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X5 E70 (2007 - 2013)
E70 BMW X5 produced between 2007 and 2013. Discuss the E70 X5 with other BMW owners here.

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  #26  
Old 04-18-2013, 01:22 AM
pdizzle pdizzle is offline
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Location: Hawaii
 
Join Date: Oct 2011
Posts: 11
Mein Auto: 528i
Quote:
Originally Posted by philooo View Post
Do you mean the stock x5 exhaust sounds different with the tune ? Or did you upgrade to Dinan exhaust ?

What impact on your mpg and throttle response at take off ?
Stock exhaust, I think it roars a bit louder

I get less than 13 mpg, because a majority of the driving is short trips (Wifey's car). Throttle response seems the same. Very powerful tune.
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  #27  
Old 04-21-2013, 09:52 PM
scotts10x5m scotts10x5m is offline
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Location: San Jose
 
Join Date: Feb 2013
Posts: 27
Mein Auto: 10' X5M, 14' 535d M-sport
Quote:
Originally Posted by Brian425 View Post
If you want a fun and fairly accurate way to compare horse power, take the X5 to the drag strip pre tune and record your best time and MPH. After you get your tune, return to the track. (This is best done where the temp and humidity are similar and the vehicle is set up the same way, i.e. tire pressure, full tank of gas, same octane gas, etc.)

Then calculate HP based on the formula below. Please note, these will give you actual rear wheel HP. There is at least a 15% driveline loss on X5.

HP = [(MPH/234)^3 * Weight
That formula is ok for ballpark, but if you're talking about ~50rwhp, I don't trust it given the amount of error. DA, wind, launch, grip, etc., all vary enough to overpower a 10% error, and in my opinion, that formula invites at least 10% error, at least in my experience with my REAL numbers.
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  #28  
Old 04-22-2013, 03:44 AM
Brian425 Brian425 is offline
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Location: New York City
 
Join Date: Apr 2011
Posts: 203
Mein Auto: BMW X5 50i
Dinan Tune for X5

Scott,
Unless you have the engine on a stand to measure the HP, every other method of measuring HP and torque has some serious limitations.

Yes Density Altitude, wind and grip will impact MPH. In our case, grip should be a near non issue. I have not heard of tuned X5Ms losing traction on a regular basis. You can correct for wind and DA if you really want to.

With strap on dynos, there are the different readings, on inertia dynos vs eddy current dynos. These differences can approach 10%. On all dynos, there are also the questions of strapping technique, hood up or down, how big a fan is being used, the quality of the data in the weather station, tire pressure, etc, etc.

I described the MPH method as "fun and fairly accurate". I stand by that description. I also warned about set up and weather "(This is best done where the temp and humidity are similar and the vehicle is set up the same way, i.e. tire pressure, full tank of gas, same octane gas, etc.)"

The Dinan tunes should definitely be good enough to add a few MPH on a consistent basis. You will definitely see a change in MPH with a 50 HP increase.

I stand by the formula. It is a fairly accurate way to measure HP and torque.



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  #29  
Old 04-23-2013, 11:58 AM
scotts10x5m scotts10x5m is offline
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Location: San Jose
 
Join Date: Feb 2013
Posts: 27
Mein Auto: 10' X5M, 14' 535d M-sport
Quote:
Originally Posted by scotts10x5m View Post
That formula is ok for ballpark, but if you're talking about ~50rwhp, I don't trust it given the amount of error. DA, wind, launch, grip, etc., all vary enough to overpower a 10% error, and in my opinion, that formula invites at least 10% error, at least in my experience with my REAL numbers.
Quote:
Originally Posted by Brian425 View Post
Scott,
Unless you have the engine on a stand to measure the HP, every other method of measuring HP and torque has some serious limitations.

Yes Density Altitude, wind and grip will impact MPH. In our case, grip should be a near non issue. I have not heard of tuned X5Ms losing traction on a regular basis. You can correct for wind and DA if you really want to.

With strap on dynos, there are the different readings, on inertia dynos vs eddy current dynos. These differences can approach 10%. On all dynos, there are also the questions of strapping technique, hood up or down, how big a fan is being used, the quality of the data in the weather station, tire pressure, etc, etc.

I described the MPH method as "fun and fairly accurate". I stand by that description. I also warned about set up and weather "(This is best done where the temp and humidity are similar and the vehicle is set up the same way, i.e. tire pressure, full tank of gas, same octane gas, etc.)"

The Dinan tunes should definitely be good enough to add a few MPH on a consistent basis. You will definitely see a change in MPH with a 50 HP increase.

I stand by the formula. It is a fairly accurate way to measure HP and torque.
Yes, yes, I agree with all you've said. I was actually quite impressed with the output given many runs in my twin turbo 300ZX. The formula also puts my X5M at 561HP, also not bad! Now. . . what might that Dinan tune do for this ole' X5M!? 610 horsepower at 6000 rpm and 575 lb-ft torque at 3500 rpm apparently!

Last edited by scotts10x5m; 04-23-2013 at 12:01 PM.
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