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Old 04-15-2009, 09:13 AM   #1
AKSubieDubie
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Join Date: Sep 2008
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Location: Fairbanks Alaska
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2007 STI EFR 8374
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Default Mild head porting...

While waiting on the crank & lifters to arrive on thursday.. I decided I could use some of my spare time to port the heads a little.

I made a valve spring compressor out of a fourwheeler shock compressor I made a few years ago, and a modified socket.

Here's the before and after pics of the intake port. I only wanted to blend the seat into the head because I know I can't keep things perfectly consistent with a full port job. Plus it seems like I would gain a LOT from taking down that 3/32'' lip down.



It was like this for ALL of the intake ports. The exhausts were maybe half as bad.

I mentioned above how much the seat stuck out: 3/32'' (at the worst spot). It was mostly 1/16'' ish

Finished:



Camera phone pics.

I wonder how much extra flow I'll have by doing this. My guess is maybe a little more oomph off boost. Maybe 1 or 2 ft lbs? Hah!
Seriously though, I think I may gain a good 5 or 10 lb/hp out of this. I did massage the dog leg ports a tad bit more with some actual smoothing action.

I have 1mm oversize manley valves & dual valvesprings w/ Ti retainers too so I think this will help more than a stock head.
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Last edited by AKSubieDubie; 04-15-2009 at 07:52 PM.
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Old 04-15-2009, 10:06 AM   #2
FuJi K
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MY99 GF4 JDM 6spd
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Yes, I noticed that step with the STi heads I'm currently porting. However the WRX EJ205 and the EJ255 heads didn't have a step like the STi heads. The exhaust you can round off that short turn to the floor since it's almost like a 90* corner. That'll help. Port work it helps with off boost driving, which is where you're gonna feel it. When you're making lots of power it's hard to feel 5-15hp. However if 20hp you can feel that. lolz

Last edited by FuJi K; 04-15-2009 at 10:19 AM.
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Old 04-15-2009, 10:12 AM   #3
Homemade WRX
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+1mm for the seat overhang
+2 for the 90* corners on the exhaust ports

not mentioned is if you're porting them...try and aim the flow, on the dogleg in particular, to the outlet of the head. Without porting experience and or a flow bench with pitot tube setup for probing, it'll probably be a bit harder for you to know what I mean.
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Old 04-15-2009, 07:50 PM   #4
AKSubieDubie
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Yeah I still need to polish the exhaust side up. I may run to town here in a bit to pick up a longer carbide bit to reach up into the dogleg, and get some polishing stuff.
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Old 04-15-2009, 09:58 PM   #5
FuJi K
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Here's the work on the STI heads I'm working on. I ported cylinder #1's exhaust to move the flow towards the outlet. Since they are NOT as big as WRX heads, I can only do so much.



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Old 04-28-2009, 05:17 PM   #6
WcW
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What about the total length distance? How much further is it from the furthest rear port vs. the furthest front port? What would you say about porting and the use of the stock "weird" exhaust stick, that clearly will be causing a bias between the two valves.
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