Rawr... My 2011 STi Build Log by Heide264

By diyauto
( 4 )

4 minute(s) of a 127 minute read

6-14-2012

Track Day Prep (1/2) - Rear Engine Bay Venting


I saw a thread over on another forum talking about opening up the rear engine vents - the ones in between the front tires and the front doors.


Reasoning:

-Under hood pressure causes both the radiator and TMIC to loose air flow. Our car has big 'innies' and not so many 'outies'.

-They are in one of the few generally accepted low pressure areas around the hood. The windshield area is a hot topic.

-While the pressure differential will be about the same, these should allow for better flow given the same pressure differential.

-Cheap, easy, and non-intrusive. Little chance for something to go wrong.

-My car kinda felt like a fat kid running a mile at the first track day by the end of each session. I figured anything I can do on that end will help.


Procedure:

-Pop off fender vents

-Drill holes

-File down rough edges

-Tape off surroundings, apply some primer and touch up paint

-Dig up metal disks from side skirts

-Put back together


Crappy picture. Pre-filing. Crappy hole saw as well. Still worked.




For the second half of the track day prep, I plan on replacing ~50% of my coolant mixture with distilled water as per a suggestion by Crawford and some other track guys. They lean towards more of an 80/20 water/coolant mixture to help with heat transfer (circulates faster to my understanding). I will have to be careful to add coolant towards winter. I will also sand down the surface of my race pads and make sure they are smooth and good to go. Will open up each caliper for a second just to make sure there is no air in there as well.


6-19-2012


Track Day #2


Well, I skipped posting the prep 2/2 - Basically just threw the DS2500 pads back on and got them bedded in.


Track day was a blast as expected. I improved a lot, and everything felt much more 'fluid'.


Some notes:

-Picked up some knock events every session. They were all medium/high load (Bad!), inaudible in the car, and after about 10 minutes into the session. Considering my engine temps were okay, I am assuming the top mount just doesn't cut it when you are at speed and under boost for a long period of time. I could feel the car get weaker after a few laps each time. Frustrating, and hoping I didn't kill my engine. Picking up a few knock events in low/mid range now daily driving, which I had cleared up before hand. Will keep an eye on it. Possible investigation to follow 

-Brakes held up fairly well. The bleeder screw on the front calipers was oozing on both sides after each session - common problem with the Brembos apparently. Pedal held firm at least. If I get any better tires, they will need upgraded sadly.

-Tires did well again. Pressure rose from 35psi on all four to around 45psi after the session, so I let a few psi out.

-I wore my boxing shoes figuring they would help with pedal feel. In turn, I actually lost all ability to heal/toe. Fail. Oh well.

-Overall, the car did fantastic. Lotta people were extremely surprised by it. Felt pretty good to keep up with most of the cars on that track. The GT3Rs was an exception. I saw its (sexy) tail pipes several times. Also the lotus exige was pretty darn fast.



Good stuff. Now I just gotta get those pads back off and have a nice cigar.



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