dsapsfo1
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| posted on 26/4/07 at 11:26 AM |
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RV8 - AFM question
Been trying to mount the AFM in my twin-plenum RV8 Viento. Am I right in thinking that the pipe run from AFM to plenum should be as short as
possible? I tucked the AFM round the back of the engine with longer pipes to the plenum last night and it then ran really badly. I didn't have
a chance to play much more, but just want to check I haven't knackered the AFM is knocking it about etc. I'm guessing that when the AFM
is metering the air, with longer pipes it doesn't know what's already in the pipe and so the engine will run lean until it all catches up
- make sense?
Cheers
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Agriv8
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| posted on 26/4/07 at 11:34 AM |
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Is it a flapper or Hotwire ?
Hotwire can get confused with iregular flow from bends and corners. dont know about the flapper type.
another thing to check with hotwire are you running labda sensors ? and was your loom / ecu from a car that would have had these fitted
another thing for bothe systems is to ensure that you have NO air leaks.
regards
Agriv8
Taller than your average Guy !
Management is like a tree of monkeys. - Those at the top look down and see a tree full of smiling faces. BUT Those at the bottom look up and see a
tree full of a*seholes .............
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NS Dev
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| posted on 26/4/07 at 12:01 PM |
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flapper or hotwire both need approx the right volume of air between them and the throttles to combat pulsing which the engine sees as airflow but its
actually going backwards.
Retro RWD is the way forward...........automotive fabrication, car restoration, sheetmetal work, engine conversion
retro car restoration and tuning
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dsapsfo1
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| posted on 26/4/07 at 12:07 PM |
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Thanks guys.
It's a flapper type.
Everything was running fine when I had the standard pipes etc fitted, it's just I'd need a big hole in the bonnet with the parts sticking
out! I'm sure that the problem does relate to pipe length etc, was just looking for confirmation that my logic was right. I'm also
hoping that I haven't developed a fault with the AFM itself.
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NS Dev
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| posted on 26/4/07 at 12:10 PM |
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Theoretically, you can use longer pipes as long as you drop the diameter to give the same volume..........
not sure I'd want to try it though, might restrict it or cause some other trouble, plus cost lots of pipe if it doesn't work!
Retro RWD is the way forward...........automotive fabrication, car restoration, sheetmetal work, engine conversion
retro car restoration and tuning
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dsapsfo1
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| posted on 26/4/07 at 12:13 PM |
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I agree, I was always intending to use short lenghts of pipe, but need to fabricate mounts for the AFM etc. To try and get the car to Stoneleigh, I
was trying to jury-rig it all in place around the back of the engine - guess it ain't gonna work there!
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Simon
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| posted on 26/4/07 at 01:41 PM |
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quote:
Originally posted by dsapsfo1
.......it's just I'd need a big hole in the bonnet with the parts sticking out!
That's why a lot of people go for the "Westfield" type plenum, which is modified by making it rear entry, a bit like this:
 .
ATB
Simon
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dsapsfo1
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| posted on 26/4/07 at 01:56 PM |
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True, but I don't want to mess around with the standard twin-plenum set up that came out the factory. Cheers..
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mark chandler
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| posted on 26/4/07 at 05:42 PM |
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You can add a bit of pipe without any real issues, its the volumn of air that is flowing so you just delay the responce slightly, you will not notice
this.
Looking very smart Simon, Whooosshhhh
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NS Dev
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| posted on 26/4/07 at 05:49 PM |
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Mark, the problem isn't the delay so much as the pulsing. You get intake pulses and the volume is designed to minimise the effect these pulses
have on the flap, if you get it wrong the flap waggles about on idle and cocks the job up.
Retro RWD is the way forward...........automotive fabrication, car restoration, sheetmetal work, engine conversion
retro car restoration and tuning
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Simon
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| posted on 26/4/07 at 08:32 PM |
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quote:
Originally posted by mark chandler
Looking very smart Simon, Whooosshhhh
Cheers Mark
Six week project now nearly six months!!!!!
Gonna try and have a major sesh this weekend to try and get the mechanical bits done - bolt in turbos for last time, modify sump/run drains for oil,
connect oil/water feeds and fit exhausts. Fit FPR, maybe run new fuel line.
Then need to order some sphericals so I can widen track at front and try and get some self centering.
Get some smaller headlights, finish reshaping bonnet, mould and make a new one.
Blimey, list is endless
ATB
Simon
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