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Old 04-04-2005, 04:54 PM   #1
kharris4
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Default No header=Better spool?

I have a 03' usdm wrx with an 18g and all other bolt-ons to support it. my car was dyno tuned on saturday. the question i have for you is as follows...

If i were to take off my gpmoto header and replace it with my stock header and vishnu uppipe, would i then notice significantly faster spool without messing up the tune.

With bad plugs, a vishnu tbe w/catted downpipe, and gpmoto header i ended up with 269tq and 290whp on a dynapack. full spool by 4000rpm's or maybe a little after.
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Old 04-04-2005, 07:22 PM   #2
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Significant? No. Headers don't add a whole lot of lag for a whole lot of time. Maybe ~300RPM lag for 1-2000 RPM. If you want that gain, go for it though. You will loose top end pull though.
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Old 04-04-2005, 08:57 PM   #3
shyguyk27
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Quote:
Originally Posted by Unabomber
Significant? No. Headers don't add a whole lot of lag for a whole lot of time. Maybe ~300RPM lag for 1-2000 RPM. If you want that gain, go for it though. You will loose top end pull though.

Do you currently have the Borla header on you car Unabomber? How does it sound? I'm considering it after reading you FAQ and the dyno testing. Stage 4+ is the plan, but Borla seems the best buy even though it didn't do as well on the stage 4 as it did on the stage 2. I'm going to be around stage 2-3 for awhile.

Keep the header Kharris. You'll miss the power more than the spool. Just my 2 cents though.
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Old 04-04-2005, 09:20 PM   #4
kharris4
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well according to dan at godspeed, my header may not really be doing all that much. look at my numbers, stock cars make that. maybe it is stimming from the cat in my downpipe.

shyguy- i might be able to get you a deal on a borla header.
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Old 04-04-2005, 09:45 PM   #5
shyguyk27
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Quote:
Originally Posted by kharris4
well according to dan at godspeed, my header may not really be doing all that much. look at my numbers, stock cars make that. maybe it is stimming from the cat in my downpipe.

shyguy- i might be able to get you a deal on a borla header.
Dan, Impreziveone, made 358whp on an 18g with a highflow cat. On 93 he made 317 I believe. Maybe it is your header thats hurting you. I don't remember all of your mods off the top of my head, but I know before they wnet to TXS they changed plugs, fuel filter, etc.
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Old 04-04-2005, 10:10 PM   #6
kharris4
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another thing that dan said was that txs had a dynapack 4000 or some odd number and that it might read 10 to 15 hp higher than dan's 5000 series. i'm probably twisting dan's word's around a bit so please don't take my word for it. but if this is true, than imprezive one's car and my car might be closer in power than they appear.
his car did read alot more tq than mine did though.
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Old 04-04-2005, 10:12 PM   #7
kharris4
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also the cat is only about a foot from my turbo.
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Old 04-05-2005, 12:38 AM   #8
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I've definitely had to tune for the header in to maintain boost, (GPmoto 4-2-1) but the low end torque is worth the minimal boost lost at high rpm, and the time I spend in 6th gear before I bury the speedometer is GREATLY reduced with the header.

Within the distance it took me to just barely touch the (innacurate) 160 mark with the stock manifolds, I can now hit it, hold it pegged (as it doesn't move past 160) and still slow down for the exit with ease. Probably taking 15 or more seconds off the full 6th gear pull.

So, yes. The header can hurt, but it depends on where and how you are trying to make power. And whether or not you like seriously outrunning the cops.
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Old 04-05-2005, 11:20 AM   #9
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Quote:
Originally Posted by 2phless
I've definitely had to tune for the header in to maintain boost, (GPmoto 4-2-1) but the low end torque is worth the minimal boost lost at high rpm, and the time I spend in 6th gear before I bury the speedometer is GREATLY reduced with the header.

Within the distance it took me to just barely touch the (innacurate) 160 mark with the stock manifolds, I can now hit it, hold it pegged (as it doesn't move past 160) and still slow down for the exit with ease. Probably taking 15 or more seconds off the full 6th gear pull.

So, yes. The header can hurt, but it depends on where and how you are trying to make power. And whether or not you like seriously outrunning the cops.
Where you runnin' brotha man? I'm from Davie county originally.....now in Burlington. Would be interested to know where you've found to run top end.
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Old 04-05-2005, 11:43 AM   #10
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Stock manifold will do about what Unabomer said 300-400 increase in response. Another advantage is heat retention which will reduce under hood temps and the hotter the gases are coming out of the engine to the turbo, the faster they'll move and the quicker your car will spool... consistantly.

Downside is top-end flow (who cares about top-end?? ) isn't that good and they're heavy.

IMHO stock is the only way to go, but I'm an avid autocrosser.
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Old 04-06-2005, 02:48 PM   #11
jlee8196
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One thing I read about is the lean condition on cyc. #4 with stock header. Not the number 3. and it's related to exhaust flow and not fuel flow.
Someone did a test that with aftermarket exhaust and gtmoto's header the EGT in all 4 cyc. went down. I think cyc#4 drop almost 100 F. You have do a search on the topic. I readed in a hydra post.
I wonder if it's the lean condition of the cyc. (2 and 4) on the driver's side that cause faster spool with stock header.
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Old 04-06-2005, 07:10 PM   #12
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Quote:
Originally Posted by shyguyk27
Do you currently have the Borla header on you car Unabomber? How does it sound?
Yep, I've had a Borla header for over a year now. Sounds like your car. Though others have reported a difference in the sound of headers, mine sounded 100% the same.
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Old 04-06-2005, 08:01 PM   #13
kharris4
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so would it effect my car(switching back to stock header and vishnu uppipe) in a way that would possibly hurt my engine and/or lose me alot of power?

and...

would switching back to such mean that i've wasted my money on the dyno tune?
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Old 04-06-2005, 08:03 PM   #14
kharris4
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i really miss the sound, and i would appreciate a little extra spool up. but not if i drop alot of power after 5,000 to redline.
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Old 04-06-2005, 08:08 PM   #15
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Don't beleive everything you read. There's so much speculation as to what might make one cylinder run leaner then another that the question might never be answered correctly. Course this isn't what the thread's about.

I'd put my money on the cat hurting perfomance b4 I'd put it on the header. If ya change the header out(for stock), you will probably lose a little top end power for a little spool(like everyone else said). I'd stay with whatever exhaust manifold/header is on the car. I just don't see the difference being worth the effort it takes to change em out. As always, this is just my opinion and I'm no expert.

peace
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Old 04-09-2005, 11:15 PM   #16
bboy
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Headers have a bigger volume to fill-up during spool up.
Cooler exhaust gas with headers also slows spool up (header is about 0.1 inch thick and a manifold may be 0.25 inch thick).
Gas moves faster through header, smoother piping, improved path, no sharp turns (that helps to spool faster).

When you add a TBE at the same time as the headers you will not notice much of a spool-up difference (the pressure drop across the turbine is better with the TBE). If you add headers after a TBE install, you may notice some loss in spool-up-- how much depends on many things including your tuning. Headers, add volumetric efficiency at high RPM and thus extend the torque curve, or you could also say they push the torque peak into a higher RPM site--it depends your perspective of air flow through the engine are you looking at total flow or just peak flow.
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