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Rolling road · Maidstone, Kent · Est. 2011
Rolling road.
Rolling road.
Find out what it actually makes.
A brochure figure is what your car made when it was new, on a test bed, in a factory. Our rollers measure what yours puts down today - across the whole rev range, not one headline number.
Book a rolling road session → See a live power curve →
Sessions from £150 · Mustang AWD linked dyno, 2,000bhp, in Kent.
Interactive
What a power curve tells you
Pick a car and watch its curves draw. Then drag across the chart - it reads out power and torque at whatever engine speed you are pointing at, standard against tuned.
Drag or hover across the chart to read the figures at any engine speed. On a phone, slide your finger across it.
Not your car?
Peak power
0 bhp
Peak torque
0 Nm
Standard
0 bhp
Where it changes
-
biggest gain
Tuned power
Tuned torque
Standard power
Standard torque
Straight about what this is. The peak figures are real - ours, from our own vehicle database, the same ones the tuning builder quotes. The line between them is drawn from those peaks, not recorded from a run. It is the right shape, and the maths behind it is the real maths, but it is not your car. Only the rollers can tell you that, and that is the whole point of a session.
Reading it
Peak is the least interesting number
A dynamometer measures torque and engine speed; power is calculated from those two. That is why a proper run gives you a curve, and why the shape of it matters more than the number at the top.
Power
What the engine is making at every point in the range. A car that makes its power early is quicker on a real road than one with a taller figure at the red line that you have to chase.
Torque
What you actually feel. This is the line that decides whether the car pulls in sixth or wants a downshift, and it is where a remap usually makes the biggest difference to how the car feels day to day.
The gap between them
Run standard, then run tuned, on the same rollers on the same day. The area between the two lines is the honest measure of what changed - not the two peak numbers on their own.
How it works
A dyno cannot measure power
It measures two things - twisting force and how fast the engine is turning - and works the third one out. Every power figure you have ever read was calculated, not measured.
01
It measures torque, and rpm
The rollers apply a known load and measure how hard the car resists it. That is torque - twisting force, in newton metres or pounds-feet. At the same time the engine speed is recorded. Those two numbers are the measurement; everything else on the sheet is derived from them.
02
Power is torque multiplied by engine speed
Power is the rate of doing work, so it is torque times how quickly you are repeating it. In pounds-feet: bhp = lb/ft × rpm ÷ 5,252. In newton metres: bhp = Nm × rpm ÷ 7,127. That is why an engine can make huge torque low down and still not make big power - it is not spinning fast enough to turn that force into a rate.
03
Which is why the two lines always cross at 5,252 rpm
Look at any dyno sheet plotted in pounds-feet and horsepower on the same scale: the power and torque lines cross at 5,252 rpm, on every engine ever built. It is not a coincidence and it is not a property of the engine - at exactly 5,252 rpm the two calculations give the same number, so the lines have to meet. Switch our chart to lb/ft and watch it happen. If a graph you are shown does not do that, it is not plotted the way it claims.
04
And the “brake” in brake horsepower
It comes from the Prony brake - a friction brake clamped to the output shaft to load an engine while its output was measured. The brake is long gone, the name stuck. Horsepower itself is James Watt’s: selling steam engines to mine owners who thought in ponies, he defined one horsepower as 33,000 foot-pounds of work per minute. Divide that by 2π and you get 5,252 - the same number the two lines cross at.
Why any of this matters to you
Because it explains the arguments. Two shops can measure the same car honestly and print different numbers - different load, different correction, different day. What cannot be argued with is one car, one set of rollers, one afternoon, measured before and measured after. That is the graph worth paying for.
The awkward question
Why the number looks low
Two things account for nearly every “my car should make more than that” on a forum, and neither of them means anything is wrong with your car.
01
Wheel power is not flywheel power
A manufacturer quotes power at the flywheel. A rolling road measures it at the wheels, after the gearbox, driveshafts, differential and tyres have taken their cut. The difference is real and it is not a fault - it is the drivetrain doing its job. Always check which figure you are being quoted before comparing two numbers.
02
Two rollers, two answers
Air temperature, the make of dyno, tyre condition and half a dozen other things move the result. A graph made here in February and one made elsewhere in August will disagree, and neither is lying. Which is why the comparison we care about is the same car, the same rollers, the same day - before and after. A number on its own is an opinion; a pair of runs is evidence.
