SteveAngry

Been doing some portwork on my spare head.

Done so far:

Exhaust side: ported, polished and portmatched.

Intake side: Casting marks removed, slight blending. Still need to portmatch.

I paid special attention to the valve throat, short side radius and the valve pockets on both sides.

I blended in everything as good as I could and tried to not remove too much material...

I polished the exhaust side only and left the intake side slightly rough to encourage good fuel/air mixture...

I will admit I went a bit bigger on the exhaust side but I think I'll be ok since I don't have any downlow torque anyways. It wasn't much so I don't think I killed too much exhaust velocity...

I did portmatch the exhaust side. Lot's of BTDT says not to due to reversion but I talked to a couple VW guys who have all had no problems portmatching the exhaust side on similar VW 1.8 heads.

We'll see if I made a mistake or not.

I did not grind down the valve guides as some others have recommended. I hear doing so will shorten valve guide life. Just how long it shortens the guide life, I don't know...

So far I've got about 12 hours into this project. No too bad. I saved myself some cash doing it myself.

Regardless, I totally have an appreciation for professional auto machinists now...

I'll finish up polishing the combustion side of the head this week and that will be that. I'll post some more pics when it's done.

Sorry about the crappy pics.

<img src="http://pictureposter.audiworld.com/4612/portandpolish_021.jpg">

<img src="http://pictureposter.audiworld.com/4612/portandpolish_011.jpg">

<img src="http://pictureposter.audiworld.com/4612/portandpolish_028.jpg">

Steve
Michigan

birdmanmt

lookin good! two things..

first, i don't know why portmatching would hurt. sure you're enlarging the hole slightly, but your eliminating turbulance. which is more important? i'd say the latter...

second, on the IM ports...polish them in until where the fuel is injected. keep that velocity up. since your going EFI, it'll get mixed plenty. besides you're going batch fire..."puddling" will occur on the backside of the valves for the 1/100th of a second the valves are closed. it'll get mixed nicely when that valve opens and yanks that fuel in.

SteveAngry

Well I hope it's not a big deal.

Most people say to leave the mismatched step between the exhaust port and manifold to stop the backup of exhaust gases(reversion) back into the combustion chamber...

I was unsure so I hit up the VW G60 guys for info...

I'm gonna polish the intake where you mentioned once I do the intake portmatching. I need to track down a intake gasket first.

Steve
Michigan

AudiSport4000

Wow, quite impressive Steve. Nice work.

Avant Sport

Looks good Steve

boxerfan

keeping the inside slightly rough actually increases velocity. It's like those new Olympic swimming suits that emulate shark skin. The sandpapery texture actually reduces drag.

birdmanmt

hey steve...iv'e got a really good source for some info on this stuff. the guy i'm working for this summer has a degree in automotive engineering. the school he was at had a superflow dyno, and he just happened to swipe the "owners manual" for it which talks about how to use the machine and also some very in depth info on polishing &amp; porting. He was also the head engine builder at doug rippey's corvette shop here in the cities, who is #2 to lingenfelter in the country for race cars. we're taking a 10v head out there soon to do some work.

i don't know you're time frame on this project, but maybe if we get this done soon enough, i can let you know what got us what on the flow bench. we've got a junk head that we're gonna use a 40mm intake valve and 33 exhaust to see what the numbers are.

oh and as far as the port/polish etc...porth match it all as best you can, and polish it all as much as you can. even past where the fuel is injected.

you've already worked on the big spots that get you the highest percentage increases, now your down to matching and polishing. polishing gets you only about 2% flow increase. but that's for NA. port matching is huge...i'd say the guys who told oyu about stopping the back pressure etc..are unpracticed....my buddy who has hundreds of hours porting/flowing heads said to get them as even as possible so there is NO turbulance. especially on a turbo. you want that pulse coming out of there to stay as "together" and uniform as possible all the way to the turbo.

HTH
Jeff

dans5ktq

So shiny!! Looks good man...