156 v6 intake mod - Alfa Romeo Forum
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156 v6 intake mod

im wondering if i can replace the intake hard pipe on my 156 v6 with a silicon hose to get rid of the 2 chambers on it.what effect on performance will this have and why did alfa design it like that in the first place?

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Re: 156 v6 intake mod

Originally Posted by beast
im wondering if i can replace the intake hard pipe on my 156 v6 with a silicon hose to get rid of the 2 chambers on it.what effect on performance will this have and why did alfa design it like that in the first place?

These are helmholz resonators. Two functions. The resonating wave that reverts from these chambers causes a small pressure wave to return to the intake valves; if these are timed correctly they assist in chamber filling, especially at low revs, where such small effects have greater impact. Also, the destructive interference of the resonance reduces noise.

Don't think though that just because they also reduce noise that they are for wusses. If you remove the chambers your low end power will be adversely affected. Very top end power might possibly improve but I dont need to tell you its the spread of power that matters not the peak.

Id say leave them in.

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Re: 156 v6 intake mod

I've been looking in to replacing mine with a carbon pipe between the airbox and the throttle body but I've been advised to keep it for the reason listed previously. I've decided to fit a performance K&N filter in the original airbox instead. If you do the same, make sure there isn't too much oil on the filter as this can damage the air flow meter.
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Re: 156 v6 intake mod

I have tried a few mods on my V6 intake. I`ve got an Autodelta carbon-fibre intake which removes these chambers but gives a slightly wider bore and smoother corners in the pipe for better air-flow.

You can quickly hear where the original resonators had an effect, the noise IMHO is much nicer when driving (who needs the radio in a V6 ). The two areas are approx 2.25 - 2.5K revs and 4-4.25 revs where the note is discernably louder (it growls) and the power is *slightly* affected. The power is not such a smooth curve any more but has small dips at these two points. By dip I mean the amount of power delivered increases at a slower rate if you see what I mean. This is hardly noticable but is there if you concentrate. I also found that the brain had a problem getting used to this so didconnected the battery for 30 mins to reset it. After that and a few days driving everything was ok.

Benefits (apart from noise ) are mainly a real urgency over 4.25 revs. This was alway the 'power-band' anyway but now the car seems to be off like a rocket. In oparticular the 5-6K range where it really flies. Would I recommend it? Well I like a little more growl to my engine but for increase in power its not startling enough to warrent 100+ for the new part (mine was 30 2nd-hand). If you can do it cheaply then try it, otherwise don`t bother.

I also ranm the car for 12 months with no intake pipe into the airbox and just a wire mesh over the hole. This made the engine extremely loud to the point where everyone in the stree would look round if you put your foot down. A huge growl! This mod really depends on your drivng style. The lower revs are a little less stable and smooth delivery is lost, it can be a bit jerky when on and off the pedal in traffic. Revs up to 2.5K are more noise than power. However, power delivery from 4-7K is very good, especially at the 6K+ range where power drops off normally, presumeably because not enough air gets delivered. With this mod you can pull like a train up to 7K and the difference is remarkable. The worry for me was that the temptation to drive at such high revs would blow out the timing belt or something! Recommendable as a mod? Yes for the fun factor for a few days but tiresome after a while - it realy is that loud. Its so easy to take the pipe off and put it back on its worth a go for a weekends blast. I kept it for a year through sheer laziness. BTW, don`t drive through any fords with this mod as the air intake is only 8-10 inches off the floor!

Final verdict? Try your silicon hose (as wide a bore as you can fit, of course), so long as its not too expensive. I will not go back to the original pipe now as my car drives as sweet as a nut and souinds great
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