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Old 08-23-2004, 01:02 PM   #676
Full Throttle
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Quote:
Originally Posted by NavyBlueSubaru
It looks like the right time in this thread to inject what I have to say...

My Gp-moto headers are leaking like a SOB at the point where the pipes come together infront of the oil-pan, and so far I havnt gotten any response from gp-moto at all. A vendor was supposedly helping me but i've yet to see any results. Im still in the dark here, several months later. Not to mention, one of the brace brackets broke off the headers too, so they are flawed in more ways than one.

If you buy gp-moto, pretty much forget about the warranty and pray they dont crap all over you after a few months.

Jeff
Jeff,
The headers no longer have slip joints. they are fully welded in those areas in a jig. If you would like to send your headers in to them I am sure we can make arraingments to get that done for you. Thet will solve your problem with the leak and eliminate the need for brackets
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Old 08-23-2004, 02:11 PM   #677
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Quote:
Originally Posted by SaabTuner
Also as a side note. Please do not port match the ehxuast port to the size of the header/manifold. The lip at the edge is used to prevent exhaust gas reversion. It's there for a reason. Some manifolds actually had anti-reversion lips build into them, but the OEM found that by simply using a slightly larger header than the port size they could recreate the same effect.

Ok please explain this revesion, I am unfamiliar with the term. And if its so bad why hasnt anyone complained about that particular solution. And seems to offer the best gains.
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Old 08-23-2004, 09:38 PM   #678
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Originally Posted by 0260B4U
Ok please explain this revesion, I am unfamiliar with the term. And if its so bad why hasnt anyone complained about that particular solution. And seems to offer the best gains.
I'm all for smoothing the inside of the factory manifolds if that's what you want to do. What I'm advising against is enlarging the ports on the stock head to be the same diameter as the manifolds.

Here's a quote from page 119 of Corky Bell's "Maximum Boost" on reversion:

"Reversal of the exhaust gas flow back into the combustion chamber during valve overlap is called reversion. Creating and aerodynamic barrier that reduces the reverse flow, yet does not impede outward-flowing gases can pay dividends in performance."

Page 120 shows a diagram explaining what they mean by that. The small difference in internal diameter between the exhaust port and exhaust manifold creates a one-directional obstruction to prevent reversion. It can be found on almost all factory setups. Leave it be unless you really really know what you're doing.

Adrian~
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Old 08-24-2004, 03:18 AM   #679
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Quote:
Originally Posted by totoherbs
Ya, theres a hand full of companys that cool.... sad that 90% wont even offer a warranty or even bother to pick up the phone if you call. The list I have on good vs ****ty companys is far too lop sided.
My secondhand Borla header cracked at the cylinder heads. Borla said that the million-mile warranty is only good for the original owner, so I put the stock manifold on, after port-matching it. I complained about Borla's quality and warranty in another thread, and later on David Borla, in his first post, offered to help me out, presumably with a new header. I like my current setup, so I'm not sure what to do.
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Old 08-24-2004, 04:40 AM   #680
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Quote:
Originally Posted by SaabTuner
I'm all for smoothing the inside of the factory manifolds if that's what you want to do. What I'm advising against is enlarging the ports on the stock head to be the same diameter as the manifolds.
Now what about porting out the stock header so it's about the size of the gasket? Will that affect revesion? I also wanted to port the header to cross-pipe (leaving the crosspipe alone), header to up-pipe, and up-pipe to turbo. I was going to port all these out to about the size of the gasket.

What do you think about this idea? I know I won't see alot if any gains from it, but if it will help smoothout the exhuast flow and lower egt's even a smidge I'll do the work.
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Old 08-24-2004, 07:31 AM   #681
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Quote:
Originally Posted by scrappydoo
Now what about porting out the stock header so it's about the size of the gasket? Will that affect revesion? I also wanted to port the header to cross-pipe (leaving the crosspipe alone), header to up-pipe, and up-pipe to turbo. I was going to port all these out to about the size of the gasket.

What do you think about this idea? I know I won't see alot if any gains from it, but if it will help smoothout the exhuast flow and lower egt's even a smidge I'll do the work.

As long as the header/manifold diameter is at least a millimeter or two larger than the exhaust port the anti-reversion trick should still work.

As for smoothing the exhaust parts I think it's a great idea as long as you don't go over-board. Remember that it all has to funnel down to an opening the size of the turbine inlet. Making the transitions smoother is a great thing to do though, gains or no gains.

Make sure not to make the walls of the header/manifold too thin.

