Hypothesis: That the R56 Cooper S stock exhaust restricts power by some amount. Removing the entire exhaust will result in a power gain. That gain will represent the upper bound of how much is to be gained by switching from a stock system to an aftermarket turbo-back system.

Test design: Build a dump tube that runs straight from the turbo outlet to the ground. Dyno the car before and after.

Conditions: Dynapack resistance dyno. 60 degrees F ambient temp, before and after. '07 Cooper S, 1000 miles on the odo, 93 octane gas. Several runs were made after the car was fully warmed up. The best of each were used.

Qualifications: Air/fuel analysis was NOT performed.

Results:

Stock exhaust (all figures are at the WHEELS)

Peak power 189.6 hp @ 6000 rpm
Peak torque 190.9 lb-ft @ 4600 rpm

Dump tube

Peak power 203.5 hp @ 5000 rpm
Peak torque 214.6 lb-ft @ 4500 rpm

The graph:



Note that the dynapack (in my experience) reads higher wheel numbers than some dynos. I would NOT advise comparing this with other dyno figures. The change is what we're after.

Note that the dynapack software scales the graphs differently, so don't make too much of the huge vertical swings in the torque graph -- the vertical scale is very small, so the swings are exaggerated.

Even though the graphs are titled, "Flywheel torque graph," that's not true. These numbers are as measured at the wheels. (TCF = 1.00)

My thoughts:

The torque curve is funky -- it has two peaks, which is not normal for most any car. Clearly there's some boost control strangeness going on. I may take boost control away from the ECU and play with that to see what we can easily do with the torque curve.

The change in peak power is lower than the highest differential power gain, which is 23.5 hp at 5000 rpm. It appears the turbo is simply running out of breath at high rpm, and the biggest exhaust in the world won't help that.

Clearly there's some room for ECU tuning. We'll get to that in due time. I'll also be looking more closely at air/fuel ratios and boost levels next week.

To me this is the best possible world of what exhaust could add to this car. If someone claims more hp gain at the wheels than this by swapping exhausts, be skeptical.

--Dan
Mach V
FastMINI.net

GREAT JOB!

That is some good info!

Hope you wore earplugs during the second run!

For the mechanically challenged: This was just a test of getting rid of the back pressure without any change to engine timing, ignition, or fuel scheduling, yes?

Yes.

--Dan
Mach V
FastMINI.net

I've been wondering about that. Could it be that they did something silly just to get good govt. MPG ratings? Perhaps this is programmed just for their test conditions?

Is this where a redesigned air intake/filter system would help? Supposedly the first stage JCW upgrade will be intake, exhaust, and ECU.

With better intake and ECU, could the benefit of freer exhaust make more difference? Remove other bottlenecks and previously irrelevant restrictions start to show their effect.

BTW: I think this was a great test.

It's probably to get good low-end torque without ripping the tires off when the turbo fully spools up. Emissions testing doesn't really deal with full-throttle running, so I don't think that's the reason.

Maybe, maybe not. Back in the dark ages, putting an intake on a turbo car could add 10-15 hp. These days, that's usually not the case. Some factory intakes are excellent, and all have very good cool-air ducting. We'll be conducting our own tests to find out if there's power to be had.

Sure, we'd get lots more power if we tweaked the air/fuel and timing. But this baseline test was just to see what the effect would be of removing all exhaust restriction.

Thanks!



--Dan
Mach V
FastMINI.net

I would expect the numbers to get better as the car accumulates more miles. After all, it wasn't even run in at the time of the dyno runs. With any turbo system it is helpful to limit the pressure on the down side of the turbo. Doing so creates a higher differential between the input pressure and the output pressure in the turbo system. A larger exhaust pipe and free flowing muffler should make for a good modification to the Cooper S. I want mine now! But, I do want that muffler to be light weight and quiet. And, please, just one large, nonflashy exhaust tip. No coconut cannons, and particularly no dual coconut cannons.

Awaiting gratification,

Joe

I went ahead with the twin potato launchers!

https://www.northamericanmotoring.co...74#post1475574

Thanks for posting your dyno results Dan!

