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Old 26-03-2017, 08:03 AM
rotrex rotrex is offline
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Join Date: Jan 2014
Location: Germany
Posts: 187
Default Re: WMI tuning and results Part 2

DP should help here.
Your inlet manifold is not desiged for wet flow. Injecting a lot of fluid upstream of the plenum will have a lot of fluid running along the walls.
And this flow is not uniformly distributed among the cylinders. WW2 aero engines were designed for wet flow.
A good indicator are your cylinder trims. The more they increase with increasing spray, the less uniform the spray is distributed.
You might also get EGT related artifacts from big droplets passing straight through the engine and evaporating in the exhaust manifold. You might get more cooling from more fluid coming out of the exhaust port.

Unequal water contents across the cylinders will lead to unequal flame front speeds.
Cylinders with more water will hit max torque before the ones with less water.
This will flatten the power vs ignition timing curve leading to lower max power.

The methanol acts as a high octane fuel that is partly vaporized before entering the cylinder. It masks some of the distribution issues. This is the reason I believe many have better success with higher methanol content. They benefit form the high octane number, not that much from evaporative knock surpession in the cylinder.
If you run pure water, any issues in spray distribution show as knock on the cylinders that get less flow or the bigger droplets.

Any methanol that evaporates from heat extracted from the manifold or pipes leading to the engine will reduce air density. Any meth that does not evaporate from heat extracted from the air will cause no air temp reduction and hence no density increase. This effect is, as mentioned before, contributes only a part of the effect.
It works well for low flow rates injected in the front section of the inlet tract.
To get it to work well for higher flow rates, you need a very fine mist from air assited nozzles. Riceracing's setup is nice example.

With 350kw, you will need way bigger jets than 4 140cc jets for DP.


Air saturation is largely irrelevant at high methanol flow rates.
You do not gain much power by charge cooling outside of the cylinders.
You want small droplets within the cylinder for knock supression.

If you still get knock with DP before hitting best torque, increase flow rate.

Mount the jets on top of the manifold in line with the injectors.
If mounted elsewhere, the spray will not be distributed well within the cylinder itself, especially front to rear.
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