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home-made header for the G13B
http://www.teamswift.net/viewtopic.php?f=11&t=55285
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Author:  t3 ragtop [ Thu Nov 07, 2013 9:17 pm ]
Post subject:  Re: home-made header for the G13B

on my current engine the pipe works okay at around 3000 rpm and the engine pulls harder as the rpms go up to 6000+ rpm. it's probably happiest between 4000 and 6000 rpm.

i'm running a 2" exhaust.

the last cultus header i ran on another car with a 2.25" exhaust, a 60mm maf and throttle body, and a rallye 2 chip was as happy as a clam from 3000 to 7500 rpm and i would pull the shift lever at 9000 rpm. that engine was a little balky around 2500 rpm and i suspected that it was the eprom more than anything else.

like everything else on an engine, you trade this for that and you have to understand that you have to also stay within logical constraints. if you have room for 30" tubes and the equation calls for 40" tubes, you either use the 30" tubes that fit or make changes that will allow for the 40" tubes. :wink:

for my desired usage, the cultus header works really well for me. my car isn't a balls out race car, though, either. it's a fun time street cruiser, not a dragster, so i can respect it's limitations. i built it to drive on the street and wanted an engine that was quick but still had enough manners that it wouldn't be a chore to drive. i left all the cold start, step down fast idle, and heated throttle body bits on it, factory vented induction lines and all. the exhaust is a modified stock design that doesn't depart too far from the original equipment.

Author:  elbola [ Sat Nov 09, 2013 2:52 pm ]
Post subject:  Re: home-made header for the G13B

t3 ragtop wrote:
on my current engine the pipe works okay at around 3000 rpm and the engine pulls harder as the rpms go up to 6000+ rpm. it's probably happiest between 4000 and 6000 rpm.

i'm running a 2" exhaust.

the last cultus header i ran on another car with a 2.25" exhaust, a 60mm maf and throttle body, and a rallye 2 chip was as happy as a clam from 3000 to 7500 rpm and i would pull the shift lever at 9000 rpm. that engine was a little balky around 2500 rpm and i suspected that it was the eprom more than anything else.

like everything else on an engine, you trade this for that and you have to understand that you have to also stay within logical constraints. if you have room for 30" tubes and the equation calls for 40" tubes, you either use the 30" tubes that fit or make changes that will allow for the 40" tubes. :wink:

for my desired usage, the cultus header works really well for me. my car isn't a balls out race car, though, either. it's a fun time street cruiser, not a dragster, so i can respect it's limitations. i built it to drive on the street and wanted an engine that was quick but still had enough manners that it wouldn't be a chore to drive. i left all the cold start, step down fast idle, and heated throttle body bits on it, factory vented induction lines and all. the exhaust is a modified stock design that doesn't depart too far from the original equipment.

That's great info, thanks. It's a good reference for me. The fact that the cultus runners are shorter than they should be for their diameter, is probably why that header works so well at higher RPMs. I think/hope mine will be similar...

Author:  elbola [ Sat Nov 09, 2013 2:52 pm ]
Post subject:  Re: home-made header for the G13B

So I installed the header today... it was a tight fit, only a few millimeters from the block on the bottom. I had to remove the lower bracket that connects the gearbox with the block, cuz it was in the way. Do you guys know if that'll cause a problem?

About performance: the exhaust is a lot louder now, with a lower tone. The engine feels happier at upper RPMs, that's for sure. However I didn't get to do a proper test, cuz I'm still running in the new clutch. I'll make a video when the clutch is ready for abuse :P. It feels like I've lost some torque between 0-2k RPM, but that's actually a good thing cuz I've a 60mm throttle body, which makes the throttle really sensitive. Now the car more easy to control in traffic.

I also need to replace the first 10 cm of the exhaust pipe, right after the header, cuz that's a remaining piece of the stock exhaust system and it's acting as a restriction (it's 42mm ID). Once that's replaced with a 2" piece, the exhaust gasses will flow better at high RPMs.

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Author:  shingoku [ Wed Nov 27, 2013 5:25 am ]
Post subject:  Re: home-made header for the G13B

Nice work on your fabrication man. I have a question though? Did the flange you got off the stock gti work for this car or did you have to fabricate a flange that could work for the head?? Because I need a flange for a header I want to weld it onto but I can't seem to find one for sale in the U.S

Author:  elbola [ Wed Nov 27, 2013 8:18 am ]
Post subject:  Re: home-made header for the G13B

shingoku wrote:
Nice work on your fabrication man. I have a question though? Did the flange you got off the stock gti work for this car or did you have to fabricate a flange that could work for the head?? Because I need a flange for a header I want to weld it onto but I can't seem to find one for sale in the U.S

I used the flange off another header that was cut in pieces... got it free from a local guy.

Author:  elbola [ Sat Nov 30, 2013 4:24 pm ]
Post subject:  Re: home-made header for the G13B

The flange was hitting the oil-pan, so I moved it and removed the restriction at the same time... now the whole system is 2" from the header all the way to the muffler. I'll see if I can find an opportunity tonight when there's no traffic to see if there was an improvement in top speed. I wish we had highways over here :evil:

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Author:  elbola [ Sun Dec 01, 2013 1:47 am ]
Post subject:  Re: home-made header for the G13B

So I repalced the sparkplugs and air filter this afternoon and went for a little race earlier tonight. Got the car to 185km/h on a relatively short road where I normally can't even get to 170km/h, so I'm REALLY pleased with the results so far. There's only one road on the island where I could possibly test the car's top speed, but it's really hard to find it without traffic... I'll see if I can get lucky the upcoming week.
There's a noticeable power increase at the upper half of the tacho, that's undeniable; but I suppose because the bigger throttle body is working better now that the exhaust was upgraded.
I bought an Ostrich emulator from a member, so I'll be busy tuning to get the most out of my mods in the next couple of months. I hope I can get this bebe to 200km/h on these roads 8).

