[David Szweda]

I know that the manufacturer states a horsepower rating of 163hp for the Cooper S. But I have begun to see an increasing amount of horsepower figures from dyno runs that are reporting somewhere in the neighborhood of 150-155 hp at the wheels. Even taking the low number of 150hp at a very efficient drive train loss of 12% is showing a flywheel number of 168hp. The 150-155hp figures have been reported in Grassroots MotorSports magazine, Robb Report, Mini-Madness (shows a 150.6hp at wheels on the intake dyno sheet),and I thought I saw it in Road and Track or Car and Driver. Has anyone seen these numbers as well? Does anyone have any thoughts on why some of these figures are obtained? It keeps bugging me, so I thought I would ask.

[Wynn]

This issue keeps coming up, and people go bonkers over it. *chuckle* I think it's all pretty easy to explain; there are a lot of ways to test power, and a lot of people conducting the tests with various different equipment, and different results are going to be reported. Also, everyone wants to believe that the car really has reserves that MINI hasn't reported.

The truth is probably that the reported power is pretty nearly accurate, or at least as accurate or biased as is typically the case for other, similar cars. And even more fundamentally, if the car has more than 163 horses hiding somewhere, they're the SLOWEST horses around-- it would be hard to explain why a car with the MINI's modest mass should take over seven seconds to reach 60mph if it really had 170hp in there. That would make it slower than many competing cars. The Cooper S is already not particularly fast, relative to its competition, so I think the quest to find evidence of under-represented power is a little bit backwards; it would only suggest that even more power is lost in the car's inefficiencies elsewhere.

I'm satisfied with the reported 163hp, and the performance associated with that figure. The car is quick and agile, and not a monster power plant.

[Casey]

I'm no expert on dynos, but I believe most if not all dynos have a correction factor in them...depending on what you set the correction factors you numbers can be much higher or lower then others. The main thing you want to look at a dyno is for comparisons...under the same conditions with and without a product what are the differences.

I'm curious though that with these correction factors - does it scale the increases? Lets say you set up your dyno and dyno your stock car at 150hp with one correction factor and with another you dyno at 200hp with no changes to the car.

Now do the same thing with the addition of some product on your car, say an intkae. Lets say that the intake gives 10 extra hp at with the settings that at stock levels that gave 150hp. What will it give with the settings that gave a stock level of 200hp? Will you see a 10hp increase as well? Or since the correction factor resulted in a higher baseline by 133% increase over the other baseline...would it result in a 13.3hp increase?

Not sure if i made sense here or not.

[Casey]

Wynn brought up a good point...we can call it 163hp or we can call it 175hp...the performance isn't going to change at all from what we have seen....it will still accelerate the same no matter what we call it....unless you add some gofast stickers of course :P

[David Szweda]

I agree with you Wynn. Whether it is 163hp or 175hp it is still accelerating the same. The other reason I brought it up is that I have seen very different figures for weights as well (2400 - 2700lbs) and I have seen very different figures for acceleration (0-60mph) anywhere from 6.8sec to 7.6 sec. This is a pretty big difference. (Although I know that it also makes a difference with drivers, weather conditions....) I was wondering if some of the cars are faster. Either variably during production, or whether they have increased since a certain point in production due to manufacturing fixes. This isn't the first time that cars have gotten faster. The Subaru WRX has a real swing in horsepower, although it seems to be just variable. The Subaru has had reported times of 5.1 sec stock, which is way faster than its 227hp suggests. I have noticed also that some of the older posts sometimes complain about speed and some of the newer posts don't. I am not saying there is a difference in horsepower, just a curiousity that I had, especially since a lot of fixes have been made to the ECU and other things since the beginning of production. Wondering if anyone else thought the same thing.

P.S. I wasn't thinking too much about it, except that I see the horsepower ratings are very consistent, it just seems that two different sets are reported. Some report in the 140-143hp range and some sites/magazines report in the 150-155hp range. I have never seen any other figures outside these two ranges.

One more thing to add. The Mini-Madness S was rated at 160hp at the wheels on their dynojet, even though they included an ECU upgrade (22.9hp) an intake (9.3hp) and an exhaust (? hp), which should have reported nearly 170hp, which probably just means there isn't much consistency in dyno measurements.

