pcmhacking.net

Thanks for that link V6Bucket. Price was the same as the US with free delivery if you wanted. (I prefer registered post). I had a look at all the setups you all listed and ended up choosing the MTX by innovate. The gauge was really close to what I already have installed so it would fit right in. Thanks for the feedback.
Jon

Just a quick question that I wanted to see people's idea on. A friend owns a BF xr8 ute that has has countless tunes done to it and it keeps getting flashed back to stock because they can't seem to get it right. He was telling me the perfect a/f ratio on pump fuel is 12.5 for power and not the 14.7 that everyone talks about.
Is this true?

Its not as simple as a single number - 12.5:1 is quite rich and somewhere around where you want it at wide open throttle, 14.7:1 is stoich and good for light throttle cruising with hopefully as complete burn as possible with better economy (modern EFI systems actually lean out considerably at high speed cruise conditions but that's another story). There is a whole range of target AFRs throughout different engine conditions, in general these are similar numbers between engines but can differ somewhat depending on various factors.

It sounds like your friend is a bit one-eyed about his requirements, he's only thinking about maximum power and wide open throttle. Also if his engine is reasonably standard there won't be much to gain from a tune alone, the engine won't move more air without physical changes. The other issue is that a tuner who's not confident in his abilities will often err on the rich side to avoid engine damage, this can negate any small gains sometimes.

Plenty more reading to be found on the web if you want gritty details, just take everything with a grain of salt (including my post above!)

Yeah thats correct. You normally target 14.7, and use power enrichment or accelleration enrichment (terminology varies on different systems) to get the extra fuel when you hit the throttle. You do want 12.5 under load, and 14.7 normally for a normally aspirated engine. If you tuned it for 12.5 always it'd chew through the juice like nobodys business and thus not be a good tune. With most EFI systems you can have your cake and eat it too (or something)

Just about to install the Mtx from innovate but curious on the bung supplied with the kit. If I weld the bung on with its current length the sensor would only be in the exhaust about 3-5mm. Will that be enough? Normal O2 sensors are buried in a lot further. Not sure if I should cut the bung down a little to get more of the sensor tip in the exhaust pipe.

Shouldn't be a problem as the wideband sensor is heated.

Sorry, just got home from work and checked it again. It is flush with the end of the bung. If I hole saw a hole slightly smaller than the bung and weld to the outside of the pipe it would not even be in the path of the exhaust gases.

VL400 Edit: Resized ya pic

I would have thought some of the sensor has to be inside the exhaust pipe.

Whoa that is a long one! Ones like that are designed for when you have really hot EGTs to keep the sensor from overheating.
If you are mounting it in the usual position you can probably cut it in half.

I cut off a fair bit (prob half) before welding to the exhaust pipe so the tip of the sensor is in the stream.