Subaru Impreza GC8 & RS Forum & Community banner

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.
 

Attachments

See less See more
1 5
#163 · (Edited)
Updates!
good news and bad news.
Bad news - car's not running yet.
Good news - fixed several problems and managed to limit further scope to fuel issues.

First. If you dealing with early COP cars make sure that you remember that ignition channels in ECU pinout are numbered by firing order, not cylinder numbers!!! With this in mind, coils on the schemes are numbered by Cyl number, because why not?
Anyway... My fault. Checked numbers of connectors on the diagram and it's quite obvious which pin is which cyl...
Second - with any car make sure that after trying to diagnose power distribution and inspecting fuses condition you actually put all the fuses back before trying to start the car. Not an easy thing to do, I understand, especially if you working mostly at late nights and occasionally leave the car in the middle of something for a few days...
Spark check was a success, we have a spark. After that I tried to start the car on brake cleaner and it fired up immediately! Oil pressure is fine, so I decided to drain old fuel... Drained it all until pump started to work dry, added 10l of fresh fuel, put everything together and decided to try starting it next morning because it was 2 AM and car has no exhaust after turbo...
Today before leaving to office I tried to start in but unfortunately nothing happened... Still cranking and no starting..

So plan for today is injectors!! They are yellow STi 440s. original and old. They were cleaned and flow tested, but it was in 2015... will try grounding them at ECU checking wiring and operation at the same time by looking at pressure in the rails... My friend has some 800cc ones, maybe worth swapping them in. After making sure that stock ECU survived my patch harness I swapped it with ESL one, so I can change anything now..
Managed to log the car during cranking - log has good TPS, inj pulse, IAC signal, RPMs are 175, volts are around 10 from my new lithium battery... All looks fine (to me) except for MAP which is not changing for some reason.. anyway, V4 and v2 MAP have different scales and should be not necessary for the start.. Need to disconnect it at all next time...
 
#165 ·
Quick update - all four injectors were stuck completely, swapped them with old 380cc from V2 manifold and car started up.
I recalibrated map sensor and IAT, all work fine although IAT is not used in the tune yet.
Only issues I see now is idle problem - rpm cange up and down in quick bursts, sound like car gas rotational idle :) if I disconnect idle control valve it goes away. Also turbo sounds funny. It's very loud and sound comes somewhere from downpipe. It's distinctive whining turbo sound like car has open turbo exhaust, and it increases on any slight rpm increase from idle. I wonder if turbo actually got damaged in that valve drop incident...
Looking forward to road test soon...
 
#166 ·
So, the car successfully made it to new garage location. I thought that I fixed idle issue by adjusting TPS a bit, but issue came back again as soon as I took off from my old house... Didn't have time to stop and fix it, so I drove like that with idle at 2000RPM at traffic lights )))
It was a bit of risky because car was fully loaded with spare parts and garage stuff for the move, there was literally zero free space inside and in the trunk, but previously I only drove it like around the block in residental area... Anyways, the drive was pretty short and car made it!
It needs tune because now it runs crazy rich, but I had no time for further tweaks.. most likely it will be left as is until beginning of 2019 when i'll start preparing it for new season..
 
#168 ·
Working on the car every Saturday for about 4-5 hours... not enough space in my garage for all my stuff. Every time its a challenge should I actually do anything on the car or try to organize things around...
Getting more time to work is nearly impossible because my garage is at the property that closes after 3 p.m. on Saturday till Monday and during the week I'm busy..

I managed to figure out couple of issues with ECU and wiring.. Got to figure it out by trial and error, not the best way.. Somehow my IAC valve's "open" and "close" wires ended up being switched over. Can't understand how it happened because these two pins are the same on V2 and V4 ECU.. probably got them wrong while merging engine harness connector.. Anyway - i swapped them over at ECU plug and now car idles fine.

Also it seems that TPS wants to be in some specific range on idle so car can run happy. Trying to figure out all ESL ECU settings, adjust fuel pressure and so on... right now car woks great fully warmed up. Definitely trying to figure out this stuff without any prior experience and on the engine that never worked in this configuration is not the best way to go...

While I was trying to figure out ECU, car started to leak coolant and oil...

Coolant leak was due to a loose clamp on heat exchanger - easy fix, but oil leak seems to be the cover on the back of the engine... So it means the gearbox need to come out. bad news, probably will take the car to a shop for that, because in my garage it will be quite a hard thing to do...

New flywheel bolts and other parts already arrived this week to do all seals and covers on the back of the engine, but I want to do whatever I can myself to limit work scope for the shop to minimum..

And for now there are quite a lot on "to do" list:
- oil pressure sensor wire got burned on the exhaust and shorted;
- brakes need bleeding;
- BC inverted coilovers need to be re-greased and serviced;
- new fuel pump install;
- new 850 cc phase 2 injectors are waiting for adapters to be installed;
- GD bucket seat base needs modification to GC floor;
- clean up wiring mess after troubleshooting;
- wheel alignment;
- ECU tune,
- MOT (road-worthiness test to be able to drive it on the street)

these are major tasks without even touching anything cosmetic and lots of misc stuff... But it's moving forward :)

On add a bit of positive stuff - I went to a trackday with MR2 and had some proper fun :) Trying not to forget how to drive.
There was nice variety of cars there including including this drift GC8 with S62 engine:

And this properly prepared hawkeye:
 
#174 ·
Thank you!