[Wynn]

That's a bunch of good points... I don't know! I imagine there ARE probably some small differences from one car to the next, with regard to output, and perhaps the recent tweaking to the computer (to resolve the "cold start" problem, and apparently improve mileage very slightly) might also have increased efficiences to deliver a little more power.

But there are other factors that vary from car to car that we know will influence accelleration simply due to physics, like mass of the car (which goes up, for instance, if you add the huge sunroof), and the mass of the wheels, where more massive wheels require more torque to spin up to speed. I'd bet that these factors have a greater influence on accelleration than modest variations in true horsepower at the engine. A Cooper S with 16" wheels and no sunroof is sure to be a little quicker than an S with 17" wheels and the big glass and reinforcing ring of steel atop.

I have a friend who is an innovative car designer, who has contributed some real improvements to car technology, most notably new manufacturing processes for carbon fiber components. Dave is a huge car enthusiast, but usually shrugs off claims about tweaked performance here and there from various small changes or variations, and said to me once, "The biggest improvement you can give any car is a better driver." I think that probably explains differences in reported performance as much as anything.

wynn

[HarryHBMCC]

My favorite read when looking at mod stuff is the guys who've never dynotested anything and yet they like to add up the advertised 5hp intake, 10hp exhaust, 20hp chip, etc. etc. and then proclaim their proud ownership of a 240hp car. This stuff is usually overhyped, it isn't cumulative and some mods actually make things worse! The only real test is on a track. If it works better, use it -- if it is worse, change it or take it off.

Numbers for hp or 0-60 are just numbers. So are design methodologies, saying DOHC is better than SOHC, etc. is silly unless you look at the implementation, materials, etc. If you want to drive your car on paper, go by the numbers and be worried about them. If you actually want to drive your car then take it out and drive it!

Harry

[kshapiro]

Quote:

Originally posted by Wynn
This issue keeps coming up, and people go bonkers over it. *chuckle* I think it's all pretty easy to explain; there are a lot of ways to test power, and a lot of people conducting the tests with various different equipment, and different results are going to be reported. Also, everyone wants to believe that the car really has reserves that MINI hasn't reported.

The truth is probably that the reported power is pretty nearly accurate, or at least as accurate or biased as is typically the case for other, similar cars. And even more fundamentally, if the car has more than 163 horses hiding somewhere, they're the SLOWEST horses around-- it would be hard to explain why a car with the MINI's modest mass should take over seven seconds to reach 60mph if it really had 170hp in there. That would make it slower than many competing cars. The Cooper S is already not particularly fast, relative to its competition, so I think the quest to find evidence of under-represented power is a little bit backwards; it would only suggest that even more power is lost in the car's inefficiencies elsewhere.

I'm satisfied with the reported 163hp, and the performance associated with that figure. The car is quick and agile, and not a monster power plant.

Hmmmmm...not a monster power plant? If 100 HP per liter isn't monsterous, what is?

[Grinder]

a 1 HP .01 litre engine would still have a 100 hp/litre ratio but would be puny. And a 400 hp 8 litre engine would be massive, even at the 50 hp/litre ratio.

[Tom D]

Ken,
If my memory serves me correctly, and that is highly suspect, formula 1 turbo cars in the late 70's had 1.5 liter engines developing in excess of 500 HP. That is a MONSTER POWER PLANT!

[Wynn]

Quote:

Originally posted by Grinder
a 1 HP .01 litre engine would still have a 100 hp/litre ratio but would be puny. And a 400 hp 8 litre engine would be massive, even at the 50 hp/litre ratio.

Exactly.

Too, 100hp/liter is impressive for a naturally aspirated engine, as in the s2000, but is less spectacular in a supercharged car; it's kind of cheating to compare the two. But the more fundamental point has already been made, that although it's a good bit of output from such a small engine, the total output is still nothing monstrous.

And that, I think, isn't inappropriate; the car isn't trying to be a Mustang. It's a MINI. Though I do rather wish they'd found a way to offer one with perhaps 180hp, but that's what the 'Works is about.

[stryder]

Quote:

Originally posted by Wynn

And that, I think, isn't inappropriate; the car isn't trying to be a Mustang. It's a MINI. Though I do rather wish they'd found a way to offer one with perhaps 180hp, but that's what the 'Works is about.

