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Homebuilt GC8 for Time Attack

63K views 269 replies 24 participants last post by  bue car 
#1 · (Edited)
Hi!
Always wanted to start a build thread but never had enough time or interesting things to write about. Now looking back I thought that I have something to share, some ideas for this season in local racing series, and it will be good to start a journal just for my own record and as a motivation to move forward.

Short background story.

It all started in 2013, by that time I already owned Impreza STi type-R for couple of years and found myself a bit confused with it. Here I need to mention that I live in Cyprus. It's rather small island in Mediterranean Sea :) Cars are RHD here and before country joined EU lots of JDM cars were imported. So, sometimes you can spot quite rare japaneese cars here. When I saw my Type-R I was amazed because in Europe you rarely could see 2-door Impreza. At that point I wasn't even aware of existence of these models, I thought that type-R sticker is just a bad joke of some honda fan. Also, I wasn't big subaru fan at that time. Imprezas were just much cheaper than similar vintage EVOs.
So, after owning this car for some time I was confused. It was old (1997), poor market value, not very reliable but eating money really fast. Insurance was expensive, fuel costs were crazy... Then I ran into head gasket problem while trying to sort out mess with vac routing. I had engine rebuilt only to get a dropped valve 6 month later (the next week after I got car mapped after prolonged break-in period). So, I just put in used engine from salvage yard and thought "what to do next?"
I wanted to mod the car but I kept questioning myself, why do I need to do that? Well, at that point I ran onto local time attack series and it was perfect. Owning this car become full of sense in one moment and participation in "Street" class with strict regulations promised to save me from expensive mods. Basically I had to keep engine stock and no lightweight parts were allowed, so I could only get suspension. I was happy with this because I wasn't excited in modifying good and quite a rare car extensively. I even bought DZ03G tyres in size that fits without any modifications like arches rolling.
On local track where all time attack events are held I got lap times around 1:18 after I changed some shitty lowering springs for stock sti ones and I managed to get nto 1:15.xx on the first event I took part with coilovers and group N bush kit installed. It was mid-season 2013 and I even managed to win that event in my class although I knew that there's one EVO 6 lapping the track in low 1:14.xx, he just wasn't taking part in that event.

Then my Dunlops arrived. That was the day when I realized that tires are probably the most important single thing that will define your lap time. This time fast EVO came to the event and did low 1:14.xx lap again. I managed get to 1:13.xx. (he had same tires btw ;)) It was a shock, for me in the first place. The next event was on the next day and some guys came to check the car asking if turbo was stock and so on, because such time for street class car was rather surprising :)

Long story short, this car took me to second place overall in 2013, and win in 2014 in AWD (Unmodified) Street class. The car won every race it participated in. In 2014 I managed to set fastest unmodified street awd class time ever and if I recall it right - second fastest time among all street cars time loosing more than 0.5 sec to GDB from senior "Street Modied" class (engine mods allowed + removing aircon and stuff) and winning just 0.03 sec from Corvette ZR-1 in third place.

This is how it looks like




And this is one of the most fun videos - free ptactice session before final 2014 event, in wet

2014 Time Attack 5 Practice:


At the end of 2014 season I decided that keeping a track dedicated car in good looking condition capable for driving around city is hard, expensive and not worth it. I promised myself to stop tearing good rare car in competition.

So, this journal will be about this one:


I don't plan anything extraordinary, it's not going to be record breaking project, rather story full of pain and suffering about fixing old cars :)
hope you like it.
 

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#189 ·
Stock pan for now. It wasn't an issue on 215 tyres. Not saying that I'm not worried about that, but I've seen cars faster than mine running stock sump as well.
This is one of there reasons I want standalone ECU to monitor things like oil pressure.
 
