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Recirculating valve, supercharger, and no intercooler

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Hi,

i have some interrogations, but i'm unable to find any experience on this kind of setup :

i have an Ariel Atom with a K20a engine, and i added a Rotrex C30-94 supercharger, and decided to try a no-intercooler setup.

The supercharger is producing 14PSI of boost at 8100RPM, for a total of 350hp (at 8100rpm).

So, to cool the compressed air, i installed a AEM Water/methanol injection system, and the result is pretty impressive : i have acceptable IATs, and the methanol allows to run good advances without detonation on "SP 98" fuel (RON 98).

Because of the water/methanol injection post supercharger, i decided to use an external blow off valve : i wanted to avoid recirculating water/methanol in the supercharger turbine (it seems that it can damage the turbine?).

But since i have a supercharger, on idle / cruise, the valve is always opened and this is very very noisy.

So i want to put a recirculating valve just after supercharger, and just before methanol injection (so methanol does not recirculate in the supercharger).

But, what about recirculate "hot" air that has been compressed, that will be re-compressed again and again ?

Will i end up with very high IATs on cruise (when i go WOT, ok i will take fresh air) ?

Do you have any experience with this kind of setup ?

Also, where would you put the IAT sensor ? i installed it before the throttle body, would you put it before or after ?

Thanks

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That's an interesting setup and to be honest if you'd asked me before doing it I probably would have advised against it with no intercooler, so good work getting that sort of power!

I don't know how much of an issue the recirc will actually be with the WMI. The reason is that I'm assuming you're only injecting at or very close to WOT and under these conditions the BOV will be closed. When you lift off and the BOV opens, the WMI should be inactive. But it's not going to be a bad idea to fit the BOV pre WMI anyway. On a side note there are actually some real upsides to pre compressor WMI as it increases compressor efficiency. The challenge is that the injection needs to be very finely atomised to avoid damage to the compressor wheel over time. This is not something I've personally tried just to be clear.

Recirculating hot air is really not a big consideration since the moment you get back on the throttle the BOV will close and the supercharger will be getting fresh cool air. The only time the BOV is open is when you're off throttle.

The IAT sensor location is a little challenging with WMI because if you spray liquid onto the sensor you're going to get an unrealistic reading due to the cooling effect of the liquid (much like what happens if you put your hand out the window while driving down the road in the rain - your hand will feel colder than the ambient temp). It's not a deal breaker as long as you account for this in your tuning, and everything is a compromise. If you place the IAT sensor in the manifold where it's a good distance from the injection point you should get realistic numbers but then you introduce heat soak issues.

The only big concern is "what if the W/M kit fails" (low fluid level is unlikely to happen, i have direct sight on it, but a pump fail can happen, i need to install a monitoring + failsafe setup).

The Kpro/Honda ECU will cut the engine if the pump is failing since it will measure an un-acceptable lambda value when W/M is supposed to be sprayed, but a dedicated monitoring on the W/M circuit is a must have, to cut the engine before the lambda is going high. I will install it soon.

Ok, i will try a recirc BOV if it isn't really a problem for temperatures.

And i'll keep the IAT at the same location

Thanks Andre !

One of my biggest concerns with WMI is the system failing somehow so a failsafe is in my opinion essential. AEM's WMI kit includes a flow sensor that's used as a failsafe. you could perhaps look at something similar.