suck through to blow through
Turbo Mini Forums

Following up on a previous topic, i've decided experiment by converting my suck through supercharger to a blow through system using 2 chargers in series.

Some questions for you turbo users.

I looked through some of the well known suppliers sites for a hif44 carb and although they list the carb and they list turbo service kits they don't advertise a specific turbo hif44, is the carb completly different?

Do i require a plenum and if so what is its purpose?

Where is the best place to purchase the pipework?
For the early stage of this experiment I shall not be installing an intercooler as the chargers take time to heat up and they never reach turbo air temps.

superchargers will heat the air more than a turbo due to the poor adiabatic efficiency.

how do you mean two chargers in series? what is the aim of having the two chargers in series?

Im supercharging my hillman imp and im using an intercooler off of an audi RS2!!! monster monster

J

My thinking behind the 2 chargers is that each charger is more efficient at lower pressures, so 1 charger will flow a higher volume of air at 6psi than it will at 12psi and efficiency really drops off beyond 12.
Therefore (and as I already own 2) if I front mount the chargers and fit a throttle body to the front of the first one and connect its discharge to the suction of the second then I could produce a higher charge pressure by also creating a higher flow.

As I said its only an expirement and since writting the thread the information I could find on the hif44 suggests a fairly straight forward conversion using a turbo service kit.

I think that the internal passages are different on the HIF44, the float is different as it is stronger to withstand collapsing. Im sure you have thought about the fuel pump , return lines, and pressure regulator.

The superchargers would have to be very carefully setup, the first spinning significantly faster than the second otherwise they will just move the air without any boost.

This kind of setup is much easier if a turbocharger is used as it will just flow enought air to create pressure up to a set limit.

What i suggest is very careful porting of a single supercharger, this post contains some interesting information -

http://turbominis.co.uk/forums/index.php?p=vt&tid=128332

A supercharger is a stragne device as it works on atmospheric pressure to fill the gaps produced as the rotors spin round. If the inlet and outlet are ported then the ability of the natural air pressure to fill the gaps is maximised, porting will see about a 2psi rise in boost for zero increase in speed.

J

Edited by blown_imp on 26th Jan, 2007.

Fuel pump needs to be capable of supplying fuel at a pressure greater than max boost!
Not sure about the pressure regulator, my understanding is that the float chamber is pressurised by a take off from the charge air pressure.
For now both chargers can spin on the same size pulleys, maybe the first stage pressure increase will be less that the second stage but I dont think that will matter to much.

Unfortunatly that wont work mini23, the fuel pressure regulator is a must as it will provide 3psi to the carb under all conditions, as boost is introuduced it will add the 3psi to the boost. So at 5psi boost the fuel pressure will be at 8psi and so on.

having both superchargers working at the same RPM will not work either, as they move a fixed volume per revolution, the second chager will do no work. The first charger will have to spin faster than the second to provide more air than the second one can move. This will create an increase in pressure in the intemediate section between blowers that the second blower can work with.

J

turbo 16v k-series 11.9@118.9 :)

Denis O'Brien.

Thanks for the information on the fuel pressure regulator, maybe you could suggest a good product/source?

As for the second supercharger doing no work that would only be the case if the final discharge were open to atmosphere and not restricted.
Thats also the case with one charger!
As said this is only an experiment and what its based on is the chargers capability to shift larger volumes of air at a lower discharge pressure.
My prediction is that the second charger will have a greater load imposed on it than the first.

As for running them in paralell, that would be a simple conversion for this setup and is something that may be tried if the series setup fails to work.
If this proves to be the case then it would probably be easier to fit a larger single charger!

Edited by Paul S on 27th Jan, 2007.

Saul Bellow - "A great deal of intelligence can be invested in ignorance when the need for illusion is deep."
Stephen Hawking - "The greatest enemy of knowledge is not ignorance, it is the illusion of knowledge."

Edited by danboy on 27th Jan, 2007.

Yes, ok, good reply, that all makes sence.
So I probably need the first to run around its full rated speed and the second at maybe half the speed.

Mini 23
You could do that with two superchargers but it would be really inefficent. I would urge you to research the use of a turbo blowing into the blower, the advantages are far greater than any other method of forced induction. The only downside is packaging the set up into a Mini but than again so will two blowers.
Regards
Dave

Edited by danboy on 27th Jan, 2007.

I may end up going down that route!
However as a little expirement and as the car is not a road car and will see no use until may at the earliest and I have the 2 chargers i'll start with them.
If I have to purchase a hif44 some pipe a fuel regulator and pump and an intercooler then its not money wasted as I would need all of them for a turbo/charger combanation.

or run boht chargers in paralell...

turbo 16v k-series 11.9@118.9 :)

Denis O'Brien.

Saul Bellow - "A great deal of intelligence can be invested in ignorance when the need for illusion is deep."
Stephen Hawking - "The greatest enemy of knowledge is not ignorance, it is the illusion of knowledge."

Axel, do you want to edit that to NOT a lot of boost and........
Mini 23 How would you drive the Two blowers? Where would you mount them?
What pulley arrangement would you have? Would you use an intercooler?
Not trying to be negative about your project just curious
Regards
Dave

Edited by danboy on 27th Jan, 2007.

i wouldnt run 2 blowers either, just suggesting how it may be done, 2 blowers would effectively meen they are each running into an engine of 1/2 the cc's therefore a higher pressure ratio for less RPM.

turbo 16v k-series 11.9@118.9 :)

Denis O'Brien.

Saul Bellow - "A great deal of intelligence can be invested in ignorance when the need for illusion is deep."
Stephen Hawking - "The greatest enemy of knowledge is not ignorance, it is the illusion of knowledge."

Edited by mini23 on 28th Jan, 2007.