Also as a side note, to those considering polishing any of their interior piping either to or from the engine, a slightly abbrasive surface actually lends itself to flow by giving the boundary layer something to "hold on" to. A mirror shine on your intake ports can actually hurt flow. Just a side note thought.

Good luck and sorry for the OT.

Adrian~
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Old 08-24-2004, 08:52 AM   #682
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Thanks for the help Adrian.
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Old 08-24-2004, 11:15 AM   #683
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Quote:
Originally Posted by SaabTuner
Leave it be unless you really really know what you're doing.

Adrian~
I agree, and add that to get results, you need test equipment.

BTW, the scenario described in CB's book is an exaggeration of turbulent flow; matching the intake/exhaust sealing area precisely and accurately is a good thing.
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Old 08-24-2004, 07:16 PM   #684
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Quote:
Originally Posted by SaabTuner
...Also as a side note, to those considering polishing any of their interior piping either to or from the engine, a slightly abbrasive surface actually lends itself to flow by giving the boundary layer something to "hold on" to. A mirror shine on your intake ports can actually hurt flow. Just a side note thought.

Good luck and sorry for the OT.

Adrian~

wow thats good to know. This is strange...if this is true than why would one want to polish your piping ? are some places better left relativly "rough" compared to other places where you would want it smooth as glass? I am verry curious to this entire porting and polishing bussiness. If you see websites like http://www.deadboltspeed.com/ they actuly polish the crap out of your turbo.

Can anyone refer me to some info on P&Ping...or anyone know would know the best ways to P&P my Impreza?My budy just bought a die grinder and I am anxious to try that thing out. what parts should I thoroughly port out and smooth...and what parts should I stay away from?

I am sure there are many others out there just a curious! Not only does a little P&P work give you some killer improvments to your car, but its fun as hell being able to customize your car for free!
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Old 08-24-2004, 08:42 PM   #685
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Porting and "smoothing" is great and good for flow. But if you can part your hair in the reflection off your intake ports you might have gone a bit too far. Smooth is good, slick can be bad.

The part in CB's book about reversion can be found on 80's turbo grand prix cars. Some headers even have built into them anti-reversion chambers. Generally a small lip in the exhaust system near the port someplace is desirable.

The bit about turbulent flow is mentioned in Hugh MacInnes book and can be applied to turbine discharges. This is because the gasses exit the turbine in a helix or spiral. The path for those exhaust gasses is longer if they remain in the helix, so a sudden diameter increase at the discharge converts the helix to turbulent flow. The pipe can then be smoothly reduced in diameter a foot or two later. This alos muffles the exhaust note considerably.

Now to your regularly scheduled header debate.

Adrian~
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Old 08-26-2004, 03:04 PM   #686
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Quote:
Originally Posted by IllNastyImpreza
wow thats good to know. This is strange...if this is true than why would one want to polish your piping ? are some places better left relativly "rough" compared to other places where you would want it smooth as glass? I am verry curious to this entire porting and polishing bussiness. If you see websites like http://www.deadboltspeed.com/ they actuly polish the crap out of your turbo.

Can anyone refer me to some info on P&Ping...or anyone know would know the best ways to P&P my Impreza?My budy just bought a die grinder and I am anxious to try that thing out. what parts should I thoroughly port out and smooth...and what parts should I stay away from?

I am sure there are many others out there just a curious! Not only does a little P&P work give you some killer improvments to your car, but its fun as hell being able to customize your car for free!

There was a thread about porting your turbos a while back... it had some good links. There is also a few threads that talk about porting your exhaust manifold. I would realy do your research before you start playing with the die grinder.
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Old 04-13-2007, 12:59 PM   #687
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so, after all that, the charts don't link anymore... and the website is dead and there's nothing about it on the new website...
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Old 04-13-2007, 01:24 PM   #688
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I still have all the info. What questions do you have?
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Old 04-13-2007, 01:44 PM   #689
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well, I was hoping to read the article and look at the charts.
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Old 04-13-2007, 02:07 PM   #690
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the way the shop printed the charts was asinine. I was very unhappy with the article when it was finished.

I'll give you the short version.

All the headers with the exception of the GT Spec Ver.2 made power.

The average increase in spool time was about 200rpm on the first cold pulls, then non-existant on the second pull. (all headers were wrapped w/ DEI wrap)

The Cusco Header made the most power by 1hp (I consider that Dyno error margin)

The GP Moto header was second making about 17hp more across the pull.

The Fujitsubo came in 3rd with about 12hp across the pull.

The Borla, Gruppe-S, and the rest came in about the same with 5-10hp

Please keep in mind that all headers that did not come with an up-pipe were tested with the Helix up-pipe to be fair against the one piece units.

