erm, you answered your own question. Its a belt-driven supercharger, sooooooooo no spool time.

 

But there is a bit of lag, not as instantanious but oeaks better etc.

 

The Rotrex is a centrifugal SC, the Eaton is a Positive Displacement Blower (Roots Design). Positive displacement blowers have a bell shaped torque graph, Centrifugal blowers have an incline shaped torque graph. The Eaton makes quite a bit of boost right off the line, only increasing slightly as the RPM's go up, the Rotrex makes max boost at redline, and the boost curve is very linear. It spins faster and faster and the engine RPM's increase.

Positive displacement blowers are easier to implement on street cars because of the meatier torque curve down low. The Rotrex performs similar to a turbo, without the spool delay, and a more linear torque graph (Direct linked to the engine, so there's no need for exhaust gas to spool it up, also not as "Peaky").

I think Longboard's thread has a dyno graph in it.

 

while there is no "spool time" with an SC... there's still no boost worth anything below certain RPMs. The SC M45 with a pulley doesnt have 15 lbs of boost right away... it has 15 lbs of boost at peak RPM... etc etc...

again, if you know how to drive, there's no waiting for boost on a turbo at speed anymore than an SC closing the BP valve.

They both have thier places, and it really depends on the driver, usage, track, the list goes on and on.

 

Hasn't your BV been removed or welded open???

 

we arent talking about me...

and yes it's been removed.

 

I know.. your in a different league
But whats the advantage to no bpv?? Is that for turbo only??

 

Yeah mainly a turbo thing.... since you have a BOV..

 

Damn I miss my turbo!!!
Glad to see that it made the kind of power that it did tho for sure... but you know it's good for 450hp... Let's bump it up!!!

 

That turbo kit looks like it took about 1 night to build....

 

Oh my God... That is sex. You can hear the <i>whine</i> of the super, the <i>whoosh</i> of the turbo, the <i>choosh</i> of the blow-off, and even the <i>rumble</i> of the exhaust.

A-freakin-mazing!



Got a list of mods done?

 

easy... that was one of the first of its kind and is still running and never broken even after it toasted 3 motors... no haters allowed on this one!

 

try the first post by the user....

 

I promised to provide some additional information on the engine modifications. But before I go into that, I should mention recent events. As the saying goes, as you make one part stronger, you'll find out what else is weak....and in this case it turned out to be the 3-year-old aftermarket flywheel.

As I was driving on the freeway one day the pins in the flywheel torqued out and proceeded to destroy the flywheel, clutch, and the inside of my transmission...before leaving the transmission case at high speed!

After replacing the whole transmission (except for the Quaife LSD fortunately), I decided to try a different approach for the flywheel and got one of the Clutchmasters FX700 dual disk clutch/flywheel combination from Jan. It should handle considerably more abuse than the old combination...but it does take a bit getting used to. Thanks again to BHS for all of their hard work on this....

As far as the engine itself, the only significant issue so far has been around heat management. The temporary heat shield didn't really work too well. And I didn't originally wrap the header, so plastic bits near it tended to...um, melt... But I've now wrapped the header with a high temp fiber wrap (very cool stuff) and am working on improving the heat protection around the Turbo itself. I'll take a picture when I finish it up.

Regarding the other engine mods, I've attached a list of the key changes below. And to help my understanding of the behavior of the system I put together a crude system diagram of the intake/exhaust paths showing both the Supercharger and Turbo, as well as the valves, bypasses, and controls (I didn't including the exhaust past the Turbo so far). There are some interesting interactions in the system, and definitely still room for more improvements...






Here is a partial list of the engine, exhaust & transmission mods:

Turbo Kit
Air Intake (attached directly to the turbo right now)
Custom Turbo header and pipes
3" Racing CAT
JCW Exhaust (next item to be replaced)

RMW big valve head
CP pistons (coated)
ARROW rods
(Rotating Assembly balanced by BHS)
APEXi AFCS (programmed by BHS)
Stock-size Supercharger pulley
JCW Supercharger
GTT pulleys and tensioner

Clutchmasters FX700 Twin Disk Clutch (includes lightweight flywheel)
Quaife LSD

 

That's quite the list of parts to a good combination for power!!! I'm glad you got it right the first time... thats where i went wrong... Sorry to hear about the trans tho... My buddies DSM threw a flywheel once but i shot up and severd the bellhousing and thermostat and everything above it and got lodged in the carbon hood halfway thru... crazy shizzle to see that! so at least it could have been worse... Nice clutch choice too!!! Once you get used to the pop, watch out when you launch! haha... I gotta see this setup sometime! Maybe at the dragon next time, by than my car will have another setup worthy enough to roll and hang with you

 

Couple of quick updates. First, I finally had time to install a better heat shield for the Turbo. It seems to be doing a *much* better job.

