RV8 Intake Route Length

RV8 Intake Route Length

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Discussion

chunder

Original Poster:

746 posts

253 months

Tuesday 15th March 2005
quotequote all
Any advice on the following would be most appreciated.

Having made some recent modifications that have altered the characteristics of the engine can anyone tell me what effect altering the length of the plenum to AFM (flapper injection) air intake pipe would have ?

Is there an ideal length for all applications (or specifically a TVR 4.5 litre) and if not then what effects would shortening, lengthening or straightening the route have ?

Thanks in advance.

rev-erend

21,536 posts

291 months

Tuesday 15th March 2005
quotequote all
chunder - you are welcome to copy mine ..

chunder

Original Poster:

746 posts

253 months

Wednesday 16th March 2005
quotequote all
Reverend,

Aside from the fact that it looks like you have a hotwire mass AFM that is pretty much what it looked like after I moved the coolant tank - although I did move it to the windscreen bulkhead leaving the left inner wing clear.

Basically all I have now done (and I don't have the savvy to be able to get pics up) is to enclose the whole AFM and filter in a box with a big flexi hose running down the left wing and then under the PAS pump down to where the scoop will be mounted.

I did have to reduce the pipe between plenum and AFM further though in order to make room for the box as otherwise the bonnet strut hit it when closed. As the flapper AFM is bigger than the mass meter anyway this pipe is less than half the length of yours - around 110mm.

Shortening the pipe made a big diference to power delivery, almost as if the engine was unable to pull enough air. Tried it with the box lid off and inlet hose disconnected and just the same so it was purely shortening the intake pipe that did it, the box and hose aren't adversely affecting it.

Obviously it has had some kind of detrimental effect on airflow but does anyone have a definitive answer as to the hows and why and what is the ideal length ?

GreenV8S

30,489 posts

291 months

Wednesday 16th March 2005
quotequote all
When I replaced the original long intake duct with a short one taking air from a cold air supply on top of the passenger's footwell, it seemed to me that the throttle response improved. Somebody else reported a similar effect.

Graham

16,369 posts

291 months

Sunday 20th March 2005
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ANy one got a more scientific answer? I've got to work out where to mount the afm and the intake/filter on the tuscan...

GreenV8S

30,489 posts

291 months

Sunday 20th March 2005
quotequote all
Somewhere cold. Never mind about lengths etc as long as it is getting plenty of cold air!

Graham

16,369 posts

291 months

Monday 21st March 2005
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The bonnet does have a large hole in it where the ajp filters went. ( two actually) i was wondering if i could make up an inlet box to fit there, although getting the afm in might be interesting....