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#65: 11-14-2012, 10:22 PM
fahr_side's Avatar
Title: Royal Pain in the Ass
Rank: Donating Member
Location: Fahr, fahr away
Car: '08 1.5XTR+meth 6MT GH8
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Time for some results. Thanks to those who've asked me by PM for progress with this part.

I want to say first that I've had a long and complicated process of working with this intercooler, much of which is my fault. For example, I installed the IC and allowed my Innovate LC-1 to start up with the heater wires open-circuit. This causes the heater (not the sensor) to lose calibration, which throws off AFR readings. I had first installed the Spearco while running on stock exhaust manifolds and immediately noticed I had lower boost and richer AFRs. I did indeed have some boost leaks, apparent from the way boost rose and then quickly fell to a lower level. I fixed the boost leaks but didn't believe that to be the case, since both boost and AFRs were still consistently below my targets. Those who have spent time chasing down real boost leaks will appreciate the frustration of chasing down imaginary ones.
It is a big core and a bit of a pig to get on and off, hence the slow progress.

I had the IC core pressure tested, and the BPV, and confirmed all other connections were solid before realizing my LC-1 needed recalibration. With that done I could see AFRs matched my previous MAF scaling, which was within 2% from the end of rich dip in spool up to redline. At this time however I had fitted a new Tomei EL header which of course skews the results somewhat. I'm being careful here to only show you results from the same setups.

First thing I notice is that when running the same tune as with the stock TMIC I am at far lower boost. By this time it had been mentioned by several tuners, including Eric Minehart who I hold in high regard, that the '09~ (VF-52) WRX models had needed a lot of extra WGDC added to regain the original boost levels seen before installing the Spearco. This is the other factor that convinced me I'd fixed the boost leaks.

This is pre and post-install of the Spearco. Same BNR 16G turbo, Tomei header, 3-port BCS etc.

Attachment 133932

You can see clearly the much slower spool and overall failure to reach boost target. I'm not actually running that rich... it's the LC-1 that needs recalibration. Turbo dynamics is wound up to the limit here trying to hit target boost but to no avail. Note that the blue curve with the stock TMIC is hitting about 274g/s vs. 265g/s from the Spearco (my MAF scaling, not stock). Although the peak numbers are close the car is noticeably slower past 5k5rpm! It may be possible to add timing at high rpm and regain the power I had on the stock TMIC with lower boost.

After talking a bit with Eric I opted to redo boost control and increase WGDC across the board in an effort to prop up the sagging boost curve.

Attachment 133933

Please note that the blue line in this case is the same pull as the stock TMIC line above, also in blue, used for reference. All I've done here is increase WGDC to match the original spool, regain the original boost peak, and attempt to hold the same 16.5psi at redline. You'll see how on the Spearco, boost falls about 2psi short of target at redline despite having cranked WGDC up to 92%. Note the Spearco is still only pulling 265g/s despite winding WGDC up to the limit.

It's been said on many occasions the stock VF-40 boost actuator is weak. Mine cracked open at just on 10psi which leads me to believe it's easily blown open at high manifold EGBP. My buddy put together a 1bar actuator for me from spare parts laying around the shop. It actually opens at around 13.6psi adjusted fully tight, but it will do for now.

Attachment 133934

With the stiffer actuator I could hold 17psi at redline with about 63% WGDC but quickly realized I had to pull 3* of timing up there to do so. Net result is a loss of about 10whp and 10wtq vs the stock intercooler. The car is here quite noticeably slower past 5k5rpm despite the extra 2psi of boost. Seems fairly obvious the poor little 16G is maxed out at this point. I also note spool is slower than with the stock actuator, so something's not right there either.

At this time I'm tapering again to 15psi at redline while I formulate the next plan of attack. Options include:

1. Raise timing beyond 5k5rpm to compensate for lower boost.
2. Further lean AFR to 11.2:1 for more power.
3. Combination of 1 and 2. Rely on (supposedly) superior cooling from Spearco IC to allow this.
4. Step up to larger compressor.
Obligatory 'build thread'
Terrible things like this don't happen where I come from. Other terrible things happen instead.

Last edited by fahr_side; 11-21-2015 at 08:47 PM..
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