Forgive me if this has been covered before but a search on various terms brings up precisely nothing. I'm trying to assess whether the "twin path" variable plastic manifolds found on the 1.6 AKL/AEH and 2.0 AZJ (and others?) engines have any advantages, performance or otherwise, over the standard aluminum types. Pics for kicks - 2.0 ABA manifold 2.0 AEG (and others) manifold - which I believe is proven to flow better than the above 1.6 AKL manifold 2.0 AZJ manifold This from the Audi Self Study Program on the 1.6 The thing that interests me is the fact that (on the 1.6 at least) the switchover from long runner to short runner is ECU determined - albeit fixed at 4000 rpm (I'm not entirely sure how it works on the 2.0 but I assume it's similar). This makes me think that with MS or even an rpm switch this changeover could be "tuned" for a particular camshaft to coincide with the power band. Or am I talking b*ll*cks?
You could possibly activate via a switchable ground to a relay May require MS2 or MS3 for this, not entirely sure as I havent looked into it properly. e.g. post 4000 rpm activate relay & that powers a solenoid that switches the intake manifold flap to the shorter runners.
Thanks - I saw this on DIY Autotune so I think MS1 can do it too - "This is one example of what you can do, in this example I used the JS3 output from the MS-I CPU as the input into this circuit (telling it when to switch on/off) and the output routes to Jmp SPR1 which sends the signal out to the DB37 on pin3 which is a pretty good choice since on the v3 it's not used for anything else. You'd then use pin3 on the DB37 to control your relay which controls your electronic doodad of choice......variable intake system...."
There you go then Intake system seems wasted on mildly tuned engine. My Mondeo 24v V6 had switchable intake runners. Occasionally they didn't work and the difference without the switch to the short runner made the engine feel like a 2.0 8v instead of 2.5 24v
You should be able to use and the "shiftlight output" in software and take the output to your relay earth. This output is RPM configable.
The bonus of having to remove the inlet manifold to get to the spark plugs. I believe the two stage inlet manifold is an attempt to compensate for the the fact the intake charge is heated as the plenum sits above the exhaust!
Agree on spark plug removal, though not too much hassle. On the heat issue not exactly...1.6 units are made of plastic as are most OE inlet systems these days. Variable manifolds are the OEM's way of enhancing low speed torque/response/ FE yet still extending this torque further at high speed ranges. This is similar to what Ben S did in his inlet experiment using fixed lengths matched to his calibration and engine spec..
Besides which, I have never kept a car/engine long enough to have needed to change spark plugs. Or oil filters for that matter
I'd avoid plastic manifolds if you're going for an overlappy cam. Maybe I'm being over cautious, but I'm thinking maybe there's a potential for some blow back up the inlet. It's not a condition you'd get on a road car. Having said that... and thinking as I go, people don't seem to melt the silicon hose on their bike carb / ITB installs... You can get twin path aluminium manifolds too though - I've got one on the 1.6
I think it's an AFT. I'm using the bottom bit, but not sure if I'll need the top part. Might fit your ABA bottom half.
It happens on new factory engines as std Mike. I would only worry about plastic manifolds when it comes to certain turbo engines i.e. R32T for instance running moderate boost.
We've gone over this on various courses as there are a lot of OEM VW with this design for different flows as Toyotec has outlined Whats great, on the 16V 170BHP Mk5's / passats have a flap which covers 4 of the 8 inlet tracks to increase/manage the flow though one side of the head/pair of valves
Plastic manifolds will be made from a thermosetting plastic, so blow back should not be an issue as hey will not melt, also plastic is a much better thermal insulator that aluminium, aluminium will transfer heat very well, thats why radiators are made from it!
I think it's an interesting way to manage the air flow, but would it be worth increasing to sub 4000rpm power of engine, at the disadvantage of the higher rpm the other manifolds my offer? Could performance not be increased in other ways first?
Pics of the ally one from my 1600 AFT engine. Top half. Bottom half looks the same as your ABA one. Control flaps under the cover.... Seems to be vacuum controlled?
Is that the one you got off me Mike? I resurrected this thread as I still have the aluminium blocked 1.6 crossflow AKL in my workshop (a couple of people have said they wanted it, but never did).. As I've got the factory loom for it I'm just going to cut the ECU connector off and wire it into a DB37 for the megasquirt.. it has a coilpack, a 60-2 crank wheel and a hall effect camshaft sensor and the injectors are individually wired so I can easily run it as wasted spark and sequential injection.. like mentioned above I'll use one of the programable outputs to power the variable inlet manifold To get it into my mk1 all I need to do is pull out the ABF with its exhaust manifold and drop this AKL in with a mk1 8v manifold.. the clutch on the AKL is for the 020 so I don't even need to change that! Then refit all the VW engine covers, airbox etc for a OEM look.. I realise that swapping from an ABF to a 1.6 crossflow will be a bit of drop in power, but it will be interesting to see what this AKL can do without restrictions.. I'm confident that 120bhp is achievable without changing anything.. its approx 100bhp in the mk4 with cats etc.. Then I'll sell it as a running conversion and drop the ABF back in
That's the one! Now cut up ready to get custom bits welded on. A light ally block might make for a really quick little car - light and better balanced than an equivalent iron block. Any idea what the relative weights are? Does it need mods to the mounts, and is there a 2.0 version??
