D24tic cyl head porting

fudge · #1 03-30-2010, 11:39 PM

Hi all, i have 2 940 diesel estates, one a 95 auto and the other a 92 manual.
Having done many 1600/1800 vag (golf/scirocco) cyllinder head porting jobs when i ran a vw workshop in the 90's i am thinking of doing the same on the earlier manual 940's head as a starting point.
Have any of the members noticed when their heads were of if the usual poor castings and restrictive port shape is the same on the diesel head ? especially round the exhaust ports ?
One of my flowed 1600 petrol heads would up the power by 15-20 % i felt mainly due to the ammount of rubbish we could take out the exhaust port area ( the 1.6 gti head is flat with the combustion chamber in the piston bowl)
So my version of logic suggests that flowing the deisel in this area could lead to worthwhile gains in getting more spent gas to the turbo.
Any thoughts/ comments would be appreciared.

Slobodan · #2 03-31-2010, 05:16 PM

I bet somebody out there would have info or first hand knowledge about this. I for one, never tinkered or thought about it.

Jason · #3 03-31-2010, 08:22 PM

The heads are always where the power is made, that goes for any engine. I'm sure you can improve on whats there, but the castings on the diesel heads are pretty nice compaired to many heads I have seen. There is room for improvement, but I wouldn't expect to see a 200% increase in flow...

Jason

fudge · #4 04-01-2010, 03:42 AM

You are correct, 200% is'nt possible with the exhaust valve size and rpm limit of 5500.
Got the manifolds off and i can see where the short radius of the port is just crude ,indeed just cored out , just like the petrol ones.
From my records with the std valve size the gain will be around 10% flow increase.
Well i will over the next few months post a few work in progress pictures.
I am putting the manifolds back for now ( its my work vehicle) and will get an accurate boost gauge fitted, and see what maximun i can get with the waste gate plugged.
Then once the head mods are done i will see any increase in max boost my work has had.
cheers. Fudge.

DWL_Puavo · #5 04-05-2010, 02:01 AM

I just handled an -94 N/A casting head last summer because our old one (-84, N/A) was quite a bit broken. New casting was very nice, much better intake and exhaust ports than in older casting. No casting scrubs or poor casting quality. Also match porting the intake and exhaust was pointless because they were aligned just right. Our engine is in VW LT so there was LT's intake and exhaust manifolds.