Lack of understanding

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jont
Joined: Tue 18 Oct, 2005 10:54
Posts: 82

  Z3 roadster 1.9
Location: Brisbane

Lack of understanding

Post by jont »

Hi all
Knowing we have a lot of potential experts I thought I would post this comment.
I have a 1.9 m44 super charged now according to BMW a 1.9 puts out 138 HP and the supercharger gives you another potential 80 HP now the the potential figure is 218 HP.

Yesterday the BMW Qld had a dyno day yesterday and I put my car on for the first time since I bolted on the supercharger
5 years ago my Klm is 265,000 or 165,000 miles .

Now the question is the dyno showed 136.5 BHP I think this is pretty good considering my milage on the car can anybody confirm or deny that this is ok as I can not get my head around HP and BHP .

Regards johnt :head:
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PCSAM
Joined: Sat 13 Aug, 2011 01:19
Posts: 1002

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Location: Taynuilt

Re: Lack of understanding

Post by PCSAM »

something wrong i think . im no expert but =cars will loose bhp over time a gradual thing . so i think the problem is with how the supercharger is set up or how the dyno was setup and run?
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Captain
Joined: Thu 28 Jun, 2012 06:43
Posts: 520

  Z3 roadster 2.8
Location: Durban

Re: Lack of understanding

Post by Captain »

Dynos measure power in two ways either at the wheels or the flywheel, if yours was measured at the wheels the figure sounds about right with that sort of mileage.

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Del
Joined: Sat 19 Nov, 2011 18:35
Posts: 2136

  Z3 roadster 1.9

Re: Lack of understanding

Post by Del »

Ball park average loss = 1% per year. There are a lot of variables and with an engine that has been really looked after eg oil changes twice as frequently as suggested by the manuafacturer, the loss can be less.
geminimustang
Joined: Mon 11 Jun, 2012 21:06
Posts: 487

  Z3 roadster 1.9
Location: Wirral

Re: Lack of understanding

Post by geminimustang »

Del wrote:Ball park average loss = 1% per year. There are a lot of variables and with an engine that has been really looked after eg oil changes twice as frequently as suggested by the manuafacturer, the loss can be less.
I'm not believing this,sorry.Our 1997 Z3 has done 66k,full service history,zeds of a similar age are advertised for sale with 140K miles with little service history.My point is there are too many variables to come out with an average loss.One website i was just reading states there shouldn't be a substantial loss of horses until an engine has completed 100K-150K miles.Each car is individual and would have to be measured as such,surely?
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jont
Joined: Tue 18 Oct, 2005 10:54
Posts: 82

  Z3 roadster 1.9
Location: Brisbane

Re: Lack of understanding

Post by jont »

Guys

Thanks for your input in some ways you are all on the money, I spoke to a mechanic friend of mine after putting this on Zroadster.

They normally use a figure of 33% less at the rear wheels which gives a reasonable BHP to expect on a well looked after engine and they allow 1% per year loss of BHP.

So now lets look at my figures

Std HP 138 when new
Supercharger 80 Hp possible gain
Total 218 Hp Possible gain
218 Hp -33% = 146.06 BHP
Car 15 years old 1% loss per year =15
146.06 - 15 = 131.06

Current BHP 136.5

Figures now make sense to me :lol:
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