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05-10-2007, 02:44 PM | #1 |
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How hard is it to port and polish headers?
I'm looking to pick up a set of stock STi headers, and getting them ported / polished. Although i've thought about doing this myself. How hard is the process? I got plenty of time, but will a dremel and some carbide / stone bits do the trick?
Also, when porting them, is the whole entire piping ported, or just the openings of them? I'm pretty new to all this "porting" stuff, but definitely willing to learn. Once done I plan to put these on the car and get a ProTune for my Stage 2 setup. And yes, I have read the Manifesto, and yes, I have searched. I'm posting this to get some opinions from people.
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05-10-2007, 05:30 PM | #2 |
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From what I've seen of people's pics, they're just porting in about .5 inch or so.
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05-10-2007, 06:03 PM | #3 |
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^^ Ditto. They just port match the pipe ends and then smooth out any internal edge transitions. If you're at all handy with a dremel, it'd be a snap.
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05-10-2007, 06:13 PM | #4 |
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Is it true that there are not really any real gains to be had doing a P&P of the exhaust manifold w/o tuning?
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05-10-2007, 06:17 PM | #5 |
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I watched horsepower television a couple of weeks ago- they used a gasket as a template then used a sharpie to outline where to grind the header/manifold.
Might consider this method. Do some research before you start grinding so it's not fubar afterward. Good luck! |
05-10-2007, 06:21 PM | #6 |
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05-10-2007, 06:26 PM | #7 |
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Easy to do... I did mine on a Saturday, with just a dremel. It would go much faster if you had something better like a die grinder.
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05-10-2007, 06:54 PM | #8 |
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One wonders if extrude hone might be a better choice than just abrading the portions of the manifold within reach of a die grinder.
Mike |
05-10-2007, 07:07 PM | #9 |
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I think I may pick up a set from GrimSpeed already done. I'd hate to screw it up, lol.
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05-11-2007, 02:52 AM | #10 | |
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Quote:
I think you best bet may be grimmspeed if you really want it done. To be honest, youll see much better gains by wrapping or heat coating the manifold, upipe, and downpipe. Reducing heat in the engine bay is a big help. Not to mention the Ceramic coating helps the exhaust to flow smoother as well. To be honest, ive been looking at the Grimm Speed stuff as well. Looks like he does a nice job. |
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05-11-2007, 09:30 AM | #11 | ||
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Acejam - i'd be happy to give you some pointers if you'd like to tackle the PnP on your own. I'm going to warn you though, porting cast iron is not a just a "snap", especially with just a dremel lol Justin www.grimmspeed.com |
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05-11-2007, 10:04 AM | #12 |
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remove from car. Remove cross pipe. Dremal and 2 hrs and you should have nice header parts. I suggest using the sanding wheel 80 grit I think. Don't go bigger then the gaskets. Yet I think GrimmSpeed does nice work. Should replace the crosspipe while your in there.
