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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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#2 · (Edited)
So, in 2014 my best time was 1:12.73 with following specs:

1997 Impreza STi Typre-R, Version 4
EJ20K engine, VF22 Turbo, stock STi Yellow injectors (I believe 440s), ESL-upgraded ECU running @1 bar boost
Stock V4 intercooler, stock full intake incl air box with air filter
Magnecor competition 8.5 mm spark plug wires
Redline 10W-40 fully synthetic oil
Unknown stainless steel exhaust manifold, 4-in-1 design, 3-inch turbo-back custom exhaust with 200 cpi sports cat
Whiteline roll center andjustment kit
Whiteline front 22mm and 24 mm rear sway bars set to max soft*
BC coilovers Type MH inverted type, pillowbal adjustible top mounts F and R, 5/4 kg/mm springs
Hardrace rear trailing arms and adjustible track arms (more camber adjustment) with hardened rubber.
ALL other rubber parts in suspension and engine/transmission mounting are replaced with STi Group N parts.
Coilovers set almost to max hard setup 27/30 - F and 25/30 R.*
Camber -2.0 F and -2.5 R
Stock GC8 STi brake setup with 4-pot front and 2-pot rear calipers, vented front and rear discs, EBC yellow stuff pads all around and new unbranded "performance" grooved brake discs
walbro 255 lph fuel pump with wrong in-tank fuel filter causing starvation in right turns with less than 3/4 fuel in tank and super-cool custom anti-surge tank which made problem even worse...**
Advan RG-like replica wheels (9kg) with Dunlop Direzza DZ03G (H1 compound) in stock size 215/45 R17. Slightly rubs inner fender in front due to less ride height .
Exterior - original V4 Type-R exterior, except for e-bay fiberglass JUN-replica front lip.
Stock STi V4 5-speed transmission with DCCD
Stock diff (R180) with LSD overhauled using original STi LSD overhaul kit*
Motul transmission oils where applicable
MapDCCD controller adding automatic center diff mode - great tool, really allows you to use AWD on GC8
RaceDAC data aquisition system allowing to record 8 analogue data channels and 2 digital channels, with built-in 3-axis G-sensor and supported by RaceChrono - great tool to measure and improve your performance.
VDO oil temp and oil pressure gauges mounted in original gauge pod
fuel pressure sensor connected to oil pressure gauge trough 2-way switch, also logged by RaceDAC.
All the rest is stock.
 
#4 ·
About white car. It's 1996 with stock EJ20G, wrx 5 spd tranny and R160 diff. Bought together with my friends for trackdays as joint project but finally ended up on my driveway after rest of participants lost interest or got their own cars.
in fact I was trying to sell it to get something n/a rwd for this season but offers were too low. These cars are quite cheap here, so after lots of time and effort invested in it I couldn't justify selling for price offered...

The plan:

Suspension
Swap coilovers, sway bars and rear arms from STi and putting stock STi psrts back on the black car.

Engine
Check ECU for compatibility and install ESL daughterboard for pre 96 cars
WTA intercooler - it's quite hot here so I thought that it might be useful. Also that's something I always wanted to do. I even got some bits like temperature controller. Thinking about frozenboost coolers, the only problem might be limited space on phase 1 engine. type 13 core will definately fit, but it's rated up to 350 h.p. which is not really far from oem setup. Even if I will drop this idea I will use controller for automatic intercooler water spray
Aircon will be removed for weight reduction with chargecooler radiator fitted instead of aircon one.


Interior
interior should be stock as per regulations, except for bucket seats, so I plan to get harness bar and driver bucket seat (I already have OMP harness installed)

Brakes
Car has yellowstuff pads. Will probably delete abs (not working anyway). Considered 4/2 pot swap, but not sure if it's worth it.
Possibly cooling ducts.

Wheels/tires
Same as in 2014.

Exterior
reverse scoop if get chargecooler installed
will remain without wing - imo only adds weight on this track
fog lights will be removed.