03
And you might not need us at all
For most cars a rolling road session is not strictly necessary to tune them. The software is near enough identical across matching makes and models, and we have already worked on the vast majority of the popular tunable cars in the UK. The rollers earn their keep on a car we have not seen, on unfamiliar software, or on a high-power build where a graph shows where the next gain is hiding. If yours does not need a session, we will say so.
The equipment
Our rolling road
Ours is on site in Maidstone, which is why a car does not have to leave us to be measured, mapped and measured again.
2,000bhp
Mustang dyno capacity, so
high-power builds are measured rather than estimated
AWD linked
Front and rear rollers linked, so
four-wheel-drive cars run as one car rather than an axle at a time
Full range
Power and torque plotted across
the rev range, not a single peak figure
On site
Measured, mapped and re-measured in
the same visit, in Kent
Your car
What does yours make?
The chart above is a worked example. Put your registration in and the tuning builder pulls up your exact model - what it makes standard, what we get from it, and the parts that fit it.
Free, no details needed. If we hold figures for your car you will see them straight away.
What you can book
Four ways to use the rollers
They are different jobs. Tell us which question you want answered and we will put the car on the right one.
Dyno session
A measured run to see what the car makes now - power and torque across the whole range, with the graph to keep. Book this if the question is simply “what has it actually got?”, or if you have just bought the car and want to know what you bought.
Tune and dyno
Measured, mapped, and measured again on the same rollers in the same visit. Before and after from one machine on one day - the only comparison that means anything.
Data logging session
Run under load while we log what the ECU is actually doing, rather than inferring it from how the car feels. Useful on an unfamiliar build, after other work, or when something only shows up at full throttle.
Diagnostics session
Some faults will not appear on a driveway or a short road test - they need load, heat and time in the rev range. The rollers let us hold the car exactly where the problem happens and watch it happen, safely and repeatably.
Not sure which one?
Tell us the car and what you are trying to find out and we will tell you which session answers it - including when the answer is that you do not need one.
Sessions from £150
Book the rolling road
Tell us the car and what you want to know, and we will come back with a price and a slot. What a session costs depends on the car and the job, so we quote rather than guess.
Questions
Rolling road questions
How much does a rolling road session cost?
Sessions start at £150. What yours costs depends on the car and what you want from the session, so tell us what you have and we will quote it.
What can I book the rolling road for?
Four things: a dyno session to measure what the car makes, a tune and dyno where it is mapped and re-measured in the same visit, a data logging session to record what the ECU is doing under load, or a diagnostics session to reproduce a fault that only shows up under load.
Why is my figure lower than the manufacturer’s bhp?
Because they are measuring in different places. A manufacturer quotes power at the flywheel; a rolling road measures it at the wheels, after the gearbox, driveshafts, differential and tyres have taken their share. The difference is the drivetrain doing its job, not a fault. Always check which of the two figures you are being quoted before comparing numbers.
Why do two rolling roads give different numbers?
Air temperature, the make of dyno, tyre condition and several other things all move the result. A graph made here in February and one made elsewhere in August will disagree, and neither is wrong. That is why a dyno is most useful as a comparison: the same car, the same rollers, the same day, before and after.
Do I need a rolling road session to have my car tuned?
Usually not. For most cars the software is near enough identical across matching makes and models, and we have already worked on the vast majority of the popular tunable cars in the UK. The rollers matter for a car we have not seen before, unfamiliar software, or a high-power build. If yours does not need a session we will say so.
Can you run four-wheel-drive cars?
Yes. Our Mustang dyno is AWD linked, so front and rear rollers turn together and four-wheel-drive cars are run as one car rather than an axle at a time.
How much power can it handle?
Up to 2,000bhp, so high-power builds are measured rather than estimated.
Where are you?
Maidstone, Kent. The dyno is on site, so a car is measured, mapped and measured again in the same visit.
Next
Related
Build your tune
Your registration, your car’s figures, the stages and the parts that fit it.
Start with your reg →What is a dyno?
The longer article behind this page - what the machine measures and how we use it when writing a map.
Read it →Abarth tuning
Stage by stage for the 500, 595 and 695, with the figures from our own rollers.
See the stages →All our services
Servicing, repairs, diagnostics and everything else we do in Maidstone.
Browse services →Meet The Team
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