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Old 12-18-2003, 09:50 PM   #1
Cappx
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Default Headers = LAG

It has been suggested to me that headers are one of the biggest causes of LAG on our turbo cars? Any thoughts?
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Old 12-19-2003, 12:21 AM   #2
mlambert
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Nice thread title

The header design does factor into spoolup times but saying HEADERS = LAG isnt accurate. A properly designed turbo manifold can actually decrease lag.
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Old 12-19-2003, 12:47 AM   #3
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guess my question now is what should i look for to know its "A properly designed turbo manifold "

only aspect i have come across thus far is uneven vs even lenght headers!

thanks again
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Old 12-19-2003, 07:18 AM   #4
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probably any header + thermal coatings will get you to almost stock spool...plus theyll provide with much more power once boost hits.
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Old 12-19-2003, 11:40 AM   #5
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Quote:
Originally posted by happasaiyan
probably any header + thermal coatings will get you to almost stock spool...plus theyll provide with much more power once boost hits.
Will they?

Boost is a function of how much energy the turbine can scavenge from the exhaust. Lower exhaust temperatures = less energy to scavenge = less boost = less power. Of course this may be offset by other factors, such as more energy to scavenge due to less restrictive flow through the new headers.

I can't see any headers matching the stock headers for spool, unless they copy the simple (yet good) straightfoward design of the stock headers.

Capxx: For spool you want two things:
1. Quickest path possible to the turbo, the stock headers do this fine
2. Good heat retention. Out cast iron headers with heat shield do this decently also.

Headers can be a big cause of lag on some turbo cars, but not ours.
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Old 12-19-2003, 11:54 AM   #6
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equal length headers have a bit more lag over the others, but better top end as I under stand it.
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Old 12-19-2003, 12:45 PM   #7
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Quote:
Originally posted by pierceman
equal length headers have a bit more lag over the others, but better top end as I under stand it.
I have heard that too.

As a counter point I have heard that unequal length headers will increase the low-end sacraficing some top end power.
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Old 12-19-2003, 01:54 PM   #8
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I have a thermal coated equal length GP MOTO header on my 2.0L WRX. There was a slight increase in lag, but it was still less lag than a comparable unequal length setup. After installing and tuning engine managment, the car put down 260 lb ft of torque (on the STOCK turbo) to the ground and spools to 1.2 bar in fourth gear by 3000 RPM. With the proper setup, headers DONT EQUAL lag. I would reccomend having engine management at some point to fully extract all the power you can out of a equal length header setup.
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Old 12-20-2003, 07:16 AM   #9
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i have the gt-spec II headers on the sti.

The up-pipe they supply with it tapers on the turbo side to speed up the exhaust gasses as they are squeezed through a smaller diameter opening (think of putting your thumb over the end of a garden hose).

My spool is noticeably faster. Almost scary-fast.
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Old 12-20-2003, 10:52 AM   #10
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GT SPEC GEN II Racing Header - $499
With Detachable Uppipe
GTSpec GEN II exhaust manifold is the revision of the orginal. The revolutionary velocity chamber design and the high quality finish are unchanged on the new generation as we strive to bring the best value to our customers. The flanges are completely redesigned: the finish is upgraded to stainless steel; and it sports a three pattern to help prevent leaking between the up-pipe and the header. The EGT bung is revised as well.

Detachable up-pipe is included. The up-pipe comes with a velocity chamber inside the pipe. This special feature is structure for increasing airflow velocity. This full stainless steel header and uppipe is covered under GT-SPEC's 2 years warranty.

The complete package includes header, up-pipe, block gasket x2, and upipe gasket x1.


I spoke to dan about the header last week. I am ordering it as soon as he's back. He gained something like 15 ft lbs of torque with it.
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Old 12-20-2003, 11:58 AM   #11
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The OEM uppipe on the STi and WRX is also velocity stacked.
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Old 12-20-2003, 12:02 PM   #12
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15 ft lbs and 15 hp for 500 bucks is a lot of bang for the buck in my opinion.
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Old 12-20-2003, 07:23 PM   #13
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Acually, you will get a better exhaust flow with a header that does not retain heat, that is why most turbo manifolds on race engines are ceramic coated.

Quote:
Originally posted by Corn-Picker
2. Good heat retention. Out cast iron headers with heat shield do this decently also.
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Old 12-20-2003, 07:38 PM   #14
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Quote:
Originally posted by BGPKR
Acually, you will get a better exhaust flow with a header that does not retain heat, that is why most turbo manifolds on race engines are ceramic coated.
The hotter the gases are prior to the turbo the better the flow. The ceramic coating by design on race engine retains heat to promote spool and minimise heat soak.
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Old 12-20-2003, 07:45 PM   #15
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I stand corrected. I understood the theory, but could not put it into words correctly.

