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Custom air intake (and breather pipe)

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CARRisma
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Custom air intake (and breather pipe)

Post by CARRisma » Sun Nov 20, 2016 4:44 pm

Following on from this thread http://www.ludegeneration.co.uk/honda-p ... 18651.html, some 5G owners will know, that the rubber in the ribbed section of the final section of the air intake does perish after time. Mine wasn’t too bad and was only perishing underneath, possibly due to heat rising from the engine? Here’s a photo showing the perishing to my original intake pipe (after being butchered for this project):

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I’m sure it had many years left in it before it would become no longer air tight. But as I’m a perfectionist with OCD, I decided to action it sooner rather than later. Being nearly 17 years old, rubber is expected to perish, especially when subjected to highish temperatures.

I don’t think it would be sensible simply replacing the pipe with another used one from a breaking Prelude as that would likely have the same problem. Only a new (expensive) one would cure it, or an alternative new part. A replacement from Honda (H22A8 part number: 17228-P5P-J00) would cost a slightly silly £64.65. Sourcing suitable alternatives is not easy, reason being is that the tube is narrower at the throttle body end than the other end and there is a curve. So finding a tube with similar end diameters and a similar angled curve is ‘challenging’, as management type would say. According to my measurements, the outside diameter of the H22A8 throttle body is 72 mm and the outside diameter at the dynamic chamber end is 79 mm. @honda-hardy had already replaced his a few years ago with a 45 degree pipe which resulted in a slight kink, concluding that a 60 degree pipe would be better. So thanks to Sam for contributing this this (http://www.ludegeneration.co.uk/post307565.html#p307565).

I managed to source the below pipe from DO88 (http://www.do88.se/en) who are based in Sweden via their UK distributor PFS Parts Ltd (http://www.pfsparts.com). It’s described as "DO88 black reducing elbow 60 degree 70-80" and the part number is DO88SBR60G70-80. As you've probably guessed it has a diameter of 70 mm at one end, 80 mm at the other end and has a 60 degree curve. Including P&P the total cost was £34.16 during June 2016 and took about a week to arrive. The UK distributor provides a good friendly service, originally they supplied me with the incorrect part. After notifying them of the mistake, they immediately reordered from Sweden while trusting me to return the incorrect part to them, for which they promptly refunded the postage costs.

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And here’s a photo of it next to the OEM part, as you can see it’s a lot longer:

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So firstly I had to cut it down. I removed 5 cm from the throttle body end and 4 cm from the dynamic chamber end.

If you're wondering what that black plastic screw is for embedded in my original intake pipe, it's for when I periodically (before every oil change) spray intake & carb cleaner into the intake manifold via the throttle body. I can poke the spray can pipe through that tiny hole rather than having to faff removing the intake pipe. I use Wynn's Air Intake & Carburettor Cleaner.

To customise it to my desired specification, I wanted to keep the extra bits which hold the vacuum hoses and other stuff along the side, like the OEM part. After being given the run around by a time waster who I had hoped to source a spare intake pipe from, I sourced a spare from a breaking 2.0 litre 2000 X reg Prelude near Eastbourne. My original plan was to butcher the spare part so if anything went wrong, I still had my original intake to rely on. Interestingly, I saw that the part from the 2.0 litre Prelude was actually in better condition than mine, it had no visible perishing, so I decided to butcher mine instead rather than the new one. My car is a 2000 V reg so there's not much of an age difference between the two. Maybe the pipe from the 2.0 had been replaced an some point? Or maybe the 2.0 litre non-VTEC engine emits less heat? Anyway, the 2.0 litre intake pipe looked identical so I thought all would be OK, but didn’t quite work out how I had hoped. After butchering my original part, I tried to fit the 2.0 litre intake then discovered that its throttle body end was a lot narrower so didn’t fit onto my car’s throttle body. Doh! In retrospect, even though they look the same, I suppose an intake from a 2.0 litre Prelude obviously won’t fit on a 2.2 VTEC, #facepalm #blondemoment. Anyway, I made it fit by making 4 slits at the end, forcing it on and making sure it was tightly secured with the hose clamp. This allowed me to take my time with the new part while allowing my car to still be driveable in the meantime.

