Missed out on the peaks run yesterday because my MINI Cooper was booked onto the rolling road at Interpro, Bristol.
Anyone that beleives the official '115' bhp figures are wrong, may well be surprised by my results. I'll scan the graph in when my brother gives me back my scanner, but results are here:
Max BHP (at flywheel): 116.5 Max Torque: 122 lb/ft BHP @ Wheels: 82 BHP lost through transmission: 34.5
The only engine mod was an induction kit - if you're serious about getting power from any form of modification, the ECU will have to be modified (it doesn't give full throttle). I'm going for a superchip next, and then possible a Unichip...
The 116.5 bhp figure (don't forget the .5!) was only what the engine was pushing out. By the time this and gone through the transmission to the wheels, some of it has been lost due to friction and other such factors.
This is about 26% in this case, don't know if this is good or bad. In essence, I guess you only feel what's at the wheels...
In reality, everyone talks about BHP at the fly wheel anyway so no-one really cares what it is at the wheels. I don't think losing 26% through the transmission is all that bad as most cars lose a similar amount.
What everyone seems to have ignored though is the torque...
The Citroen Saxo VTS pushes out 120bhp (more on newer models), yet can only muster 107lb/ft of torque. The MINI has 122 lb/ft, so is excellent in that respect. Just need to up the bhp to match!
A cold air induction kit and exhaust would all help, but would be best with an aftermarket chip.
The differences between a unichip and a superchip would not really be noticeable on a standard engine. Indeed, the unichip really comes into it's own when mods such as cams have been done, as each chip is set up specifically for the characteristics of your engine.
Cold air induction would help a bit, but the fan on the rollers was blowing air into the engine bay at the time so may have cooled it a little.
Either way, if you're serious about power and not just sound, then a chip of some sort should be done!
How can theY "read" flywheel BHP on a rolling road?
OH, just for reference;
The original Mini also lost are 26-28% of the power thru the gearbox. A straight-cut 'box would loose a bit less, somewhere between 21-25% depending upon the type of 'box.
I have no sound figurs for 'dog boxes' but I would think they'll be close to SC/CR gears.
A rolling road always measures output at the wheels. The flywheel figure is worked out mathematically. True flywheel power can only be measured on an engine Dyno which is usually done with the engine on the bench.
At the end of the day it is the power at the wheels that counts, as this is what is put down onto the road. Also bhp is more about top end speed, whilst torque is about how quickly you get there. A high torque figure is only really useful if the torque curve is relatively flat. That means the engine gives nice progressive power making it more enjoyable to drive.
Hope this helps
...1996 Rover Cooper in Tahiti Blue with white...and rust. Chipped windscreen, blowing RC40 exhaust and cheapo spanner tyres...
www.derbyminiclub.co.uk - THE club for Derby Minis
The AutoGuide.com network consists of the largest network of enthusiast-owned enthusiast-operated automotive communities.
AutoGuide.com provides the latest car reviews, auto show coverage, new car prices, and automotive news. The AutoGuide network operates more than 100 automotive forums where our users consult peers for shopping information and advice, and share opinions as a community.