The lip is cheap fiberglass replica from JUN item, I belive. It just so happened that it was on my black car before. And I really like it in black :))
Painted it back in 2013 with rattle can, a bit closer it looks terrible in fact )) Whole car is rough and looks quite bad (no rust though), needs complete paint job probably. But it's not on my priority for now. In fact, I'm really enjoying not caring about it that much for some weird reason, while with my other cars noticing new scratches, paint chips and other stuff makes me sad ))))

Car is off to a friendly shop for gearbox removal, engine rear seal replacement and DCCD central diff install.
then I still need to tune it a bit, sort out wiring in general, make switch panel where stereo used to be, wire in DCCD controller and datalogger, align it and put new tyres on.. And then we can start making benchmark laps for new configuration )))

By the way, tried some 17x8 wheels with 255/40 R17 hankooks..




Considering that car is not aligned yet and more camber is probably possible, it looks doable.. although I'm not sure if I'll need all that camber that might be required to fit those..
 
#179 · (Edited)
And she's ready!

Rears look OK-ish..

Fronts show some signs of rubbing after drive home (this corner on photo is a bit compressed)


Car needs alignment, maybe more camber will be added, ride height may increase a bit when I'll check available suspension travel as it is now.. And frankly it might need stiffer springs, because I have big hopes on these tyres and 5/4 kg springs were on soft side even for 215s...
But! Car drives and makes some great turbo sounds, need to make a video ASAP )))
Frankly was a bit disappointed with ESL. It definitely may be tuned with OEM drivability and good power, but I understood that I need something else. It'll probably end up on my black Type-R, and for track car I want modern standalone with array of external sensors on CAN network, CAN switch pannel, safeguard strategies, datalogging and expansion possibilities.
That'll probably will be idea for V2 of the car for the next season..
Initially I was excited to go with MS3Pro, but it looks like here in Europe ECUMaster's EMU Black seems to be a wise choice... There is even their dealer here in Cyprus building many drift cars and stuff.
Now car runs MAF-less on 850cc injectors, works fine off-boost with lambda reference and normal mixtures but occasionally throws check engine light for ICV. It seems to want some specific physical settings of some sensors which are adjustable on EJ20K like TPS and ICV.. I noticed that TPS affects calculated load which needs to be in the sweet spot to trigger idle mode with fixed 15 deg timing and some black magic happening with ICV... Also some combination of fuel table values, map scale and injector scale parameters seem to work better than others because some of the parameters also seem to affect other stuff that is not available in the software like injectors dead time. None of this is documented in the manual and I'm not a tuner by any means. This is first ECU tuning project for me...
It may look like I'm doing some stuff the hard way, but that's my type of fun, probably...
:stupid:

Anyway.. Next on the list are ride height check and wheel alignment, GM3 bar map sensor (current one reads only till 1.2 bar of boost, I believe), new fuel pump, sorting out and tidying up the wiring, installing MAPDCCD and datalogger and then we can start with the tune ))) I'll probably tune it for light loads and take it to the track for WOT runs on the main straight. Can't wait :)
 
#181 ·
Progress update:
Alignment is done!


with -2.5 degrees of camber on all corners there seems to be more space available.
Managed to get 4.5 degrees of caster as well, steering now feels heavy and racecar-ish )))

Also I finally dialed in my 3d printer and made myself a string alignment system to quickly check toe myself.

That took some time, but now I feel I can print stuff quick enough with more or less predictable quality, and I'll probably use it more from now on.
3Bar GM map sensor is installed, showing about +0.05 bar now, need a bit more time dialing it in ECU
Next is wiring. Car has a bit of wiring mess under the dash left from original swap and me installing gauges and wideband.. It's a bit scary because I feel it may immobilize car again for a few months if I'll not finish it in one blow, but I got to do it someday...
 
#183 ·
For street car that works fine )
This year I expect that competition will be pretty tough.. and my goals are really optimistic ))
I don't think I can win anything in horsepower arms race, so my focus in general will be on learning, tuning and getting as much as possible from the package I already have. So, I plan a lot of experiments with suspension and since almost any change in ride height or camber will affect toe, I decided to invest some time and effort in strings system.

need also to spend some time managing this process, maybe make some kind of logbook/worksheets to leave comments for different setups, some calcuated fields and other stuff..
 
#186 · (Edited)
I'm interested in this process as well. Also, got them files?

I have used this a few times working on family/friends cars when doing major front end repairs and have always come out in spec when they got their alignment done after the fact.

Toe settings I always use the chalk line around the circumfrence of the tire and a tape measure method. Also, always within spec.
 
#187 ·
Basically the system I made looks like any other string kit available. In fact, all components of the system are in the photo in my post above. By the way, it took three or four hours to print those parts ;)
And that's probably about 1/4 of components needed...
I got one one 8 hour print and one 10 hour print sessions and rest of the parts (around 30%) were test items from previous iterations that were "good enough".
I made all components myself from scratch and personally I think that it would be easier if I had a welder - just weld three pieces of square tube together to form three 3*90deg fixtures, drill holes and weld nuts on them to screw something in to fix tubes sliding inside them.
Dimensions are affected by materials that you have locally. I found aluminium tubes in hardware store nearby, namely 20*20 mm square tubes and 16mm round ones. That's it!
End result:

Strings tensioning:

Disassembled:


I don't know how durable it will be, to me the weak link is glued connection of three square pieces that form each fixture.
Quality and strength of any 3d printed part depends on your skill with 3d printing and understanding of the process :)
It just so happened that to me this was more accessible than welder and I wanted some practice with CAD :)
 
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top