The V8 Owners Forum -

hello all,

Anyone ported their own inlet manifold & trumpet base?

Think 45mm seams to be the norm for porting or enlarging.

Where do you get 45mm trumpets from???.

And is it really worth it, or just buy one from usual places.

Just thinking about my next upgrades for my GEMS engine.

cheers

scott

What size engine and what RPM ? - no point hogging it out if on a 3.9 - 4.2 mild engine as you will loose port velocity. As far as I'm aware only the 5L TVR engine ran 45mm induction but still retained the 65mm plenum (for cost saving, rather then performance) - the bigger engines benefit from 72mm plenums.

will be on the 4.6 im building at the mo....

finally spec not decided yet just going through some options....but could be like this

stage 3 heads
piper 285
mark adams gems Chip
modding my own 4.6 plenum....standard diameter at the mo.

dont want to be taking parts off later, like my last engine...spent 10 years tuning it...

scott

Tim @ ACT will sell you the trumpets, not expensive either.

I have some waiting , just got to get the base machined now.
The trumpets have to be slightly angled to fit, I think about 10degrees.

Would be interested in porting info myself for the manifold.

with that state of tune I dont see any reason to go porting the inlet manifold. I think you will be well away from what the standard stuff can cope with. That extra 20 - 30 BHP is the bit that costs big money so porting at a later date is the least of your worries.

Some photos of ported heads and a trumpet base for my mates 3.9 seight can be found here:
http://www.mez.co.uk/westfield/index.html

I remember my dad commenting that he spent longer on the manifold than the heads. In this instance the ports were left at '37mm (std size iirc) because its only a 3.9.

The technique for a 44mm would be to put the manifold into the milling machine and bore it out to 44mm and go down far enough to get you started, then port it out manually.

I already did it myself and it is very time consuming to have an good job.



Inside before polishing


Inside after polishing and port opened

Wotland..

Here is my porting work..
Slightly bigger port than yours..
As i´m using "stage" 4 heads..

Do you just use a mixture of carbide burr bits, grinding stones and sanding reels?

topcatproduction wrote:Do you just use a mixture of carbide burr bits, grinding stones and sanding reels?

Yes ,
and just my ex-TWR heat sink insulator as guide plate.