SuperTurbo Mini Project

I certainly hope not!

 

Very valid question that has come up a few times before. The long answer is this:

Looking at all the various Mini mods, the general impression I get is that the people who have Turbos try very hard to get them to behave like Superchargers, and the ones with Superchargers try very hard to get them to behave like Turbos.

Going back to the basic idea of forced induction, I understand and generally agree with the belief that Turbos are more "efficient" power generators than Superchargers. But that comes at a price: the standard variations of boost/vacuum in a track race make it difficult to design a turbo-only system that both reacts quickly and provides peak power under all circumstances. Combining the supercharger with the turbo opens up a whole new world of potential controls & optimizations.

In a way it's easier to think of the Supercharger as a "pre-compressor" for the Turbo rather than a source of power for the engine itself. At a minimum it ensures a more even air flow when transitioning from vacuum to boost. I am *amazed* at how well the engine reacts to smooth transitions of fuel & timing in the tuning....regardless of boost & throttle variations. There are absolutely no dead-zones (that I'm aware of).

As I've mentioned before, I think the fundamental challenges with combining the two are mainly around 1) the potential for interactions between the two systems (e.g. one fighting/starving the other) and 2) making the computer understand the different behavior of the system vs. a normal forced induction system. I think I have a very good handle on 1), and I'm definitely making good progress on 2). I must admit being able to control every aspect of the tuning under all conditions definitely helps

Anyways, that's my thought process....feel free to disagree. I'm used to being "way out there" vs. the norm.

p.s. The short answer is:

That would be too easy! I never do anything the easy way....

 

Yes, it would help the downforce & thus the rear wing would not need to produce as much (and thus could be smaller). So in a perfect world it would be best to implement both at the same time. But I don't have the time or money right now to do everything at once.

Each surface of the wing is adjustable. Moreover the design of the bracket allows a relatively easy re-adjustment of the overall position of the wing in the air flow. Once I add a diffuser I'll probably adjust both settings appropriately to re-balance the car.

BTW one of the next things I want to set up are linear sensors attached to the suspension to precisely measure both downforce & overall suspension behavior. I can feed that directly into the MoteC/AIM & it will perform an analysis in real time....

 

Latest mods & picture repost

I haven't had time to post an update lately. Couple of things I've been working on:

First, I had an issue with the turbo starting to leak oil. Upon investigation I found that the turbo was heat spiking, causing it to wear prematurely. It appears that this is pretty common when you track after-market turbos that don't have water cooling.

So I decided to switch to water-cooling. You can order the turbo casing with or without the water coolant connectors. It's not really that difficult. You split off the tubes from the main line; they enter/exit 90 degress from the oil connections. You can see the red & blue connectors on the sides of the turbo in the picture below:



The trickiest part was figuring out how to attach the braided lines into the existing coolant hoses...I finally found a reduction fitting that works well. And part of the tubing rises & falls right at the level of the overflow tank. So I adapted a gas sampling connector to act as a bleeder port. It works perfectly.

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The other issue I've had is that the ignition coil is too close to the turbo (see picture above). The connector & parts of the casing are beginning to melt. And my attempts to shield it have just made it worse by blocking the air flow around the turbo.

I've wanted to switch to one-coil-per-plug to provide more individual control of each cylinder anyways. This also solves the heat problem by moving the coils far away from the heat source. I looked into changing to coil-on-plug, but I could not find ones small enough to fit in the R53's spark plug tubes. However Motec mates a coil-near-plug variant:



I purchased these & struggled with how to mount them in the Mini's very cramped engine bay. I finally came up with a simple but effective mounting scheme tying them together with small strips of aluminum:



Because I don't have the top-mounted intercooler, this *just* fits between the head and injectors and attaches with a small bracket to the header bolts:



Here's a picture of it mid-way through wiring them up:



And here's what it looks like with all the wiring:



And finally everything together:





This has not only moved all the wiring away from the turbo, but it has opened up a better air path back to the turbo:



And I'm thinking of mounting a curved metal sheet where the coil used to be to help direct the air flow between the valve cover & the turbo.


I have to re-run the ignition & injector tests, change the ignition settings in the ECU, and then I'll give an update on if I notice any change to the performance...


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On a seperate note, I noticed the pictures of my modifications to the front splitter mount were lost during the big outage. I've added a couple back to my gallery:






As always, input is welcome!

 

I'm not sure if *all* factory turbos are water cooled, but many are. OEM systems also have the advantage of being correctly designed in to the overall airflow of the engine bay....

I also considered adding a cooldown timer of some sort, but I'm not sure if that would have solved the problem on the track. And I'm not sure it's appropriate for a racecar.

So far the impact on the water temps seems minimal.

Yes, I did have to have the turbo rebuilt.

And funny you should mention the oil fill cap. It rubs a bit on the air intake when you take it off. I'm considering switching to a smaller metal cap if I can find (or fabricate) one....

 

Thanks!

 

Actually in this system the water cooling works via convection when the engine turns off. The turbo manufacturer does not recommend adding a water pump because it *reduces* the heat dissipation effect.

Regardless I am keeping an eye on it & I have checked the water temp in the data log for spikes indicating boiling. I have not seen anything so far....

The problem with any kind of timer is that generally when you turn the engine off on a track car they want it *off*. Things staying on is frowned upon...

 

My original idea was to fabricate a new air box that fitted around the filter and draws in air similar to the factory air box, but I haven't had a chance to do that yet. Now that I understand better the airflow around the vents directly under the windshield (or lack thereof), I'm not sure that's the best approach anyways.

I now have air temp sensors in four locations: directly in the front air path (before entering the engine compartment), inside the engine compartment itself (near the filter), in the intake before the supercharger (but after the turbo), and after the intercooler. I'm planning on gathering more data from those under varying conditions to better understand the behavior of the overall system & then figure out the best approach....

In the mean time it seems to be working well where it is.

 

Funny you should mention that...ok, not really (for now )


...but did I mention the aerodynamic dimples I'm adding?