The Sa Wasteland

[craig R33]

??? i have simon michelmore (sp) runs his afm on the cool side of the fmic... so it obviosuly can be done, whether there was

any other tuning behind it i am not sure..

[Damo_R34]

anyone know?

also dale if you read this or anyone else,

i wanna put my afm between plenum and cooler, coz my intake pipe is too big to fit it, will this be better as it wont have air recirculating?

grab a Q45 afm, larger diameter, i think?? 90mm from memory

[rad100]

damo dont need a q45..

ill get it put into the cool side.

makes it hard to fit and afm infront of turbo when the induction pipe is 4inch haha..

[heslo]

you cant do that as the air in that section is compressed by the turbo, which means its temperature is different from ambient, and it cant calculate the volume properly. afm's must be before the turbo.

-D

Wrong, it can be done. As Craig said, proof is in Simon's drift car. Andrew made an awesome clamp setup so it wouldn't burst under pressure and the car takes a beating. Not a problem in the world

[scandyflick]

you cant do that as the air in that section is compressed by the turbo, which means its temperature is different from ambient, and it cant calculate the volume properly. afm's must be before the turbo.

-D

as luke said. wrong. been covered numerous times. the afm cares not for pressure or temperature of the air passing through it, and any air passing through it will be the exact same volume after the turbo as it would be before the turbo.

Edited March 1, 2010 by scandyflick

[rad100]

edit.. awsome ill get andrew to hook up a setup like simons..

Edited March 1, 2010 by rad32

[Weezy]

On my RB30ET inside my VLCT - I had the AFM positioned on the 'cool' side of the intercooler and never had problems with it ever. If you can, use the T-bolt style hose clamps either side of the AFM to ensure that you wont blow intercooler pipes off.

Will be fine Age.

Edited March 1, 2010 by Weezy

[D_Stirls]

I 'll reply too the others when i get home, i'm on the mobile at the moment.

I'm wondering who is going to the AC-DC concert, i'm thinking about buying a ticket on eBay but none of my mates are going.

[Dohmar]

as luke said. wrong. been covered numerous times. the afm cares not for pressure or temperature of the air passing through it, and any air passing through it will be the exact same volume after the turbo as it would be before the turbo.

I stand corrected... MAP sensors work in the same position ?

-D

[nicr4wks]

MAP sensor runs off manifold pressure, I see VLT's with AFM just before the throttle body so they can bolt up a dose pipe so def works.

[DIOR 33]

anyone know were to get defi gauge sensors?

need some like yesterday!?

gauge works on pt rd near your house

[D_Stirls]

anyone know?

also dale if you read this or anyone else,

i wanna put my afm between plenum and cooler, coz my intake pipe is too big to fit it, will this be better as it wont have air recirculating?

You will need a remap went you do it, it will run without the remap but to make the most from it you will need a tune.

The thing that i question with the cool side AFM mods it the integrity of the AFM casing itself, with the AFM i have i can push in the square section above the circuit board with my finger so i don't know how 20+ psi of boost will go with it. (some quick maths, that plastic section is 4"square inches. So that is 80 pounds (36.67 kg's)of force on a thin piece of plastic.

Edited March 1, 2010 by D_Stirls

[Dohmar]

You will need a remap went you do it, it will run without the remap but to make the most from it you will need a tune.

The thing that i question with the cool side AFM mods it the integrity of the AFM casing itself, with the AFM i have i can push in the square section above the circuit board with my finger so i don't know how 20+ psi of boost will go with it. (some quick maths, that plastic section is 4"square inches. So that is 80 pounds (36.67 kg's)of force on a thin piece of plastic.

i guess thats how its constructed, I've seen a few companies that have removed the nismo AFM electronic components and welded them into steel pipes of the same diameter... not sure if thats why they did it..

