Just pondering really - My alloy intake pipe has to be rather long (about 500mm) to place the K&N filter in a 'cold air' position in the engine bay (middy btw)

Question: Is it better to have a long intake pipe with the filter on the end or a shorter pipe with cold ducted towards it?

Discuss

500mm
I'd expect a very dodgy idle, but good top end if you haven't got icing problems by then. It does sound excessive, look at F1 and lesser categories as a guide.

Id go shorter with cold air feeds myself. Much less distance for the air to travel..

And i thought it was short for top end and long for lower down torque?

Cat. Pigeons.

Now post this question on the se7ens list...

quote:

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Originally posted by stevebubs
Cat. Pigeons.

Now post this question on the se7ens list...

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Huh? You got me too Steve

Looking on eBay there are loads of so called 'induction kits' which have these long alloy intakes and a cone filter, in fact I once installed one on SWMBO's Honda CRX. It didn't have a dodgy tickover. Can anyone explain the theory about this?

is for high rpm, high power..


long is for low rpm power... (wich is often converted to torque)

500mm would be long,

would make them as small as possible and make a scope with tubes wich points at them..

TKs

I think a lot of people are getting confused with inlet pulse tuning, which is more applicable to itb's/twin carbs where there is a separate runner per cylinder. In that case you are right that a shorter runner will produce benficial peaks higher up the rev range. However in a plenum inlet the pulses only occur betwwen the plenum and the inlet valves, so the length of the tubing from air filter to throttle/plenum is of far less importance in this respect. The major considerations here are adeuate diameter, and any heat transfer issues.

Are we talking about intake runners or the intake pipe before the throttle body?
Sounds to me like its the latter. In which case the length of the pipe doesn't make a noticable difference on a street car but the cooler air will. Keep it smooth internally (don't use dryer duct ) and have the inlet in a cool, high pressure area.

If we are talking intake runners, then its a whole different story.

[Edited on 26/6/06 by C10CoryM]

Looking at my original post, I may not have been very clear - I am definitely referring to the intake pipe that runs from the air filter to the TB. It is smooth bore 100mm alloy tube so it won't be a restriction to the 65mm TB.

My V6 Duratec has dual length intake runners which DO make a difference to torque at low speeds and power at high speeds. Having said all that they are an uneccessary complication on a lightweight car and I am going to remove the secondary butterflies & shafts, allowing maximum airflow and leaving full control to the throttle body & ecu. This keeps things nice and simple.