Mini supercharger on 1zz

[MrT]

Carolynne
Sorry for hi-jacking the thread, tell me to shut it if off topic.

Hi Scotte
Yes, I'm well versed in the function of the 2 types of chargers. The trick is your BOV will be blowing lots of bypass at high rpm if your charger is not restricted. But restricting it means you can run the Rotrex at a higher rpm meaning it reaches decent speeds lower in the revs then the restrictor (a smaller inlet trumpet insert) limits the volume/flow of air into the charger meaning it cannot output too much air and the BOV has an easier time controlling the flow and limits the back-flow of air.
Assuming your BOV returns before the charger but after the MAF this is not detrimental as the returned air will cycle through the Rotrex but the heat will build up if it is happening a lot as the same air is receiving more and more heat. This will happen to varying degrees depending on your application so may be insignificant for you but we won't know until your build is ready to start, or understand fully the spec of your build, not for this thread.
Note, the BOV is beneficial (thought not essential at low boost) to control closed throttle boost as the SC keeps pumping at the rate of engine rpm regardless of throttle opening unlike a Turbo so that is good. Make sure the BOV isn't cycling back upstream of the MAF as it may fool the ECU into thinking there is more air entering the engine or be harder to control. That is also why it is not vented to atmosphere (aside from turning the car into a job mobile...).

Happy to discuss further outside Carolynne's thread.

Carolynne, thinking about it, was there a logic for you using a BOV at lower PSI? I think you are running ~8PSI currently, but might have missed a change somewhere.

[Carolyn]

In my experimental car, the BOV is acting as a bypass valve, to deal with rapid shutting of the throttle (as in the original Mini application).  As you assumed, it returns to the input of the supercharger.  The MAF is upstream of the return.  There is quite a discussion of the BOV earlier in the thread.  In my case, the whole point of the exercise is to give more oomph lower down the rev range.
Bahnstormer: I'm lucky in that I have plenty of space and a big workshop, and another MR2.  This is a hobby project and I work on it only when time, inclination and (unfortunately) my health allow.  I reckon (fore-armed with knowing exactly what to do and how to do it) the actual physical build could be accomplished in a couple of weeks.

[lamcote]

Thought I might chip in ;

A turbo setup uses a BOV and a wastegate valve. (In the Mclaren P1 vids you hear the wastegate making a chirping noise and the BOV makes the whoofling noise). The BOV protects the turbo when you lift off the throttle, the wastegate limits boost by diverting exhaust gas.

An Eaton supercharger needs a BOV but not a wastegate, indeed a wastegate won't work at all with a positive displacement supercharger. They do however usually have a bypass valve for part throttle operation when boost isn't required. This is separate from the BOV.

Also an Eaton supercharger won't actually produce max boost at very low revs, it should in theory, but it suffers from inefficient rotor sealing at low revs so an engine won't see full boost until typically 2-3000 revs, but it does still provide a proportion of its max boost even at tick over so you will still be getting much more boost than with a Rotrex or turbo at that bottom end.

A Rotrex needs a BOV and I believe it may be possible to fit a wastegate to a Rotrex however, it is far preferable to operate a wastegate on a turbo by diverting exhaust gas, not inlet air, so most if not all wastegates do this. With a Rotrex you would obviously only be able to divert inlet air in some form of wastegate. I'm not sure if such a thing is available? A BOV is too much of a blunt instrument to use as a wastegate as it is either open or closed.

I know Rotrex setups do use restrictor plates but to get significant low end boost the restrictor would be so small you would severely choke off high end boost and be running very inefficiently.

[1979scotte]

Should take this elsewhere.
Total thread hijack.

[MrT]

So to return to topic, lesson is Carolynne knows what to do and this is an example of a GOOD well thought out installation, with creative solutions for the packaging issues of the MR2.

Well done so far Carolynne.


cheers

Tyler

[MrT]

Carolynne

Just looking over your thread and pics, would there be mileage in turning the SC over and plumbing the outlet under the engine beside the sump and into a charge cooler or direct to the intake? Seems a simpler clearer route to me, if a little longer. And a bit further from the heat of the exhaust. Just an idea, wanted to ask your thoughts on it.

Thanks


cheers

Tyler

[Carolyn]

I suppose it could be done.  Not sure how the mounting points would work out. The lubrication of the supercharger is (it seems to me) pretty much designed to be one way up. I'm not sure it would be happy upside down. The present route to the intake is as a simple as...  Heat is dealt with by a fan drawing the heat upwards.  Going underneath would leave very little ground clearance, when you think about it.  Turning it over would also just swap the heat from exhaust issue to the intake of the supercharger. Same net calories going in.  
There's a lot to be said for a Rotrex - it's the expense that put me off.

[MrT]

Good points, thanks.


cheers

Tyler

[1979scotte]

There's a lot to be said for a Rotrex - it's the expense that put me off.

Agreed.

[Carolyn]

To sum up.  The supercharger is on. It works.  It gives the low-end improvement I was looking for.  It needs to go on a dyno to be properly set up, but that will have to wait a while (watching pennies).
If anyone wants to copy the set-up, you're welcome to come and have a good look, take measurements for brackets and exhaust and have copies of the files for the project.
In my opinion, the idea is pretty much proven out, though dyno work with a better ECU than I'm presently using would be need to get the final optimum result.
Biggest challenge would be reproducing the special pulley we had to make, though one could simply measure and take to a service with a CNC lathe.

