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Old 11-28-2004, 02:45 PM   #1
jmussetter
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Member#: 15350
Join Date: Feb 2002
Location: Bay Area, CA
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2002 WRX Sedan
Midnight Black

Default UTEC Tuning for Headers?

Hey guys, just wanted some theory advice about tuning...

I've got my road map pretty well sorted out with no knock and nice AFR's. Tuned by me with an LM-1. Anyway, I'm not running ragged edge tune so I should have some headroom already. My CR is around 7.4:1 or so with the 2.2L block swap with stock heads, so I'm running timing around 22deg at redline (less at 4K area) at 100%map.

I recently installed a new set of headers, and I wanted some advice as to where to tune to get the best from the headers? Or are headers not going to need a new map for gains. I realize that headers will have some HP gains just from the part itself, but are there added benifits to fine-tuning the map for headers?

In other words, would headers allow me to advance timing more than currently without det.? Or can you run leaner AFR without det? The more I think about it, I don't see how headers could let you do either of these, so fine tuning the UTEC map for them might be a moot point. Any added HP is totally bolt-on HP gains and not tuning gains?

Pointers anyone? Thanks.

-jason
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Old 11-28-2004, 03:18 PM   #2
WhiteKnight
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Hi jason,

Its likely that headers will make your car run lean, have you checked your AFR's after putting the headers on ?
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Old 11-29-2004, 08:38 PM   #3
jmussetter
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Yes, I've checked my AFR's and they havn't seemed to change that noticably after the header's were installed. Should I leave the tuning alone, or is there some changes I can make to get more gains?

Spool up is a little slower now, since it's a 4->1 design, and the uppipe is larger diameter than my old godspeed uppipe.

-jason
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Old 11-30-2004, 01:40 PM   #4
zaxrex
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From what I can remember in the 4-channel EGT gauge thread, the EGTs actually dropped. Go back to the 2.0l factory turbo forum and dig that one up.

I leaned the fuel way out, but I don't know how much of that was from the header and how much was from the water.
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Old 11-30-2004, 02:51 PM   #5
jmussetter
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Yeah, you're right about the EGT dropping. I'm seeing an average of about 50-100degF drop than with the OEM manifolds and catless uppipe. So are you saying that I should try lean the fuel out to obtain the same EGT's as before (if possible without det. of course)?

What about timing? Does that stay the same? I always worry about leaning it out *too* much. I like having the safety margin of a rich AFR, and then making more power by adv. the timing. But I think I have enough fuel overhead with my current AFR's that I could lean it out some without knock problems.

Any other tips? Thanks!

-jason
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Old 11-30-2004, 07:53 PM   #6
dnolek
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Headers should help lower the exhaust backpressure as seen by the combustion chamber. The stock manifolds tend to cause the pressure wave from cyl 2 to be seen by cyl 4 in terms of higher EGT's on cyl 4. This contributes to knock. Since your previous maps were probably tuned to the worst cylinder (4), and the pressure waves are now equallized with the header, you should be able to both run more advanced timing, and a bit leaner fuel. You'll get the most gains from advancing the timing. I would start with advancing the timing until you start approaching the knock threshold. Similar setups can run better than 25 deg of timing above 4500 rpm. Have fun with your new parts.
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