#191 · (Edited)
Yeah, -2.5 front and rears is what worked for me before, that's why I decided to start from these as base line... wider tires with same roll stiffness might call for more camber, but with good caster angles I have now car is gaining more camber when steering is off center then before. We'll have to wait for trackday to find out for sure..
In the meantime I started removing dash to delete remains of AC system and sort out the wiring, and my worse forecasts came true.. I managed to spend only several hours on Saturday with the car and now it looks like this:



And pic under the dash shows how things are done there, I haven't done anything to make it look worse.... yet. ))

Instrument cluster is what made me stuck right now... Car has cable speedo and it seems that it needs to be disconnected from gearbox first to get dash out, which called for removing intercooler and some other stuff that was in the way..
I have electronic VSS laying around, and V4 ECU will be happy with it, I believe, but then I'll have no speedo reading on my V2 dash.. Anyway, I couldn't remove dash on Saturday and on Sunday some other things got priority, so car left undrivable until next weekend.. Hopefully... Because the more time passes from disassembly, the more time it usually takes me to put it back together. And also it means more unnecessary parts in the end :naughty:
Also I wanted to put steering angle sensor for datalogging somewhere and it seems to be more difficult than I expected. I ordered some generic 360 deg hall sensor with 0-5v output, so I need to connect it to steering shaft somehow with 2.5:1 reduction or whatever lock-to-lock turns my rack has now. Any ideas?
 
#194 ·
I remember that cable should pop out somewhere... Dash just doesn't move to get any access behind it and I didn't wanted to apply force to it... I planned to check manual before I approach it next time.
Regarding electronic VSS, it'll probably will go in together with standalone. someday :)
 
#195 · (Edited)
Had a chance to spend several hours working on a car yesterday.
removed the dash to get better access to wiring...
Frankly, it was scary to touch that mess ))

Don't have "after" pic bud dash is installed and all junction blocks and holders are now in their places and everything is much cleaner now...
also removed steering column switches to clean them from 20+ years of dust and install steering position sensor somehow. There seems to be plenty of space under the housing:

Can someone confirm me that these keys on the ring are just interface for airbag spring ring thing?

This is my understanding of their purpose since I can't see any way they are used in my current setup (have no airbag)
the idea is to design and 3d print this ring with toothed wheel on the outside for small timing belt going to the sensor...

Also I confirmed that speed sensor cable just pops out from the cluster, but also it consists of two parts - lower short piece bolted to the gearbox and upper part going in the dash. Connection between them is easy spring lock and it was very easy to disconnect to get some extra cable length for removing the cluster with cable still connected...
 
#197 ·
From what I can see, keys that cancel turn signals are the ones that are a bit deeper in the assembly on this ring. You can even see spots where they are a bit worn working against this white piece on the left.
Also these two keys I'm asking about are different in size like there should be something that you only can install one way, with respective slots in it... It really looks just like a spacer about 10mm deep... So I think it's for airbag ring, as well as many unused screw spots on the front face of the assembly. It even seems to be able to accommodate different styles of it according to number and location of those screw holes...
 
#198 ·
Lesson learned today, never use cheap swivel AN fittings )
Car was parked for a while, I was testing some electrical stuff and heard sound of a leaking fluid. Turns out there's a river of fuel flowing on top of the engine from a leaky swivel hose. Not from threads or hose connection, but from actual factory swivel joint...
It was a no-name one that I got as part of ebay billet fuel rail kit.. I was lucky with chinesium stuff before but it seems that I might be running out of that luck...
All my AN fuel hoses are out and all three similar fittings are going to be replaced. I wanted to go for non-swivel ones, but local shop got only the ones of exactly the same design. At least quality seems to be much better.. No time to change the design now, next time attack event is this Sunday and I still have a lot of work to do with the wiring...
The one that leaked held up 6 months (with barely 100 km/60 miles driven)... Probably it would have started leaking earlier if I drove the car more...
I don't know when I'm going to start it without fire extinguisher in the other hand though... It's just fuel for nightmares... Literally :)
 
#203 · (Edited)
Well )
Car is running. Not finished everything that I wanted, but I drives and functions )
Now has two fan override switches for both fan speeds, remote logger "on" switch wideband and EGT gauges installed, MapDCCD and wiring mess behind pretty nice center console pannel )))
Bad thing is I couldn't finish it on time to get to start of the event, and when I drove there to catch at lease second session, car died on highway with no fuel pressure... I thought that it was fuel pump and called for toe truck only to find out later in the evening that I ran out of fuel :(

