Makers and dubious HP gains

[obi_waynne]

Should car makers be obliged to ensure that all of their cars meet the HP figures they quote.

I note that some companies like Porsche and the Nissan GTR tend to exceed the quoted figures but many mainstream models are typically 10bhp down.

I take the focus as a case in point, the HP tends to be 10 down but the torque figure is generally higher than quoted.

Does this matter? Is it a sign of poor quality control?

 

[stamford]

Mainstream are down to cover themselves, makes them look good when owners find out they have more than the manufacturer quoted. Those at the upper end don't care and it's about bragging rights even if they never use the power. If it was down they wouldn't tell anyone about it! Some quote different units, like PS not BHP, confuses people into thinking they have slightly more.

 

[obi_waynne]

I guess it's a lot like speakers which are rated at PMPO!

 

[Loz]

The thing is, when you put your own car on a dyno the figures are never going match the manufactures. The manufactures figures probably come from an engine bolted to bench where your own car will be sat on it's tyres or at best on a hub dyno, so when you add variables such as tyre pressure, atmospheric air pressure, temperature & the competence of the machine operator a difference of 10 bhp isn't that surprising really.

Wasn't Jaguar guilty of being overly optimistic about power figures back in the day of the E type?

 

[Stevearcade]

My car on paper is 187bhp, 163ft/lbs, 0-60 in 8.4 seconds and top speed of 138mph. Having driven it for over two years and flexed its muscles from time to time, I feel this to be an underestimation.

I'm confident that dyno tested it would come out higher bhp/torque. Not loads higher, but higher. I also believe the 0-60 can go at least mid-7 seconds and the top speed is higher than 138mph (not that I've ever really cared about top speed).

I recently saw a video of the same car as mine with no mods on a dyno kicking out 211bhp!

But then we all know simply putting more expensive petrol in your car or running a tank with some Redex in, new spark plugs, fresh service, oil change and so on can all give you higher performance. Paper stats make for good bragging rights and good pub banter, but it doesn't mean a great deal really does it.

And yes, because of these many variables it's generally safer for manufacturers to underestimate stats. If I buy a car and it doesn't do what it claims (even if for reasons that go beyond quality control). I'd be unhappy. That car would get bad press too as other people would have the same experience.

If you buy a car and much to your surprise, it's kicking out 10bhp more than it should, you smile to yourself and be quietly smug. That extra bhp might actually be the norm, but it's lower on paper to afford the manufacturer a buffer, should things not be 100%.

If I built cars, I'd underestimate the car on paper!

 

[kain35m]

My car on paper is 187bhp, 163ft/lbs, 0-60 in 8.4 seconds and top speed of 138mph. Having driven it for over two years and flexed its muscles from time to time, I feel this to be an underestimation.

I'm confident that dyno tested it would come out higher bhp/torque. Not loads higher, but higher. I also believe the 0-60 can go at least mid-7 seconds and the top speed is higher than 138mph (not that I've ever really cared about top speed).

I recently saw a video of the same car as mine with no mods on a dyno kicking out 211bhp!

But then we all know simply putting more expensive petrol in your car or running a tank with some Redex in, new spark plugs, fresh service, oil change and so on can all give you higher performance. Paper stats make for good bragging rights and good pub banter, but it doesn't mean a great deal really does it.

And yes, because of these many variables it's generally safer for manufacturers to underestimate stats. If I buy a car and it doesn't do what it claims (even if for reasons that go beyond quality control). I'd be unhappy. That car would get bad press too as other people would have the same experience.

If you buy a car and much to your surprise, it's kicking out 10bhp more than it should, you smile to yourself and be quietly smug. That extra bhp might actually be the norm, but it's lower on paper to afford the manufacturer a buffer, should things not be 100%.

If I built cars, I'd underestimate the car on paper!

If it's measured on a chassis dyno, it's not Bhp. It's Whp. Brake horsepower refers to the amount of power at the flywheel. When you put a car on the dyno, you actually take into account drivetrain losses which is what usually is the reason for the lower numbers. You're getting the power at the wheels. Or wheel horsepower. Whp.

 

[e36drifter]

when a company put the engine to the test that is what goes on the paper work then down the line when that engine is in your car they have put in safety measures to give the engine less tolarence for longer life and thats why you gain 10-30 bhp after a remap because all there doing is taking the tolerance level back up.

 

[HDi fun]

The tolerances will always be built in for production cars simply to allow for poor maintenance and some drivers' propensity to explore every last ounce of performance all the time.

This is why I don't understand why people are frightened of the red line. My car's red region starts at 6300rpm but it will go through to 6600rpm under full kickdown. I imagine the engine would stand 7600rpm quite easily (you can't because the limiter and the transmission won't allow you to do so anyway) so using the available power isn't an issue so long as you maintain the car correctly and don't work it too hard when the engine is not fully warmed up.