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box wrote:

I think I asked you this before, but what does dyno time cost you down there? Every time mine goes to the dyno, my wallet ends up about a grand lighter. 

magn1t wrote:

Did you fit the link without an IAT sensor?
It defeats the purpose of having an aftermarket ECU

BATOOH wrote:

Yeah he said the IAT was a nice to have. 

magn1t wrote:

BATOOH wrote:

Yeah he said the IAT was a nice to have. 

Think about this very carefully.
SD means "speed density"
Speed density is named as it is because the tuning tables for AFR and timing have an X and a Y axis.
One of them is speed (RPM) the other is density, as in air density inside the intake manifold.

Density needs 2 sensors, one being temp, the other being pressure.
You can't determine density without the IAT sensor which should be mounted IN the manifold, not before it.
I,m learning!

Now your wannabe tuner / parts fitter might tell you that you don't need it and you just lock in a fixed number.It's several steps backwards from having a factory ECU....The factory ECU measures flow, temp and pressure all in the same place and that gives the air mass. SD determines mass from density, RPM and VE, so when you're tuning SD you're putting in numbers that correspond to the engines VE at various RPM and manifold density points.
Probably added to the power decrease I experienced last year … went from 2 min 32 to 2 min 36....???

A turbo pumping out say 2 bar of boost will have a typical outlet temp of about 130 deg C, that goes through an intercooler of continuously varying efficiency.The 130 C at 2 bar might temporarily drop to 60 C through the intercooler but it'll creep up with time. What your manifold sees in terms of temp can be anywhere between maybe zero c on a cold morning all the way to 130 with 2 bar boost.
Probably does.
That means that at a constant boost level the actual density will vary a lot.....so your tune will change with the weather as does the efficiency of the intercoolers. 
Yes hopefully the IAT will cover this.

Not only that but most fitters fit the AIT before the throttle body, that's wrong too because a partially closed throttle drops the pressure but it drops the temp too, That's why the throttle is heated, to stop it from freezing with ice on a cold morning.It might be OK for a drag car that only sees full throttle, useless for anything else.
All factory SD installs have both sensors in the manifold and in fact a lot of modern cars have both sensors built into the same package for ease.

Throttle got disemboweled from heating many years ago. Worked fine even on a cold morning,  and It always got heated up before the runs which everybody racing a car does anyway. Installing the Link changed that however. That's why I'm putting in the IAT. personally I don't think it will matter much if it's pre TB or Post. I'm going to go with the advice of the race seasoned Pro's!.