Thanks for the dyno.

I would think that second peak comes from the second cam. Do we have VTEC in our cars? Perhap Double Vanos that we don't know about?

Anyhow, I for anything that makes big power for this little car...

clubspec330i: The 2nd power peak isn't from the cams, it's all in the boost controller letting the turbo provide more boost, creating more torque. The boost curve through the RPM band is like a roller coaster ride, and resembles the shape of the torque curve. You can see this with my stock MCS baseline dyno run and the boost curve from my datalogging:



Cheers,
Ryan

I'm confused. MINI claims peak torque at ~1600-1700 rpm, no? I know dynos do a crappy job showing low numbers, but this stock graph doesn't hint at the fact that the car's already at peak torque before 2000 rpm. So is overboost messing with this curve?

perhaps from the twinscroll, no?

Not likely. The twinscroll turbine snail just allows quicker spool-up and a lower Boost threshold while maintaining decent flow rate. The turbo is spooled by 2200 RPM, after that the boost controller built into the ECU takes over how much boost is delivered to the engine via the vacuum controlled wastegate.

so, two small impellers of equal size then?

The turbine has just one standard-shape impeller. It's the shape of the snail, or housing, that directs the exhaust gas flow in two paths, hence "twin-scroll". Cylinders 1 and 4 are directed in one snail path, and cylinders 2 and 3 in the other. The location of the snail nozzles directed onto the turbine impeller are in different locations such that one pair of cylinder has more mechanical advantage over the other pair. The effect is you get low boost threshold and high peak flow rate, two typically contradictory terms for turbos.

I'm sorry to revive an old thread here but, Dan's research provides a good starting point to find the Cooper S's main bottleneck(s)

I wonder if, we're already seeing the limitation of the mini's small turbo here. Clearly the power in the 'dump tube' dyno falls off sharply way before the redline. In my experience, the bottleneck is often the intake cam or intake manifold. However, looking at Ryephile's boost log, the boost peaks around 5000RPM and falls off to redline. This alone, could be the reason for the hp drop.

Has anyone dynoed with a simple manual boost controller yet to see if the power holds to redline? I'm very curious what the stock turbo is capable of....assuming the ECU dosn't have a conniption fit first.

Great work Dan! I've actually had work done by Ultimate Performance and purchased from Mach V in the past. I'd recommend you guys to anyone.

go here
https://www.northamericanmotoring.co...ghlight=pulley

i believe what your looking for is somewhere in there. Alta tested out a boost controler if i remember right.

Excellent technical post. I look forward to reading more on what you are doing here... and possibly opening up some safe HP on the MCS (without wasting money on wanna-be bling mods).

Thanks. We also did a recent dyno test with all the older models of MINI -- read about that over here.

We'll have more testing of the R56 car sometime soon.

--Dan
Mach V
FastMINI.net

Thanks for the link! It looks like alta's test boost controller eliminated the torque drop around 3k and held power a little past the stock 5k drop point (maybe 5500-5700) but, the power still crashed the rest of the way to redline. So, the boost controller certainly adds more "area under the curve." However, that peak number at redline will remain elusive until a flash keeps the ECU from tapering boost at the end of the power band. I can easily see these cars putting down 225/225 whp/lb-ft with a safe flash and bolt ons.

Vishnu, Dynoflash, WORKS, Jestrtuning, Turbotrix, Cobb, and so on have been offering flashes for the EVO, WRX crowd for years. Hopefully someone will step up and offer, what should be a straightforward solution, to hold the boost steady and maybe raise the redline a bit

It's possible that you won't be able to make much (if any) more boost at high RPM, because the turbocharger just can't flow enough air to do it. In that case no amount of ECU tweaking will give more boost; only a different turbo would.

--Dan
Mach V
FastMINI.net

Dan,

I would have to completely agree with you. This lil ol turbo is past its tipping point. Its blowing like a hair dryer and with its size it even looks like one .

a 2.5 inch freeflow exhaust was worth 10 whp over the factory jcw exhaust when i dyno tested my car