Who is running Supercharger

[Chalkie]

Evening chaps

Who is running a supercharger on there Mini Please

Need alittle bit of help with something

thanks
Stephen

[minibitz]

I have an SC12 and HIF44 setup on one of my cars.

[Chalkie]

that's the little Toyota charger off memory
what size pulley did you have to put on it to slow it down enough?

thanks

[migliacars]

https://www.youtube.com/watch?v=TTRpjmzTNwM

[mk1]

I ran an 850 with a shorrock a few years ago,.

M

[Chalkie]

I ran an 850 with a shorrock a few years ago,.

M

they are mega money though.

but how did that drive?

[59fan]

I'm running a Shorrock at the moment, they are not cheap but it depends if you are looking for power or style?

I love them, I had the Shorrock I'm running on my pickup on an otherwise standard 850 and it was excellent.

They work best on smaller capacities, i am getting less benefit on my current 1040 than I did on the old 850 and I've read of cases with a 1275 that the Shorrock only gave a handful of extra horses.

In short, if you have a small engine, are not massively concerned with ultimate power but want the engine bay to look period then a Shorrock is awesome.

Ian

[mk1]

Couldn't agree with Ian more. All good points.

The C75B Shorrock is a unit that gives 750cc per revolution at 3000rpm. It works well on capacities upto about 1100, depending on how you gear it. On an 850 1:1 drive ratio works fine, but 1.2:1 would give you more boost throughout the rev range. The limiting factor is always the blower max rpm this is realistically 6,000rpm but you can take it out to 6,500 for periods. If you are using a 1.2 : 1 drive ratio, this means max engine revs are limited to 5,000.

Most of the blowers that are cheap & readily available are WAY to big for a Mini, this can cause all sorts of problems, possibly the biggest being the fuel condensing on the walls of the inlet manifold & pooling. People have got these to work OK, but it's not easy or simple.

M

[Chalkie]

Period looking don't bother me in the engine bay to much grandad looks, robotic heart

I have smallest supercharger they make currently and it's the m24 Eaton

[mk1]

The M24 is a good bet, there is loads of good info here;

http://www.turbominis.co.uk/forums/inde ... tid=447065

I can't comment myself as I haven't used one.

M

[smithyrc30]

Hmm I think the M24 is a bit small. The '24' is the displacement in cubic inches and this means it is about 390cc per revolution. You need 499cc per engine revolution on a 998cc lump just to be where you were. To drive the SC requires power, so you are going to need a bit more than the 1.27:1 indicated by the ratio of engine displacement to SC displacement. Plus you have to factor in blower efficiency and temperature rise as well

To drive its larger sibling the M90 at 12000rpm (its maximum speed) takes about 60kW of power to do.

It is not simply a proportional relationship more of an exponential one and also the faster you drive the SC, you generate more heat in the air you are compressing and the less efficient the SC becomes. The Eaton units have no internal compression and rely purely on delivering more air than the engine can use to provide boost. The hotter the SC case gets, the shorter the life of the case and rotors gets and the bearings at the inlet end (needle rollers) suffer a lot more especially if you are using it as a suck through the carburetor device (another thing which hurts the efficiency as they are not good on inlet pressure restrictions).

All in all, I would say the 24 is just ok for an 850, starting to be small for a 1000 (you will have to work it quite hard) and definitely not big enough for anything bigger. If you use a bigger SC unit you can achieve the same boost at lower SC speeds thus having less heat to get rid of and running in the better compressor efficiency range so you need less power to drive the blower so you get more at the flywheel. The other issue of higher SC speeds is of course the belt and pulleys. To achieve enough air flow to make it worthwhile on 1000 you are going to need to drive it to its maximum speed which means more power to drive the SC which means a bigger belt and bigger diameter pulleys to ensure you have sufficient belt in contact with the pulley to deliver the power to the SC otherwise you will have belt slip issues. There is not much room on the front of the mini engine for wider belts to dissipate the power across and not much room for large diameter pulleys either.

I found a copy of the compressor map on line and looking at it the best you are going to achieve out of it on a 1000 is about 0.7bar boost if you have perfect inlet and outlet plumbing. You will lose pressure ratio if you restrict the plumbing which will affect the efficiency. (Even a 1000 uses nearly 200m3/hr of air at 6500rpm) To do that you are going to be running it to about 14500rpm which will consume between 8 and 9kW, more if the plumbing is anything other than straight. Should be good for about 75kW at the flywheel.

I think if you are sticking to Eaton units then an M45 would be a better bet.

In Japan they have kei cars which have small SC units. Typically they used to run AMR300 units (300cc per revolution) but they now run AMR500 units. The engines have to be 660cc or less to achieve the tax threshold.

I have an AMR300 on a Honda 200cc motorcycle engine and an AMR500 on a Honda 400cc V4. They are a little bigger than they need to be, however finding space for charge coolers is never easy on a motorcycle so less heat to dissipate is always a good thing. I also have an M45 for a 1300 mini engine I'm working on.

Cheers

[Chalkie]

Evening

Thanks for the feed back. I see your point but after talking with the turbo mini lads and working out pulley sizes i shouldn't have any trouble hitting 100bhp goal of mine, the m45 is far to big for a 998 the m24 is just right on the flow charts and running a blow through with injection i shouldn't have to many issues on that front.

pulley ratio wise we have worked it out to be 1.08:1 and I'm using MEDS Management pulley and then machining up a custom pulley for that to keep the size down and weight down since rotational mass takes up alot of power for the engine

but thanks for the input its been taken on board, considering a lot of this is new to me on supercharging front I can't wait too see how it comes out

thanks
Stephen

[mk1]

Stephen,

Don't worry mate!

Supercharging is a really easy way to get good manageable power in spades!

As long as you get your pulley ratio something like correct you will be amazed how much usable power you get with very little effort.

[Chalkie]

Stephen,

Don't worry mate!

Supercharging is a really easy way to get good manageable power in spades!

As long as you get your pulley ratio something like correct you will be amazed how much usable power you get with very little effort.

Thanks!! haha

I worry way to much but thanks for the input