**CHALLENGE** - TURBO LAG TEST using a log

jkholder09

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Jan 8, 2012
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I think 4 hi in 5th would be ok. You are going to have more drivetrain loss but you can ride the brake to 50 mph...........mahaha

from mobile
 

Magnus

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Jun 22, 2013
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http://en.m.wikipedia.org/wiki/Density_of_air


Pv=nrt
Pressure and volumn are the same.
R is the gas constant so we solve that to
N/t I think where n is maf and t is iat.

So basically the difference between 300 degree air and 150 degree air is 50% of the mass.

I hope this makes sense to you guys and I did the math correctly.

Why would gm add a maf if boost measured total airflow.


from mobile

:thumb: science is cool...

What truly matters is the amount of oxygen reaching cylinders. Pressure is caused by resistance, and boost pressure is roughly proportional to volumetric flow divided by cross sectional area it flows through.

Assuming the temperatures are identical and starting environmentals are identical, resistance is resistance and 20psi with each charger is the same. If the temperatures through the system are not identical, 20psi means two different chargers have identical volumetric flow but whichever yields lower outlet temperatures has a higher mass flow for that volume and will push more oxygen into the engine.

Basically if the post-intercooler temps are the same across different setups then JoshH is right and 20psi is all the same.

This is a good test
 

coker6303

Keep Calm and Chive On!!
Aug 6, 2009
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long story short, from what I can gather from IAT and IAT2 (at filter and then Y bridge) under throttle holding 20psi total boost and steadily accelerating I only see a max of 20-25F increase in temp through the turbo system.

Waiting to see the results of the same test through a stock turbo to see if there is more heat introduced into the system at the low boost levels.
 

ecc_33

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Aug 10, 2006
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I would be all over this like white on rice on a white paper plate in a snow storm but..............Its winter time here and my truck is a fair weather truck. Never seen salt and never will under my ownership. You can still eat off the frame of it! Still has 51,000 miles on it lol.
 

LBZ

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Jul 2, 2007
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I can make it spot on though. I don't do close on it. I use before and after MAF readings and adjust by percentage from readings. Pipe sizes will not be accurate. Especially in compound setups.

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Very True. Extremely tough when using twins. Different radius bends in the piping, different diameter, length of the tubing. It's best guess even for stock piping when changing turbo's.

Has anyone checked the times to spool to 20psi on a stock turbo? With stock tuning? For a baseline ref?
 

JoshH

Daggum farm truck
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Feb 14, 2007
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I can put a stock tune in it and test it, but with the intake, exhaust, and EGR delete, I'm not sure how accurate it would be to a totally stock truck. Here's what my truck does with a hot street tune, probably in the 475 hp range, runs low 13s. My truck is 7200 lbs, 285/55R20 tires (about 32" tall), 1058 converter.

Here are my numbers:

Zero boost off idle 20 psi: 2.400 seconds, 683-3292 rpm, 0-25 mph. It really starts to light at about 1600 rpm.

1500 rpm locked in 5th to 20 psi: 2.848 seconds, 1496-1730 rpm, 52-60 mph. Boost and rpm don't even really do anything for the first half second.

Locked in 5th at 60 mph to 20 psi: 1.851 seconds, 1754-1936 rpm, 60-66 mph. Boost starts to climb after about .3 seconds.

Locked in 4th at 60 mph to 20 psi: .801 seconds, 2483-2602 rpm, 60-64 mph. Boost doesn't really start moving until about .3 seconds like above, but once it starts, it really takes off instead of the gradual climb like the other tests.
 

A. Stock Lbz

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Aug 13, 2013
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can I post a log from a autocal? I didnt tune the truck and dont want to post the log if it reveals to much about the tuning. dont want to make the tuner mad.
 

coker6303

Keep Calm and Chive On!!
Aug 6, 2009
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can I post a log from a autocal? I didnt tune the truck and dont want to post the log if it reveals to much about the tuning. dont want to make the tuner mad.

I've never done a log from an autocal, but if you use the v7 software with it then you can select the PID list to only reveal what you need for the log :thumb:
 

Dozerboy

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Jun 23, 2009
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I don't have IAT2 in my PID list any longer. Its not in EFI Scan and Tune BBL. If anyone has the computer code for me to put in the Options file I will log it too.

I did some logs the other day and I was logging Converter Duty Cycle (if thats the right one?) and never could get it to read over 65% from what I saw on the screen of my V2. Built trans in TH, M, and 5th gear.