[rodgerq]

just been lookin at a few DD vids again and keep goin back to the fact that he runs his afm on the pressure side of the inlet. a few question if i may....

1. correct me if im woring but isnt the LET afm a hotwire type. therefore wouldnt the extra heat in the pressure side of the intake cause it to read falsely. probably right out of its limits in fact ??

2. other than helping to solve one of the space issues, on the nova, what other advantages would moving it up very close to the inlet have ? better throttle response perhaps? would having it too close to the throttle flap have any diasadvantages?

3. wiring it up - would lengthening the wires to reasch across the engine bay have any affect on the reading that the ecu sees? or would the extra 2ft or whatver of wire not be enough to cause an difference?

discuss please as im actually considering tryin this during my reshell

rodgerq

 

[DarrenH]

what management is the car using. obviously its only a metering device, aslong as you told the ecu that X reading from teh meter requires X fuel injector dwell then it wouldnt really matter where it was. closer to the throttle body would make repsonse much better.

 

[rodgerq]

he is running phase 5 as far as i know so its still on the motronic!! what about the heat factor any comments?

rodgerq

 

[Barnes]

i cant see there being a great deal of difference in the temperature of the air going through it if it were in either place, infact after an intercooler, maybe colder if anything

 

[DarrenH]

according to the motronic manual the hot wire meter calculates air mass completely independant of air pressure or temp. i dont understand that at all.

 

[Andy K]

1. Been done and asked before. It appears to work.

3. No problems with extending the wire.

 

[Haynzee]

nah that can't be right

 

[Haynzee]

or maybe it is then

 

[Barnes]

works as in its beter, or as in it just works like it did before?

 

[Rick Draper]

He only did it because he did not want a restriction before the turbo inlet and the AFM aint 4" diameter which the turbo inlet was so he therfore placed it in the pressure side. He also mentioned it was not ideal but it was all he cud do at the time. Rick

 

[rodgerq]

seems to be working fine for him though eh!! think ill give it a go and see what happens when i bung the LET in the new shell.

rodgerq

 

[Rick Draper]

seems to be working fine for him though eh!! think ill give it a go and see what happens when i bung the LET in the new shell.

rodgerq

In them vids it was still phase 4 running a KKK turbo. Also its not just a case of moving it, EDS seem to be able to remap motronic and i think there is probably far more to it than just bunging it in the pressurised boost pipe. Rick

 

[Barnes]

why is there more to it? its an air mass meter, it senses air mass, the volume of air is the same at one side of the turbo to the other so its doing the same job surely wherever it is?

 

[Rick Draper]

If you know how to use it, the motronic is the best ignition system you can get for this engine. Then it´s like a free programable ignition system. There are many correction lines for fuelling and ignition and it has to work under every condition. If you place the afm at the pressureside, there is no airflowlimiting factor before the turbo. The motronic doesn´t watch at the afm at full load It isn´t as stupid as many people think...

We use our cars every day, they aren´t only for races and never come on a trailer to an event! The lsd is for my alldayuse, I cant drive on slicks to work!

Dare Devil is right, but this name was allready in use.
Last Year with eds-phase 3.5, also race against 360-Modena.

Hi,
I´m still running Bosch Motronic 2.7.
The airfilter is a really bad solution, but there is no space for a 100mm piping, because the inlet of the turbo has 100mm!!!
And thats also the reason, why I put the afm (only 80mm) to the pressureside.
Power is about 420-430bhp at the moment, but we still have to work on the setup.

There you go, quotes off the man himself. Rick

 

[tomstickland]

I guess that the meter gives the right answer for air mass flow rate (ie: Kg/s or whayever units of air mass per unit time you want) regardless of the temperature and pressure. So it gives the same answer before and after the turbo since the air mass flow rate is the same both sides. It works something like by measuring how much current it takes to keep the wire at the correct temperature. Heat flow from the wire will depend on the air mass flow rate.

 

[rodgerq]

yeah but if pressurised air is hotter its gony heat the wire up more than i would just sooking air through from an air filter. thats what i dont understand....it must work though its been proved

rodgerq

 

[Jamie C]

So the motronic setup will function the same with AFM at either side of the turbo?

Makes sense if temp and pressure sensing arent part of the equation, as all its metering then is quantity of air passed, which is the same regardless of which side of the turbo you measure on.

Are there no issues with changing the path length from AFM to throttle body though, this is a kinda tuned length isnt it? Or you just gotta be dead careful what cams you run, although thats less of an issue on a turbo is it not?

 

[rodgerq]

well the closer the afm is to the throttle flap the better the throttle response is.

rodgerq

 

[sb_scottmonkey]

according to the motronic manual the hot wire meter calculates air mass completely independant of air pressure or temp. i dont understand that at all.

The AFM has two main components hanging into the pipe, one is the hot wire, the other is a thermistor.. thats there to compensate for any changes in temperature! but this will only be able to work up to a certian point, so i'd say put it after the intercooler.

And wire lenghts shouldn't have much efect.

Hope this helps! Scott

 

[Jamie C]

So how does it work then, hot wire is fed current to get hot, air flow cools it, the resistance of hot wire varies according to temp reached and tells ECU whats going on. Thermosistor (sp?) tells ECu what the temp of the airflow passing through the AFM is and varies power fed to hot wire accordingly?

So providing you are talking a very efficient IC that does its job well you shouldnt have issues, if you tryed this on the stock IC however it could cause big probs?