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Old 03-11-2007, 12:16 AM   #1
disaster999
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Default port and polish question and doubts

today i was helping my friend with his uppipe leak. we basically took out the downpipe, turbo uppipe and passenger side manifold. we didnt want to jack up the engine and we were planning on doing some port and polish work to the manifold and turbo too...thats why we took out the turbo...

this is where my suspicion begins. i was reading up on how to port and polish a while back...and basically port the manifold holes and the turbine inlet to match the gasket. smooth out all the casting lines and all. so when i was looking at the car today. i checked the diameter of the exhaust ports on the block and manifold, and they were the same diameter, then i checked the uppipe and the turbine inlet hole diameter and the uppipe was smaller than the turbo. so im thinking to myself how port and polish would smooth out the flow? its not like the flow of the exhaust is hitting a flat flange before continuing. true that smoothing out the weld lines and all would help a bit, but i dont see how it would make a noticable difference. im not saying that its false claim, but just want to understand how it would help when there isnt much of blockage of the flow.
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Old 03-11-2007, 09:47 AM   #2
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As you have already guessed...
Porting and polishing is basically finding restrictions, and getting rid of them to increase the flow...
Porting the exhaust manifolds and pipes will not do much for hp numbers for the reasons you mentioned...
There isn't that much to gain there...
Typically, the gains that can be found in porting are in these places...
Throttle body and Intake, including Tumblers...
Cylinder heads (see my thread on that, http://forums.nasioc.com/forums/showthread.php?t=973620 )
And the turbo itself... There are a few threads on here about porting turbos...

There are things you need to remember when porting...

The first thing is to try and keep a constant diameter...
A perfect example is the exhaust side...
If there is some difference in size between two mating surfaces, there is probably a difference in overall diameter of the entire port...
You wouldn't want to do just taper the inlet of an exhaust manifold, you should enlarge the entire passage...
That is called extrusion honing...

Something else to keep in mind is that the mating areas of exhaust flow better if the area gets bigger as it passes a mating surface...
Think of step headers used in drag racing...
This step breaks up the shock wave returning to the valve...
The up-pipe and the crossover pipe (the flex joint) are examples of a diameter change to break up the shock wave on the WRX exhaust...

If you port the cylinder heads, your exhaust ports will end up larger than the ports they flow into...
The heads on my thread will require a least 2" id header just to keep from covering the port on the head...
The intake side of them, will require custom tumbler deletes and intake manifold to match those ports...

Too make matters worse in the porting department, you can do more harm than good, unless you know what you are doing...

If you deciede to port anything, research it first, and make sure you take your time doing it...
Taking metal out is easy, putting it back is another story....
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Old 03-11-2007, 12:12 PM   #3
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Quote:
Originally Posted by shvrdavid View Post
As you have already guessed...
Porting and polishing is basically finding restrictions, and getting rid of them to increase the flow...
Porting the exhaust manifolds and pipes will not do much for hp numbers for the reasons you mentioned...
There isn't that much to gain there...
Typically, the gains that can be found in porting are in these places...
Throttle body and Intake, including Tumblers...
Cylinder heads (see my thread on that, http://forums.nasioc.com/forums/showthread.php?t=973620 )
And the turbo itself... There are a few threads on here about porting turbos...

There are things you need to remember when porting...

The first thing is to try and keep a constant diameter...
A perfect example is the exhaust side...
If there is some difference in size between two mating surfaces, there is probably a difference in overall diameter of the entire port...
You wouldn't want to do just taper the inlet of an exhaust manifold, you should enlarge the entire passage...
That is called extrusion honing...

Something else to keep in mind is that the mating areas of exhaust flow better if the area gets bigger as it passes a mating surface...
Think of step headers used in drag racing...
This step breaks up the shock wave returning to the valve...
The up-pipe and the crossover pipe (the flex joint) are examples of a diameter change to break up the shock wave on the WRX exhaust...

If you port the cylinder heads, your exhaust ports will end up larger than the ports they flow into...
The heads on my thread will require a least 2" id header just to keep from covering the port on the head...
The intake side of them, will require custom tumbler deletes and intake manifold to match those ports...

Too make matters worse in the porting department, you can do more harm than good, unless you know what you are doing...

If you deciede to port anything, research it first, and make sure you take your time doing it...
Taking metal out is easy, putting it back is another story....
Time for a public service announcement.
NEVER LISTEN TO ANYTHING THIS MORON HAS TO SAY.
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Old 03-11-2007, 12:18 PM   #4
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Seriously. You are wrong on pretty much everything you said. At this point I have to assume that all your experience lies in another manufacturer, because not much of anything of what you said applies to subarus. As such, it should never have been posted,=.