I'm not mentioning the GT Spec Gen.3 as it has been discontinued and had a catastrophic failure shortly after this test (on RiftsWRX's car).

As for fitment, the Cusco, Borla, Gruppe-s, and Fujitsubo fit the best and were the easiest to install.

The GT Spec, GP Moto were the hardest.

If you have any further questions feel free to pm me.

btw- I have since tested a set of extrude honed/ cnc port matched, jet hotted stock manifolds. The results were interesting. No loss of spool (cast iron holds heat better), and a gain of about 5hp across the band.

For the money spent ($700) to do the port job right (by hand is impossible to remove as much material as extrude hone) and the cross over pipe and the jet hot coating, I would rather spend the $699 on the GP Moto header, $60 on header wrap and make about 10 more whp.

For all those who complain about losing the "boxer rumble", remember it's the sound of inefficiency.

Dylan
DS1 Inc.

Last edited by downshift1; 09-29-2007 at 02:10 PM.
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Old 04-13-2007, 02:10 PM   #691
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so, you'd pick the GPmoto one?
what problems did you have with fitment
What about ones without the integrated up pipe?
I have a Perrin up pipe already and that's the biggest problem to install
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Old 04-13-2007, 03:46 PM   #692
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I'm all ears on this too. I tried reading through all these pages a few weeks ago only to discover the same sad truth: the links were dead.
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Old 04-13-2007, 05:03 PM   #693
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Keep in mind these are 2.0 dyno results. Generally the FJT, Cusco, etc. headers employ smaller runners for better performance results on mildly modified 2.0 cars. On 2.5 cars or more heavily modified cars, you will see more power gains going with bigger runners. The same Gruppe-S 4-1 header made 10whp and 18ft/lbs on a 2.5 car, with NO LOSS throughout the entire power band. For 2.0 cars on stock turbos running the 4-1 headers I would definitely coat or wrap and employ a 2.0" uppipe. For modified 2.0 cars with bigger turbos, a 2.25" uppipe and coated wrapped headers work best.

Cheers,

Gary
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Old 04-13-2007, 07:22 PM   #694
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Originally Posted by downshift1 View Post
For all those who complain about losing the "boxer rumble", remember it's teh sound of inneffecency.
Haha, very well put.
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Old 04-13-2007, 07:38 PM   #695
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Did you guys happen to test the DC header?
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Old 04-13-2007, 08:19 PM   #696
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Originally Posted by downshift1 View Post
....For the money spent ($700) to do the port job right (by hand is impossible to remove as much material as extrud hone) and the cross over pipe and the jet hot coating, I would rather spend the $699 on the GP Moto header, $60 on header wrap and make about 10 more whp.

For all those who complain about losing the "boxer rumble", remember it's teh sound of inneffecency.

Dylan
DS1 Inc.
\


how much did GP moto pay you for that one?

how can u justify spending SEVEN HUNDRED dollars on a mass produced piece of metal? when you can basicly replicate the exact same results...AND keep your awesome BOXER RUMBLE !

...all of this WHILE being able to say... "Yeah I Ported and Polished that all myself"... FOR FREE
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Old 04-13-2007, 09:27 PM   #697
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Gary@ Gruppe-S- Actually the Cusco has the biggest runners of any header in the test. The FJT was a close second in size. The rest were about the same. And in my opinion (having installed 100+ up-pipes, the large diameter Helix up-pipe is still the best bang for the buck.

btw- I never did get to say thanks for your help with this.

TheblackRex- The DC wasn't made at the point the test was done.

IllNastyImpreza- I wasn't paid anything by anyone, I did this out of a desire to find out which was better. Sure you can waste your time porting and polishing a stock manifold set, but you'll never make the power you could. Hope the "rumble" helps you feel fast

-Dylan
DS1 Inc.
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Old 04-25-2007, 01:36 PM   #698
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Originally Posted by downshift1 View Post
...Sure you can waste your time porting and polishing a stock manifold set, but you'll never make the power you could. Hope the "rumble" helps you feel fast

-Dylan
DS1 Inc.

Yeah...actualy it does
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Old 04-28-2007, 12:02 PM   #699
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So, between the gt spec gen2 or a borla ceramic coated, which one would be the best? I'm looking to purchase one now and so far I'm down to these two. Since the borla is ceramic coated, would this in turn produce better results throughout the band? Also, are they both unequal or equal? And what are the diameters of each? Thanks for the help.
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Old 04-28-2007, 11:50 PM   #700
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I would definatly do the Borla, the GT spec were the only header that lost power in the test.

Ceramic coating does help. both are unequal, primary and collector diameter are almost identical. The Borla fits a lot better too.
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