12 replies to this topic

[Verbaliser]

I'm poised to fit my charger to a low mileage 1982 mini 998cc. I have made some improvements already:

SW5-07 cam
Minisport Stage 3 head
Maniflow LCB and RC40

So expecting to hit aorund 100bhp at the flywheel - don't want anymore as I can't afford to start upgrading other components.

I have acquired an HIF44 carburettor which I have stripped down and serviced - put in a new float valve, jet assembly and have a choice of needles - BDD, BCA and BCE - to take to the rolling road. Also, I've put in a yellow damper spring by recommendation.


This forum has been an excellent resource and has answered a lot of questions - the DIY section was particularly good, and as a result I have purchased an RS PCT heater element (max temp 80degs) for a tenner and mounted to the inside of a K&N on the central pillar. I thought I would give a bit of info on my project so far to assist other wannabe self tuners!...and ask a few questions too.

I am pretty confident that the charger will be a successful installation - low mileage, optimum compression ratio (approx. 8.5:1) but I am just concerned with the rather restrictive air flow through the induction system.

I considered taking the rotors out and grinding the air intake duct wide open since the Jonspeed inlet manifold I have sits above a fairly solid block of aluminium - can't be good for air flow. So I have compromised and ground a rounded section directly below hole on the manifold (see pics attached). Do people think this will work? I used my Dremmel with a series of cutting discs - takes a while, but its brilliant!

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I went to BMW directly for an inlet manifold gasket - £2.95 - much cheaper than going to the specialist mini charger suppliers. I had to cut it slightly, so not to block half the inlet hole.

More general questions:

Do I need to get an extension pipe for the heater pipe to go over the charger body. Looks to me like maybe I do - I suppose i'll need 2 x 1/2" flow connectors and a 20-30cm extension flexi pipe? Am I on the right lines?

Also, I imagine I will need to get an extension fuel pipe to reach round to the new carb position. Again, will a flow connector be OK with 60cm of extra pipe? I'm not sure if i should go braided or not. Advantages? I'm not worried about the look, merely the function.


Perhaps at a later stage I will flatten the triangular section of the air intake duct on the charger to improve the airflow further.

[Verbaliser]

I am also keen to find out the best way to fit the charger unit without taking the engine out. I'm guessing it will be fiddly. I'd be grateful for any hints / tips...

[Wil_h]

I think you'll be doing well to see 100bhp, what boost are you planning on running?

Not sure about the heater pipe, but just extend it where needed.

As for the fuel pipe. I'd take the old bit of rubber pipe off from the pump outlet and but a new piece on with no joints to the carb (presuming you are using the standard pump).

[Verbaliser]

Standard boost - around 8psi... perhaps you are right - 100bhp is probably a bit optimistic - I'd be happy with 90.

With my current set up, the rolling road showed results of 47bhp at the wheels - so roughly 60 - 65 at the flywheel - I would expect another 20 - 25 at least with the charger.

Cheers for the advice on pipes.

[Wil_h]

What's your current spec. An SW5 and a stage 3 head would give maybe 60bhp on a good day.

by my calculations, 8psi on a 998 will give more like 80bhp with an sc and a little over 90 with a turbo

[Verbaliser]

2 hours of grinding tonight with my Dremmel (got through 6 cutting discs) - taking the lip of the triangular section off the intake duct to improve the air flow

Perhaps I have wasted my time, but i think it was worth it. I probably wouldn't do it again!

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[Wil_h]

Isn't the area shown in your photos the outlet rather than the inlet? I can see all your work being of no benefit I'm afraid. In fact you may have ground away a strenghtening rib.

[Verbaliser]

That section of the charger doesn't really need a strengthening bar, its made of thick aluminium - its not going to break.

Rationale behind it was that when the inlet manifold is screwed to the face of the charger 'outlet', apart from the two triangular holes, there is a slither of space for the air to flow through the charger and into the inlet manifold. By flattening out the V shaped strengthening bar, there is at least another 5mm of open space.

