VWDiesel.net The IDI, TDI, and mTDI source.
Engine Specific Info and Questions => IDI Engine => Topic started by: Smokey Eddy on May 17, 2010, 12:23:10 pm
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how much, and im looking for measurements here, can you port these IDI heads?
I did gasket match my 1.9 head but i want to go above and beyond. I was just using abbrasive bits on a dremel before but i bought a carbide bit yesterday to go crazy with.
How big can you make the ports and the runners inside the head?
Does anyone have or know of measurments?
I dont want to go into a water jacket and ruin the whole thing.
I recall seeing pictures of i think Aki-76's ported head and the ports looked massive (as well as glass like on the inside).
Also, I've added a semi-related poll. Please do not discuss the poll - just vote.
the reason i ask for no discussion is because it has been discussed before and some people get very passionate on what they think is correct. I just want to see what concensus comes out of the poll.
thanks.
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Here is this.
http://www.vwdiesel.net/forum/index.php?topic=15782.0 (http://www.vwdiesel.net/forum/index.php?topic=15782.0)
The guy that did mine would probably tell you what to do if you called him. His name is John alder*I think* and it is air cooled engines plus in tiffin ohio. He said the exhaust is pretty good from the factory, but the intake is what needs help. He also told me it was more on the sides of the port and not as much on the top. I had mine done and it is about the same size as the gasket on the intake, but I got close to double the flow. He said it is all about velocity. Good Luck.
EDIT- air cooled engines plus also told me that most of the work was done in the bowl area. The ports can't be done too much as he has had some that leak coolant if he goes too far.
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ooooh okay
so i want to cut away until its almost flush with the valve seat. I see i see. Rounding off the valve guide would be a good idea too i bet.
ps. I already had the PDF. :)
I was speaking specifically on how big to go on the intake side of things. the "top" as you would call it. but i'll spend much more attention to the areas outlined in the pdf then.
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I used extrude a hone on my head and my PD130
www.extrudehone.com (http://www.extrudehone.com)
550.00 for the head
PD130 was less $$
They are both like a mirror
Liquid plasma polishing...
I did my intake manifold on my aircraft years ago and it idled very smooth, compared to before
GB
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thats a little too pricey for me GB ;) :P
i think a polishing bit on my dremel will do fine.
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I have heard the opposite. Threads on tdiclub seem to say heavily porting the exhaust gives more of an advantage, especially with big turbos.
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I have heard the opposite. Threads on tdiclub seem to say heavily porting the exhaust gives more of an advantage, especially with big turbos.
I dont think he is saying not to port the exhaust side, just that the intake has different casting? perhaps because of the size difference in the valves? i dunno.
and i am talking about how some people say to leave the intakes rough to ... stir up the air going into the cylinder or some crap. but i think that's only a gas thing.
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and i am talking about how some people say to leave the intakes rough to ... stir up the air going into the cylinder or some crap. but i think that's only a gas thing.
That is my understanding of it. If you make a gasser's intake port mirror then there won't be enough turbulence to mix the fuel and air.
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and i am talking about how some people say to leave the intakes rough to ... stir up the air going into the cylinder or some crap. but i think that's only a gas thing.
That is my understanding of it. If you make a gasser's intake port mirror then there won't be enough turbulence to mix the fuel and air.
is such the case with diesels? i figured the air is going to be in there already and its all going to get excited as it compresses and gets hot to the point of combustion.
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is such the case with diesels?
Shouldn't be as the fuel air mixture doesn't happen in the intake runner at all ;) With the diesel it shouldn't matter of finish just how much and how quick you can get it in. A smooth finish (to me) should be able to more easily flow air then a rough bumpy surface that will cause turbulence and crossing waves of air.
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is such the case with diesels?
Shouldn't be as the fuel air mixture doesn't happen in the intake runner at all ;) With the diesel it shouldn't matter of finish just how much and how quick you can get it in. A smooth finish (to me) should be able to more easily flow air then a rough bumpy surface that will cause turbulence and crossing waves of air.
my thinking as well.
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But the boundary layer of little vortexes coming off a rough surface may do more for flow than a smooth part that isn't following an aerodynamically perfect path....
Id be more about flushing the intake guides than exhaust, the exhaust valve has a lot of heat to shed
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Look at the surface of a golf ball. It is not smooth for a reason. The dimples actually make it go farther than a smooth ball would. I saw it once on mythbusters. All my intakes are smoothed to about 80 grit to keep the turbulence up. The exhaust on the other hand is smooth like glass, don't want the carbon to build up on the ports. Also do not gasket match the exhaust port to manifold. Keep the port on the head smaller than the exhaust manifold. You can match the port to the gasket but make sure the manifold is bigger than the gasket. This creates a low pressure and helps suck out the exhaust gas.
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Look at the surface of a golf ball. It is not smooth for a reason. The dimples actually make it go farther than a smooth ball would. I saw it once on mythbusters.
AH YOUR RIGHT!! Where they took that Ford Taurus and put clay all over it and dimpled it, and did better numbers then without the 1500lbs of clay? I stand corrected. :) Ed leave some golf ball dimples in the intake
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I've always wondered if rifling ports would help eliminate the boundary layer, or at least thin it out ???
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Yeah I've heard the incoming air should tumble rather than flow smooth and for some reason that lets more in. But remember though, you'll have a turbo pushing the air in.