[shnazzle]

I do wonder why the EMB doesn't work for you but others have run pretty hefty turbo power with it.

It's not the best solution obviously, but you'd think it'd do the trick

[Carolyn]

It probably will.  I'll let you know when we've done the dyno. It has its limitations. It will never be optimal (because of the things it can't do) but probably acceptable. Hell the car's running ok with it.

[MrT]

Carolynne
From post 658 ish, are you using the 105mm pulley and have you measured actual boost? Would the car not run on stock ECU at that boost?
How many pennies are needed for the Dyno? I'll contribute for the research benefit.


cheers

Tyler

[jvanzyl]

I'm happy to contribute to the Dyno fund as well...
It'd be great to see what the kit can do and be incredibly useful for others who want to go down the same route...

Oh and plus the are a few us running (or wish we were) EMB so the map would be a good place to start for those wishing to leverage it if they went down the route..

Sent from my Moto G (5) using Tapatalk

[Carolyn]

Thanks for the offers, guys.  It will be a while.  Not wanting to make a big deal, but health not cooperating....This project is going to have to stand while my geriatric skeleton is giving me problems.
Yes running 105 mm pulley.  Boost around 8psi... It's not legal on the street, so it's not really been up to temperature and run hard, just a couple of short local runs.  Hard to justify tax and insurance and MOT at this stage.
Yes it will run on standard ECU - to a point.  
If someone wants to take the idea forward, I suggest copying what we've done to this point and taking it from there..

[MrT]

Thanks Carolynne
Hope you feel better soon.


cheers

Tyler

[BahnStormer]

Thanks for the offers, guys.  It will be a while.  Not wanting to make a big deal, but health not cooperating....This project is going to have to stand while my geriatric skeleton is giving me problems.
Yes running 105 mm pulley.  Boost around 8psi... It's not legal on the street, so it's not really been up to temperature and run hard, just a couple of short local runs.  Hard to justify tax and insurance and MOT at this stage.
Yes it will run on standard ECU - to a point.  
If someone wants to take the idea forward, I suggest copying what we've done to this point and taking it from there..

All the best with the health and let us know if you need to take a collection for the dyno research  s:) s:)

[alancsalt]

Smooth pulleys - smooth side of belt, Grooved pulleys - grooved side of belt. The pic looks like the idler pulley has grooved side facing it? These belts come in a range of lengths, so you'd want best match for this, maybe?

[attachment=0:3491vfho] ia0 serpentine belt.jpg ia0 [/attachment:3491vfho]

Am I talking thru my hat?

Ah, health.. shame.. this was interesting. Take care.

[Carolyn]

The extra idler pulley is indeed smooth side to smooth side.  It sits on top of the belt to guide it down past the tensioner (The supercharger pulley sits a tad high). Grooves on grooves too!!  The belt length is spot-on.

It ain't over....  yet.

The fact is the supercharger is in, working reliably and making boost. All the systems are in and working.  The thing runs and revs.  So if the question is 'can it be done?', the answer is yes.

Here's a pic of the idler (not a brilliant one, I admit):

[MrT]

Hi Carolynne
I hope you are feeling better. Any progress with the supercharging? I'm running out of hair brained schemes to squeeze this thing in on the cold side of engine...

[Carolyn]

The mechanical part of the job is done, and has been done for ages.  I'm just holding back on the expense of the needed ECU and dyno work....  Runs pretty well just on the stock ECU, but (obviously) it's not quite 'right'.

The trickiest part of the job is making the pulley and modifying the supercharger to make it fit.

You're welcome to come and have a look and hear/see it running.

I really don't understand why people keep asking about 'progress'.

Jobs is done.  Supercharger is in and running.

[jvanzyl]

I think it's because "progress" is defined by some as driving it around and posting YouTube videos of track days etc..



Sent from my Moto G (5) using Tapatalk

[MrT]

Apologies Carolynne, I understood it to not be running correctly for regular use therefore being unfinished. If it runs ok as is that's great.

I was looking at your photos again and wondered, do you think if the SC was flipped 180deg with outlet downward would a 2zz manifold fit above it? And run charge pipe under the sump? Just thinking aloud.

Thanks

Edit: ah is the subframe in the way? Not too clear in the later pics.

Edit: nope looks like it'll clear the subframe. You might have just solved my problem Carolynne. Thanks

[Carolyn]

Apologies Carolynne, I understood it to not be running correctly for regular use therefore being unfinished. If it runs ok as is that's great.

I was looking at your photos again and wondered, do you think if the SC was flipped 180deg with outlet downward would a 2zz manifold fit above it? And run charge pipe under the sump? Just thinking aloud.

Thanks

Edit: ah is the subframe in the way? Not too clear in the later pics.

The supercharger will be in the way of the manifold either way.  Custom manifold required.  You're guessing.



Edit: nope looks like it'll clear the subframe. You might have just solved my problem Carolynne. Thanks

[shnazzle]

Seen this kit in the flesh now and I must say the noise of that supercharger is quite something.
you'd definitely turn heads.

The manifold is one thing but the mounting is the genius of this. The custom manufacturing of parts would set anybody else back a hell of a lot of money.