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Homebuilt GC8 for Time Attack

64K 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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#108 ·
Well, I never touched that nut. I always thought that it's not a good idea to remove the wheel without balancing it all again, so I only cleaned it from the outside and put housing back.

Got some hi-temp RTV sealant today, will put it together soon.
Meanwhile, had to return loaned dremel tool, so tried to install bonnet locks yesterday.

Sort of final position of the latch:


Still need to clear the underside to finish the installation. And repeat it all on the left side.

Not the best place to mount aerocatch locks because there are three layers of metal in that area, and two of them bonded together with some rubber glue. I need to carefully remove it all but outer skin to install the backing plate on the underside...
But... there is no way back now :)
 
#110 ·
Never thought about that. There are pates on this bonnet, they where painted quite bad by previous owner, look awful... And Shipping them out of Cyprus will probably cost more than they cost )
Meanwhile, end result:

Looks nice on the outside but from the inside it's quite a mess... Was in hurry to finish it, so cut some corners.. literally... Anyway, this bonnet had some damage to the structure form accident, so it's basically a good piece to train on.
 
#112 ·
I've done one more stupid thing.. After I cleaned turbo I decided to fill the cartridge with oil so, I had turbo laying on the table like this:

And filled both supply and return lines with fresh oil...
Couple of days later I decided to put turbo back together and i found all that oil in the turbo housing..

Thinking about that I decided that it's probably normal because cartridge seals are not really supposed to work in this situation... Correct me if i'm wrong.
Gave it all a good clean and put it al together.
 
#114 ·
Semi-annual update! :)
Well... almost. I hope that I will find more time for the car and it will be running somewhere in March.

Not much done since last update... For some reason I became really excited when I saw some inconel WRC heat shielding stuff, so I got myself some heat shields and spent about the month shredding a lot of paper for templates.
Finally one month later I got this:

In fact it took less than couple of hours once I decided to proceed with actual material rather than figuring out 20th edition of perfect template...
Anyways, prepearing for final assembly, need to decide on where to mount GM IAT sensor. What do you guys think about this spot?

I will have COP ignition, so there will be no coil pack at the top of the manifold. I heard that heatsoak might affect iat readings if it will be mounted on the manifold, how bad is it?
I wanted to start it with oem intercooler first, so I can't figure out better place for it now. Also thinking about adding meth injection to help stock topmount... probably add a nozzle at intercooler outlet, so IAT will be downtream from the system. Need to read more about it, it's kind of new thing to me...
 
#116 ·
Yes, it's another option to consider. In fact wall thickness in not very good at the top, the idea is to drill and tap threads for the sensor which, I believe is 3/8 NPT. If it will not work , then I will have to get it somewhere to weld the bung in (bye-bye nice paint job)

I will try to fit it on the bottom somewhere today. Wall thickness there is probably the same, but it's flat, so will be easier to tap there. On the other hand, I believe that it's generally better idea to place any sensors in intake or exhaust facing downwards. We'll see. Need to put the manifold on the engine and to see if there's any space available.
 
#117 ·
the iat element, on a gm sensor anyway, is inside a little plastic cage. If its heat soaking then its from the slower air flow inside the hot manifold and its still measuring correctly.

if you still using the pcv, dont put it anywhere near there or it could get oily
 
#119 ·
I couldn't figure out what manifold you have, but the USDM wrx/sti manifolds have an 1/8" npt fitting for an evap vacuum line. Yours looks different but may have a similar fitting somewhere?

If you don't have the purge valve stuff you can remove the fitting and thread in the 1/8" npt sensor. Don't know if GM makes one, but AEM makes am 1/8" npt IAT sensor.

This picture shows the fitting on my mock up engine with ej205 manifold:





Sent from my iPhone using Tapatalk
 
#120 ·
It's EJ20K manifold. Basically my engine is going to be EJ20G STi longblock with EJ20K electronics conversion except for keeping COP igniton. Thats... wierd :)

I already have four GM IAT sensors, three of them are 3/8 NPT and one is M18x1.5 because Chinese ebay seller, that's why :)
Got four of them since I was excited with water-to-air intercooler setup and I wanted to log it's efficiency vs stock setup
 
#123 ·
I read that recommended drill bit for 3/8 NPT is 37/64 and alternate size is 9/16. In mm it's 14.6844 and 14.2875, so my plan is to get 14.5 mm drill bit, 15 will probably be too much )

Living all my life in metric part of the world, fractional inch sizes are a bit confusing :). Not saying that I had to order 1/8 and 3/8 thread taps and wait for three weeks for them. Anyway, most of good and affordable aftermarket stuff comes from USA, so there are no other options )

I tried to put the manifold on top of the engine and it looks that sensor can be mounted on the bottom. Here:

Just enough room to get it in and out with manifold installed and I can't see any problems with the connector as well. Probably will be easier to tap because manifold is flat there. But I still want to try spot on the top. I believe it's the best spot in terms of airflow although wall thickness and rounded shape may require welding the bung in...

