212 | How to choose a Supercharger

Hello, So im learning more towards the idea of a little positive displacement supercharger as ive only played with turbo cars in the past.

Engine is a KA24DE Twin cam 2.4L 4 cylinder, originally NA and pretty much stock rebuild except for ARP rod and main bolts so only looking at running 5-10psi

Im not 100% sure how to actually choose an exact model of charger? ive attached some efficiency maps of a Eaton M45, 62, 90 roots blowers and plotted 4 lines on each

Blue 5psi

Green 7psi

Red 10psi

Yellow 13psi

To work out flow I used this online calculator with Max rpm of 6000

https://www.boosttown.com/forced_induction/air_amount_calculator.php

So if im correct from what I can gather is the M45 would be too small, Anything over 5psi would be over speeding it since its recommended max speed is 14,000rpm

The M62 would be the best out of the 3 with all lines mostly on the graph

M90 Starts well off to the left of the graph. What actually happens if you operate to the left of the graph with a supercharger? is it just really inefficient there?

So yeh just looking for confirmation that the M62 is the best choice (out of those 3)? it also happens to be the hardest one for me to get in Australia haha.

Then I was looking at modern versions and I contacted Harrop/Eaton and they suggested the TVS1320 as they use that in the Subaru BRZ kits and plotting on the map it does fall on it nicely but on the Eaton website it says its recommended for 3.0 - 4.5L engines.

The TVS900 is recommended for 2.0 to 3.5L engines and it still plots nicely on its map so I would have thought that would of been a better choice? it also achieves 70% efficiency.

And then I realized Eaton superchargers are roots superchargers and Andre says no one really uses roots anymore? Who maps Twin screw superchargers then? and did any factory cars come with them and may be somewhat affordable?

No one?

From what I recall, the TVS900 is going to be about right - most installations are looking for higher boost levels and that's probably why Harrops suggested the larger capacity 'charger.

The lower boost level should give you a nice torque increase without the hassles of higher boost's supporting modifications.

You might find a good s/h one, but in the long run you may be better off buying new - especially if there's a kit available. If not from harrop, you may be able to source an engine/vehicle specific conversion from the US, or some other country.

Centrifugal superchargers, such as Rotrex, seem to be relatively popular for Hondas - but they're really for higher rpm power and, if expecting low rpm improvements, they'd be disappointing.

Might need to budget for a clutch with a bit more torque capacity, especially if the mileage is getting up there, but other than that you may need little additional work.

Which would you choose between the M45, M62 and M90 as they are the ones that are readily available second hand.

There is no supercharger kits availiable for my motor, Generally a Turbo is a better choice but since I am only looking for around 5-7psi, want instant response and never done a supercharger before id like to give it a go.