As for mixing the air fuel mixture, that happens inside the swirl chamber where the air is really spinning so no worries there :). But if a rough intake allows more air in then there's that much more to be packed into and spun around in the swirl chamber.
A flow bench would be nice.........
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(http://c3.ac-images.myspacecdn.com/images02/21/l_d32b370c5d4d44c5950378f28ea121a6.jpg)
1.6 head, but theory is the same. He said it would make more power than a head that flowed more. Here is what the ports looked like for reference.
(http://c2.ac-images.myspacecdn.com/images02/52/l_90bca9efd5a94fcf93f9b72ae56f801d.jpg)
(http://c3.ac-images.myspacecdn.com/images02/21/l_6d9f380045ba4fb185618c652150b132.jpg)
(http://c4.ac-images.myspacecdn.com/images02/27/l_77ffb09fade04dbba684b8d6b74cea1b.jpg)
You can see where the gaskets matched up and it is still smaller than that on the exhaust side. You can also see what is about a 220 grit finish or better if you can pick it out in the crappy pic.
Just trying to encourage you.
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According to NASCAR people, 120 intake and polished exhaust (to keep the carbon down). Tests show 120 grit flows better than polished. Think of the boundary layer created on racing swim suits. my .02 cents
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big gate does not necessarily mean big power,bigger valve and nearly constant channel already provides better results
http://s434.photobucket.com/albums/qq68/Aki-76/asiakas%20osia%20ja%20muuta/?action=view¤t=tsivirtauslappu.jpg (http://s434.photobucket.com/albums/qq68/Aki-76/asiakas%20osia%20ja%20muuta/?action=view¤t=tsivirtauslappu.jpg)
this case is 41mm intake and 35mm exhaust..
http://s434.photobucket.com/albums/qq68/Aki-76/moottorin%20osia/?action=view¤t=03042010812.jpg (http://s434.photobucket.com/albums/qq68/Aki-76/moottorin%20osia/?action=view¤t=03042010812.jpg)
port is also very shine
http://s434.photobucket.com/albums/qq68/Aki-76/moottorin%20osia/?action=view¤t=07102009606.jpg (http://s434.photobucket.com/albums/qq68/Aki-76/moottorin%20osia/?action=view¤t=07102009606.jpg)
next week we see results in dyno.i hope break 200kw ;)
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Aki-76 posted on one of my topics! I'm honoured!
theman, WOW that went from 72.6 to 90.5 ?!?! that's a huge increase to me.
and that's with a slightly less than polished finish eh?
Okay so i'll mirror the exhaust ports and matte the intake.
And from Aki's photos i'll cut the valve guide al the way down (mine stick out a lot) and smooth the cuts up. I'll also widen the port just below the valve seat.
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I've always wondered if rifling ports would help eliminate the boundary layer, or at least thin it out ???
that would be really interesting to see if you could do it somehow? some sort of hone?
Look at the surface of a golf ball. It is not smooth for a reason. The dimples actually make it go farther than a smooth ball would. I saw it once on mythbusters.
AH YOUR RIGHT!! Where they took that Ford Taurus and put clay all over it and dimpled it, and did better numbers then without the 1500lbs of clay? I stand corrected. :) Ed leave some golf ball dimples in the intake
will do Jer
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Aki-76 posted on one of my topics! I'm honoured!
theman, WOW that went from 72.6 to 90.5 ?!?! that's a huge increase to me.
and that's with a slightly less than polished finish eh?
Okay so i'll mirror the exhaust ports and matte the intake.
Yeah I just wanted to have AKI's name next to mine in a post as well:D
I can go get another pic if you want but the intake is smooth. I say 220 grit finish, but I don't have any way of proving that. My buddy has an RA gauge deal you drag across the surface to tell you what the surface actually is, but that tool doesn't leave his shop. The finish on the intake side you cannot feel any abrading marks. It feels and pretty much looks just like the exhuast side real smooth. Could be a finish from AVFN scotch brite on a mandrel. That is supposed to give a finish somewhere between 240 and 320.
Let me know if you need a pic I am leaving to go to the farm soon.
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Aki, where did you get your valves from? Are they solid stainless steel? Did you need larger valve seats?
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I used very strong special cromy alloy steel in seats,because valve seats is only 1mm wide.seats is also very much bigger than orginal 36mm = > 42mm (intake).
If i calculate correct that engine produce 120-130hp without any boost or turbo.Whit turbo mayby slightly more ;)
Valves are stainless steel and longer than orginal ( 2.2-2.5mm )...
that number ( 90.5) is prosent,no flow..correct flow is 115 cfm/10" = 200hp na gasoline engine !
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dear god Aki...
i keep typing a sentence and deleting it.
I am so stoked to see the results
im really hoping the head doesn't warp/lift.
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I used very strong special cromy alloy steel in seats,because valve seats is only 1mm wide.seats is also very much bigger than orginal 36mm = > 42mm (intake).
If i calculate correct that engine produce 120-130hp without any boost or turbo.Whit turbo mayby slightly more ;)
Valves are stainless steel and longer than orginal ( 2.2-2.5mm )...
that number ( 90.5) is prosent,no flow..correct flow is 115 cfm/10" = 200hp na gasoline engine !
Why did you use longer valves than stock? Running solid lifters?
Any dyno results that you could add to this old thread? ;)