You may want to rework your ports just a tad bit. The part of the port where it splits into two channels for the valves should be razor sharp. The way you have it now it is rounded, and that causes some peculiar flow tendencies. We noticed this on Tjepkes' head when we pulled it apart. If you need to look at the way Paul's new head is in his N/A madness post.
okay ill try to work on that thankz
GMR has got nothing on this
I was under the impression that the intake ports aren't supposed to be polished.
X2, ohvrolla.
Doesn't fuel tend to collect on the walls of the port if they're polished??
Yes, the intake ports need to be textured to help with turbulance. The air needs to tumble around so the fuel can atomize properly. You can polish the crap out of the exhaust side though.
DOHC_tuner wrote:I did my own port n' polish on my LD9 head. Was real easy but very time cosuming and dirty. Well I just ported the exhaust ports just a bit and polish them up. I did not port the intake ports, just polished them
not a bad job.... just keep in mind the suggestions above.
did you gasket match the openings to the intake side? thats something to consider. you can remove a bit of material for added flow. also if you have a local shop....def get it flow tested. there was one runner that i didnt do to well and i fixed it up before the end so they were all even.
as for the exhaust side, i'm not sure how much you polished em, but if they are like the intake side you showed above, you can go a bit more on the polishing.
also you can polish the HELL out of the combustion chamber... the less carbon build up there, the better over time... you dont want hot spots down the road.
heres some pics from my project of DIY with head work....
if its to be polished, make it shine!
bmxludwig wrote:You may want to rework your ports just a tad bit. The part of the port where it splits into two channels for the valves should be razor sharp. The way you have it now it is rounded, and that causes some peculiar flow tendencies.
i disagree with this on the intake side.
but knife-edge the exhaust all you want.
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I am just going off of experience here. And pauls new, professionally ported head, is knife edged on both the intake and exhaust side. There is no reason to have a rounded edge there, it would cause a "hump" in the airflow going over that area, making an unequal flow into the combustion chamber.
bmxludwig wrote:Pauls new, professionally ported head, is knife edged on the exhaust side.
wrong. his is NOT knife edged, mine IS. this is the only thing we could notice that my head had better than his. his may be more edged than stock, but it is by no means as sharp as mine, not even close.
ask him.
Wanting a nice set of black 17's with mint tires? Pm me.
bmxludwig wrote:I am just going off of experience here. And pauls new, professionally ported head, is knife edged on both the intake and exhaust side. There is no reason to have a rounded edge there, it would cause a "hump" in the airflow going over that area, making an unequal flow into the combustion chamber.
I will counter your idea by referencing many other easily viewable examples of things/designs that are meant to easilly and smoothly cut through air.
Thing like raindrops and any major mass transport airplane (707, 727, 747, dc9, a430, etc).
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You haven't opened up the exhaust ports at all....? That first little carbon line is the edge of the exhaust manifold gasket. I'd open the ports up to that, at the very least.... smooth it all the way back....
What kinda tools are you using to port it?
Did you gasket match the exhaust (cut it down to about a 1mm difference)? I would definitely recommend it if you have not.
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I know many of you probably won't listen to me, but I've been building engines for 11 years now. When it comes to port and polish, you are only to "polish" the combustion chambers and exhaust ports. The reason is the smooth exhaust ports won't cut down the velocity when the burnt mixture is exiting the engine, and the smooth combustion chambers help keep the fuel from puddling under the spark plug when coming up to the compression stroke. If the intakes are smooth at all, the turbulence won't be there when the air mixes with the fuel, and it does stick to the port walls like stated above. If you don't have anything to go all the way up to the pocket, just do from the start of the port up to where the injector is, you'll get good velocity, but not as great as going through the entire port. Thanks to anyone who listened to me.
Project Resurrection is in full swing!
Why wouldn't we listen to you? That's how I understand it... and that's how I did my P&P head as well. I always leave the intake side nice and rough.... and I leave the shape the same too, no knife-edging on the intake side. Exhaust side... oh yeah, lots of it. And lots of smooooooooth...
