U-928

Got my ported cylinder heads back from having the new guides put in and the valve job. Talked to the second shop that I was going to have flowbench the heads, and it's looking like a (quite) expensive endeavor if he's going to have to make up a custom fixture for the heads.

By any chance, does anyone out there in the 928-verse have a fixture already made for the 928 16V cylinder head that they'd rent/loan out?

Or as a secondary solution, is there anyone out there that has the fixture and is willing to flow-bench them for me?

slate blue

Jeremy what my guys did was dowel the head to a 928 headgasket and then the head gasket was attached to a flat piece of wood with a hole for the chamber and then the wood was doweled to their bench. It shouldn't cost very much at all.

Fogey1

The same fixture used to get the baseline flow figures before the head was ported should work.

U-928

I see what you're doing here. I hadn't planned on having the heads flowed after the prt work was done, so no prior measurements were taken.

IIRC, slate blue has stock flow numbers from a 16v head, somewhere back in the archives. While not an entirely accurate comparison being that they're different heads, the numbers should give me a ballpark.

There was no intent on going super scientific like others do with their r&d, i simply didn't plan it and don't have the financial allowance to do pre-mid and post flow experimentation. It's more that I just am curious now as to what they flow, now.

IcemanG17

from what I recall.....the stock USA heads flow around 185cm and the Euro about 210cfm....I now some ported heads (Terry GT) got as high as 280cfm from his, but that was pricey....

Doc Brown has a flow bench....

GregBBRD

Superflow provided an adaptor that V8 heads sit on, quite nicely.

Anyone with a Superflow bench should have one....

The one thing you do need is either an intake manifold or an adaptor that smooths out the flow on the intake flange.

James Bailey

AH, so the heads are finished, done, already ported !!! Little point in testing them as it is what it is.....

ptuomov

???

James Bailey

I did not realize that he ported them himself so understandably is curious to see what the results are of all his efforts. Initially thought the machine shop that milled the heads, installed guides did the porting. In which case the job was done no matter what the flow happens to be.

Imo000

Maybe its better not to know.

U-928

Did GB do Terry's heads? I'd prefer not to ship the heads clear accross the country, but if it comes down to it and Greg is up for it, good to know someone familiar with these has the tooling.

I have the gasket matched Euro intake manifold I can provide should he want the intake (which I'd prefer) if he doesn't do a rounded edge with clay, as many places do.

It's good to know that superflow has the adapter for that, I don't know what his operation is, so I don't know if he's using one.

Fortunately the 928 16V heads are pretty similar to a pushrod ford/chevy V8 in that they don't have cam bearings mixed inbetween the valves like a conventional overhead cam equipped cylinder head would.

Ah, understood now. I've been doing all my own portwork for about ten years now, after having many bad experiences with shops doing the work. If you want it done to your specifications, I've learned, better to do it yourself. At the time I didn't have the facilities or finances to buy the tooling to do it myself.

Confused as to why you'd think this... That's like Tuomo not knowing what his TT car makes for HP!

I find it incredibly unlikely for the heads to flow worse than stock. And any number above Greg Grey's baseline numbers, I'd see as a positive gain. I have no expected numbers, so I won't be disappointed either way.

Fogey1

Busted. I admit i was being snotty. Sorry about that.

slate blue

I do recall we got 212 cfm at 0.500", when you get your numbers I will go searching and I think I will be able to find them.

ptuomov

Knowing what the head flows on a flow bench and what the port dimensions are is useful inform in making decisions about the headers, intake, cams, etc.

Imo000

There have been posts where ported heads had a decreased flow from stock. Just because the ports are increased, doesn't mean they flow better. There is lots of info on the net on this. On an N/A engine, porting mostly results in nominal improvement. Sometimes so little that a but dyno won't notice it. Just be cautious of the expectations, that's all I'm saying.