Since VW released the 1.8T GTI just about the same time as the MINI, I wouldn't be surprised at all if BMW comes up with a slightly more powerful S to compete directly once demand quiets down a bit.

My thoughts on the HP issue: Many different manufacturers have gotten into serious political snags by overestimating their HP figures. Ford and one of the Korean ones most recently that I remember. Its perfectly logical for BMW to underestimate by a small about (say they designed the car to have 170) to be absolutely positively sure it puts out at least what they say it does. Such underrating seems very common among their different models, and the MINIs shouldn't be any different. Because of simple differences such as air temp and the specific equiptment (I highly doubt most dynos have NIST traceable calibration) its always better to err on the conservative side.

[HarryHBMCC]

Yes, Hyundai had been overestimating HP for over 10 years. They offered extended warranties on cars as compensation but the class action lawyers are gearing up for a BIG lawsuit. Some cars were low by 15-25HP, others by just a few. It is much better to say it is 115 when it is actually 123 then the other way around.

Harry

[911ETR]

Since we are talking about Dyno's and I just had done a entire day last weekend I thought I would share some things. Yes correction factor, no one EVER states what it was. We made a Cooper S (modified) show over 200hp at the wheels in a matter of a second. It changes the entire overall picture so if you get a 20hp gain its 220 etc.. You cant get 40 hp out of a 20hp gain unless you use the MSpaint program

JLM found this and I suggest we all take it seriously. Not that we dont take him serious other times.

http://www.sgmotorsports.com/mz3/obdii.htm#ODBII

This scared me today to say the least.

Basically unless you are BMW or MINI you are really never going to get a accurate dyno run. This adaptive ECU is tricky. You either have to fool it with faults or have a factory serial port connected to a laptop with factory software to reset the ECU per every run. There is no other way to reset the system.

"Take your car.. OBD-II.. chipped or stock.. drive it one week like a MADMAN and dyno it.. then drive it for another week very meekly.. and dyno it.. compare the results.. and they WILL NOT be anywhere NEAR the same.. and we didn't change the car at ALL.."

This would explain the dyno results being way off from pretty much everyone.

So how am I going to dyno test you ask. I am working on getting a reset tool as a tester from BMW. I hope!

[HarryHBMCC]

You can feel the madman/granny effect without a dyno. Let my wife drive the car for a while and I have to retrain it all over again. This is especially true with the FBW throttle which has to assume how much to open the throttle for a particular pedal position.

Harry

[David Szweda]

All of these dyno issues, really make the need for a governing/certifying body all the more relevant. Not just for the mini, but over the industry. You can never trust the results shown by manufacturers because you never know how they were done. No one publishes there environment or testing conditions that were used. The industry really needs a set of standards for dyno runs to adhere against.

I personally like 0-60 times and 1/4 mile times much better than dyno results. As you state it is easy to boost results, besides no matter how hard you work at it a dyno will never recreate an actual driving environment. Only real runs in the car will provide that stability.

[jlm]

I posted that link to make it more obvious that the waters are murky, as they really are. That doesn't mean I am in complete agreement with the content of the link. There are a lot of dyno tuners out there who know their stuff. The idea is to standardize, right down to whether the hood is latched, how air is supplied and the if the car, (water, intercooler) and ambient temperature, barometric pressure and humidity are noted.

[911ETR]

This is exaclty my point for starting www.mcshp.org. I have had so many people and manufactures contact me I dont think any of you would believe me.

Now if my test bed would show up I can start testing!!!!!

Its in the port LA. Put it on the truck already. We are thining about a second S for testing as well.

I have been talking to the manufactures and I cant get specific but I think you are all going to be pleased with whats coming. I think 220 and above is going to be here sooner than you think.

Quote:

Originally posted by David Szweda
All of these dyno issues, really make the need for a governing/certifying body all the more relevant. Not just for the mini, but over the industry. You can never trust the results shown by manufacturers because you never know how they were done. No one publishes there environment or testing conditions that were used. The industry really needs a set of standards for dyno runs to adhere against.

I personally like 0-60 times and 1/4 mile times much better than dyno results. As you state it is easy to boost results, besides no matter how hard you work at it a dyno will never recreate an actual driving environment. Only real runs in the car will provide that stability.