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Homebuilt GC8 for Time Attack
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Old 09-08-2019, 10:50 PM   #211
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Well the problem is right in the title

Homebuilt GC8 for Time Attack





kidding <3
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Old 09-09-2019, 01:09 AM   #212
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knock on wood, but nothing I touched broke on the car ))
Stuff I did mostly works.
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Old 09-09-2019, 01:35 AM   #213
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I was tuning car before the event and noticed that IAT was climbing really fast while in boost. I decided that intercooler needs to be ducted because my early version 2 bonnet and V3-4 intercooler never ment to work together from factory and stock ducting was removed.

I found this to be good occasion to practice my cad skills and 3d printed.. It did not went smooth and I couldn't print final version in time because i kept having issues with my printer...
Model came up nicely:

As plan B I made another model to make duct from sheet metal, but couldn't get aluminium sheet to make it...
So there came plan C to make the duct from salvage of failed prints of different iterations..

And it works!
I need to find logs of IAT before and after, it's just night and day.
also got washer fluid tank with two pumps and wired one of them to spray the intercooler via switch on the dash and 6 psi pressure-driven relay.
it sprays a bit too much, draining half of the tank in 10 min session, but end result is great.

regarding the situation with the diffs.. It appears that it was on this car from the very begining.. When I bought it, it was swapped with V2 STi engine, but gearbox was from early 2000s WRX... By the code it should have 4.44 ratio and viscous center..
Since i swapped in DCCD ceneter and installed MapDCCD I never actually tested the car on track and frankly never drove it hard on the street as well..
So when I got on the track, swithced on MapDCCD in agressive map, whenever I got any lock loud noises came from the transmission.. something was definately wrong.. So I jacked the car up, got it in first gear and tried to count revs of front and rear wheels on fully locked diff and it appears that fronts turn slower ((((
Probably old viscous center was blown long time ago and car was driving like this who knows how long..
It was effectively free diff with bias towards FWD due to higher reduction in front...
So, this trackday was a disappointment in a way, but still a big WIN in my books because car finally hit the track first time since 2015!!! )) That's great )
Need another rear diff now to match the front.. Suspension is also way too soft for these tires - without DCCD control i can't apply any throttle on corner exit - one wheel just spins..
Also I got really nice logs of brake pressure - it's really cool and gives nice insight on corner entry. Will try to write post about it soon.
there where couple of really nice cars on the track.. too bad I spent most of the time dealing with my problems, should have get more pics..



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Old 09-09-2019, 04:31 AM   #214
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nice updates. Saving for that vss info
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Old 09-10-2019, 12:48 AM   #215
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good stuff!
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Old 09-17-2019, 01:22 AM   #216
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Noob tuning question... What is the best safe way to check knock feedback of my ESL (stock based ECU).
Before increasing boost and getting my slightly retarded timing tables back I wanted to make sure that knock control features of my stock ECU are working correctly to keep is safe(ish).
Up until now i was running 0.9 bar boost with peaks around 1-1.1 bar plus quite rich fueling and knock event counter in all my logs was sitting on static number. although I can see it was changing between logs, but never during the logs. IAM always stays 16..
I have DIY det can in form of Bosch wideband knock sensor connected to my laptop in mic in, and I can hear different mechanical noises very clear, I listened couple of normal and knocking noise examples and what I got sounds similar to normal... I tried to increase the timing around 2500-3500 RPM in load area before boost comes up (up to 100kpa absolute press) and listen for knock in det cat, but I can't hear anything that sounds like knock, and ECU did not register anything either... At which level of load/RPM/ignition advance I definitely should get (SAFE ENOUGH!) knocking to confirm it is being detected in ECU?
Knock sensor is new 1-wire sensor that is correct type for my ECU, det can sensor is connected on the back of the block quite near to stock one...
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Old 09-27-2019, 09:57 AM   #217
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So, I did it.
Wisely decided not to go for Time attack event last Sunday, but went to practice on Saturday.
On Friday evening i managed to get to the friendly shop to change the diff. 4.444 ratio was correct and DCCD now not binding on the straights...
Managed to make 4 sessions with 3 of them mostly used for logging and optimizing fuel map, and on fourth one I finally tried to set the baseline time. Due to hot weather it was first fast lap out of the pits.. The result - 1:14.8 is whole two seconds more than my PB on narrower tyres (215 vs 235), but I made couple of mistakes and PB was in late October evening session with around 10 dec C colder ambient conditions. Looking at GPS logs of both runs, it's safe to say that car has very close pace and capable of doing 13.xx laps as is..
Unfortunately next day on time attack event I saw that to get to top 3 cars in my class I have to do something closer to 1:10, so still a lot of work ahead..
Those cars running 265 semi slicks and big turbos, but still... original plan was to use the driving skills, not muscle )))
By the way, got Greddy T518Z from a friend and sent it for rebuild.. Not sure when I will try to fit it on, current VF29 has some potential too, probably will try to find it.
Also, probably interior is coming out to rip all the speakers and audio wiring as well as electrical part of ABS. Thinking about leaving wheel sensors wiring to restore it and somehow use wheel speed sensors in future, but most of it needs to go.. Also need to remove sound insulation and seriously approach to baseline suspension setup.. I believe changing diff messed up my alignment, so it needs to be re-done anyways...
Some logged data from the day that I found interesting:
Log of my AFR.. I made some changes based on this, adding some fuel at to the bottom right..
each 24 units of load is roughly 100kpa, so 24 is atmospheric pressure, 48 is one bar of boost... Time to raise boost! )))


Next one is MAP and DCCD plots over Lat and Long position, gives you visual representation of boost and DCCD lock on the track. That MapDCCD is working hard!! Probably should tweak the map and remove lock on speed over 100 km/h.


TPS and RPM give rough idea of how gearing suits the track and when i'm able to open throttle.. Probably need to make some smart math channel with TPS, boost and RPM, will think about it..


This was my study of braking zone on big straight.. I thought that my heel-and-toe downshifts are not good enough and I unsettle the car during braking trying to blip the throttle.. Well.. accelerometer and brake pressure channels on bottom graphs are saying that it's ok... I just generally suck at braking, braking too early and not using brembos and tyres on their full potential...


And this is g-forces plot with TPS overlay on the left and my effort to map math channel that should represent total acceleration in m/s^2 on the right...


Looks nice and smart ))
Now I need to figure out how to use all this data to shave couple of seconds of my lap time ))

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Old 09-27-2019, 10:11 AM   #218
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all the data
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Old 09-27-2019, 10:50 AM   #219
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Them g-forces are sending you love <3
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Old 09-27-2019, 11:53 AM   #220
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Quote:
Originally Posted by bue car View Post
Them g-forces are sending you love <3
Wow! I can't unsee it now. ))))
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