Bart-Jan

Somewhere, I read about a guy improving his inlet pipes of the spider, right above the injection position. The tube is a little squashed there. Would it improve air flow to grind them open untill th enormal inner diameter of the pipes?

I've tried looking for the info, but didn't succeed; anybody knows more?

Dave928S

Greg Gray who posts here has done a LOT of R&D on 16V heads, and so doing a search and looking through some of his posts will be insightful.

The bottom line is that the 16V Euro intake isn't too bad (I'm assuming you have a Euro motor). I've just finished the heads for my 82 16V Euro, and I'm about to get going on the intake and exhaust. All I'll be doing is port matching the heads to intake runners and 86.5 exhaust manifolds, honing the runners, and honing and matching the plenum to runner junctions. I believe that Greg has already tried enlarging the runners but got zero gain.

As to your specific question ... I don't have data (perhaps others do) but believe it's likely that removal of that material will give little or no benefit. I'm leaving them alone apart from a clean up. On a standard motor, doing more than honing and port matching without supporting flow bench data, is likely to be a waste of time and money, and could send you backwards. Greg is likely to know the answer, and maybe he'll chime in.

Bart-Jan

Thanks Dave, what do you mean with 'honing the runners, and honing and matching the plenum to runner junctions'? I'll do the port matching and have a pair of 86.5 headers to go on as well.

James Bailey

Years ago "extrude honing" the pumping of abrasive mud under high pressure was popular but never really tested since other things were done at the same time. The end result LOOKED nice and smooth inside but may or may not actually have flowed better.