christian655321

iTrader: (5)

Here are some questions for the group, I’m just trying to educate myself on the entire AF deal, do you mind explaining the A/F ratio for our cars
(GTM stage II kit G37)
Questions might seem a little redundant but without fully understanding it I am not sure what to ask.
What should be the minimum AF range for turbo or non-turbo applications?
1. At WOT?
2. At idle?
3. Normal driving without going into boost?
What should be the max AF range for turbo or non-turbo?
1. At WOT?
2. At idle?
3. Normal driving without going into boost?
What is the BEST AF range to have for a turbo application?
1. At WOT?
2. At idle?
3. Normal driving without going into boost?

ANMVQ

iTrader: (13)

normal driving you will not be able to monitor it cause the air intake charge and metered air will change all the time and you will not see KR or have issue with normal driving, Part throttle and hard accell is what you need to worry about,, WOT turbo should be in the 11-12's range anything in the 10's is pig rich and high 12's 13's are a little lean( IMO).. If you get a tune shot for high 11's mid 12's you should be fine,, I was running my MS3 in the 12's at WOT..

Weiboy718

iTrader: (10)

Isn't it weird that we're F.I'ed and don't fully understand the basic's of the A/F LOL

christian655321

iTrader: (5)

I just got a pretty good lesson from alberto

Weiboy718

iTrader: (10)

I need to buy that hks knock amp

GraphiteG37S

iTrader: (29)

Your motor shouldn't be knocking anymore... LOL

Weiboy718

iTrader: (10)

Still good to have af gauge

ANMVQ

iTrader: (13)

Let me get this right you have FI and boost/Vac gauge or AF gauge, those are a MUST when you have FI. :/

christian655321

iTrader: (5)

I plan on taking it out tomorrow and checking to make sure it is still hitting the right AF numbers

i have these gauges in my setup

EGT
water temp
oil temp
AF
fuel pressure
boost\vac

Mike

iTrader: (1)

1. WOT - depends. Richer will run cooler, while leaner will run hotter. Leaning out tends to make slightly more power. Most FI applications will run rich to be "safe". Typical range you see is 11.5-13.0, depending on the engine and application. AFR can vary by RPM as well.
2. Idle: 14.7; stoichiometric, always. If you have very aggressive cams, this may be difficult, but that doesn't apply to the VQ37
3. under light acceleration: slightly richer than stoichometric, or stoichiometric. As you apply more throttle, it should get richer to whatever your target is. It's easy to tune for WOT. Partial throttle tuning takes MUCH more work. Most tuners only tune for WOT, and 'derive' from that.


Best? There is no best. It depends on your application. It is generally better to run cooler, rather than hotter, in the interest of not overheating, and longevitiy.

Weiboy718

iTrader: (10)

I have boost, oil temp, oil pressure. No AF yet, planning on getting one soon

Mike

iTrader: (1)

The only really essential gauges, IMO, are oil temp, coolant temp (or recalibrate stock gauge), EGT, and oil pressure.

If you don't have boost, you'll know. If your AFR is out of range, you should notice it when you're driving. You're not gonna be looking at those gauges as your driving.

Weiboy718

iTrader: (10)

very useful info Mike. Once my cash flow get's better I do have plans on getting the rest of the sensors for my hks camp2. I have a S/C and don't feel I really need the egt gauge although it would be nice to have one but I heard installing that thing on the header is The best location and worse part to get to for our car's.

Staples

iTrader: (9)

12s on a turbo application is lean, especially on a stock block, stock NA vehicle. You should be shooting for 11.5 - 11.8, maybe a little lower if you want to be on a conservative side, but I wouldn't go under 11.2.

As for your Mazdaspeed 3, I had one too that was tuned mid 11s, 12s would cause detonation and eventually bend / snap a rod which was well known especially when the car first came out since no one actually knew the limits on the block - 12 is way too lean especially since the internals were weak from the get-go.

Mkai0

Good post and good info. I had a 1992 Honda Prelude with a stock 2.2 SOHC motor that I turboed and kept in the low 11's (AFR). I ran that thing hard, and it was very reliable. I would say mid to low 11's on our cars sounds about right.