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#179: 06-22-2014, 10:23 PM
Stromung Divorced Downpipe
covertrussian's Avatar
Title: MPG Tuner
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Location: VA
Car: '05 LGT, '12 OBP, '00 G20+T
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The downpipe seems to be the main thing that suffered the deer running, though the plastic belly pan is worthless now too.

Looks pretty nasty...

I had an exhaust leak from the oring and from where the primary and secondary connected, you can see it being slightly bent.

Stock vs Stromung Divorced Shorty and unknown secondary part.

Stromung Divorced Shorty

Not sure what turbo this was meant for, but with VF40 it wouldn't go any further.

Used a carbide burr and compressor to cut it out

Wastegate flap fully opened and it moves freely now

Secondary and cat

Turbo looks good, I checked for shaft play and it seemed pretty decent actually.

Installed on the turbo, sadly still have deer fur everywhere...

Spent a good amount of time cleaning up the midpipe and the doughnut gasket crud from it...

The stock bolts wouldn't close the gap all of the way so still had an exhaust leak. Had to get new fully threaded bolts to get it close enough not to leak (not pictured).

Required Tune Changes
Disable Rear 02 (if not running one)
Disable AF3 Correction and Limits

Stock Wastegate Duty cycle map:

I subtracted 10 points across the whole map, that got me to very similar peak boost, but with boost coming along much earlier still.

Here is some virtual dyno runs. Getting rid of the down pipe increased the boost by 1-2psi, boost comes along much sooner with this downpipe, which is a problem if left untuned.

I did a 300 some mile roadtrip today to Global Rally Cross (GRC) up at Washington DC, it around 80*F so not even a hot day, came back and saw a ton of knock down low. Sadly this means I have to reduce boost more down low @3200rpm and less.

MPG Gains
I had the best MPG gain by running 15* of AVCS advance, before the deer wreckage I was testing 20* and saw somewhat minimal gains. I think this was because I was starting to get too much reversion. With the freer flowing downpipe, it seems to like 20* advance a lot more.

Going to GRC we were in a hurry and where going 75mph plus had a good amount of city driving while in metro area, this netted me 25.7mpg which is still fairly good. On the way I fueled up and avoided traffic/city driving and stayed at 70mph, this got me an impressive 31.7mpg. Once I get the WG Duty table back to stock levels down low will see how the car does on a more controlled highway trip.
05 LGT 16G 14psi - 290whp/30mpg
12 OBP Stock - 120whp/31mpg
00 G20t - GT28r 10psi - 250whp/36mpg
The Following 2 Users Say Thank You to covertrussian For This Useful Post:
Sclantz (06-23-2014), snm95ls (07-20-2014)