Air Flow Meter position...
Discussion
Does anyone know if rotating the Air Flow Meter on my V8S will effect its performance/operation in any way.
I have an issue with under-bonnet clearance (don't ask) and would like to turn it through 90 or 180 deg. There seems to be plenty of 'slack' in the wiring to the unit, so cannot see this being a problem.
Any thoughts from the V8 collective?
Pete
I have an issue with under-bonnet clearance (don't ask) and would like to turn it through 90 or 180 deg. There seems to be plenty of 'slack' in the wiring to the unit, so cannot see this being a problem.
Any thoughts from the V8 collective?
Pete
I assume you mean rotating along its existing axis, as Peter says I can't see any problem with this. If however you are talking about taking out of line with the plenum op[ening axis laterally then yes you could introduce some problems, but even then they will not be insurmountable.
IMHE it is best to have it in the straightest line to the plenum opening in all plains. The rotation about the axis doesn't make a jot to performance. I have done a lot of experiments measuring the AFM output voltage to the ECU to get the best flow to the engine by playing with AFM/Filter/piping combinations.
Harry
IMHE it is best to have it in the straightest line to the plenum opening in all plains. The rotation about the axis doesn't make a jot to performance. I have done a lot of experiments measuring the AFM output voltage to the ECU to get the best flow to the engine by playing with AFM/Filter/piping combinations.
Harry
Turning it in any direction won't be a problem, I think. The further away from the plenum the longer it takes for the AFM to react to the increase in airflow after opening the throttle. This will result in hickups when opening the throttle. So having the AFM as close as possible to the plenum will result in the quickest response of the AFM to the airflow and as a result the ECU will adjust quicker to the throttle.
Then again this is all theory, I haven't tested anything myself, I may be
totaly wrong. Over to the experts.
Fred
Then again this is all theory, I haven't tested anything myself, I may be
totaly wrong. Over to the experts.
Fred
Thanks for the replies chaps.
Funny that both Peter and Harry have chipped in as this is related to the other thread on the S forum.
I am planning to improve the 'breathing' with my own interpretation of what Peter has done, but I need to play with the position of the AFM. Yes, only by rotating it and shortening the distance between the AFM and plenum, as you have done Harry.
If my plan comes together it will result in a much more direct air inlet, breathing fresh air which has not been heated by the proximity of the exhaust.
I'll post up piccies when it's done.
Pete
Funny that both Peter and Harry have chipped in as this is related to the other thread on the S forum.
I am planning to improve the 'breathing' with my own interpretation of what Peter has done, but I need to play with the position of the AFM. Yes, only by rotating it and shortening the distance between the AFM and plenum, as you have done Harry.
If my plan comes together it will result in a much more direct air inlet, breathing fresh air which has not been heated by the proximity of the exhaust.
I'll post up piccies when it's done.
Pete
. 
, there are shorter ones that will fit quiet nicely and make the installation easier, but they are south of 300bhp 
. I have a few options to consider. I will need to fabricate a 'mock up' first to see if it all fits.
I think it is important to isolate the air intake from the heat that builds up under the bonnet and for that I intend to make a suitable air-box to sit on the 'shelf' where the AFM is currently mounted. I have been looking in detail at filter options and believe I will be able to fit an adequately sized one into such an air-box. Some filter manufacturers quote a 'bhp' figure for their products, others do not. I have roughly calculated the surface area requirements of a filter for my engine using a suggested equation based on engine capacity and rpm at max power. I'm sure there are other methods, but this will give me an idea of the sort of size I require. Nice though it would be, I'm sure my engine is not quite up to 300bhp! I'll also be speaking with the filter manufacturers for advice.
As for fresh air, there are a couple of options. I remember previous discussions regarding the high pressure area at the base of the S's windscreen. You can utilise this, as it seems Peter H has done, by removing a section of the bonnet seal adjacent to the open section of the new air-box. This would require no visible external modifications. Alternatively a suitable inlet/scoop/duct may need to be positioned to feed air into the box. A Naca duct in the bonnet could be used to do this, although this would require some scary surgery!!
Happy to discuss as I progress.
Pete
I think it is important to isolate the air intake from the heat that builds up under the bonnet and for that I intend to make a suitable air-box to sit on the 'shelf' where the AFM is currently mounted. I have been looking in detail at filter options and believe I will be able to fit an adequately sized one into such an air-box. Some filter manufacturers quote a 'bhp' figure for their products, others do not. I have roughly calculated the surface area requirements of a filter for my engine using a suggested equation based on engine capacity and rpm at max power. I'm sure there are other methods, but this will give me an idea of the sort of size I require. Nice though it would be, I'm sure my engine is not quite up to 300bhp! I'll also be speaking with the filter manufacturers for advice.
As for fresh air, there are a couple of options. I remember previous discussions regarding the high pressure area at the base of the S's windscreen. You can utilise this, as it seems Peter H has done, by removing a section of the bonnet seal adjacent to the open section of the new air-box. This would require no visible external modifications. Alternatively a suitable inlet/scoop/duct may need to be positioned to feed air into the box. A Naca duct in the bonnet could be used to do this, although this would require some scary surgery!!
Happy to discuss as I progress.
Pete
Smart people who seem to know what they're talking about have told me that the main difference between bigger and smaller filters is how long you can run them before they clog badly enough to cause a power loss. And this depends on the environment you run them in as well as the engine capacity. It is not as simple as a smaller filter will restrict the engine. Of course you can go too small, but the main reason to go for a bigger filter is to increase its working life. This may be why filter manufacturers are so cagey at quoting BHP figures for their filters.
Not saying I'm smart in any way Peter 
, but I did say in the original thread in the S series forums, the reason that I went for a big filter was to ensure that when it got dirty it didn't choak the engine 
.
Spoke to greens about it and they actually do quote power rating, K&N will let you work it out yourself. But from what I can make out, roughly 150mm long by 120mm dia is about the absolute minimum for a 4ltr car. I think the K&N ones normally used by most aftermarket suppliers is 240mm long by 110mm dia,which by my reconning should be good for 400+bhp
.
All IMHO and probably totally wrong
Harry
, but I did say in the original thread in the S series forums, the reason that I went for a big filter was to ensure that when it got dirty it didn't choak the engine . Spoke to greens about it and they actually do quote power rating, K&N will let you work it out yourself. But from what I can make out, roughly 150mm long by 120mm dia is about the absolute minimum for a 4ltr car. I think the K&N ones normally used by most aftermarket suppliers is 240mm long by 110mm dia,which by my reconning should be good for 400+bhp
. All IMHO and probably totally wrong
Harry
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