Im guessing the retune is needed due to the temperature of the compressed air?

scandy - with the air on the intake side of the turbo, are we sure its the same volume? - it will be sucking in a lot of uncompressed air before the turbo compresses it, hence making the air more dense and increasing the temperature to boot - makes me wonder just how those AFM's work with their 'flow' under vacuum and flow under pressure - I know they have a 0-5v feedback depending on the calibration of the unit, but the science of it eludes me at this time

kellie, pretty sure gaugeworks dont do defi, they do spitfire and vdo and a bunch of others (mostly mechanical gauges as opposed to the defi's being electrical)... that said the VDO's are great

-D

[rad100]

ahh i think ill just leave it infront of turbo.. just gotta get some reducers! then plumb the bov back in.

and for the guages i got no idea were to get the sensors!

[CRoNic...]

has anyone used or heard of ASHLEY HOBSON from classic performance dyno centre in hackam???

Good bad?

Yep I take my 32 GTR there after Boostworx moved out North.

He's got an awesome dyno cell setup there, and really knows his stuff. He's real friendly, and when I took my car there, he took me for a tour of the workshop, put the GTR on a hoist, pointed out a few things, explained heaps... really helpful. First place to ever really do that for me!

Dyno'd my car and told me a heap of stuff with it, awesome print out and stuff. He used to work for Graeme West for years and then decided to open up his own place. He deals with old school muscle cars and Jap imports... they used to have a 300+kw 33 down there that he built up, too.

I highly recommend them

Reminds me I have to book my car in down there again soon!

[Krishy]

cars booked into boosty worx for next week wednesday to get a bit of work done to it.....so after next week the car should be ready to run on the track.....looking forward to it

[drift_sileighty]

as luke said. wrong. been covered numerous times. the afm cares not for pressure or temperature of the air passing through it, and any air passing through it will be the exact same volume after the turbo as it would be before the turbo.

Are you sure you are not confusing volume and mass???

By definition, doesn’t compressing ambient air change its volume?

I know the AFM in the cooler piping works but I am yet to fully understand how it could provide the right reading to the ECU

[D_Stirls]

He should have said mass but a AFM (MAF: Mass Air Flow) actually measures the air mass not volume.

[Nightcrawler]

I agree I am confused too, as surely when the temperature of the compressed intake air varies so wildly (even once intercooled) the ECU cannot adjust effectively enough to not pop the engine.

[D_Stirls]

Ok here goes;

The Nissan style MAF/ AFM (hot wire) works by a wire being cooled by flowing air, which i'm sure most of you know. Now what cools the wire is the actual atoms that make up "air", now as the temp of the air increases the density of the air decreases which means that then there are less atoms per volume and the cooling affect of the air is therefore less per volume.

This also means that there is less oxygen per volume which is why we run intercoolers to try and regain some extra density from the intake charge before it enters the plenum/combustion chamber.

So this mean that a MAF is less sensitive to temp changes that other forms of systems because what it is actually measuring changes as the temps are increased.

Now the reason that i said that the after turbo AFM mod's needs to be tuned is more to do with the VQ table that the ECU uses than temp correction. This table says that for a set voltage there is a set mass air flow. This air flow is calibrated to the size of the AFM body amongst other things, so if you change the body size you change the amount of air that passes for the voltage put out.

These calibrations (and the tune in your ECU) are worked out with the AFM being in a vacuum and the air being drawn through the AFM, once you put it on the pressure side for the set voltage you will be getting more airflow as it's now a pressurised system and the flow is therefore increased.

The AFM being out of calibration doesn't really matter though as you can tune around it, it just means that you can't just swap it to the other side and drive away. It would drive fine once the mod has been done while you are driving around under vacuum, as it is the same as it being before the turbo in terms of calibration but once it hits boost it'll stuff up your mixtures.

When i say you can tune around it is because the ECU doesn't care about air, infact it doesn't even know what air is. The ECU takes the voltage reading from the AFM and says well i have this voltage so i need this amount of fuel (using the fuel tables set in the ECU). When you tune an ECU you are adjusting the amount of fuel for the amount of voltage the ECU is seeing from the AFM. You adjust it using a wideband O2 sensor as reference and you are adjusting it to achieve the desired Air Fuel Ratio that you want to run.

This is a simplistic view of tuning and what is going on, but you should get what i mean.

Edited March 2, 2010 by D_Stirls