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05-11-2007, 02:16 PM | #13 | |
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If you look at a lot of the pictures on the forum (check out the PnP Madness thread), look closely @ the before/after pictures. If you actually took off your manifold and compared the opening in the manifold w/the opening in the gasket, you will see that you can open up that hole in the manifold a fair amount to meet the same opening as in the gasket for that hole. Once you have done that, you need to make a smooth transition from the larger hole opening down into the runner. Some people open that runner up as much as possible, but by doing this you are sacrificing the integrity of the manifold by removing too much material. In the case of the exhaust manifold, you want to retain the heat as it feeds the turbo. The more material you remove, the more heat loss you will get. You will also increase the heat stress on the exhaust manifold, increasing the opportunity for manifold failure due to less material to handle the high heat. Even though it has been done w/a Dremel, a Dremel is not a good tool to use. It will take a lot more work as compared to using the proper air tools (air grinder & carbide bits). And, it is really easy to screw up the job. Real easy w/air tools and good bits because it will be like a knife through butter. You can do it yourself if you have the right tools and just take your time. Don't rush it and check your work often. |
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05-11-2007, 03:46 PM | #14 | |
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And, yeah, it is a snap if you have the right tools, and take your time. I used to get anal about little crap like this when I raced, but I finally woke up to the fact that there was much lower hanging fruit on the tree. My driving skill, for one.... Last edited by flycaster; 05-11-2007 at 03:54 PM. |
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05-11-2007, 04:14 PM | #15 | |
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This is a graph that was run in the big header dyno last year. multiple pulls where taken and these were the avg of the two. Grimmspeed had NOTHING to do with this. In this graph, if you measure, every 1/8 of inch of difference between the lines is 10 whp or 10 wtq. These are UNTUNED numbers even, you'll gain even more with a tune. This graph shows exactly what we all thought, it helps down low and in the mid range. There is some goofy stuff going on at the end which i cant explain because i wasnt there dyno'ing it. You'll see on some of the biggest differences there is almost a 20 wtq difference. |
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05-11-2007, 05:25 PM | #16 |
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I remember Rainmakers test well. If you will recall, he acknowledged he didn't lock down the ECU so there was no way to keep all parameters the same...and that he had noticed almost as much variation in run-to-run differentials. Again, folks will draw different conclusions, but to me this is within the range of repeatable tolerance. Chris even went so far as to state that he could feel zero "butt dyno" difference and it wasn't until he started in with the header comparo that he started to get some real differences.
Look, I'm not arguing that it won't make any difference, I know better than that. I understand Ve and airflow. But when we're talking about numbers that could and would be exceeded with a 1/2 psi increase in boost...well, I know what I'd do. It's that "lower hanging fruit" thing. |
05-11-2007, 06:32 PM | #17 |
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So far my quickest times were on self pnp'd oem manifolds. Quicker than the Gruppe-s header in fact.
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05-11-2007, 08:27 PM | #18 |
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^^ I don't know much about the G-S tubes specifically, but pretty much every header test that I've seen (here and on the Porsche/Bimmer boards) show that unless they are wrapped, you're wasting money. Wrapped and hot, however, the story is far different.
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05-11-2007, 09:17 PM | #19 | |||
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People that are only doing that little arent doing it right and should bother. I get almost the entire passage on the drivers side manifold, and in a good 6 inches on the passenger side manifold. If you are only going to do .5 into them, dont bother doing it at all. This is why I told him that if he doesnt know what he is doing and isnt sure he can do it 100***37;, not to bother. Quote:
Again, anyone doing that isnt porting their manifolds. They are wasting their time. Even if you are only gasket matching them, it takes more distance down into the manifold to make a smooth transition. Quote:
The big part that I am NOT convinced on is the larger crossover pipes. There is no sense in having that crossover pipe that large because the manifold just necks back down anyway. If the gases are coming out of a small tube, into the larger tube, then back into a smaller tube, there is zero reason to have that larger tube in place. In fact I am thinking that the small>large>small flowpath would slow down flow compared to just staying at a constant diameter. Last edited by Davenow; 05-11-2007 at 09:24 PM. |
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05-11-2007, 10:37 PM | #20 | |
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I'll get reamed for saying this, but wrap or at least coat aftermarket headers. If mine crack because they are wrapped, so what, I'll pull them off and weld em up, the lag compared to pnp'd manis was just too much. Wrapping made a very noticeable seat of the pants difference in spool. |
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05-11-2007, 11:23 PM | #21 |
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Last edited by flycaster; 05-11-2007 at 11:44 PM. |
05-11-2007, 11:25 PM | #22 |
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05-12-2007, 12:42 AM | #23 |
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Chapter 2 of Justin's dyno sheet showings
This one is for you Davenow PnP Exhaust Mani vs. PnP Exhaust Mani with bigger crossover again grimmspeed has nothing to do with this one either. picking up some dang nice gains up high |
05-12-2007, 10:28 AM | #24 | |
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Same goes for the enlarged cross-over tube. It just doesn't seem logical that dumping into the larger cross-over pipe and then back down into the smaller header opening would be benificial. I did notice on the graph provided that there are temp and humidity differences between the runs. |
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