The largest gains by far come from the exh manifolds and Turbo's exh housing, with the TGVs in a 3rd. The throttle body port is ALMOST worthless, but is easy enough to do, that you may as well.


If you werent such a bonehead you would understand that while PEAK gains are not that large (as we have always said), the gains are HUGE when it comes to driveability. The difference in boost response from just the exh housing port is night and day, 300+rpm faster spool from ONLY the exh housing. The gains is the lower RPM ranges are very noticeable, and boost is carried out to redline better as well. Going on/off/on throttle, the boost comes back much faster as well.

Extrusion honing was proven COMPLETELY useless on Subaru's years before you got here. You SHOULD have already known this. But instead you damn near sat there recommending it. Based on your post, someone who really doesnt know better could end up sending their stuff out to be extrude honed, and the result would be the same as it was years ago, they would have flushed their money down the toilet, and messed up their part. Way to go



again, 14PSI before 3000rpm, 21+ before 3500 on a VF22 on a 2.0. But hey, porting is a waste of time right?


I hate you effing idiots that go around handing out bad info, all you do is pollute the tech forums with your completely knowledge free drivel, and cause people to spend money on things that dont work, or do things that may damage their motor.

Guys like me on the other hand have poured years of time trying to get good info out there and to keep the info in here relevant and more importantly TRUE. Your post, for the most part was bad, untrue, uneducated guess CRAP.


Please refrain from opening your e-mouth until something worthwhile can come out of it. I dont see that happening anytime soon.

Last edited by Davenow; 03-11-2007 at 12:29 PM.
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Old 03-11-2007, 12:21 PM   #5
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^^^ LOL wow!
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Old 03-11-2007, 12:23 PM   #6
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Old 03-11-2007, 12:26 PM   #7
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I will say this, he is dead on right about one thing, DO NOT DO THE PORTING YOURSELF IF YOU DONT KNOW WHAT YOU ARE DOING.


Dont bother crying back to me in this thread, I wont be here to read it. I have said what I have to say, and hopefully it will steer at least a couple people away from the damage you have done. Dont bother PMing me either. I dont play that game anymore.
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Old 03-11-2007, 01:20 PM   #8
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Wow owned....

I'd just like to reiterate the fact that the gains on the exhaust manifold are tremendously good and well worth a port and polish.... Bottom end power is improved so much more, instead of your car feeling like a slug until 4500 rpm's it gives you that "put-you-back-in-your-seat" feeling a lot quicker.

By the way if anybody is interested I have port/polishing tools available for sale

http://forums.nasioc.com/forums/show...1#post17268431
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Old 03-11-2007, 01:25 PM   #9
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On a dyno day here, my car had the most torque of all the TD04 2.0L WRXs. I, coincidentally, had the only set of P&P'd headers and TB.
Not worthless.
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Old 03-11-2007, 01:26 PM   #10
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wow..thanks davenow, i guess ill go and port the exhaust manifolds
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Old 03-11-2007, 03:07 PM   #11
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thanks dave. we are getting sick of seeing bad info on this topic as well. i also want to emphasize that the exhaust mani, turbo, and tgv deletes are by far your biggest gainers when it comes to pnp.
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Old 03-11-2007, 06:45 PM   #12
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Wow... I have been bashed by the subaru god...
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Old 03-11-2007, 08:11 PM   #13
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You should feel priveledged
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Old 03-11-2007, 10:14 PM   #14
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So, the moster port from deadbolt is a great idea mr. davenow?
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Old 03-11-2007, 10:29 PM   #15
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Wow, I guess that I am from the old school...
I did recommend porting the exhaust side in my post...
Look at the part that says "A perfect example is the exhaust side"

I guess i should have phrased it differently...

I have used extrude hones as part of the porting process on lots of cast iron exhaust manifold designs in the past...

But I fail to see how porting exhaust will make more power than porting the heads...
Please correct me if I am wrong.... I gained 75 whp from an experimental head porting... The set I have posted here, should do even more...

My car doesn't make 14 psi before 3000...
it doesn't make 21+ at 3500 either...
it spools about 3400... 4000 up 28 psi to redline...
I have a highly modified 30r on my car...
The first post in the thread doesn't talk about any mods to the car at all...
I guess it was my mistake in assuming otherwise...

I guess I should get Davenow to port me a set of manifolds...
If I gain 30 whp from them, I will break 500 whp...
But that won't happen... My compressor is already maxed out, as are my injectors...

But I guess all of the mods I did were a waste of time on my part...
I could have just ported everything Davenow mentioned, left everything else stock, and BOOM 470 whp... Not...

