Power figure disparity/variance ?
Discussion
Either plus or minus, the M5 story, with the F10 alledgedly makign more than the headline 552 bhp got me thinking as to what cars are known to make more, or less than the book figure ?
I know E36 M3's are sometimes down a little on the 321 bhp they were meant to pack, VAG 1.9 130 TDI engines generally make more than 130 bhp.
I know the Japanese manufacturers in the 80s and 90s were a bit economical with the truth around the power output of their engines relative to the 280 bhp "gentlemans agreement"
It always interest me as well as to how much difference can exist between different examples of the same car, having owned four MK2 Golf GTI 8 valves, two were a bit flat and the other two were a lot better and felt like they should, could perhaps explain some of the opinions of various cars on here, i.e. might be down to the particular example driven ?
I know E36 M3's are sometimes down a little on the 321 bhp they were meant to pack, VAG 1.9 130 TDI engines generally make more than 130 bhp.
I know the Japanese manufacturers in the 80s and 90s were a bit economical with the truth around the power output of their engines relative to the 280 bhp "gentlemans agreement"
It always interest me as well as to how much difference can exist between different examples of the same car, having owned four MK2 Golf GTI 8 valves, two were a bit flat and the other two were a lot better and felt like they should, could perhaps explain some of the opinions of various cars on here, i.e. might be down to the particular example driven ?
V8RX7 said:
TVR is the obvious example of over estimates.
My Griff 500 allegedly made 340bhp (depending where you look) it actually made a genuine 300 on the rollers and the operator said it was the highest he'd seen - most making 280ish
Yeah, TVR had a reputation for exaggeration with power figures didnt they, suspect that people didnt really complain as the light weight made up for the slight fiction in the brochure. My Griff 500 allegedly made 340bhp (depending where you look) it actually made a genuine 300 on the rollers and the operator said it was the highest he'd seen - most making 280ish
turbo engines tend to under estimate the figures because they are taken at standard temperatures and pressures. Difference between running on a cold damp day when the air can be compressed more to the 25deg dry air (or similar) used in the test can account for the difference. Veyron was tested so it would still give 1000bhp at 50 deg heat in the desert mountains or some such, which could equate to another 200 + bhp at sea level on a cold damp day.
I had a bog spec 2001 Saab 9-3 LPT, I cant believe how quick that was for 150 bhp, I replaced it with a 210 bhp Aero of the later shape and it didnt feel much faster, pretty disappointing give that it supposedly had another 60 bhp, it needed a remap to feel markedly quicker. The older one could pretty much match a Civic Type R and Cooper S.
J4CKO said:
I had a bog spec 2001 Saab 9-3 LPT, I cant believe how quick that was for 150 bhp, I replaced it with a 210 bhp Aero of the later shape and it didnt feel much faster, pretty disappointing give that it supposedly had another 60 bhp, it needed a remap to feel markedly quicker. The older one could pretty much match a Civic Type R and Cooper S.
Perhaps the LPT had already been mapped before you got it....?J4CKO said:
Either plus or minus, the M5 story, with the F10 alledgedly makign more than the headline 552 bhp got me thinking as to what cars are known to make more, or less than the book figure ?
A lot of the newer turbo generation of BMW's seem to be 'conservative' in terms of stated output.Most *35i N54 engines dyno'd 10-15hp more than stated figure, as is the newer N55 engines in the M135.
The ///M version of the N54 in the 1M is significantly understated
V8RX7 said:
TVR is the obvious example of over estimates.
My Griff 500 allegedly made 340bhp (depending where you look) it actually made a genuine 300 on the rollers and the operator said it was the highest he'd seen - most making 280ish
Didn't they claim it was 500bhp/tonne.My Griff 500 allegedly made 340bhp (depending where you look) it actually made a genuine 300 on the rollers and the operator said it was the highest he'd seen - most making 280ish
Or something like that?