First of all, I cut off the bits I wanted, marking the edges with masking tape. A Stanley knife was used for this job. I cut off the various hose clamps from the back and underneath (in one section) and the breather tube orifice from the front. There’s one single wire clamp between the breather tube orifice and the throttle body end, but I didn’t bother with that.

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I prepared the surfaces of the new DO88 pipe by cleaning it with washing up liquid and wiping it down with cellulose thinners. I stuck the long section of rear fixings to the new pipe using Loctite Premium Black silicone sealant and tightly tied it on with string while the sealant set for 24 hours. Before doing this, I surrounded the area with parcel tape for protection so if any excess sealant was to seep out, it would be easy to remove.

Imagehttps://postimage.org/

I purchased a 5 cm length of copper pipe with a 10 mm diameter through eBay (http://www.ebay.co.uk/itm/282068923959) costing just 99p including P&P. I cut off about 5 mm, splayed it out at one end and poked it through a hole which I had drilled in the new pipe. The hole is slightly smaller than the copper pipe, so wasn't easy poking it through, but this means that it's totally air tight around it. The original breather tube orifice had to be modified as my copper tube pokes straight out of the new pipe (perpendicular) whereas the original breather pipe comes out at a slight angle. So I had to flatten its base to make it more of a right angle then carve out a curve so it would seat onto the new pipe without a gap. Again, black silicone sealant was applied and the modified part was slid onto the copper pipe then tightly tied on with string for 24 hours. This breather pipe orifice from the original pipe which I've stuck on isn't strictly necessary here as I believe that the hole around the copper pipe is totally air tight around it, however, it improves aesthetics. But it's also there for good measure. The reason it's splayed out inside the new pipe is if I ever need to pull off the breather pipe for whatever reason, that would involve tugging at the copper pipe. As it's splayed out on the inside, it totally secure and won't budge.

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Here's the finished product:

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And here it is fitted:

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The hose clamps at either end aren't really needed now as it is such a snug fit, but I've put them on anyway just to be double sure.

As you can see above, the breather pipe is no longer standard. The original setup uses a short rubber pipe which connects to a rigid metal pipe with pokes into the intake. Bound to this is a coolant pipe which connects to the intake manifold. This coolant pipe consists of: rubber pipe -> rigid metal pipe (bound to the metal breather pipe) -> another rubber pipe. Why? Why is this mess so complex? I'm sure Honda had their reasons, but I just don't get it.

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Here's the overly complex setup removed:

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I've replaced the hybrid metal / rubber coolant pipe with a straight forward rubber pipe. This was actually a PCV breather pipe from another Prelude which I've cut down:

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Only a tiny amount of coolant leaks when removing the old monstrosity, but I bled the system regardless.

The new breather pipe setup I've fitted consists of a breather pipe from a Mazda MX-5 (found at a local breakers yard) and a Honda Prelude PCV valve. A standard Honda Prelude PCV breather pipe won't fit the wide inlet end of the PCV valve hence why I've had to use a slightly wider diameter pipe.

There's a few reasons I've done this:

Firstly, it is my understanding that air is supposed to go from the intake pipe, into the cylinder head cover via the breather pipe then out through PCV valve into the intake manifold via the other breather pipe on the other side. Feel free to correct me if my understanding of this isn't quite right. However, it would seem that flow is sometimes reversed at the intake breather pipe as oil can be found inside the air intake pipe. I don't think oil finding its way into the air intake pipe then subsequently the intake manifold is a good thing. I know it's not a major issue and won't cause big problems, but I don’t think it's an ideal situation. So I've fitted a PCV valve mid breather pipe which allows flow of air in one direction only (out of the intake, into the cylinder head cover) so no oil can find its way into the intake manifold via that route. I understand that this hot oily air will now go through the other original breather pipe with PCV valve fitted, and that's the route it should take. To combat this, like many others, I have an oil catch can fitted (http://www.ludegeneration.co.uk/honda-p ... t2095.html). So hot oily vapours can now only get into the intake manifold via the correct route and oily deposits are reduced by the oil catch can.

