20 replies to this topic

[pusb]

When people on here quote BHP figures that they got at a rolling road, or the official ones issued by BL/Rover, are they using flywheel or road wheel figures?

 

I took my Mini with its newly installed engine to a rolling road today. It has a 1275 a+ engine from a Sprite fitted (low compression type), with a stage 1 kit added.

 

It was giving out just over 50 Bhp at the wheels. The guy there seemed to think that was quite good for the set up, but with the stage 1 kit added, I was expecting a little bit more.

[Dusky]

Your engien only has 55 bhp at the flywheel in std form, so 50 at the wheels with the stg 1 kit is nice imo.

 

Now wait for all the 998 stg ones with 60 bhp @ the wheels and a topspeed of 110 mph.

[pusb]

Your engien only has 55 bhp at the flywheel in std form, so 50 at the wheels with the stg 1 kit is nice imo.

 

Now wait for all the 998 stg ones with 60 bhp @ the wheels and a topspeed of 110 mph.

 

Haha, I am happy with how it drives, feels nice and responsive.

 

I just wasn't sure if the original 55 bhp quoted figure was at the fly or road wheels.

[jamesquintin]

My 1275 Cooper 'S' gets 84bhp, much better than standard Cooper at 63bhp!

[Guess-Works.com]

Manufacturer quoted figures are flywheel ( as they are higher and it looks better )

 

Rolling road figures are at the wheels, but can be a corrected flywheel figure when you take into a measured transmission loss.

[yeti21586]

I'm now confused, I always thought that the figure I got given was flywheel bhp rather than at the wheels bhp. Does anyone know if BHP in West Byfleet do it at he wheels or fly??

YetI

[Northernpower]

I'm now confused, I always thought that the figure I got given was flywheel bhp rather than at the wheels bhp. Does anyone know if BHP in West Byfleet do it at he wheels or fly??

YetI

The rolling road can only give a figure at the wheels. They may have given you a corrected figure for the flywheel but that is only an estimate, the only true figure they can give you is what their rolling road says your car is giving on that day at the wheels. All rolling roads give slightly different figures so its difficult to compare one rolling road with another on different days. They are affected by things like atmospheric pressure and humidity because that affects the air density; unless you're running a turbo.

Edited by Northernpower, 02 August 2016 - 04:32 PM.

[yeti21586]

Ok cheers

[Cooperman]

Then again, there are two different bhp figures at the flywheel: DIN & SAE. DIN is the figure with the alternator and every other ancilliary running, whilst SAE used to be known as 'Standard American Exaggerated'!

 

BHP means nothing really unless taken in context. What is more important for normal driving is torque. BHP is for bar-room bragging  .

[CityEPete]

My 1275 Cooper 'S' gets 84bhp, much better than standard Cooper at 63bhp!

I've heard both of these figures are largely fantasy in reality?

[racingbob]

when i take mine to Slarks dyno at Amesbury its always at the flywheel

 

but i take more notice of the torque

[jamesquintin]

 

My 1275 Cooper 'S' gets 84bhp, much better than standard Cooper at 63bhp!

I've heard both of these figures are largely fantasy in reality?

 

 

Mine was from a rolling road session...

[Batmini]

As above, on a rolling road the flywheel figure can only be estimated, but a decent operator should get you within 5% or so on their estimate. I had my engine dyno'd at swift tune at 102bhp and the other week had the car on a rolling road where they calculated 98bhp. Allowing for the engine now being in the car with my exhaust not clamped to a bench that is pretty close. As others have said though, that number isn't too important. It's the 90 foot pounds of torque which makes it fun !

One thing, i have heard that some operators will "massage" the figures slightly either through lack of knowledge, or because they know the owner of the car just wants to see big numbers.

Edited by Batmini, 04 August 2016 - 07:21 PM.

[nicklouse]

The main thing is keep with the same rolling road then you can compare each time.

The last rolling road I took mine to (who I have always used) told me mine was a very good 1380 when they had finished dialling it in.

Not bad for a 1293.

[CityEPete]

After owning quite a few minis I've found the most important thing is that they run right, a 53 bhp 1275 running like a Swiss watch is better than a badly tuned 1380 with nitrous and a supercharger that has the wrong carb fitted and a rubbish cam and brittle HT leads!