I put together a dyno day on Saturday for some of the guys I motor around with up here in the northeast. The results were pretty interesting.
Thanks to all the guys at Swift Motorsports in Norwich, CT.
Read all about it here...
http://nemini.org/Forums/viewtopic/t=3598.html
page 7 is where you can see the see the posting of results.

 

For reference, a bone stock 2003 MCS showed 140hp at the wheels.



My 2004 MCS with the following mods worth noting:

Helix 15% reduction pulley
K&N Typhoon Intake
UUC Cat-back exhaust
63mm big-bore throttle body from Minimania
Denso IK22 plugs
Upgraded wires (don't remember which)
Screamin Daemon coilpack




29HP difference at the wheels! Outside temp was right around 44 degrees F.
169HP and 169 lbs/ft of torque!!!

There were two different types of readings: DynotDynamics (unadjusted) and DynoJet (1.13 correction factor, I'm assuming this means the dyno was attempting to calc crank HP assuming a 13% loss). Can someone please confirm this?

Here are my DynoJet #'s:




I ran two pulls with s-lites on my fronts and got this graph:





As you can see the s-lites made a negative 17HP difference on the unadjusted Dyno Dynamics reading, and a whopping negative 30HP+ difference on the DynoJet reading!

Can you believe it??

Also for reference there were a couple of JCW MCS's there that were showed these numbers:

1: 155hp DynoDynamics, 170hp Dynojet
2: 165hp DynoDynamics, 185hp Dynojet

Meanwhile we had a 2005 MCS with a Helix 15% pulley and a Rogue intake (no other mods at all!!) showing this:

166.3hp DynoDynamics
181.5hp DynoJet

 

Here's the Dyno Dynamic reading on my silver car, you can see the mods in my sig...

Here's the Dyno Jet reading on the same car...

 

so basically switching s-lites for a lighter wheel is close to the same gains as a 15% pulley. I knew ordering the sport pack a la carte without the wheels was the way to go!

 

The lighter wheels made a difference that we didn't expect.
The JCW cars also had interesting results.

 

I dont get it. I read the NE forum posts that hypothesized that the heavy wheels made the engine work harder to accelerate the wheels, so more heat-soak and less HP. But if the machine is measuring power output of the engine, it shouldn't make any difference what the wheels weigh. I know there's transmission losses due to friction, and maybe there's a friction loss with the run-flats (carcase flexing or something) hence the need to post engine HP and wheel HP.
I'd love to be corrected here, especially as I'm running really light wheels and tires...
Where's the summary of each car, the mods, and the figures?
thanks,
phil

 

This has also been proven in the several tests done by car magazines. The quickest 0-60 that I have seen for a stock MCS was 6.4 sec, done on 16" X-lites. By comparisson a MCS JCW package with 18"JC wheels did a time of 6.4 seconds.

How do you like them apples?

In R&Ts own tests a stock '03 MCS with 17" S-lites beat an '05 JCW MCS with 18" JC wheels thru the slalom course by over 2 mph.

Big heavy wheels are just plain slow.

 

The dyno machine at Swift is not hooked up directly to the hub - the wheels stay on the car. Therefore, having heavier wheels will definitely make a difference.

If you have a hub dyno then the whole wheel issue is completely taken out of the equation.

I will try and gather up all the info on who has what mods but for now you have 4 cars listed above to give you a general idea of where the HP distrubution lies.

 

Carcass flex is not one of the short comings of a runflat tire. They have very stiff sidewalls to enable them to run without air support.

I do believe that devices like the Dynojet calculate Hp by how fast a given vehicle can accelerate a known mass, the mass of the drums the drive wheels sit on. The mass of the wheels does not enter into the calculations, so if you have lighter wheels (wheels with less mass) the Dynojet sees the quicker acceleration as more Hp, not lighter wheels.