Like I said to Davenow in another one of his threads that he posted...
Next time you feel the urge to bash someone, let it go...
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Old 03-11-2007, 10:35 PM   #16
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You never said porting the heads in your post, you listed intake tgv's and throttle body..... porting the exhaust is WAYYYY more beneficial than those.

edit: I'm wrong, i just saw cylinder heads.... I actually must have had selective reading when I read your post LOL because I skipped RIGHT over it


We're talking a couple hundred dollars to pay some one to port all of those things... bringing in head work bumps another zero into the equation, which not a lot of people have the money to just go out and port/polish their heads.

And porting the ex. manifold doesn't do much for peak or top end.... so don't count on 30whp, like mentioned above the gains are the better bottom end and boost response.
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Old 03-12-2007, 09:56 AM   #17
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i find shvrdavid's posts informative, and i'm not going to stop reading them.

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Old 03-12-2007, 10:17 AM   #18
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Haha, it's funny to read people's posts that are on e-steroids!! Not sticking up for anyone or taking sides, but like ride5000 said, I have read quite a few of shvrdavid's posts and he posts up a lot of excellent information on here (including his current head porting project).

I can understand if someone has an opinion that another person may have posted wrong information, but that is no reason to freak out, call people names, and tell eveyone not read anything this person has to say!!

~.02
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Old 03-12-2007, 10:25 AM   #19
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When we are looking into PnP work, should we gasket match or port match the headers to the heads? Second, should we port the "exit" of each section? IE, should we port the passenger side header around the area of the O2 sensor? Wouldn't this just be increasing the volume of the pipe and thus hurt spool? I would think that each of the exhaust pieces should be port matched where the exhaust enters and remove any casting marks. All these PnP jobs that gasket match every bit of pipe would seem to be harming spool/exhaust speed, with SOME of the porting they are doing on their headers.

Seth E.
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Old 03-12-2007, 12:19 PM   #20
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^^^

What I had my guy do was just port out the head->exhaust mani and the exhaust mani ->uppipe parts by matching the gaskets. Like you said, I think it's best to only port out the "main" exits of the mainfold and keep the ID the same. I don't have any results yet to back this up, but this seems like the best way to go.
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Old 03-13-2007, 10:45 AM   #21
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I have a picked up a aftermarket set of PnP'ed OEM headers, but I am not so sure I like what was done. It looks like everything was just gasket matched with the maximum material removed. Many people talk about how it is so important to keep the stock inner diameter of the up-pipe to improve spool, but isnt this sort of porting going against that theory? I think I may do the following with a another set of stock headers i have laying around.

-Port match headers to match the heads.
-Remove any internal casting marks.
-Maybe polish the exits of the pipes.
-Light port on the entrance of each of the pipes.
-Sand blast
-Thermal coat.

Tell me what you think.

Seth E.
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Old 03-13-2007, 11:02 AM   #22
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Quote:
Originally Posted by Ru fan View Post
I have a picked up a aftermarket set of PnP'ed OEM headers, but I am not so sure I like what was done. It looks like everything was just gasket matched with the maximum material removed. Many people talk about how it is so important to keep the stock inner diameter of the up-pipe to improve spool, but isnt this sort of porting going against that theory? I think I may do the following with a another set of stock headers i have laying around.

-Port match headers to match the heads.
-Remove any internal casting marks.
-Maybe polish the exits of the pipes.
-Light port on the entrance of each of the pipes.
-Sand blast
-Thermal coat.

Tell me what you think.

Seth E.
no it is not going against the theory. the inlet lip on the up pipe is one of the more important ports to gasket match.

now, you are saying you picked up a ported oem exhaust manifold, but then go on to say stuff about the up pipe being ported. i'm confused.

whoever did the porting on that manifold did it the correct way.
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Old 03-13-2007, 11:46 AM   #23
Ru fan
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I guess what I am asking is should we be gasket matching (grinding out as much material as the gaskets allow) on the exits of the various headers, cross-over, etc.? What is the advantage to this? I see this as increasing the internal volume and losing exhaust speed. All things to hurt spool.
My thoughts would be to remove just enought material to remove the restriction, but not so much as to increase the internal volume. What is the point of opening up huge ports if the pipe leading into it is not any bigger?

I am not trying to be a smart-a$$. I just want to know how people are thinking when they make these changes.

Seth E.
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Old 03-13-2007, 02:18 PM   #24
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Old 07-02-2007, 11:00 PM   #25
disaster999
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i have another question, on the driver side mani, the outlet of the mani that meets up with the crossover pipe, should that be ported as well or it doesnt matter?

my friend tells me i should because of better flow. if i remember anything from my fluids class, i think it make sense. the exhaust would slow down quite a bit because of sudden volume change if theres no transition between small diameter and big diameter, but i just want to make sure

thanks

Last edited by disaster999; 07-02-2007 at 11:15 PM.
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