Why do so many people get the BHP figures wrong

T

trottski101

Member
 Northumberland
In the E85 M Roadster, the S54 engine is rated at 343 hp (DIN) or 330 hp (SAE) at 7,900 rpm and 262 lb/ft of torque at 4,900 rpm.

I also thought the European version was the 343 HP, not 330 HP. And the Americans have a a far stricter speed limit too. Or, will they be the same there a bouts?
 
Why do so many people get the BHP figures wrong
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Oh the irony :poke:

US:
330 (imperial/SAE) hp
335 (metric/DIN) hp/ps
246kW

UK:
338 (imperial/SAE) hp
343 (metric/DIN) hp/ps
252kW

To confuse you even further, there is a difference between HP and BHP:
  • DIN measures the power with all standard accessories installed, the way the engine is used (if power steering or AC is option, than this is not installed, if standard, it should be hooked up).
  • BHP (not too often used British standard IIRC) is the bare engine, with exhaust and the air filter taken off.
  • SAE meaures the power without many accessories (alternator, water pump [basically anything belt driven], air filter, exhaust, cats, etc.) to get the max value engine can produce
 
mmm-five said:
To confuse you even further, there is a difference between HP and BHP:
  • DIN measures the power with all standard accessories installed, the way the engine is used (if power steering or AC is option, than this is not installed, if standard, it should be hooked up).
  • BHP (not too often used British standard IIRC) is the bare engine, with exhaust and the air filter taken off.
  • SAE meaures the power without many accessories (alternator, water pump [basically anything belt driven], air filter, exhaust, cats, etc.) to get the max value engine can produce
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Which is definitely odd as you'd expect SAE to be more power than DIN, but in the cases above it isn't.
 
:| So, we do have the more powerful engine. I noticed on the Pistonheads advert listings its showing as 338, why can they show 343.
I wonder what the average Z4M would show on a rolling road in terms of HP
 
trottski101 said:
:| So, we do have the more powerful engine. I noticed on the Pistonheads advert listings its showing as 338, why can they show 343.
I wonder what the average Z4M would show on a rolling road in terms of HP
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id guess around 320hp..... ive never seen an s54 dyno at the bmw stated power :? :? :?
 
Beedub said:
id guess around 320hp..... ive never seen an s54 dyno at the bmw stated power :? :? :?
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Same was said for the S38b38 in the e34 M5 (officially 340bhp and 295lb/ft), but a rolling road day of 10 cars at Noble's garage in Chesterfield in 2004 we got between 320bhp and 345bhp and between 282 and 299lb/ft.

Maintenance/state of tune didn't seem to matter as we had cars that had just been services (with shims) and cars that were due a service, along with ones that had been chipped.

Mine made the highest torque of the day and 5th highest HP - not bad considering the youngest car there was 9 years old.
 
Yes,looking at other info over the yrs,this engine would appear to test on a rolling-road at between 320 and 350bhp..which isnt too far away,tbh,from the official 338bhp/343ps as quoted.
Also the z4 m has been tested for 0-62 times at both 4.9 and 5.0 s to secs,depending on tester/conditions,etc..so things can obviously vary a bit,but wouldnt bother me,as the are great cars to drive :driving:
 
Beedub said:
trottski101 said:
:| So, we do have the more powerful engine. I noticed on the Pistonheads advert listings its showing as 338, why can they show 343.
I wonder what the average Z4M would show on a rolling road in terms of HP
Click to expand...

id guess around 320hp..... ive never seen an s54 dyno at the bmw stated power :? :? :?
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Correct. Mine was 318.
 
craig3.0 said:
Also the z4 m has been tested for 0-62 times at both 4.9 and 5.0 s to secs,depending on tester/conditions,etc..so things can obviously vary a bit,but wouldnt bother me,as the are great cars to drive :driving:
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I thought it was 0-62 mph (0-100 km/h) in 5.0, 0-60 mph in 4.9?
 
Perhaps the ram air effect being discussed on the other thread isn't applicable on a static dyno. :)?
 
I was under the impression that when the engine is bench tested after assembly they were set up so that they produced the rated power as a minimum.
 
Mine made 321bhp @ 7,300 rpm in April on a BMWCCGB rolling road day. The car is totally stock. I'd hope that it would be pretty close to the 338 figure at 7,900 based on those results.
 
original guvnor said:
Mine made 321bhp @ 7,300 rpm in April on a BMWCCGB rolling road day. The car is totally stock. I'd hope that it would be pretty close to the 338 figure at 7,900 based on those results.
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why didnt they continue to max revs??
 
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