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Dandy Highwayman
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1,314 Posts
Discussion Starter #1
I'm looking into getting a pipe that relocates the air filter pod fabricated for my r32 gtst. like the one jock had made for his.

I'm just wondering if any of you bright sparks know whether it makes any different if you put the pipe

a)between the filter pod and the AFM or
b)between the AFM and the turbo

b) would increase the distance between the AFM and the engine/turbo while a) doesnt.

somewhere in the back of my mind I thought that might have an effect on lag or something

any ideas?
 

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Hmm.... First off,
apparently a 90 degree bend in pipework is like around 3 feet of straight pipe I heard. Not sure if its true, but makes sense to me. So, I went ahead with the relocation cos I was gambling on the fact that while the air has further to travel ( a virtual metre, for arguments sake), its coming in colder (ergo denser) hense offsetting, and to my mind overriding the negatives of longer pipework.

AFM mounts onto filter pod. My pipe then goes between the AFM and the rubber pipe the AFM used to connect to, which leads to the impeller of the turbo itself. ie my AFM is same place relative to the pod as it ever was, but now 1 foot (physically) and 3 feet (in bernoullis) further from the turbo.

Actual relative distance between the turbo and AFM, however, to my mind, should be as little as possible so that the car has got as accurate knowledge of the airflow entering the turbo as possible.

However, is the AFM and ECU set up programmed to cope with measuring at a specific distance (ie standard)? Can it 'learn' sufficiently to cope with relocation..?

Think the definitive answer would be expensive to discover.

Personally, I go with the 'AFM as close to the turbo as possible, ideally' theory, although at the moment its not how mine is.

I'd rather just bin the thing if I could. My worry is that I am measuring air at present BEFORE it encounters an 80-90 degree bend, which causes turbulent flow instead of laminar flow, and does several things to pressure in the pipe. Even with a constant diameter.

Mind you, the rubber pipe just before the turbo is like one of those flexi straws anyway, which will create turbulent airflow, as well as slowing airflow.

In conclusion, it probably makes feck all difference as once the ambient temp goes up 5 degrees all the maths changes anyways, and the fuelling is out again.

A straight pipe would be the best solution. As short as poss. Cold intake - pod - AFM - short straight hard cladded pipe - turbo.

Oh well, thats enough rambling. Time for my pills :crazy:
 

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Dandy Highwayman
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1,314 Posts
Discussion Starter #3
1)i feel like keeping the AFM near the turbo is good (i'm thinking about the turbulence resulting from being downstream of a pipe bend now you've mentioned it though)
2)i want to make a cold air partition for the filter pod, the current position of the pod makes this rather tricky.
3)i want to make a forced air or at least free flowing feed for the enclosed partition. coming from a scoop behind the centre section of the bottom of the bumper.
4)i dont like jubilee clips so if i can design something that bolts together with gaskets so much the better

I'm not sure whether the cool air will come in from new ducting to the existing hole behind the headlight (opened up to its full size, not just the little hole the original air box had to breath through) or the "new" bigger hole behind the washer bottle. i spose it depends on being able to relocate the washer bottle or finding a tiny weeny replacement (a visit to the scrappy may be on the cards)


well there's some rambling back at yer to peruse when the pills have worn off:)
 

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Hmm..... Re point 1:

Probably better to measure the air before it gets turbulent in case this causes a screwy AFM signal. However, that may not be the case. There won't be that much more turbulence probably (I now think, having given it some thought) with the bend, when you consider what the air goes thru to get to the AFM in the first place. You'd need some very flashy test kit to come to a conclusive answer on this one I fear. At the end of the day, play with it and see is my answer (short on time just now to think about it properly I am afraid).
Problem is, once the weather changes the car will feel different again anyways......

The sole reason I got the metal pipe to relocate the pod was to get it lower down and further from the engine, nearer to the cool air coming in, and in a place where I can easily partition it off.
 
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