Mythod wrote:I know many of you probably won't listen to me, but I've been building engines for 11 years now. When it comes to port and polish, you are only to "polish" the combustion chambers and exhaust ports. The reason is the smooth exhaust ports won't cut down the velocity when the burnt mixture is exiting the engine, and the smooth combustion chambers help keep the fuel from puddling under the spark plug when coming up to the compression stroke. If the intakes are smooth at all, the turbulence won't be there when the air mixes with the fuel, and it does stick to the port walls like stated above. If you don't have anything to go all the way up to the pocket, just do from the start of the port up to where the injector is, you'll get good velocity, but not as great as going through the entire port. Thanks to anyone who listened to me.
sounds good to me sir. i didnt know that smoothing the combustion chamber was a good idea, i believe ill go work on that this weekend.
Wanting a nice set of black 17's with mint tires? Pm me.
Yea, it's always good to do that. Like I said, cuts down of fuel from puddling under the spark plug. Forgot to tell you though, awesome job on the exhaust side man. Good work! Here's what I did on my Eco head!
I've still got a lot of work to do, but it'll be worth it.
Project Resurrection is in full swing!
Im also going to tackle this job on Sunday
Planning on using my dremmel
What bits do you recommend or other tools?
Thanks guys lots of good info in this thread
Mythod wrote:I know many of you probably won't listen to me, but I've been building engines for 11 years now. When it comes to port and polish, you are only to "polish" the combustion chambers and exhaust ports. The reason is the smooth exhaust ports won't cut down the velocity when the burnt mixture is exiting the engine, and the smooth combustion chambers help keep the fuel from puddling under the spark plug when coming up to the compression stroke. If the intakes are smooth at all, the turbulence won't be there when the air mixes with the fuel, and it does stick to the port walls like stated above. If you don't have anything to go all the way up to the pocket, just do from the start of the port up to where the injector is, you'll get good velocity, but not as great as going through the entire port. Thanks to anyone who listened to me.
thats basically what i did with mine...
just followed the standard abrasives port and polish kit and what i researched from books i bought and the engine shop and people i learned from on here. kept it simple.
i downloaded
THIS .pdf file a while ago and read it over when ever i get chances. Shows you step by step Gasket matching, and polishing (exhaust) with nice detailed pictures. google, ftw.
sUiCiDe wrote:Im also going to tackle this job on Sunday
Planning on using my dremmel
What bits do you recommend or other tools?
Thanks guys lots of good info in this thread
careful with the dremel....
i actually went out and got a dremel version of die grinder. with the higher speeds of a dremel, usually the smaller non-speed adjustable ones or 3 speed gimmicks, you can accidentally take out or off too much material in a certain area....remember its just aluminum...
most of the standard abrasives kits i;ve seen reccomends something that does as low as 700rpm up to 1500 rpm.... also the SA kit uses a 1/4 inch bits, so the collet size i needed was only with the big dremel setup...
dont rush on the job... i spaced mine out over a week or so of time.... even machine shops, unless CNC, usually take their time on it.
personally, i'd pick up a port and polishing kit....most speed shops (old school muscle car oriented places) should carry em... as well as summit, jegs, etc... i'm all about getting the right tools before doing stuff...
http://search.stores.ebay.com/Summit-Racing-Equipment_port-and-polish_W0QQfciZQ2d1QQfclZ4QQfsnZSummitQ20RacingQ20EquipmentQQfsooZ2QQfsopZ3QQsaselZ178360995QQsofpZ0
or summitracing.com
also heres some info on the whole job itself...... i read this atleast 3 times and took notes...lots of good tips...
http://www.sa-motorsports.com/diyport.aspx
well thanks for all the info everyone. Now for the intake being polished, a fellow LD9 modder told me that the fuel does puddle up and thus should be kept rough BUT only on the old carburated engines, and thats because fuel injected engines spray a mine mist of fuel versus the carburator that draws in fuel.
GMR has got nothing on this
A dremel? Damn... I spent 8 hours doing mine, and that was with a proper die grinder and lots of different bits.... and liberal amounts of WD-40 to carry the crap away....
I can't imagine doing head work with a dremel....!!
John Lenko wrote:A dremel? Damn... I spent 8 hours doing mine, and that was with a proper die grinder and lots of different bits.... and liberal amounts of WD-40 to carry the crap away....
I can't imagine doing head work with a dremel....!!
It's a long and arduous task, I started over 6 months ago (then again part of that is not having the chance to work on it).
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A dremmel is pretty much an electric die grinder
Mine has 10 steps of speed adjustment
I don't have a air setup at home so i can't use my die grinder here
Edited 1 time(s). Last edited Saturday, March 08, 2008 10:58 AM