That happened because I still didn't managed to fix my temp and fuel gauges after ECU swap and I was 100% sure that I filled it two month ago. with only about 60 miles max driven since then, I was sure that it was not an issue... Also I had new fuel pump laying around and replacement was planned for a while, so when car died I was hooked on idea that it finally died... Also didn't helped that OEM pump is very quiet, so when I tested it on highway i was seeing 12v on a plug but couldn't hear it over highway noise... And lack of sleep for past few days was not helping either.
Well... Sort of "meh" story... Happy that i's finally running and running well... Definitely going to the racing event in untested car that just was started for the first time hour ago was not a great idea... Everything I done works... surprisingly... But that was a stupid mistake not to fill the car before the trip. After all the effort put in the car for the last few days and knowing that gauge is not working...
 
#205 ·
Good advice. I have only small one, but still I'll probably fill it up and keep with me on trips like that... But this time car was stuffed with tools and supplies since I was working on my apartment's parking lot and used car as a storage for a while :))
So when I decided I was ready to go - fastest and safest way was to gather stuff around, put it in the car and go )))
The major contributor to this situation except for sleep deprivation was the fact that I usually keep records of all fuel stops in app on my smartphone. It shows real fuel average, running costs, nice graphs of odo readings over time... I just save mileage, price and total cost while pump is running..
And this time before I left I checked this log and I saw full tank filled in March which seems to be right. I just didn't noticed that it was march 2015)))) and my actual recent fill-up on this car (not included in my log properly) was for like 10-15 liters because I didn't wanted full tank because I PLANNED TO REPLACE FUEL PUMP ))))))))
I remembered it all clearly after I had some sleep yesterday )))
 
#206 ·
I did the same thing to myself the other day. I'd been driving around tuning and *did* have a working fuel gauge, but it was behind the tablet (showing sensor readouts) mounted in front of my stock gauge cluster. The car went lean on the freeway and I was like "Well, I guess I killed it. FML." Only minutes later did I realize I'd just let it run dry about 2 miles past a gas station. I did not feel clever.
 
#207 ·
Well, it turns out I had working fuel gauge as well. How? I just filled it up and it showed up ))) All this time... That hits hard ))) what a shame...
Aaanyway... At least my temp stock gauge IS properly messed up! There's the wire going from the dash to ECU sensors ground that has 12v, and disconnecting it allows car to run and see all the sensors, but that stupid gauge is not working... need to check diagrams and see what it wants...

Another issue with my ECU swap that I found out reviewing logs is that ECU can't see signal from VSS2. It seems from manuals that my V4 ECU wants to see 12V square wave from sensor on gearbox and sends out signal to the dash, but my car's dash being V2 receives speed signal via cable from gearbox and sends square wave to ECU which I thought I'll just use instead of gearbox signal, but.. It turned out that it's only 5v and ECU is not happy. I have proper gearbox sensor but in this case I install it, I will loose speed on the dash so I opted to try to get a workaround and amplify voltage using optocoupler. We'll see how it will turn out when parts arrive.
Other than that, I try to drive the car to develop fuel map but living close to office doesn't help much. Also got a bit frustrated by some of the settings of my ESL ECU but it seems to be solved, so now I mostly need to spend some time mapping it. At least car is running...
Another disappointment was being unable to log my Innovate EGT gauge signal as I planned. Don't know if I got wrong version of the gauge or they all like that but it seems that it only can be logged via serial in their software which I don't like and never used except for setting up the gauges... hopefully I can figure out the way to integrate it in CAN stream later on with proper ECU. Still will require some adapters and expensive stuff...