Electronics
Unfortunately no dccd here, will try to swap RaceDAC from black car ir get another one. Racing without datalogging is not that fun ;)

right now I'm trying to swap suspension and it appears to be a major challenge... progress post later...
and btw, first race is on Sunday :)
 
#6 ·
Well, I don't think it will be competitive in time attack then :)
I wanted to get mk3 toyota Mr2/MRS. I like tricky platforms and MR layout is one of the things I wanted to try...
There's something in underpowered cars when you can floor it throgh turns trying to keeping momentum and concentrating on steering. There is cool mx5 competition here, they have their own cup. But I can't fit in these cars :)
 
#8 · (Edited)
Thanks! Well, this is the only "big" track here in Cyprus, build with drift in mind, but it's great to have it! )
There is also one quite big cart track here, need to visit it sometimes, it used to held time attack events in the past...
Cyprus has great rallying history, it used to host WRC events in the past (only ERC now). Lots of cool gravel roads. Also there are a lot of competition in Hill climb championship, mountain roads are very nice here. I'd love to try it some day, but you really need a caged car, that's not for amateurs. You can spot some great cars there, some of them are also competing in Time attack events. If anything goes well, I will make some photos on Sunday.

So, back to topic. I wanted to swap all suspension bits from STi last Saturday... well, saying that I was too optimisstic is wrong. I failed. In fact on saturday I only managed to find nice looking turbo-back exhaust, bring it home and clean original STi suspension bits I had laying on the shelf for a while. I tried to catch up on Sunday, but... I couldn't break loose subframe bolts on track arms and knuckle bolts of trailing arms of the white car. I worked untill 3 a.m. the day befor yesterday and currently I only managed to remove rear coilover struts and sway bar from STi and put original bits back

This is my driveway where I work on both cars (they parked back-to-back currently)


[CENSORED] bolts...


Coilovers vs. OEM struts and springs.


Catch of the day


So, my plans changed… I have about 6-9 hours left to work on the car. Being realistic I dropped the idea of changing arms. Plans updated.

Today:
Front coilovers and sway bar are getting removed off STi. Need to put stock parts on STi not to leave car disassembled. If I have time - rear coilovers and sway bar will be installed on white car

Tomorrow:
everything goes on white car. Remaining struts, sway bar(s), exhaust, intercooler...

Saturday:
Wheel allignment, finishing works…

Wait, did I said “intercooler”? Yes, I bought new intercooler!

TaDaaa!


Yes, in this journal new parts may look like this…
I removed my intercooler to unbolt one of downpipe nuts, and I found that blow-off flange was broken by someone who did this before.. I really wounder how it held any boost pressure at all. I went looking for replacement and found this one. It’s same as mine but In better condition anyway. [/FONT]old one:

Bad photo, but it snapped right after 90 deg bend...

The tank will be used as expansion tank for chargecooler setup or (most lkely) for intercooler water spray system. It was the only one they had complete with the pump for the moment...
 
#9 ·
managed to get front suspension components removed
New ride height


Just before I got coilovers I thought that stock suspension is fine for me, but I wanted more camber. So I got mooresport top mounts. These are great parts, but I wasn't aware that I won't be able to use them with stock springs because they add about 30 mm of ride height. After I got coilovers they came with their own top mounts so these left attached to original struts. Wanted to put my my Group N top mounts but they are currently installed on white car and I had no time for swaping it.

It looks like my R160 diff might have limited slip in it. it was painted black by someone, but under the paint I found badge with letters "TR". Any ideas what it might mean?



So, for this nigt I have big plans...
Swap coilovers into the white car, swap sway bars, install exhaust which I haven't test fitted yet (but it was removed from same car, so hope it will be fine)

Need to clean coilovers before intallation and somehow make a guess on ride height.. After making allignment it cannot be changed. So basically I have one shot. Probably take measurements on current settings and add 5-10 mm... STi was sitting quite low, but it had ALK installed. I plan to get ALK for white car as well, so it will be interesting how it's going to affect cap times ))

Asked in some shops about conerweighting the car, but it seems that "ain't nobody got time for that!"
need to find somebody with the scales...

All mounting hardware and subframe/diff bushes look terrible on white car, probably will order all suspension/subframe bolts and bushes. Group N kit was kind of expensive... Anyone can advice cost effective bush kit for track car?

