[W126 Coupe] 0-60 times?

[Steve Lemberg]

Jim,

I did error on the altitude; it has been a long time since I taught ground 
school, the actual figure is 18000'.

Steve
Who ought to know better
CFI-A-ME-II  ATP DA 20 HS 125
----- Original Message ----- 
From: "Jim Ham" <jimham at porcine.com>
To: "Mercedes Coupes Mailing Lists" <mbcoupes at mbcoupes.com>
Sent: Monday, March 20, 2006 6:27 PM
Subject: Re: [W126 Coupe] 0-60 times?


> Well, I have to admit that I didn't get much farther after reading your 
> post that "At roughly 10000 feet MSL or 3000 meters the air is half as 
> dense as it is at sea level".  My sources suggest that at 10,000' the 
> density ratio is 0.74. But I agree that 0.4 or 0.5 is right as with my 
> extremely rough calculations it would be about 0.8 secs. My "less that a 
> second" was really aimed at Mike to say there's not going to be a dramatic 
> correction.
>
> Regards,
>
> Jim Ham
>
> At 05:40 PM 3/20/2006, you wrote:
>>Jim,
>>
>>Are you seeing the point in front of the 4 and 5, POINT 4 seconds or POINT 
>>5 seconds error.     The drag strip in Palmdale has a correction for 1/4 
>>mile times and from our own testing with a G-tech at the same track we 
>>generally use the 4-5 tenths as a figure at 3000' MSL.
>>
>>Steve
>>----- Original Message ----- From: "Jim Ham" <jimham at porcine.com>
>>To: "Mercedes Coupes Mailing Lists" <mbcoupes at mbcoupes.com>
>>Sent: Monday, March 20, 2006 5:30 PM
>>Subject: Re: [W126 Coupe] 0-60 times?
>>
>>
>>The density ratio of air at 3000 feet vs. sea level is 0.91 assuming
>>standard conditions. Standard temperature at 3000 feet is 48 deg F., not
>>too far from your test temperature of 52 degrees. So at a first guess, 
>>your
>>power will be down by about 9%. I doubt that the lower drag at elevation
>>will make much difference in a 0-60 run as the average speed is only 
>>30mph.
>>Windage (loss from internal friction in the engine and transmission) won't
>>change much with altitude. So my first guess is that your time should
>>increase by 9% over sea level and that's less than a second. Have I missed
>>something here?
>>
>>Regards,
>>
>>Jim Ham
>>
>>At 05:09 PM 3/20/2006, you wrote:
>>>
>>>The altitude compensation is for the MIXTURE only; all air breathing 
>>>engines suffer from loss of pressure at altitude and the effects of 
>>>density altitude.     A forced induction engine may be able to normalize 
>>>the charge or it may not depending on many factors.
>>>
>>>At roughly 10000 feet MSL or 3000 meters the air is half as dense as it 
>>>is at sea level.    All air breathing engines start to show the effects 
>>>of altitude at as little as 1500 feet or 500 meters in standard 
>>>conditions sooner when it is warmer.     Standard conditions for sea 
>>>level are 60 F or 15 C and the temperature lapse rate is 3.5 F or 2 C 
>>>drop for every 1000 feet of elevation.
>>>
>>>All air breathing engines only produce rated power at SEA LEVEL in 
>>>standard conditions.     Every other situation reduces power output to 
>>>some degree. High humidity also adversely affects engine performance; the 
>>>water vapor in the air displaces oxygen that would be present in dry air.
>>>
>>>Cold dry air is best for air density, while hot dry air produces the 
>>>least drag.    In a car the drag issue is minimal at low speeds so the 
>>>cold air is preferred.
>>>
>>>There are correction factors to normalize for the above and most dynos 
>>>factor these into the data they provide.    The G-tech is not able to 
>>>solve the problem only raw data.    The numbers could easily be .4- .5 
>>>seconds slower then sea level.
>>>
>>>Steve
>>>----- Original Message -----
>>>From: <mailto:vance.rowley at tiscali.co.uk>Vance Rowley
>>>To: <mailto:mbcoupes at mbcoupes.com>Mercedes Coupes Mailing Lists
>>>Sent: Monday, March 20, 2006 4:17 PM
>>>Subject: Re: [W126 Coupe] 0-60 times?
>>>
>>>Mike,
>>>
>>>  If I am not mistaken, all the SEC's have an altitude sensor that is fed 
>>> into the ECU. This in turn will adjust the mixture to compensate for the 
>>> altitude above sea level. So unfortunately, I don't think you are going 
>>> to get much of a different result at sea level. Unless of course you are 
>>> in thick fog which would improve your engine performance considerably 
>>> with such dense moist air. The only problem is you can't see where you 
>>> are going.
>>>I also have a G-Tech pro and found the accuracy extremely good. Have you 
>>>tested your braking from 60 as well?
>>>
>>>Good luck with your conversion.
>>>All the best,
>>>Vance.
>>>----- Original Message -----
>>>From: <mailto:mramay at att.biz>Mike R.
>>>To: <mailto:mbcoupes at mbcoupes.com>'Mercedes Coupes Mailing Lists'
>>>Sent: Monday, March 20, 2006 4:56 PM
>>>Subject: [W126 Coupe] 0-60 times?
>>>
>>>Went out last night and did the final runs on the SEC before the 
>>>conversion work starts. I wasn't particularly pleased with the results 
>>>but it is what it is. The empty, dead - end road I found was not 
>>>especially level.
>>>
>>>
>>>
>>>For the mathematicians amongst us, can these 0-60 times be corrected to 
>>>sea level? How much did I lose in time as the runs were made almost 3,000 
>>>feet above seal level?
>>
>>Porcine Associates
>>+1.650.326.2669
>>www.porcine.com
>>
>>The MB Coupes Website!
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>>Postings remain property of MB Coupes, L.L.C.
>>
>>
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>>
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>>The MB Coupes Website!
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>>Postings remain property of MB Coupes, L.L.C.
>
> Porcine Associates
> +1.650.326.2669
> www.porcine.com
> The MB Coupes Website!
> W126 SEC Mailing List
> Postings remain property of MB Coupes, L.L.C.
>
>
> -- 
> No virus found in this incoming message.
> Checked by AVG Free Edition.
> Version: 7.1.375 / Virus Database: 268.2.4/283 - Release Date: 3/16/2006
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