Secondly, it simply looks much tidier!

Going back to what I said earlier about spraying intake & carb clear into my intake manifold, I've designed the new pipe with this in mind. The breather pipe is now located a tad closer to the throttle body and points slightly upwards for easy access. I'll now need to just remove the breather pipe and spray in via the copper pipe which is a simpler task than having to remove the intake pipe.

I'm very happy with the way it's turned out. Like I said, it's a very snug fit at both ends so this particular pipe is a good choice. On a side note, the original air intake pipe is ribbed (where it perishes). I don’t believe a ribbed section is conducive to optimum air flow. The new pipe is not ribbed, it's smooth all the way through, albeit with my splayed out copper pipe poking in by 1 or 2 mm, so I believe is a better design for optimum air flow. This must add about 30 BHP, yes?
Last edited by CARRisma on Mon Dec 05, 2016 6:25 pm, edited 2 times in total.
2000 Honda Prelude 2.2 VTi (H22A8 / BB8).
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Post by hondaddict » Sun Nov 20, 2016 5:17 pm

Really well done, good job ! :hail:
Accord Type R , "what else" :lol:

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Post by nitin_s1 » Sun Nov 20, 2016 8:15 pm

:hail: Rep well deserved :hail:

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Post by BrokenSpring » Sun Nov 20, 2016 11:31 pm

wow man, that is serious good work :rock: :hail:
I really need to man up and swap the gaffer tape on mine for a custom one.
Will be saving this page a guide. This should totally go in the wiki.
Offloading 5th Gen bits.

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Post by CARRisma » Thu Nov 24, 2016 6:27 pm

Does anyone wanna buy this off me:

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It's the 2.0 intake with the breather pipe orifice cut out (supplied) and a spare cable clip (from the 2.2 intake).

PayPal me £5.00 and it's yours.
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Post by wurlycorner » Fri Nov 25, 2016 8:35 am

Very good work and dedication there, making up that pipe.

As for the original breather arrangement, I think one pipe provides support for the other, to prevent sag, accomodate engine movement and prevent the pipe (under vacuum) collapsing on the bends.

A bit of oil going into the intake early on, keeps the butterfly lubricated. It could though, cause a bit of carbonising on the intake valves. H22s aren't heavy breathers from what I can see though (not in comparison to some modern cars where they can suffer from attrocious intake valve carbonising, within 30k!) so I don't see the original pcv setup as being a major issue.

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Post by CARRisma » Sun Nov 27, 2016 4:40 pm

wurlycorner wrote: As for the original breather arrangement, I think one pipe provides support for the other, to prevent sag, accomodate engine movement and prevent the pipe (under vacuum) collapsing on the bends.
When I first fitted it, I did wonder about it imploding under vacuum and I can say that it doesn't suffer from this. The new pipe seems rigid enough to withstand this.

Revised offer on the spare pipe as I'm keeping the spare breather pipe orifice:

Imagehttps://postimage.org/

I'll supply a donor 2.0 litre air intake pipe (which has a big square hole cut out, not quite visible in the photo), a spare wire clip (not really needed) and a PCV valve. The PCV is new, unused. I bought it through eBay during the summer, think it was designed for a Saab from memory. I found the ends too narrow for the Honda PCV pipes. However, you might make it fit snugly buy wrapping the ends with insulating tape or something?

£5.00 including P&P.
2000 Honda Prelude 2.2 VTi (H22A8 / BB8).
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