Author:  DTM GTi [ Sun Dec 01, 2013 2:28 am ]
Post subject:  Re: home-made header for the G13B

Just so you know you will be cracking that exhaust pretty soon. You can not built it without some way to allow for engine movement. I don't see in your pics any flexible bellows or joints. I know its a four banger and it runs smoother then 3 banger but it still needs something just about in the place where you moved that flange.
Many moons ago I built my first exhaust that way and pretty soon I had to redo it. It was on T3 where engine movements are lot more severe but I think it applies to G13 too. Just my 2C.........

Author:  elbola [ Sun Dec 01, 2013 10:59 am ]
Post subject:  Re: home-made header for the G13B

DTM GTi wrote:
Just so you know you will be cracking that exhaust pretty soon. You can not built it without some way to allow for engine movement. I don't see in your pics any flexible bellows or joints. I know its a four banger and it runs smoother then 3 banger but it still needs something just about in the place where you moved that flange.
Many moons ago I built my first exhaust that way and pretty soon I had to redo it. It was on T3 where engine movements are lot more severe but I think it applies to G13 too. Just my 2C.........

Thanks for the tip. I was thinking the same thing, but the guys from the muffler-shop said it wasn't necessary. Is the stock flange with the 2 bolts and springs really that flexible? Where do you think I should weld a flex pipe, before or after the flange? And how long should it be... 4", 6" or longer?

Author:  elbola [ Sun Dec 01, 2013 3:12 pm ]
Post subject:  Re: home-made header for the G13B

Here's a video of a second gear pull with the new header... what do you guys think?


Btw the only is only mods so far are: 60mm throttle body, custom headers and 2" exhaust.

Author:  DTM GTi [ Sun Dec 01, 2013 6:16 pm ]
Post subject:  Re: home-made header for the G13B

jankoelbola wrote:
Thanks for the tip. I was thinking the same thing, but the guys from the muffler-shop said it wasn't necessary. Is the stock flange with the 2 bolts and springs really that flexible? Where do you think I should weld a flex pipe, before or after the flange? And how long should it be... 4", 6" or longer?


Stock flange works like a ball and socket joint, springs apply just enough pressure to keep it sealed against that Teflon/steel wool doughnut . If you look inside when you take them apart you will see mating surfaces are nice, clean and shiny because of the movement. 4" stainless braided flex pipe should do the trick right in the place of that new piece of pipe you welded in on the engine side.

Author:  shingoku [ Mon Dec 02, 2013 1:13 am ]
Post subject:  Re: home-made header for the G13B

could you do a vid from first to second or first to third because i cant really make the distinction with it from second gear only. 0-100kph i would find interesting to see vs stock :D

Author:  elbola [ Mon Dec 02, 2013 8:35 am ]
Post subject:  Re: home-made header for the G13B

shingoku wrote:
could you do a vid from first to second or first to third because i cant really make the distinction with it from second gear only. 0-100kph i would find interesting to see vs stock :D

yeah I know, but it's hard with a phone and there has been way to much traffic these days with Holiday-sales and all. I'll make a proper video soon, but want to get the flex pipe welded in before driving the car hard again...

Author:  shingoku [ Mon Dec 02, 2013 1:28 pm ]
Post subject:  Re: home-made header for the G13B

alright man and yea its true. i cant even drive my gti hard without keeping a close eye around for cops now. they're everywhere since the holidays are here. i look forward to seeing the vid though. :twisted:

Author:  elbola [ Mon Dec 02, 2013 5:39 pm ]
Post subject:  Re: home-made header for the G13B

shingoku wrote:
alright man and yea its true. i cant even drive my gti hard without keeping a close eye around for cops now. they're everywhere since the holidays are here. i look forward to seeing the vid though. :twisted:

yeah I hate cops... and my car is really loud so if I'm pushing it hard they can hear me coming from the distance.

About the header: I welded two brackets to the header... one bolted to the block and the other to the gearbox.... I hope that keeps the header from cracking until the flex joint arrives in the mail in a couple of weeks.

Author:  elbola [ Sat Jan 04, 2014 5:44 pm ]
Post subject:  Re: home-made header for the G13B

So I installed the flex-pipe a couple of weeks ago and also welded a bung in the pipe right after the header (can't be seen in this picture). It takes more time now before the sensor is hot enough to send an accurate reading to the gauge, but at least I won't have to do it all over again if I switch headers in the future.
I was busy servicing other stuff in the car, but I'm almost ready to drive it hard again... I only need to replace the oil and filter. Than I'll make a video.
I'm also waiting for a ostrich emulator that I bought from a member here. Once that's installed I'll see how much I can really get from this set-up.

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Author:  elbola [ Sat Feb 01, 2014 2:19 pm ]
Post subject:  Re: home-made header for the G13B

So I've been haunting an exhaust leak for weeks now and it was right were I would have never thought... one bolt was missing at the flange to the head. This caused not just an annoying sound but apparently loss of power. I've been trying different tunes these days with the ostrich emulator I've been playing with and there was an improvement of at least a full second in the second/third gear pulls I was doing, after the leak was taken care of. Anyway I'll make a proper video soon... probably take the car to the track too, so I can come up with 1/4 mile numbers.

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