Data Junkies + DLL dyno surprise
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Joined: Aug 2005
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From: Virginia Beach, Virginia
yep, I love me some DLL, as long as you're on flat ground and being honest with yourself it's a great tool.
I've tuned a few cars and thought I had them at the ragged edge, ran it though DLL and saw some dismal numbers for the mods/boost/octane which led me to investigate the car further for boost leaks, bum bov's, exhaust kinks etc.. and rectify the issues.
I've tuned a few cars and thought I had them at the ragged edge, ran it though DLL and saw some dismal numbers for the mods/boost/octane which led me to investigate the car further for boost leaks, bum bov's, exhaust kinks etc.. and rectify the issues.
I use Weather Underground as well, but the closest tower is at the airport about 20 minutes away and at a couple hundred feet lower elevation ... I've been getting the baro readings from my logs and using WU for the temps and humidity. I haven't checked it against a dyno though.
I use landmarks for my pulls to help with DLL accuracy. Do you guys use the same approach?
I use landmarks for my pulls to help with DLL accuracy. Do you guys use the same approach?
Another back to back
Here is another back-to-back DLL run on a car that I tuned last night. Looks damned consistent to me 
183 lbs tuner+equipment
135 lbs driver
230 lbs passenger
1/3 tank of gas
183 lbs tuner+equipment
135 lbs driver
230 lbs passenger
1/3 tank of gas
You can eliminate much of the variance by elminating the differences in your driving (namely initial WOT RPM). Bryan could you check your time values to see if it was a DLL glitch, or if it was actually just faster through the rpm range.
I agree 2.5% vs 1.3% variance does not disuade me from using Data Log Lab in the least bit. If you consider the price of the product as a tuning tool, DLL is a bargain. However if I lived closer to a AWD dyno, I would tune with it too.
I agree 2.5% vs 1.3% variance does not disuade me from using Data Log Lab in the least bit. If you consider the price of the product as a tuning tool, DLL is a bargain. However if I lived closer to a AWD dyno, I would tune with it too.
Last edited by Mr. Evo IX; Jul 7, 2008 at 08:49 PM.
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Joined: Apr 2004
Posts: 16
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From: UK
Hi guys.
As a rule of thumb you can't use dyno pulls in DLL as DLL's calculation is based around the rate of acceleration of the car in the real world, as recorded via RPM and translated to speed through the gearbox, diff and tire specifications. The rate of acceleration on a dyno does not match the real world for a given gear - it could be faster or slower, which would put the DLL calcs out.
There is an argument that a dyno power run will be down on power compared to a street pull as on a dyno you're very likely to heat-soak your intake plumbing and IC due to lack of air flowing through the engine bay, which will lead to higher intake temps, less dense air, and most likely intake temp related ignition retard.
Thanks,
Glenn
Data Log Lab Support
As a rule of thumb you can't use dyno pulls in DLL as DLL's calculation is based around the rate of acceleration of the car in the real world, as recorded via RPM and translated to speed through the gearbox, diff and tire specifications. The rate of acceleration on a dyno does not match the real world for a given gear - it could be faster or slower, which would put the DLL calcs out.
There is an argument that a dyno power run will be down on power compared to a street pull as on a dyno you're very likely to heat-soak your intake plumbing and IC due to lack of air flowing through the engine bay, which will lead to higher intake temps, less dense air, and most likely intake temp related ignition retard.
Thanks,
Glenn
Data Log Lab Support
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