By the way, here are my sidefeed fuel rails and rest of fuel system parts:



Definitely an overkill for my stock yellow injectors and expected power levels, but should be fun learning experience. Always wanted to do something with AN fittings )))
Probably should have gone with top feed conversion, but rails with most of AN stuff appeared on ebay in Europe as a kit with nice price tag on them. I think I'll still be able to find bigger side feed injectors If I'll need them someday...
 
#127 ·
Top feed kit looks fantastic, but I got all my stuff 30% cheaper incl hose and an fittings :). And my manifold is basically 97-98, not sure it will fit.
Regarding that plug - that's interesting. Plug has roughly 15 mm diameter, so should be just fine. And thickness there is much better. If only it was closer to the center... I also don't know what's under the plug. Is it for machining of some channels for IAC? Or for casting purposes? Will it be enough airflow there?
Here are some photos from my other car and while I was stripping paint on this manifold

 
#131 ·
In the meantime regulations and calendar where posted on official FB page of out TA championship.
Basically, in my class car should have stock interior, 4 point harness, not more than 7% weight reduction from stock weight, engine should be from the same manufacturer as car (looks like something like EZ36 turbo build will be legal :) ), on max 265 street legal semi slick. Water/meth injection is allowed.
Looking on 2016 season, top competitors are turbo S2000 and NA EG9 civic with B18 NA engine and light weight, stock E46 M3 CSL with nice suspension mods and sticky tryres... Well I will not guess my chances because I already done that like two years ago... Since there bar was raised higher but I'll stick to what I have.
First race is scheduled on April, 2nd. There also will be a pre-season trackday in the beginning of March.

To do list:

Mechanical:
Assemble manifolds
Drop engine in
Put exhaust together
Radiator and cooling plumbing
Figure out cold air intake with enclosed filter and MAF delete
Put together fuel system
Install walbro fuel pump (make sure that it will not result in starving fuel like it did last time)
Service BC inverted coilovers (I believe it's recommend to get them re-greased once every year)
Change all fluids.

Wiring:
Figure out a way to adapt V2 engine harness and dash to V4 ECU
Wire in IAT sensor
re-wire COP ignition in wasted spark mode
Install Wideband (MTX-L)
Install EGT gauge (on its way)
Radiator fan override
Wire in RaceDAC datalogger

Final touches:
Figure out mafless mode on ESL and START THE CAR
Check brakes operation and possible leaks
Get safe tune without meth injection
Take it to exhaust shop. Currently there are no flex sections anywhere in the exhaust (except for manifold mid pipe) so I wanted to add one and MOT might require cat install.
Get wheel alignment
Renew insurance, registration and MOT
Test on track

Is it realistic to get it dome before April? Judging from my previous progress - no way :) But what I know for sure if I will not make it for the first event, there are good chances that I might not make it to start the car this season at all, so I'll better try my best to get the car running safe for some sort of shakedown event on the first race.
 
#133 · (Edited)
Well, weekend wasn't super productive, but at least I got things moving...
Got engine out of the living room and closer to the car it had ever been since last summer

Mock-up fitted exhaust manifolds, put front damper pulley on as well as some missing clamps on misc coolant lines and some sensors preparing it for final assembly.
Also pressure washed the engine bay and tried to figure out what to do with wiring. It turns out that engine wiring between V2 and V3-4 engines is really different... V2 engine harness connects to chassis only near fuse box, while V4 harness got big connectors on moth sides - near fuse box and near cyl#3.
So, to speed up process I decided to look for V4 ECU, engine bay and engine harnesses to replace it as a whole. that way I will only need to mate it all with chassis and gauge cluster and potentially will have better condition of harness in general, because most part of my current engine bay harness is old, hard and tired.
As a plan B I have V4 engine harness from spare engine I bought. It's cut near major connections on both sides but has all engine side plugs on it so i can cut off the V2 engine harness connectors from manifold I'm not using and use it ti connect V4 engine harness to V2 engine bay harness. That way most of the engine bay harness and ECU body harness will remain V2 and all alernations will be done on patch harness I'll got long time ago. It was original plan to go what now is "plan B" but I think that it will be less work If I'll manage to get complete V4 harness.. we'll see..
Btw, COP ignition wiring for V4 engine turns out to be quite simple and common thing, there are even plug and play harness kits for sale like this one (note to myself if I become super lazy):
Subaru Coilpack conversion looms | JT Innovations
 
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