Here is a picture:




Also, while thinking about the system diagram for the umpteenth time, I decided that the vacuum source for the blow off valve could be interacting non-linearly with the Supercharger bypass. This, in turn, could be causing momentary excessive pressure in the intake & potentially causing some blow-back through the Turbo (or at least heating it up unnecessarily).

So last weekend I made a small modification to the system and connected the blow off vacuum line to the intake right before the supercharger as shown below. This decouples it from the Supercharger altogether.




This did seem to have a marginal effect on the Turbo temperature (hard to say). But more surprisingly it had a strong (positive) effect on the Turbo spool, i.e. it spools much more quickly now at part throttle. In fact I had to turn down the boost controller by a few notches to keep the boost in the same range...

This probably doesn't effect the maximum power output, since the supercharger bypass is closed in that case anyways. But it definitely gives a bit more bang at part-throttle...

Hopefully I can get some track time in again soon...

 

TDE is at MSR-C this weekend.

I'll provide the reference.

Alan

 

I'm surprised there's still openings??

Hmm. I love MSRC, but it's always a bit of a struggle to get up there. It's almost a 5 hour drive....I'll think about it.

 

Ugh! 100+ degrees forecast for the weekend...

 

It's a 100 degree's plus here everyday! Better get a FMIC......

 

Yeah, but Rick's given dispensation to wear shorts and short sleeves. And I plan to do a lot of hanging out in the AC upstairs.

Alan

p.s. And the humidity has got be less than in Houston.

 

Whats the latest on the setup? How's the car running??
Any new tuning or upgrades to the tune??

 

Well the car was running *great*. The boost change definitely improved the response....

...but now I have an issue with the electrical system & I can't communicate with the ECU via the OBD-II port (BHS tried it too)! We've traced it down to something on the serial chain holding down the signal. But given the way the Mini wiring is done, this is a pain in the butt to diagnose. And unfortunately I *think* I'm out of warranty .

I'm strongly thinking of using this as an excuse to switch to an aftermarket ECU (and wiring) & make this a track-only car. This would enable a **lot** more control over the engine, as well as shaving at least another 100lb off of the weight. I would probably go with a Motec system:

http://www.motec.com/products/ecu/ecumain.htm

This sytem has a good reputation, and comes with a very complete software system for configuration, montor & control. Moreover, the 800 series has a boost control output I could use to electronically control the wastegate rather than the current mechanical system, as well as connections for other devices (blinkers, brake lights, etc). And they will build a custom wiring harness for you to your specifications.

Then I could replace the Tach with a digital dash/logger that talks directly to the Motec:

http://www.aimsports.com/products/mxl-chooser.html

This combination enables an amazing level of information & control...as well as looking *really* cool .

BTW, one interesting accessory Motec sells is an "Aerodynamics sensor". I'm still investigating how it works, but it *appears* to allow real-time measurement of air pressures & flow around the car at a fixed number of points (e.g. 8). Theoretically you could move the points around from run-to-run to get more sample points. If this works like I think it does, then this would allow the car to become a moving aerodynamics testbed...

In for a penny, in for a pound!

 

Dude!
That sounds like a well spent investment... but why would it have to be a track only car with the Motec? There are plenty of cars running stand alone ECUs street legal...

Sounds like a pain ditching the Minis wiring too... al those computers on board you'd probably save more like 200lbs... haha....

Keep us updated if you find out why you cant communicate with the ECU via the OBD port...

 

True, from what I can tell the Motec can produce the necessary OBD-II signals to pass an emissions test if set up properly. What I should have said was a "track-mostly" car.

It's easy to throw stuff away