15:1 for a nanosecond at a given rpm on the way to 13:1. By 4000rpms, he's solidly at 12:1. From the programmable ECU tuning I've done, this seems nearly optimal. Granted, not much room for error, but his #s support that things are working very well. And considering the tempermental nature of the Mazda ECU, I've got think it'll prevent itself from hurting the hardware. Just dicing it up for conversation and exploration but it looks pretty good to me. At least we don't have rotor seals to worry over....
[/quote]

after my previous comment I wanted to do a bit of research on whats up because I found it very hard to believe that the intercooler was causing the leaner af's right before boost kicks in and I think I found the cause. GDI engines are unique and function differently than regular non GDI turbo engines. If you didnt know, our 2.3 DISI is a GDI :p ok, so you prolly knew that. anyway, I found a passage that sums things up better than I could in twice as many words.

Existing turbocharged multi-port injection engines suffer from turbo-lag, or the delay in boost response. This stems from the delay in acceleration of turbine speed when the throttle is opened, and is due to the slow turbine speed at low loads when there is only a small exhaust gas flow. The GDI Turbo engine, however, operates in a lean-burn mode at low loads, thereby producing almost twice the exhaust gas flow as an engine operating under stoichiometric conditions. The turbine is therefore already spinning at a higher speed when the driver opens the throttle to start accelerating, and so turbo-lag is significantly reduced.

I took the above paragraph from a Mitsu press release, it was extremely good reading (the bottom half) http://media.mitsubishi-motors.com/pressrelease/e/products/detail446.html

In closing, the leaner a/f is 100% cool, its on purpose and its ideal. Keep it rockin! :D
 

· Registered
Joined
·
5,697 Posts
[quote author=Kawwikid link=topic=71369.msg1255468#msg1255468 date=1173322751]
Cosmic,
thanks for looking that info up about A/F and GDI motor. It makes me feel a little better about the A/F ratio that im getting right now..... I had heard that the opt. A/F for a turbo car was 11.5 to 1[/quote]


no problem looking up the info, I enjoy sharing as much as I do learning about the cars we love. 11.5:1 is the a/f that many tuners use as a baseline, however stiochometric a/f for gasoline is 14.7:1 to achieve a complete burn (100% efficiency) which in a nutshell, is impossible since the fuel we get is not necessarily pure and when you toss ethanol and mtbe into the mix..... forget about it.
 
1 - 3 of 3 Posts
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top