P.S. I like my storage room )
 
#10 ·
Man, I just read through your whole journal and that's some awesome stuff! Love that you have kept it simple but yet your still making gains/records at the track. What is the track name?

-Ben
 
#13 · (Edited)
Finally had some to write...
I made it to the event, that's good news. Now about the rest...
I started working on car late in the evning on Friday. The plan was to drop everything in white car to get it running, then have a sleep few hours and get car alligned at 11:00 a.m. on Saturday and wash the car before event.
In the beginning it was nice and smooth. I was enjoying working on the car and decided to clean coilovers before installing them. Started with fronts.
From this

To this

I like shiny parts. But they should be cost effective :)
So, we came to a funny part. It was around 3:00 a.m. when I was putting these on the car and managed to do something stupid. I unbolted old strut on the right and knuckle went down. First thing I thought was that I need to change bushings because on black car I had to loosen arm bolts to move them and allow stock struts to move in.
Then I realised that it moved too far down and too easy - I pulled inner cv joint internals out of its housing. It wasn't in my plans and I never worked with cv joints before, so I spent some time trying yo get it back in the housing. I managed to do that but some balls fell out, so it wasn't working properly.
30 minutes and couple of youtube videos later we met for the first time

It didn't took long until this

Note the ugly downpipe.
I found all the parts inside the boot. Locking ring looked like it was chewed by something, so I thought that this is not yhe first time this happened with this cv joint.
I managed to reuse both clamps which was critical since I had no spares.
So then I just started to work in autopilot mode just ripping all parts out an throwing new ones in. Not much photos of the rest of process since I was tired andhadgreasy hands.
I managed to put all the struts, sway bars, exhaust, intercooleer on by the morning and get to the wheel alignment.
Final photo of (semi)finished product


Small teaser of next post
 
#14 · (Edited)
So, event went pretty good. Nothing broke down, car was fine. After practice lap had to remove inner fender guards snd pull front feders a bit. Competition this year will be tough. In my old S4 class (stock awd) two cars got into 1:14.xx, that's great.


Also, after making wheel allignment I tried to discover mysterious noise in rear left corner and found dead coilover damper. Had to replace rear coilovers with old shocks, destroying rear allignment, of course.

Really liked competition in my class:
ZR1, really rare car for Cyprus. 2.0l cars are alreay quite expensive in taxes (road tax is calculated from displacement) I thnk it's annual toad tax is about the same as price of my car.

I'm pretty sure that this car is the same one Iast year. I had beaten his time by few hundreds of second with my record time on last event (1:12.73). His best time on single event he took part in was 1:12,78 if I'm not mistsken. I'm pretty sure he did that race just for fun, on oem tyres and wasn't really competing, just testing what car can do. Then it used to be yellow on chrome wheels, now car is black on black wheels, has michelin cup tyres, aggressive allignment, maybe something else. Anyway, it's time now was 1:09.36. I think it might remain the record for our class in 2015 because driver of this beast is participating in serious motorsport events outside of Cyprus and really knows how to drive :)
I also don't expect to see it in competition again this year, again, it was for fun, I think. In fact he left after first session.


Btw, his tyres width is 315, and max width as per our class regulation is 285. But everybody liked this car, so... who needs these regulations anyway? :)

M3 CSL


Original CSL in perfect condition. Champion in 2wd class in previous years. Wasn't participating last year though and this was his first race on semi slicks. On slicks this car used to run low 1:09.xx laps, on street legal semis he did 1:12.1 this time

Subaru


Black STi on photo ran 1:14.xx on shitty tyres, his set of hankooks was late for the event... Cyprus is kind of small and most of the time if you looking for something specific you have to order stuff an wait for delivery... Will be much faster on proper tyres, I suppose...


Car of last year's champion, also a hawkeye STi is in rebuild now and probably be ready by next event. Last year he ran low 1:11.xx

Race classes

Always loved RX-7s


Has LS inside... kind of disappointed, i'd loved to see rotary power.

