trumpets

bodger · Post by **bodger** » Wed Dec 03, 2008 11:18 pm

you know the trumpets on the inlet manifold ( EFI flapper )

why are they differant lengths ?
is it to get the best of both , long for torque and short for revs ?
and would it be ok to have them all long as i don't really rev it that much ?

thankyou once again

kiwi303 · Post by **kiwi303** » Thu Dec 04, 2008 3:15 am

have a look at the manifold faces where they mate with the block and see how far the holes are spread, and look at how much closer the trumpets are grouped.

The air has longer to travel in the manifold from the trumpet base plate to the fore and aft ports than it does to the central 4. So the middle trumpets are longer to provide an equal length of air travel for all 8 air ducts. The fore and aft 4 cylinders have more travel through the manifold and less through the trumpets, while the central 4 have less through the manifold but more through the trumpets, making an equal overall length of travel.

Make sense?

ChrisJC · Post by **ChrisJC** » Thu Dec 04, 2008 8:27 am

Further than that, it's to make the air-flow through the AFM as smooth as possible (i.e. even out flow fluctuations that would occur if there were different lengths between the valves and the AFM).

If you look at the pipe between the plenum and the MAF on a GEMS engine, you can see a tuned port hanging from the bottom. This is to improve the situation even further (I guess there is still a resonance somewhere that needed removing).

Chris.

bodger · Post by **bodger** » Thu Dec 04, 2008 10:02 am

thankyou Guys , yes that all makes sense ...i was getting bored again and thinking of something else i could change ..lol