Damn - that is really bizzare!!

I agree. - more weird with I could paste the 13:1/afr trace onto it.

Richard

Ok, am I am going to think out loud here.

When tuning a turbo engine, you want to fuel in relation to the torque, not the horsepower. So, at high torque areas, you should runng a bit rich and as the torque drops, you can move the mixture to a lambda of around 0.85.

If you look at the graph from 2800rpm to 4000rpm (B to D) you can see that with WI the mixture was richer at this point and too lean without it. As a result, there was more power with the WI.

The extra rich mixture at the top end (G to J) is impacting on the torque hugely. As you can see, the WI was making it too rich because of the methanol content (was running 50/50). The run without WI got better results at the very top end. I think that if the graph went up to 6800rpm (limit) we would have seen it rise further.

I really can't work out what is going on sections E to G. It is possible that the AMM was not giving consistant results to the ECU and was fuelling differently on each run. Or maybe the cooler inlet charge helped keep the mixture leaner for longer when WI was running.

Richard. I will be recieving $1200 worth of kit from Inovate Motorsport in the next few days. I'll run some tests and log MAF, MAP, Lambda and RPM to produce some more graphs.

Oh - lambda is not effected by WI, the results for lambda is always correct as all it does is measure oxygen. AFR is not reliable as the stoichometric value of the fuel (due to the methanol) changes. AFR is a produce of the lambda mulipied by the stoichometric value of the fuel used, so you need to know this. If you stick to lambda figures you always know where you stand, even if you run methanol.

so 300lbft at 3000rpm need the same fuel as 300lbft at 6000rpm. Is that what you mean? :wink:

why does it go richer than 0.85 anyway?

lol - obviously you I meant Lambda, I guess I should have worded it better.


The Courtenay maps aim for 0.79 lambda for safety. A bit too safe I think though. Also, don't forget that the AFM was playing up a bit (we think).

Even lambda.
Why exactly would it have to be different?
Higher torque usually indicates better 'breathing' in that range, higher Volumetric Efficiency. More oxygen molecules per revolution.
So if fuelling adjusts to this, it will pair (say) 20% more fuel molecules to make up for 20% more oxygen molecules.
Lambda is just the ratio, it stays the same :wink:

The extra heat that might need absorbing in the combustion chambers (we're talking high-boost applications here) will be absrobed by the Water.
That is the whole idea behind this forum, isn't it? :D

we've already been through this, and it is 0.85 that we want in this case.
Their 0.79 is a good choice for a non-WI setup.

Yep - I will be aiming for 0.85 when I remap my car.

I'm saying this because I did several runs on mine on a hub dyno with various AFRs (I can adjust it on-the-fly)
Running rich 10-11:1 did nothing for power, and WI actually reduced power.
It's when you reach 12.5:1 that it starts to work properly.
It gets better at even leaner figures :shock:, but you may want to play it safe at this stage :cool: .

If you have you car maped for WI, will the engine run lean if the WI tank run dry ?

No, because I will have two maps which will be switchable. The low level sensor on the tank would automatically change the map to the safe version which will be designed to run without WI.