Only a nights work anyway. I have no way to test the results; the air flow gains may be negligible but its got to be better than it was originally.

[Sammy D]

That bit you have ground down a bit.. I cut mine all out. Then made a manifold to take the boost straight from the centre of the charger rather than make the air go around a 90deg turn all in about 10mm of space. That's silly.

[Verbaliser]

Sammy D, if you are the guy who has a topic on here with the pictures of the extensive grinding of the outlet section, then you gave me the inspiration - it makes total sense.

If I'm honest, I was not brave enough to take the rotors out, and don't have the proper tools. Mine is a token effort compared to yours, and just about the limit of what my Dremmel could manage. I bet your air flow is really good.

So you don't think I've wasted my time completely then?

[Sammy D]

I bet your air flow is really good.

So you don't think I've wasted my time completely then?

Thanks, yep that's me. Much better flow yes, with minimal thermal efficiency problems. I've actually modelled my manifold and used software to run flow analysis on it. Anyhow, that's to be discussed another day...

No, you haven't wasted your time, Jonspeed just chuck it in a mill and mill into it sideways.

To take the flow from the centre of the charger rather than over to one side, the blower is mounted much further to the left (as you look at it) on the engine. Easy enough if you run only one belt, and do away with the V belt altogether.

[Verbaliser]

Just found this on a website: http://www.eatoninsi...hread.php?t=156

Supposedly from the Eaton website...essentially saying that what I have done is about as much as you should do, but sadly that removing the plate will have a negative effect... It talks about the M62 specifically but the output plate is similar on the M45.

Porting the M-Series Supercharger:

It is not a good idea to remove too much material from any portion of the blower. Extreme porting of the blower will disrupt the air and will reduce efficiency greatly. A light porting of the inlet housing will help increase intake CFM of the pump. Typically, if a TB (throttle-body) upgrade is available, it helps to match the TB port size to the inlet port for a smooth intake of air with minimal disruption. Smoothing this opening up and enlarging it slightly will help introduce more air into the rotor housing which can then be "pushed" into the lower intake manifold. The inside of the housing can also be lightly ported to increase internal surface area. It is important to note, that internal porting of the rotor housing should be very minimal. Basically, remove any and all casting flashes and ensure complete symmetry while removing as little material as possible. Removing too much material will interfere with air flow and the functionality of the rotors. The output plate at the base of the M62 housing is what can be modified the most. This plate has one large triangular and two small oval passages in it. Right now, we'll focus on the large triangle. This is the passage that air is pushed through by the rotors to create a positive pressure in the lower intake manifold. This passage can be opened up slightly and smoothed out for best flow. Opening it up too much will also disrupt airflow. This is the most porting that should be performed on an Eaton M-Series blower to maintain efficiency.

Air Leakage Ports:

The two oval slots on the output plate are air leakage ports. Their only purpose is to decrease operational noise from the blower. Arnie, from Eaton Corp., explains their function like this, "When you stomp on the gas, the boost shoots up and the air flow goes supersonic. The air then slams back into the output plate and through the leakage slots, which reduces the hammering of the air into the housing causing less noise. The OEM can not have such loud NVH, that’s why we put them in the housing. The 2 small ports are not there to feed air, only to reduce noise." Basically, for the best flow and most efficiency, these ports can be blocked off, making the outlet port (triangle slot) the only port on the outlet plate of the housing. Closing these ports will not increase IAT's; however, it will make the supercharger much louder when in boost. As an example, aftermarket supercharger companies, such as Harrop, Roush and Magnuson do not use these slots in their blowers. It should be re-stated, that you should consult professionals regarding closing these ports; and do not, for any reason, plug them with JB Weld. Improper closure could eventually lead to pieces coming apart and loose debris destroying the rotors and housing. Opening up these ports will only have a negative effect on efficiency. Do not port them.

I feel much better now!

[Wil_h]

Interesting. I'd definately look at ways to block the smaller holes then. Maybe incorporate it into the manifold or make some plates that clamp in.