Monster EVO3 did 1:04.5 on practice day before the event




In top class race turned out to be a battle of old school vs new technology. Technology won by 0.04 sec...

red evo set fastest time in session one, but misshifted and overreved engine damaging valvetrain. It was fixable but they had no tools to fix it. In second session evo 9 had beten his time:


Now about disappoiniting moments :). My time in first session was 1:16.

engine wasnt pulling as it expected. I was hoping that 3 in exhaust will add punch a bit or at least reduce lag, but I wounder if it in fact it become worse for some reason.
then I reset and did fast re-learn procedure to ecu and did 1:15.6 in second session. Had one (my biggest ever) off and managed to set my best time on next lap.
short video of these two laps:


More pics here
https://www.facebook.com/evgenios.n...10152730651212934.1073741875.753197933&type=3

Gave my blown dampers to local rally team, they promised to show them to their trusted suspension specialist who might be able to rebuild them. Hope it will be fixable, I'm not really excited to pay BC for replacement damper.. They carhged too much...

If I want car to be competitive I have to get it to 1:11.xx...
The plan remains: weight reduction, get suspension fixed and engine... neeed more power... any ideas what to do with ej20g on budget? I have spare ej20k with vf24 turbo, yellow injectors and snapped valve. Will it help?

I'm quite sure that I can't get into 11.xx without wider tyres.. Noone else uses 215s like me.. But I'm not going to buy anything untill my Dunlops last. I think they can handle at least two more events...
Wider tyres will mean new rims and probably flares..
 
#15 ·
And brakes.. Brakes feel really bad.. With 205 AD08 tyres yellowstuff pads were enough, with semislicks it's really a disaster... I can lock the wheels, but I don't have perseision in control and they fade after 3-4 laps.
Will go for 4/2 pot setup probably.
Does Brembo setup makes sense? Alwayts thought that it's an overkill for GC8...
 
#16 ·
I think you would like the brembos, everyone I know with a GC8 who has fitted them has been impressed with the performance improvement.
I use pagid yellow (RS29) and they are an aggressive track pad on a gc8. The pagid blue RS4-2 is a good track pad that can also be used on the road.
 
#17 ·
Thank you! my coupe had 4/2 pot setup and it was fine with my 213/45 r17 dunlop semislicks, but if go for more grip/wider tires it might not be enough. Also, I remember ride in friend's evo 8, it felt heavy but I was really impressed with braking performance. They were more percise and I could brake later. So, more is better, unless we are talking about weight :)))
Will see what will be easier to source locally. Need to find time to analyse swap details in both cases, costs, etc...

Good news, my coilover damper was rebuilt in local rally suspension shop. By time it took looks like it was easy job for them. I hope they foun common parts inside... Price is 20% less from what bc charged for new damper without shipping. We'll see how long it will last, but I'm optimistic about it.
 
#19 ·
Thinking about what to do next... EJ20G with it's unique manifold and laggy turbo is a problem. For sure it's not competitive in my class, but I'm not ready to build an engine this year. I thought that putting ESL ECU might help, but after I checked their pricing I really doubt that expected hp gain on otherwise stock engine will justify the costs. On my black car I have ECU, but it's V4. Then this idea came to me. I have old engine with snapped valve. Basically it's complete with everything required for v2->v4 swap. Manifold with all sensors, throttlebody, injectors, vf28 turbo.
Pros: I can re-use better turbo, my ESL ECU and will have more intercooler options.
Cons: need to find V4 harness, it's gonna be wiring nightmare because some things will be custom, it's basically the same (peak) hp, I never done anything like that before.
I have one month till next event. So, what do you think?
 
#23 ·
Pulled ECU out yesterday, it's Z5.
Z5 ECU code = 380cc injectors, 260ps TD05H turbo
Z5 - 1995/1996 WRX-RA - 12.57PSI (0.9BAR)

ECU has bridge for expansion chip, so ESL board can be installed easily. Not sure that it's worth it though. One more argument to support V4 swap is that I have datalogger connected to patch harness, so bacisally this way I'm saving myself from doing this job once again in this car.
 
#25 · (Edited)
It's been a while since last post... Next race is in 9 days, so decided to sum up where we are to put thoughts together.
Couldn't manage get some time to work on the cars, but got some parts ordered and delivered.

