Inlet manifold lancia delta/thema/155q4

Hello,

We have a lancia delta race car with a modified lancia thema 2.0 turbo engine.

I know found that the size of the inlet on the cylinder head is a lot bigger then the size on the manfold. If you calculate it to a round hole then the cylinderhead is 42.5 mm , the manifold 37.5 mm, and the other side of the first part of the manfold is also 42.5 mm, and furter part also.
This can't be good and must restrict for high HP.

The thema manfold is the same as on the alfa 155q4.

I'm curious about the lancia delta manifold, this manifold is only 1 piece, and hopefully the oval holes are the same size as the cylinder head. Does anyone know the size or has pictures of it with measures?

I have fit a Lancia kappa inlet manifold that it is modified (ported). A modified one like this is the best for a race car. I really don't know about size. You could find some interesting things in my project in this forum
http://forum.berlinasportivo.com/showthread.php?t=2171

The Kappa inlet manifold is pretty much considered to be the best off the shelf upgrade, I'm not sure what the internal measurements are though.

Oh and welcome to the forum.

Is this kappa inlet from a NA engine, or a turbo engine?

What about the other NA engines? Do they maybe all have bigger diameter?
Still I find it strange that there is such a huge difference between the head diameter and the manifold.

And, thanks for welcoming me :).

The Kappa inlet is from the Kappa 16V turbo so is a turbo inlet. The design of it is much better than the Q4 one with much shorter runners. I think some of the Delta owners use it as well.
They sometimes come up for sale on Ebay, but make sure you get the fuel rail as well as it is different.

Love to see some pics of you 75 Turbo as well.

Stock Lancia kappa inlet manifold has 6-7 cmf more air flow. It is smaller in diameter near the head because the want to have more air speed (the stock max boost pressure is 0.8- 0.9). With a larger turbo and more boost (more than 1.3) you will have more air speed with a larger diam. Inlet manifold so you could port it

The kappa manifold is a nice piece BUT it is suffering the problem you describe of being too small in cross sectional size for a reworked cylinderhead, this is the case up the full length of the runner and to rework the runner to a correct size would involve grinding through near the top, been there done that.
A correct size can be formed if the runner is reduced in length but it is touch and go when grinding on it.
http://img696.imageshack.us/img696/3...welding018.jpg
http://img192.imageshack.us/img192/1...llmouth002.jpg
http://img706.imageshack.us/img706/1...llmouth004.jpg

About the air speed, if you want to have more air speed, why are the holes in the head then so big, they don't need to be that big.

Now you have smaller diameter in the manifold just before the head, this makes more speed, but once you go into the head the speed suddenly drops due to the much bigger holes. This will make things worse.

Anyone who has a NA manifold, they must be bigger I think? Otherwise I don't understand for wich application these heads were made.
If the manifold of the NA Thema will be bigger in the first part it would be easy to try it out.

We will definetaly make our own manifold somewhere in the near future, but for now there must be somekind of solution i hope

The incoming air doesn't really "see" the area at the entrance to the head, your right it is too big and certainly doesn't needed reworked unless getting crazy with power. The incoming air direction will skip over this section before being influenced by the smaller area sizes where the ports are split. The nature of this section being bigger than needed lends some small assistance in that it makes reversion more difficult as the reversed flow has to negotiate a step thats in it's way. Not an ideal solution to the problem but some help no doubt. A 4 valve chamber like ours is liable to suffer reversion. The main area of the port that controls the air speed that the combustion chamber sees is further down the port that the entrance.

The NA manifolds (Coupe and Thema) are slightly bigger in internal sizes, not a lot but definately bigger. If the cylinder head is being reworked to a decent level it's still not big enough though I'm afraid. A bigger problem is the section of runner that is attatched to the plenum section, impossible to rework correctly unless your prepared to chop into the plenum to get access.

By the way 1NRO this inlet manifold is amazing. By searching a good inlet manifold costs about 800- 1500 euro. I choose kappa manifold because I bought it for 100 euro and the modification of it (girding, polishing, shorten) costs me nothing. This is the only reason and I have a much better inlet manifold than stock