Quote:
Originally posted by lstepnio
The hotter the gases are prior to the turbo the better the flow. The ceramic coating by design on race engine retains heat to promote spool and minimise heat soak.
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Old 12-20-2003, 08:19 PM   #16
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After the first of the year, Dynamispeed ( soon to be vendor on NASIOC) will be having a group buy on GP MOTO equal length headers. Stay tuned for that.
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Old 12-30-2003, 10:39 PM   #17
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I think thats incorrect. Ceramic coatings do not retain heat. If you ceramic coat an object then subject it to extreme temps you can touch it with you bare hand immediately afterwards, there is little if any heat retention. The space shuttle uses ceramic tiles for atmospheric re-entry because of this. I think maybe there is a velocity issue where the lack of heat absorption causes a faster stack speed in the pipes due to ceramic coatings..
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Old 12-30-2003, 11:02 PM   #18
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The heat is retained INSIDE the pipe. I would not recommend placing your hand on a ceramic-coacted exhaust manifold.
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Old 12-30-2003, 11:04 PM   #19
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Well remember that hot air travels faster so the more heat you can retain in the exhaust before the turbo, the better spool up it gets. I can play around on the dyno and make a header have very different spool up characteristics simply by heating up the charge by heating up the header (this less heat loss). THe best solution is to get a good quality stainless header and insulate it as best as possible with header wrap or the like to retain the exhaust heat in there. THat being said, I have not seen that much loss in spool up with headers and the gains in torque and overall power under the curve more than make up for it. GT Spec is releasing their equal length spec 3 header but I will continue to use the spec 2 as it is the best value of any header on the market.
Large Orange Font, I'm curious, did you dyno that header on a Dyno Dynamics dyno or a Dynapack? I have seen some dyno dynamic dynos put out some CRAZY high torque numbers compared to Dyanapack numbers even though HP numbers are relatively similar. If you look at the latest issue of Import Tuner, their EVO baselined about same as they do on my dyno but made like 30 ft lbs of torque more. Very strange indeed.
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Old 12-30-2003, 11:10 PM   #20
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The ceramic coating works just like thermo wrap does. You're correct that the coating itself doesn't retain the heat but acts as installation "retaining" the heat inside pipe.

Quote:
Originally posted by Booosted
I think thats incorrect. Ceramic coatings do not retain heat. If you ceramic coat an object then subject it to extreme temps you can touch it with you bare hand immediately afterwards, there is little if any heat retention. The space shuttle uses ceramic tiles for atmospheric re-entry because of this. I think maybe there is a velocity issue where the lack of heat absorption causes a faster stack speed in the pipes due to ceramic coatings..
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Old 12-30-2003, 11:40 PM   #21
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Yeah I design powder coatings for a living, always been a big fan of ceramic coatings. Never used them on a car though. Used the thermal wrap stuff. I still havent gotten anybody to buy my crap audi TT yet..the sooner i get rid of it the sooner i can get into a nice black STi that I have on order. Anybody want to buy a TT 225? Its got lots of thermal wrap...but still is damn slow...
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Old 12-31-2003, 09:53 AM   #22
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Our logging has shown on several SS headers additional lag over OEM of 200-500 rpm on the TD-04 when they are left uncoated.

We found both the Gen. I & Gen. II GT-Spec's to be the lowest lagging headers of those we tried. Since Gruppe-S is a very similar design but definitely not the same - we would expect a similar outcome from them, though we believe the velocity stack of the Gen. II up pipe to be preferable.

Once the GT-Spec Gen. II header/UP were coated inside and out with J-H 2000 the spool up characteristics of the TD-04, VF-30 and VF-34 were found to have no statistical differences between the OEM manifold and the GT-Spec Gen. II header/UP combo. (Yes we sell them and some will claim bias - but we only sell them because this is what we found to be the case.)

The internal and external coating of our headers - retains heat in the exhaust not the piping. The retained heat and improved flow recover the velocity needed for stock spool up characteristics - while opening up the middle and top end torque bands.

With regards to the OEM "stack" first the collector is not efficient, second they employ a flex joint which by design makes for poor exhaust flow hardly a well designed velocity stack - there is no increasing velocity as the exhaust reaches the turbo. The cast material and thin primaries retain a lot of heat in the exhaust gases and provide good low end velocity and anyone would be hard pressed to create an exhaust with better spool up.

But the spool up can be matched with a good header that has heat retetention. And all the headers open up mid and top range torque restriction of the OEM manifolds, crossover, collector and up pipe.

Of course the biggest restriction is for those with up pipe cats. A header combo will increase peak power numbers slightly over just a good up pipe. But the increase in area under the torque curve with the good headers is what is really impressive - the small peak increases don't do the usability of the torque curve justice when people discuss the "small" peak improvements of headers.
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Old 12-31-2003, 04:56 PM   #23
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Quote:
Originally posted by yeager
i have the gt-spec II headers on the sti.

The up-pipe they supply with it tapers on the turbo side to speed up the exhaust gasses as they are squeezed through a smaller diameter opening (think of putting your thumb over the end of a garden hose).

My spool is noticeably faster. Almost scary-fast.
Are your headers coated, wrapped or left alone?
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Old 01-01-2004, 08:36 AM   #24
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no coating at all.

the one down side on the gt-spec headers: on left handers under lift-throttle, they touch the sub-frame and vibrate. This is apparently easily fixed with engine mounts and is not any major concern.
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Old 01-01-2004, 09:46 AM   #25
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You can also tap the subframe just a tad with a mallet to give it enough clearance. Every once in a while a car has that problem here too. Not a big deal. Darn Subaru and their huge tolerances.
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