 

I don't understand why people continue to compare stats from different magazines. You cannot do this, as the track conditions such as surface adhesion, tempurature and humidity, as well as launch teqnique are widly different. The test numbers are valid only for comparisons within each particular test. If the article is a single car test, it is meant to give a ballpark figure. R&T states that for acceleration runs, they do not utilise wheel spin or speed shifting, instead choosing to drive the cars more like they are bound to be driven by their owners. C&D and Motortrend do use wheelspin and speedshifting. As a matter of fact, C&D even lists a 5-60mph figure that will probably be closer to real world results.

It seems that some are hell bent on trying to prove that the JCW is junk. Even in the R&T article it says this of the JCW : "Expensive as they may be, the impact of the JCW upgrades can be felt immediately. The increased power hurls the 2620-lb. Cooper S down the road with renewed vigor, each trip up the tach generating noticeably better acceleration than a standard S. The supercharger whine and exhaust note are also more pronounced, adding to the JCW's sensation of going faster, which indeed it is."

I agree however about the 18" wheels, they should have stuck with the 17"s and maybe have gotten better results. Unfortunately the 16' x-lites won't fit over the JCW brakes.

 

Another thing I'm really happy about is how much my torque has been increased over stock! Too bad nobody else ran torque numbers on their dynos ( ) but to see the HP:Torque ratio at nearly 1:1 is pretty neat.....

 

Everyone that was there can call Swift and give them the number on the dyno sheet and Swift can print the torque curve. They have all the info stored. I think i'll get it for my silver car.

 

... but I want to know where my car fits in here.

I did not get the sport package: I have stock 16" wheels. What kind are they they? Am I the unwitting beneficiary of light wheels?

 

I think you are. I know that when I went from 17" SSR (which were 12.8lbs) running 215/45/17 tires to the holies (12lbs) and stock 175/65/15 tires I already felt a difference - car pulled better (higher gearing ratio due to the smaller diameter and lighter wheels) and was more nimble in general.

I was telling everything about the holies before the dyno numbers - you can really feel the difference.

Plus living in NYC it helps having that extra rubber with all the crazy potholes.

And you probably have the v-spokes then. They are 17.6lbs according the the Mini2.com faq here

 

I don't get it: how can I benefit if my wheels are 5 lbs heavier than the ones you tested?

Here's a side view of my car. Maybe someone can confirm the wheel type.
https://www.northamericanmotoring.co...0&ppuser=19543

This is precisely why I "a la carted" the sport package -- so I could omit the wheels that doubtless would suffer on my local crappy roads.

As it is, I must use a travel coffee mug with a top that seals. The kind with the open hole leaves my radio/climate unit covered in coffee.

 

You have what is commonly called the X-lite.
Click this link and scroll down...
http://www.mini2.com/forum/faq.php?f...factory_wheels

 

Forgive me if I am repeating what has already been said here.

Heavier wheels rob HP. It has to do with rotational weight, one reason lightweight flywheels are used for racing. It has little to do with aero drag or friction. Heavier wheels give lower factual HP numbers.

As far as the big HP gains found during the dyno, I might suggest that the better test would have been to then switch back to the heavy wheels and dyno once again. In talking with Partsman he did tell me that there was not a whole lot of time in between the two dynos, which means to me that there was a good amount of 'heat soak' at the time of the second dyno. I might guess that this could be up to a 7hp lose in itself. By then doing a third dyno with the heavy wheels again you may come up with a more accurate number.

 

I had 4 pulls with the ligher 15" holies first.

Then someone else got on the dyno and pulled quite a few times (twincharge) and they even put on their own O2 sensor to the precat bung during the runs.

I think he had at least 4 or 5 pulls.

Then I had 2 pulls with the s-lites so the car had plenty of time in between my runs to cool down.

 

Yes... x-lites

OK, so that means I'm in the middle: lighter than 17" wheels and heavier than holies. Cool.

 

The effect of wheel weight on HP measured depends on the change in RPM per unit time. The slower the RPM change is, the less the mass of the wheel (or any other rotational part) will contribute to these deltas.

HP = Torque * RPM / Some number (5280?) I don't remember. So if you have a hp vs RPm, you have Tq vs RPM and vice versa.....

Matt