Air Fuel Or Exhaust Gas Temp Gauge?

[benmwhite]

If youre using either of these I'd be interested in your experiences as I'm planning to put one of these beside a boost gauge in the ute. The aim is to monitor performance and help me preserve my engine.

I have heard that the AFR gauges can be a bit slow to react and have seen modified gauges around that apparently "have had their internals expertly modified so that they display at 5 times the resolution of the stock gauge, with accuracy and incredible speed". This would assume the use of a narrow-band O2 sensor I guess? ...or do we already have one?! It sounds like a bit of stuffing around and I have read comments like "next to useless" and "enjoy the flashing lights" in some posts that came up in my search. Then again, if an AFR gauge can tell me if I have a dodgy batch of low RON fuel or that I'm running close to the wind with hight afr's, it would be a really valuable indicator that I'd use.

The alternative is the Exhaust Gas Temperature (EGT) or pyrometers gauge. This would be useful to not only indicate dangerous overheat conditions but could be used for monitoring the reult of the air/fuel mixture. Seems simple enough - but I wonder if the reaction time is sufficient to provide warning of overly lean ratios.

If AFR is the best bet, I'll probably go for Stewart Warner or Cobalt Autometer.

If EGT is going to do the trick, the Autometer Nexus will fit the bill (a large one at that once the controller etc. is taken into account!) - shame there isnt a Nexus AFR gauge!

Thanks in advance for any experiences or opinions you can share...

Ben

[Paradoxx]

There is a simple answer to this...

If you are interested in reading AFRs as a number... get one that displays it digitally.

Otherwise, all you really need is a simple bar graph, green for rich, RED for Lean. Anything more flashy than this is a waste of money IMO. Just needs to catch your eye when you are concentrating on the road... that's all.

[TURBO4LT]

Ive got the cobalt A/F guage in my car its good to give you a rough guide as to lean conditions.

[ZAP]

The Pyro would be my choice out of the options you have listed, but you may find a oil pressure or oil temp more of a practical gauge.

[cobrav8]

I have Autometer AFR gauge - and it is next to useless really. throttle hard down - and it reads rich, throttle off - reads lean, driving it flashes back and forth - I cant see how it can provide a useful reading.

[turbotom]

Get an electrical oil temp gauge...

Buy two sender units.

Fit one to monitor engine oil,

the other to monitor trans oil.

Have a relay to switch the signal between the two to the temp gauge.

In the ute, you can buy the sedan traction control/spot light switch.

It is ideal for adding a switch for the relay.... You can swap over the original push on/push off spot light mechanism for the momentary TC mechanism.... You can even swap over the bezels too. Looks neat like factory fit.

Having done that, you can monitor the two main lubrication systems which are affected by performance enhancements with one gauge.

Heat IS the biggest enemy of the BA turbo, especially in modified applications.

I have VDO gauges for boost and oil temp, set up like this.

From what I've seen and heard about AFR gauges, they don't provide good feedback. A data logging function of O2 sensor would be a better solution.

Just some feedback from my observations....

Peace of mind, seeing my oil temp never goes over 90 degrees even when choofing hard in warmer conditions (we had close to 40 deg C temps last week)

Trans oil has never gone over 60 deg C (but I have a large cooler)

I have a 150 degree C oil temp gauge, but now that I've used it a 120 deg C gauge would have been more appropriate.

Oh, and a Vac/boost gauge might be more appealing than a straight boost gauge.

Mine sits on zero a lot, doing bugger all whilst cruising.

Under slight acceleration, the needle oscillates against the end stop causing a vibration quite a bit. maybe its due to the boost control actuator... as I also get the "clicking" from the edit tune emanating under the firewall.

The next best thing will be data loggers hooked up to the CanBus (OBDII) port

It will provide logging capability and alarm functionality, and be able to provide a whole lot of data which is impossible with a real time analog display only.

Exhaust gas temps would provide a better indication of rich/lean conditions..... but you'd need to have a few dyno runs to collect the data to establish the relationship between actual AFR's and actual exhaust probe temp on your car. ( a better method is to have an exhaust probe on all exhaust port pipes, to monitor the distribution of fuel (AFR) to each cylinder. When pushing the limits for performance, an average "safe" AFR might still include a lean AFR on one cylinder

Once again, ideal solution is for a data logger system.

tom

[benmwhite]

Thanks guys for the great feedback - Seems the AFR gauge might not be the way to go for me in this case - a rough idea could be handy, but I'd rather use the spot for something a little more precise.

Good point about the pyro - I guess it is an average afterall and it only takes one leg to pop out of bed to make a mess under the bonnet.

Really like the idea of using a moentary switch for flicking between trans and oil temp - thanks for the benchmarks too - I also have a huge trans cooler - a worthy investment IMO - so that will be interesting.

I like that the Nexus gauges can be set to change colour at a preset level. This would act as an alarm of sorts when engine oil or trans oil temps get on the high side...

Once I settle on a decision, I'll repost with some pics.

Thanks again,

Ben

[Barry Blue]

I too have the Cobalt A/F guage, and to be honest, think that it is useless unless you intend to hold a disco night in your car. Sure it looks pretty, but not practical.

I wish I had got a auto tranny temp guage instead as it would be more useful.

But nothing against the Cobalt series as they look great.

Clarke

[Guest]

  turbotom said:

Get an electrical oil temp gauge...

Buy two sender units.

Fit one to monitor engine oil,

the other to monitor trans oil.

Have a relay to switch the signal between the two to the temp gauge.

In the ute, you can buy the sedan traction control/spot light switch.

It is ideal for adding a switch for the relay.... You can swap over the original push on/push off spot light mechanism for the momentary TC mechanism....  You can even swap over the bezels too.  Looks neat like factory fit.

Having done that, you can monitor the two main lubrication systems which are affected by performance enhancements with one gauge. 

Heat IS the biggest enemy of the BA turbo, especially in modified applications.

I have VDO gauges for boost and oil temp, set up like this.

From what I've seen and heard about AFR gauges, they don't provide good feedback.    A data logging function of O2 sensor would be a better solution.

Just some feedback from my observations....

Peace of mind, seeing my oil temp never goes over 90 degrees even when choofing hard in warmer conditions (we had close to 40 deg C temps last week)

Trans oil has never gone over 60 deg C (but I have a large cooler)

I have a 150 degree C oil temp gauge, but now that I've used it a 120 deg C gauge would have been more appropriate. 

Oh, and a Vac/boost gauge might be more appealing than a straight boost gauge.

Mine sits on zero a lot, doing bugger all whilst cruising.

Once again, ideal solution is for a data logger system.

tom

<{POST_SNAPBACK}>

GOOD ADVICE

[CnC]

For an accurate A/F meter you need to be using a wideband oxygen sensor. The standard 'crap' gauges like the Autometers use a narrow band input, as this is easy to translate into a value.

A wideband oxygen sensor requires a processor box to translate and correct the signal coming from the wideband oxygen sensor in order to display the correct, and accurate value.

If you are after something good, I would try the Australian guys TechEdge who make a really good value wideband A/F meter and processor combination. Check out www.techedge.com.au for more details. This will give you very accurate results as I have the same setup on my car and it was within 0.1 A/F of the meter that was at the dyno place (unigroup engineerings Autronic UEGO).

Regards,

Kris.