Brakes.
Now basically I have everything to swap brembos in, but still waiting for flare tool and other supplies to make custom brake hard lines. Wilwood proportioning valve arrived along with remote knob kit. In fact these parts are not supposed to work together, but i've seen it was done before, so I hope I'll get functional remote brake bias control. Also I got 1600 psi pressure sensor to have brakinkg force in logs rather than just on/off value.
Suspension
I decided to not spend more money on suspension and just swapped whiteline roll center adjustment kit from black car. It doesn't need it with stock ride height anyway. will also try to rotate mounting brackets on front arms rear bushes aka free caster mod. Need to finish with rear arms swap, will try to remove adjustable arms from the black car on this weekend. Kind of dropped the idea to remove rear arms from the white car myself, bolts are just dead stuck. Hope that I will be able to remove arms from black car though and hand the car to some shop next week. Rear coilovers are rebuild and ready to be installed, so at this point I think my suspension will be finished.
Power and weight.
Patch harness is arrived. Now I can start merging 3-plug ECU and 4-plug harness to work together. Still need to pick up my old engine from mechanic to get turbo, injectors and other bits inspected, cleaned and tested. Then fun part will begin.
Got myself a bucket seat. Old steel framed sparco model with one nasty hole on the side :) It came with modified rail and it's nice that it will fit bolt-on, although i don't like the way it's done. Anyway, gave it a good clean, will do for now. Also with the seat I got rear trunk with V3 spoiler and fog light covers fro the front bumper (weight reduction begins! :)). Decided to not use spoiler though - it weights too much to justify the installation, in fact I don't believe that any legal areo mods will help in my class at my speeds.

Talking about the weight I was kind of shocked when I saw brembo brake disks in person. They are really huge comparing with my current ones. I think it will have big impact on acceleration since they all are rotating masses that need to be accelerated each time. So It would be fun to see wether increase in braking perceision and performance can overcome increase in weight and rotating masses and will i manage to improve track time with brembo mod on it's own.
It's not necessary to participate in whole event to find out that though, so I'm not sure if it's worth going to the next event. Even if I manage to get brakes done, without power and weight reduction there's not much sense wasting tyres and time spending whole day on the track to have only two race sessions... So I think I'll opt for dropping next event, finishing brakes and suspension in their planned configuration without a hurry and then testing car when it'll be ready.
 
#26 ·
Next race is in two weeks, I'm totally off the schedule and have no time for the car :(
Last sunday managed to get adjustible rear arms removed rom the black car, it now has completely sock suspension. Passed MOT (bi-annual roadworthiness inspection) that expired in February and drove the car a bit. So nice!

Other nasty problem I managed to solve was removind db-killer from exhaust. that was a challenge.

After I failed again removing rear arms from the track car, gave up on this and took car to friend's garage.. Picked it up today, now suspension is ready for race.

Had aircon system discharged, can remove it now.
Next on the list are brakes. Tried practicing with flare tool, first flare was great

next one - not so good...

Thinking about placement of bias valve, piping... It's tricky since I plan some major changes in the engine bay. Luckily I have EJ20K under black car's bonnet for reference.

Then it will be time for adding power. Thinking about two intercooler options - water to air setup or front mount with rotated intake.
Front mount looks pretty straightforward but I don't like frontmounts on subaru. So if I will go for it, I'll have get manifold rotated for shorter intake length. Another thing that I always wanted to do is water to air system with heat exchanger in stock i/c location. It will add some weight but I like the concept and short intake length. Also it's better efficiency may help in hot Cyprus weather while removing hood scoop might improve flow throgh radiators.

Got DZ03G Dunlops ordered in 235/45 R17. A bit odd size for GC8 and might require arches modification, but they don't make other 235 sizes and I really liked DZ03G performance.
 
#27 ·
If your able to do a little bit of custom fabrication you could do your own v-mount radiator/intercooler setup, or the water to air setup would work as well and could be very useful for time attack since you could install an icebox if heat is an issue. you could've probably gone up to a 245 tire without much work to not have it rub, if your rubbing with that tire, your probably too low and or too soft for the factory suspension geometry to be useful.

Are you still on stock header? An equal length one should help with spool up and response on the turbo a little bit.
 
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