basic exaust manifold polishing

[polo2k]

before i start id like to say that this procedure was done on a 2001 6n2 polo with the aud engine (1.4 8v multi point injection)
the principle behind this mod is that you want to be able to get the waste gasses out of the engine as fast and efficiently as possible. This is accomplished by enlarging the inside of the manifold. unfortunatly the stock manifold was not designed with this in mind so any gains may be negligble (at time of writing i am waiting for the final step to finish-paint drying- before i try it)
the tools you will need

10mm spanner and or short 10mm socket and retchet
22mm open ended spanner or special lamba sensor spanner
12mm deep socket with ratchet
17mm socket with ratchet and i had to use a wheel brace too
The procedure
firstly jack up the car and support it so that you can get to the 4 nuts holding the manifold and the down pipe together
then open the bonnet and you should be presented with somthing like this (after removing the engine cover (3x10mm))

then remove the plug wires and lamba sensor (22mm) then the heat shield (3x10mm theres one hidden at the bottom) i couldnt remove the lamba sensor until the heatshield came out with a good tug and possibly some cutting. then you have this:

from there you should be able to see the 12mm( x8 ) nuts holding on the manifold. remove them


remove the manifold. mine looked like this

please take care not to drop it because if you look at the exaust end of it you should see something like this

this is the primary catalitic converter which can be drilled out and removed if you dont worry about emmisions
then we get to work and change this:

to this:

the idea is to smooth exerything out in there and remove any projections. if you can leave the inside of the bend slightly rougher than the outside as it promotes a difference in gas velocity which in turn helps the gas to turn. even better still is to get the metal 1" before the joint of the 2 "tubes" really smooth to aid cylinder scavenging as one cylinders exaust will draw the exaust out of the next cylinder that will exaust into this tract.
heres a pic comparing one before and one after initial cleaning

to do this step you will need a selection of drill mounted grinding and polishind accesories (a dremal could also be used)
after all this is bone i cleaned up the outside a little and sprayed some matt black heat resistant paint on it


now that looks better dosent it

[Speedlaw]

Nice.



So you left the heat shield off then? I like the look of that matt black paint. My heat shield is all rusted up , may be a good plan to remove it all together, but can I just leave it off without any problems?

[polo2k]

the idea of the heat shield is to stop the underbonnet temp from climbing too much in stood trafic as the economy and power then drop it also gives vw a nifty place to plug the hot air feed into and seen as i run a K&N (not in optimal position and soon to be replaced) i dont have this hose any more. the purpose of the hot air feed is that when the engine is cold the engine sucks air from here in order to bring the engine up to operating temp faster and if restarting the engine after standing for an hour its supposedly easier but ive been fireing my car up at temps below -10 with no probs.
however though you could get a new heat shield from vw and paint that.
this manifold is only tempory as i have my eye on a stainless steel tubular manifold on my wish list but its 400 quid :(:(

[Speedlaw]

Right, the hot-air-feed-hose. Forgot about that. Guess it's there for a reason. Perhaps I can reroute that hose or hold it in place with some sort of hook.

I've looked into getting a new shield, they're quite affordable really. An option would be to polish the thing to a shine and keep it on for a while. I'd take it off when a spaghetti-manifold comes on thogh, that's gotta be seen!

(The Dutch seem to call it Spaghetti's, don't know if we're the only ones that do that...)

[polo2k]

i think you mean tubular manifold which is constructed so that the tracts join in a similar fasion to the firing sequence i.e.
if fireing order is 1, 3, 2, 4, then you fould have a tube coming out of cyl 1 and then another tube joining it from cyl 3 and then a little bit further down one from 2 and then further again one from 4
there are 2 systems the first is where all 4 join together at the same point but all the tracts are the same langth (4into1) and the type i described which is a (4321)
im pretty sure the spagetti version is a 4-1 cos it looks like someone has tied a knot in all that lot
and if your looking for a manifold from a comercial producer i was quoted £400

[polo2k]

The Review
so far ive done about 30 miles and im very pleased exept that the 800degree paint has all burned off
lo end torque is slightly improved but the real difference is in top end because now the limiter comes in a lot easier in top (we went to a course of course (see what i did there:P)) it took me around 2.5miles to get to the red so im happy and i could actually see the tail lights of my mates clio still which is amazing compared to before

(the clio in question is a mildly prepared 1.8 16v)

[k4lps]

pics dont work

[wul3er]

Very Intersesting.

Have you got any other mod's on the engine. One of my mates who is a mechanic owes me a favour, never thought of this. But i might ask him to have a go. Does it take long.

PS pics never worked with me either.

[polo2k]

you could knife edge the throttle body.

[GroovyCarrot]

The only way you'll get heat resistant paint to stick to an exhaust manifold is to take some really coarse sandpaper to it, leave a good rough finish, then apply a very light cost of paint from a spray can - the paint on stuff is hopeless on anything as hot as the exhaust manifold. I painted mine red by doing this, and it's still red half a year later