Thursday 3rd June 2010


PH Fleet: Tested On The Rolling Road

We take a trip to test out the power of the M6, the Caterham, the 370Z and a certain TVR...


What'll she do, mister? It's a question that enthusiastic owners of fast cars get asked a lot (not least by themselves), but most of us have to rely on official claims from manufacturers for the answer, and not what our own particular cars can do.

So when PHer Charlie (Vixpy1) of Surrey Rolling Road dropped us a line to ask if we wanted to get some power stats for the PH fleet, we naturally accepted his kind invitation. These are our results.

 

Last-minute checks before dyno session
Last-minute checks before dyno session
Garlick - TVR Chimaera 400
I had a strange feeling of 'what have I done' when we arrived at Charlie's place, odd when you consider that it was me who had arranged to come here in the first place.

It was all right for the other guys, as they were all running borrowed cars, but this was my own pride and joy and all I could think about was rolling road horror stories.

To calm myself I raised my bonnet and pretended I knew what I was doing as I made 'last-minute checks' on my engine.

Ready for its close-up...
Ready for its close-up...
To further dampen my enthusiasm Charlie cheerily told me that 'none of the 400's make the claimed power' and went to get the rollers ready, as I was going on first. Only the night before I was studying the original Chimaera brochure and knew that Blackpool HQ had claimed 240bhp for it when new; today I wanted to be as close to that figure as possible.

Once the TVR was strapped down, I watched as it was put through its paces, and a first-run figure just shy of 240 raised eyebrows around the room. One more run was all that was needed to get 240 on the nose.

On-the-nose 240bhp makes Garlick happy
On-the-nose 240bhp makes Garlick happy
Studying the graphs afterwards, Charlie told me that it was rare to see this level of power from a 400 and not only was it making the correct power but it was also fuelling correctly and had the perfect torque curve too.

To say I was happy would be an understatement. I have a car that I love, it's on the money power-wise and everything seems to be in order as the factory intended. Not only was I grinning like mad, I could now relax and watch as the other cars had to reach the high standards set by my 11-year-old TVR.

 

370Z gets 'strapped in'
370Z gets 'strapped in'
RacingPete - Nissan 370Z
Having the stupidity to swap my four wheels for two - and powered by legs - for a cycling trip, I passed the keys for the Nissan to Mr Will to take it to Surrey Rolling Road. Under the strict promise that he wouldn't take it for a 'cruise', as these young boys seem to like (though I should perhaps have clarified the definition of this with him - it had me worried when he said he only did that at the weekend).

Now, rolling roads are subject to ambient weather conditions, but comparing the other cars' base figures and the writing on the little paper printouts I am pretty pleased with the Zed's vital statistics.

Power's up (but torque's down)
Power's up (but torque's down)
The 370Z posted 326bhp, an output that beat its official figure by a whopping 2bhp. A little less smile-inducing is the 259lb ft peak torque figure - that's about 11lb ft down on the manufacturer's figure and a bit odd considering its spot-on power output.

Mind you, I can (and will) make the excuse that it's still pretty new, so the engine might be a bit tight - and anyway it still bettered its manufacturer's claimed power. Unlike a Certain Mr Garlick's car, which merely reached its target...

 

Never pick up a Caterham by its bonnet...
Never pick up a Caterham by its bonnet...
Riggers - Caterham Seven Roadsport
Caterham says my Seven Roadsport 125 Academy racer ought to be good for - and you might already see where this is going - 125bhp. Sadly, on the rolling road it could be coaxed to a mere 118.1bhp, and a torque figure of 113lb ft (factory says 120lb ft).

I'm not too fussed by that, though - Charlie reckons most Ford Sigma-engined Roadsport 125s come out around there, and my car certainly doesn't feel down on power. In fact even with a chunky Riggers pushing the weight up to near-enough 650kg, that still makes for 182bhp per ton - within sight of the far more powerful 370Z's 214bhp per ton.

Vixpy leaps acrobatically from the Caterham
Vixpy leaps acrobatically from the Caterham
What's most interesting is the way power curve flattens off after 5500rpm, meaning that if I run as close to the 6800rpm limiter as possible, a quick gearchange should drop me back in to a point near - or even in - the peak power band. Useful stuff to know to know when out on the race track.

 

Chris-R - BMW M6
Up to now my experience of dyno has been limited to the odd YouTube clip, and I must say I was looking forward to 'maxing out' our BMW M6 on Vixpy's rollers.

Disappointment number one was that it's not a DIY operation, as there's a certain amount of skill and experience required to get proper results. Not to mention the 'elf and safety' aspect of launching one's bolide off the roller platform and into the spectators. (Vixpy reckons it's never happened, but there's always a first time - either way, he does the 'driving' himself!)

Huge fan makes it hard to hear engines scream
Huge fan makes it hard to hear engines scream
Disappointment number two was the roar of the giant propeller/fan that's required to push cooling airflow through the radiator grille of a stationary car operating at maximum revs. It's so loud it was hard to hear the Bimmer's V10 being wound up to the limiter, but it's important to remember this is about the numbers, and not just for fun...

Talking of numbers, Vixpy predicted a figure of 450-460bhp for the M6, based on previous customer cars that he's measured. So it was with some surprise that we clocked 489bhp in third gear with the M button pressed, which was very close to the 500bhp figure that BMW quotes.

The PH M6 with one of Vixpy's fleet
The PH M6 with one of Vixpy's fleet
Considering that some silly b*gger had neglected to fill the M6 up with high-octane petrol before the event (oops!), which apparently might easily have delivered another 10 or 20 horses, I was pretty pleased with the result.

Not as pleased as I would have been with the 529bhp figure generated by an initial fourth gear run. For reasons I don't quite understand Vixpy reckons fourth gear always gives dodgy result on the M6, and so wouldn't issue a chitty... the spoilsport!

   
   
Author: Riggers

Get it off your chest...

92 comments on this story

Last comment was by grahamw48
on 6th June 2010