J4CKO said:
Either plus or minus, the M5 story, with the F10 alledgedly makign more than the headline 552 bhp got me thinking as to what cars are known to make more, or less than the book figure ?
I know E36 M3's are sometimes down a little on the 321 bhp they were meant to pack, VAG 1.9 130 TDI engines generally make more than 130 bhp.
I know the Japanese manufacturers in the 80s and 90s were a bit economical with the truth around the power output of their engines relative to the 280 bhp "gentlemans agreement"
It always interest me as well as to how much difference can exist between different examples of the same car, having owned four MK2 Golf GTI 8 valves, two were a bit flat and the other two were a lot better and felt like they should, could perhaps explain some of the opinions of various cars on here, i.e. might be down to the particular example driven ?
Are you thinking Audi RS4 and the coking problems?I know E36 M3's are sometimes down a little on the 321 bhp they were meant to pack, VAG 1.9 130 TDI engines generally make more than 130 bhp.
I know the Japanese manufacturers in the 80s and 90s were a bit economical with the truth around the power output of their engines relative to the 280 bhp "gentlemans agreement"
It always interest me as well as to how much difference can exist between different examples of the same car, having owned four MK2 Golf GTI 8 valves, two were a bit flat and the other two were a lot better and felt like they should, could perhaps explain some of the opinions of various cars on here, i.e. might be down to the particular example driven ?
Didn't the guy from Surrey Rolling Road say at one point that most of the GT86s he'd dynoed put out a fair bit less than he expected for a 200bhp car?
Maybe the engines were very tight on delivery.
Back in the 80s my friend used to do a lot of PDIs on new VWs at the local dealer. I remember when the 16V Golf first appeared he said a lot of them felt quite sluggish. They had someone that did 30K a year plus and he said their car was almost like a different engine to drive against a new one - felt much quicker with a few thousand miles on the clock.
EVO had a spell of dyno-ing new press cars to see if they made their quoted power but soon gave up.
Seemed academic to me - it's what the car delivers on the road that seemed more relevant.
In the 70s and 80s, when Autocar ran a long term test car they would often re-figure the performance against the initial road test. Almost always the Long-termer turned out slower but just occasionally there was a car that seemed to have picked up a bit of extra acceleration/top speed/mpg etc
Are we all assuming the rolling road dynos are accurate?
It is easy for an operator to vary the result of the rolling road to make it read +-5%.
The tyre roller interface is not the best for transfering force from car to dyno, in this respect a hub dyno is better as the dyno is fixed to the drivetrain.
Rototest keep a database of cars tested on their dynos, the results being power at the hubs and therefor taking in to account the losses within the gearbox(s), transfer box(s), drive shafts and bearings.
http://rototest-research.eu/index.php?Visitor=2&am...
I would guess that those making closest to the manufacturers claimed figures are the cars that might produce more.
It is worth noting that some (most) manufacturers quote in PS and not bhp (DIN), which gives abetter headline figure. Examples are Clio 200(ps) are 197bhp DIN, E36Evo 321PS 316bhp.
stevesingo said:
Are we all assuming the rolling road dynos are accurate?
Depends on the dyno and operator BUT very few UNDER read - it's simply bad business.IME on dyno days I've been on (with car clubs / forums) we've put on a std car to use as a benchmark before putting the modified cars on.
aeropilot said:
J4CKO said:
I had a bog spec 2001 Saab 9-3 LPT, I cant believe how quick that was for 150 bhp, I replaced it with a 210 bhp Aero of the later shape and it didnt feel much faster, pretty disappointing give that it supposedly had another 60 bhp, it needed a remap to feel markedly quicker. The older one could pretty much match a Civic Type R and Cooper S.
Perhaps the LPT had already been mapped before you got it....?May be getting nostalgic but was one of the nicest engines I have owned, in the wet the inside wheel would spin when coming off a roundabout up to 80 mph, mainly down to crap suspension and tyres but quite a party piece.
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