Sweet
haha, get on it!
Right, arranged to have a cylinder leak test over the weekend to verify the rings are all fine and then it's back over to Bill sometime next week to check the oil pressure with a manual gauge kit as well as stock back up on some methanol.
Speaking of which...as per
this earlier post I've been doing some further reading into water/methanol concentrations and am now curious as to whether my particular setup would benefit from a more water concentrated mix. Stick with me on this one...
Bill has mapped the car with no fuelling adjustments made for the WMI, meaning that it's contribution to fuel is "on top" of what the ECU tells the injectors to throw in. This effectively means it's contributing to a rich AFR on boost, erring on the side of caution with regards to controlled EGTs and ensuring I don't run lean and starting melting expensive things. All well and good, especially as it means my fuelling will remain OK should the WMI fail for whatever reason (already happened once).
However... I've always used a 50:50 mix of water/methanol on the understanding that water offers a higher latent heat of vaporisation than methanol, making it more efficient at cooling - particularly inside the combustion chamber. Methanol on the other hand is a fuel with a high octane rating of 116, meaning it can be burnt safely under higher cylinder pressures to make more power.
So, the theory as I understood it was more methanol = more power, and we use water to offer greater temperature control. Being a fuel, methanol is combustable giving it _potential_ to be used to make more power, water is not. The key word there being potential, i.e. under the right conditions.
A high octane fuel won't automatically give you more power, it must be used in the right conditions to yield any gains, remembering that the octane rating is only a measure of how resistant a fuel is to detonation. That's why filling a 15 year old 1.1 Fiesta is unlikely to see any power benefit from VPower; it's only when we can tune the car to utilise the _potential_ the high octane rating offers that we can see any performance gains. In the case of the Cupra using the ME7 management, fuelling and timing can be dynamically adjusted over time by the ECU to make more power by adding ignition advance.
The higher the octane mixture of the fuel being injected into the cylinders, the more resistant to detonation it becomes and the more advance we can run, until cylinder pressure is increased to such an extent it ensues knock. Power can also be made by adjusting the AFR in accordance with the extra methanol being burned, as well as the potential to run higher levels of boost without knock.
If we apply this theory to my setup; the methanol itself is not being accounted for in the fuelling set by the map so I am simply running rich under boost. My turbo is also already running as much boost as it can possibly produce; so there's no gains to be had there either. The only way I can make more power from this setup (without adjusting fuelling so as to rely on WMI; not clever) is to advance the ignition timing.
To advance the ignition timing I need an optimum concentration of water/methanol that prevents knock. With a high octane count, methanol does contibute towards this; but not as much as water. While water doesn't have an octane rating, it does have a much higher latent heat of vaporisation making it much more effective at controlling combustion temperatures and preventing pre-ignition. This means it is still effectively increasing the overal octane rating of the mixture, more so than the methanol alone.
By using a higher concentration of water to methanol my logic is that I can better control cylinder temperatures to reduce knock and achieve more ignition advance than a 50:50 mix. It's allowing more knock-limited performance. Consequently, the reduced concentration of methanol in the cylinders will result in a slightly leaner fuel mixture achieving a higher efficiency of combustion; all resulting in more power. As the fuelling in my map isn't being touched there's no risk of running lean should the WMI fail; I'm simply adjusting the margins to maximise power from my particular setup. As my RR results show AFRs dip into the 10s then I believe there is plenty of headroom.
From what I have read it seems that methanol is more effective at cooling IATs in the intake track whereas water is better at controlling combustion temperatures. Ergo, if I log IATs and CFs while adjusting my WMI concentrations and keeping an eye on my wideband it should be possible to fine tune an optimal balance.
Whether this equates to real world figures is another question, but if every 3 degrees of advance accounts for ~10 BHP then it's entirely possible.
For anyone interested, this is what I have been reading over:
http://www.my350z.com/forum/forced-induction/446954-have-a-water-meth-kit-come-in-here-4.html
http://www.aquamist.co.uk/vbulletin/showthread.php?p=13107
This one is probably the most relevant to my above rationale:
http://www.aquamist.co.uk/vbulletin/showthread.php?t=1334
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