On mechanical side of things, car probably needs to be raised a bit and front wheel arches need to be rolled because left wheel catches on the inner edge when loaded in turns and tries to rip it out... Seat is waiting to be installed - need to find a welder to modify the adapter frame. Installed quick release on front bumper after seeing it done on one of the cars here and it works great!
Can't wait to test it on the track!
 
#209 · (Edited)
Did you ever had this srange thing when car fixed itself? A lot of stuff happened recently and if I was keeping up with this journal, it could probably be a couple of pages of self-contradictory posts.
So, here you'll only get end result as it is now. Although I'm not sure that there will not be any new findings that will completely change my perception of stuff happening.
So… I was trying to tune the car and it all was nice except when I hit throttle fast to WOT it had wild misfires and was looking kind of flooded (to me). First AFRs were going down while car was loosing all the power but slowly developing some boost. At the same time rpms were at the same level or even slightly decreasing and AFRs jumped to 15-16 which I considered being due to misfiring…Since my ESL ECU has quite a limited number of tables available compared to full standalone, after a post on UK forum where most of the users of this ECU are and quick chat with pro guy who tuned my other car on this ECU few years ago, I came to the conclusion that those 850cc injectors are just too big for this ECU to handle without being able to tune tip-in throttle, dead times etc.
I managed to revive my old 440s… one of them appeared to be stuck even after cleaning so I had do some extra DIY efforts to get it working:

After confirming that all injectors are working I installed them and for some time it seemed that everything was fine, problems solved…
But wait, there's more! Working further on new fuel map with smaller injectors I kind of found the limit where I couldn't get more fuel on higher loads, so I finally decided to finish long overdue stuff with some electrical gremlins and extra sensors for datalogging.
I installed and wired to datalogger fuel pressure and brake pressure sensors.
Remember that stuff I wrote that VSS square wave was wrong? Don't know where I got that, both ECUs need 5v signal, but!!.... before I found that I made small transistor circuit that provided that 12v square wave to ECU and guess what? It didn't start with it.. investigating further I found out that it's not 5v square wave that ECU needs, vss2 signal it's rather a switched ground that pulls down 5v signal that comes from ECU. Figuring that out I checked dash, confirmed that built in VSS does just that and returned all my custom wiring back to starting position. and it worked! Miracle. Also, that one ground wire from instrument cluster that I had to disconnect from harness to get car running which resulted in temp gauge not working - I checked all respective diagrams, confirmed that it has to be there, plugged it in and everything just works! What was the problem before - who knows…
Anyway. I took car for test drive and what I saw was this:

Basically, my fuel pump failed to provide any pressure above 2.5 bar in fuel rail during moderate and high loads...
Lots of swearing and one new wallbro fuel pump later:

I know, I should have done this from the very start… that was really stupid… my bad.
So yesterday I was thinking that my fueling issue was due to bad fuel pump from the very start, so I swapped back 850cc injectors and it seems fine. Fuel map is still rough, but the main issue I had is not there anymore, so I'm keeping 850s and working on further development of fuel map for this setup.
Together with this finding I kind of noticed that my intercooler is not working at all. IAT increases from ambient to 50..60 deg C (around 140 F) during one 3rd or 4th gear pull… and that even during night runs, can't imagine what it will be on a hot day. That means pulling like 6 deg of timing, so not good… I believe that's because I had to remove intercooler shroud from the scoop on the bonnet because I installed larger ver4 intercooler and it interfered. Now I'm working on custom solution to seal airflow from scoop to the intercooler. I'll post the results when I have something.
 
#221 ·
Well, It didn't last long though.. Was too good to be true..
Found a leak from power steering connection on the rail...
A made 6AN PTFE hose for high pressure line and thinking that aluminium 120 degree fitting might be a problem... I already had scary experience with cheap(er) swivel AN fitting in my fuel system, but this one I bought after specifically asking seller about using it for power steering..
Wanted to go for steel fittings, but couldn't find 120 degrees one at the time...
Still need to confirm that seal of the swivel connection is the problem, but that's my thoughts for now...
Anyone knows where to get 120 degree steel non-swivel ptfe line hose end?
 
#213 · (Edited)
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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