boosted

Hi, I'm after what AFR you guys are tuning to (with wideband set to 14.7 equals lambda 1, ie petrol AFR)
With normal v power I'm shooting for 11.5:1 on boost high load.
With 20% methanol in the tank what should I be aiming for? Thanks

boosted

A wee bump for this thread, I was lead to believe that this was the most common method used by impreza owners, be nice to hear from someone that had tuned or datalogged their 20% meth AFR.
By my maths, 11.5:1 on 80% petrol and 4.4:1 on 20% methanol is 11.5x80=920
4.2x20=84 84+920=1004/100
Equals 10.04:1 AFR.
Is that correct?
Or because the AFR gauge is set to petrol AFR (lambda x 14.6) do I just add the meth and re tune to 11.5:1?

john banks

I would shoot for an indicated 12.0 and see how it responds. The AFR is much richer of course, but the sensor and its display invariably report petrol AFR, or just think of it as lambda. Any leaner and you really want to carefully consider your spec, EGT etc.

I found little extra gain from 20% vs 10% methanol relative to storage and refuelling requirements.

boosted

Thanks, just been reding this thread;
https://www.scoobynet.com/935550-afr-readings-2.html
Late great JGM says 12:1 too.
What cruise AFR you aim for? Still same 14.7:1?
So you recon there is no real advantage with 20% over 10%? Interesting

john banks

Yes I would still aim for indicated 14.7 at cruise unless I was running a fancy setup with closed loop wideband lambda and no cats in which case you could try leaner for economy, but that is no different to petrol.

My 10 vs 20% decision was based around a daily driver and the practicality, convenience and legality of storing and carrying enough methanol, plus the odd looks at the petrol station when you have to add two containers to a fill up.

boosted

I will be running closed loop wideband John, full standalone.
So if I chose a 10% mix what AFR on boost do I aim for?
Also can you still put some timing in to take advantage of the meth? 2-3 degrees instead of 5?
Thanks boosted

john banks

I added 5 degrees with 10% methanol, about 11.8 on the AFR gauge. If you are standalone there is no hassle to make lots of small changes.

I did not come across it, but with enough alcohol depending on your spec and boost you theoretically might exceed MBT.

Have you considered just using race fuel?

boosted

Exceeding MBT and not knowing due to road tuning? Therefore passing the sweet spot and actually loosing power?...
Race fuel? This is a daily driver, has to be cost effective.
I like the idea of 10% meth, that's 5l on my weekly fill.

john banks

Yes. Yes and stressing the engine. Unlikely but you have clearly considered it.

Remaining issue is how to safely store the methanol? Don't know whether it comes under the petroleum regulations but your house insurer might not be impressed. I stored it in outbuildings, that are far from anyone else, but connected to one end of the house through other outbuildings and through which the main power supply came in so still not ideal.

boosted

Storage isn't a problem, I have quite a bit of space outside. Probably put it somewhere, that if a leak were to happen spillage would not effect the house/garage.
A mate of mine has an IBC with 1000 litres of methanol in it stored with several ibc's full of veg oil, not that far from where I live (far enough!) May or may not be a good idea to put it beside my 1200 litre central heating oil tank. I'll think about it.
Thanks for the good conversation this has provoked