Twincharger
Turbo Mini Forums

Some may have seen my project on FB but I thought it may be interesting to post on this forum.

I turbocharged my engine around 15 years ago now and updated it with an IHI turbo to improve lag over my old T2. This definitely helped but I was never completely happy as it still had some lag. I built a larger 1360 higher compression engine as well which helped a little but still not enough.
With the improved electric motor technology available now I thought I would give it a go and make an electrically powered supercharger to act as an anti-lag device.
After doing a fair bit of investigation I decided upon the specification which was to take the compressor housing and wheel from a mid sized Diesel turbocharger and attach it to the state of the art high speed RC motor. This motor is capable of delivering 8kW @ 100000rpm, theoretically enough to supply around 0.7-0.8 bar boost before the exhaust driven turbo takes over. However it requires around 300A @ 24-26V to do this and thus necessitated an appropriate battery which I chose small AGM type rather than LiPo for ease of installation and onboard charging.
There were several challenges to overcome, the main one being mechanically connecting the motor to the compressor wheel reliably.
This actually proved reasonably easy but the shaft had to be machined to an extremely high tolerance in size, straightness and concentricity otherwise it would likely destroy itself quite quickly at 100000rpm!
The other challenge was making a control system. Again with recent advances in technology, this was not too bad. I used an Arduino based controller with throttle position, engine speed and boost pressure as the inputs to determine when and at what rate to turn the motor on and off. In addition a valve was obviously required to bypass the supercharger when not in use otherwise there would be a considerable pressure drop across it which would compromise the efficiency of the exhaust driven turbocharger.
Overall there has been minimal development required and the system works seamlessly. The difference with the system switched on is huge. The supercharger accelerates to 100000rpm in just over 0.1s, about the same time it takes the bypass valve to shut. Hence boost (0.7bar is achieved which is pretty close to that calculated) is instant and the engine feels like an N/A with no discernable lag at all. I guess some people may like the character of waiting for the boost to come in but I don’t.
Another byproduct of the installation is jet engine-like noise as the supercharger is activated. Very amusing!
I guess I could put a larger turbo on now and go for more peak power but I am pretty happy with the result so I think I will leave it as is.

Edited by matnrach on 30th Sep, 2023.

Very cool engineering project!

Dazed and Confused....

Brilliant! Excellent engineering and a great result.

'Where does the engine go?'

Love this idea.

There are some OEM cars now I believe sue electric motors connected to the exhaust driven turbo to reduce lag in the same way, I'd love to have a play with one

Team www.sheepspeed.com Racing

very very cool

Own the day

how is lubrication done ?

Medusa + injection = too much torque for the dyno ..https://youtu.be/qg5o0_tJxYM

Edited by matnrach on 10th Oct, 2023.

Thanks mat

Medusa + injection = too much torque for the dyno ..https://youtu.be/qg5o0_tJxYM