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Dave Freeman

Turbo air intake pipe - replacement

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Whilst playing around with the pipe work, refitting the electrics etc following the fitting of the new manifold I noticed that the air intake pipe for the turbo was looking a little tatty, also it looks like it has collapsed in a couple of places.

So, a new one me thinks, but replace with lotus part or a mod to improve air flow. The topic came up whilst talking with "changes" so would the air flow benefit from an aluminium tube of a larger diameter with some sort of reducer at the turbo end. This coupled with ram air could provide improved spool up.

Does anyone have any thoughts on what tube could be used and if anyone has done this mod, and results if possible.

Dave

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There has been much discussion about this awhile back. If I remember at least one person went for solid tube with large samco reducers to connect and to allow for some movement of the turbo with the engine. I know the original part is expensive but I think some people tried other types of tube and found they all collapse under hard acceleration and would strangle airflow. I know the internal surface may not be the best for airflow but I think the ear inlet is quite small too and maybe a place to look for improvement too.

 

Buddsy

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I wouldnt of thought a solid tube and a diameter reducer at theturbo end would flow well. A sudden change in the diameter would create a bottle neck and mess with the flow. A gradual change.as per original is good, obviously its ribbing allows it to curve around the rear of the engine and allows essential flexibility in the pipe as the engine moves independent from the body where the airbox is attached

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I don't think the cost is too bad if they are still around £90 from SJ? It will last circa 20 years and I have seen many spend close to that on silicone and alloy tube only to lose the flexibility of the original as Darren points out, not to mention originality.

Trevor.

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Dermot even reduced the gauge of the wire in the ear to increase airflow! All adds up :)

 

http://users.ox.ac.uk/~ohare/ancillaries.htm#h1

 

Mine hasnt got any wire in front? Dont think G cars did?

 

Buddsy

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For the first time I noticed the mesh in the air intake, 40% reduction looks about right. I assume it's to stop small children and furry animals being sucked in.

Need to fit bigger mesh, ram air and a new pipe me thinks.

Dave

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I assume it's to stop small children and furry animals being sucked in.

 

Honestly I was just trying to check the wire to the alternator...it was hot and was my shorts must have fallen down..... :huh:

 

Buddsy  :phone:

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Right spoke to my mate last night he is a power train engineer for a certain blue badge car maker, he also worked at Lotus. He designs engines for a living, and I mean the whole engine not just tuning stuff up. He said the taper on the hose does bugger all, it's probably just a case of lotus bought the airboxes off someone else. You could use a non tapered hose if you wanted to change the end on the airbox. It has nothing to do with air pressure drops etc.. The turbo is the important bit as that has to have a certain size diameter for the compressor. 

 

If you want to taper they work on a theory of reducing by a 5th on the straight run after that it does nothing. It's how quick it can dump the air out that affects the spool time. Increasing the airflow does sod all on a turbo engine as it is Forced induction. i.e it pulls through what it needs. Yes CAI will bring in cooler air but the turbo will heat it up, that's why you have an intercooler on the SE onwards. 

 

N/A is different I had a Honda VTEC that had cold induction and you could feel that as it forced more air in, plus it was set in the bumper well away from the engine heat, so it would drag in colder dense air.

 

Hope this helps

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Good post Chris, interesting stuff. I think the air box end is larger than the turbo end, so a reducer at the air box end would work.

I agree that it's all about the pull of the turbine, but the air has a long way to go and if the air does not move freely then it must inhibite the spool up time.

The trouble with all ths playing around is that you never know if it's better or worse than before the change. I know it's not scientific but is there an app which would provide a G value ie an average g force over a predetermined road / distanced travelled. This would perhaps show any g change, higher the g the greater the acceleration.

Anyone any thoughts.

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Ditch the original airbox and tubing. The air has to travel a long routed way from ouside of the car to the turbo. Inlarge the entry hole at the rear window, run a silicone pipe to an inline viper airbox and then straight into the turbo. I have done this on my S4s, way better than the standard setup. You will have to move the coolant expansion tank to where the original airbox is, and by doing this it shortens some of the coolant pipe runs as well.

 

cheers

Dave

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Sounds like a plan, why silicon pipe?

What filter, do you have a price and part number.

Cheers

Do you have any pics

Edited by Dave Freeman

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Did you look at the link I posted above, there's tonnes of info about better induction there.

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This is what i did and detailed in the 412 thread... based on Dermot's and 

then i took to the next level...

It all makes a big difference as part of a package .

NB. the less the compressor has to scavenge on induction the better the

spool up will be.. with an effective ram air the pull load is negligible.

 

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I used something similar to this type of airbox http://www.ebay.co.uk/itm/UNIVERSAL-RACING-CARBON-FIBRE-ENCLOSED-HIGH-FLOW-COLD-AIR-INDUCTION-KIT-FILTER-/350780840504?pt=UK_CarsParts_Vehicles_CarParts_SM&hash=item51ac2ada38#ht_1034wt_958

 

 

using alloy pipe work and silicone joining hoses. I am running a larger pipe than standard because I have a T4 cosworth housing on the compressor side of my turbo.

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Oddly enough, I've just replaced the standard hose with various bits on my 88 carb turbo:

 

76mm to 60mm silicone reducing hose (the 60mm fits the turbo)

About 50mm of 76mm alloy tubing

Flexible neoprene hose 76mm diameter to the airbox

Another 50mm of 76mm alloy tubing

Then a rubber collar I had from an earlier project which held the alloy tube and wrapped around the airbox outlet, which I couldn't measure very easily but is I think 80mm.

 

Looks convoluted but I'm happy enough.  The alloy tubing is just to give the hose clips something to grip to.

 

Can't honestly say I've noticed a difference one way or the other, but if you do go straight out from the turbo (ie in line with the turbo inlet) be careful to leave space for the back of the boot floor panel.  I had mine out when I did it and now it's back in there's a bit of contact.

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Will the neoprene hose not just collapse under vacuum?

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It's a reinforced one with a metal spiral through it; similar to the original.  Having driven around a bit more, it seems to be making an interesting noise to accompany the dump valve.  Like an angry bear some distance away...

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It's a reinforced one with a metal spiral through it; similar to the original.  Having driven around a bit more, it seems to be making an interesting noise to accompany the dump valve.  Like an angry bear some distance away...

 

What, like a koala bear?

 

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