For those that want the highlights:
- The car weighs ~1030kg dry
- I finished a track day without crashing
- Handling is the best its been
- Direzzas are a cut above AR1’s
- I have a compression problem
Geo
Dropped the car down to NADUK for him to work his magic, was supposed to be a few hours but he spent almost the entire day on getting things right. The beam was off but with some swapping of the shims he was able to get it back to where it was and an extra bit of camber. On the front we increased the camber to 4 degrees and slightly more toe out at 1mm. Dropped the ride height back down to where I had it been last year / cup racer base, as I was confident the bump issues had been solved.
Onto the scales and it was weighing at around 1030kg with the fuel taken out which is roughly what I expected. Very light for a mk3, however I think I could still remove/reduce a fair amount of weight if required going forward.
Had a few small things to fix/add to ready for a shakedown, rear view mirror, harness, seat position etc.
The ABS pump had been sat empty so I knew I was in for some fun, refusing to pay for CLIP I decided to see if I could get ddt4all to work. Once I had downloaded the ECU libraries it was actually very easy to use, the only annoying thing to deal with is that it’s all in French. However I found the ABS module and was able to start/stop the 4 solenoids whilst bleeding, lots of air came out, must have pumped through 1ltr of fluid per calliper before I got a pedal.
I then checked through the 4 ABS / wheel speed sensors and the steering angle as I was worried I had bolted it back up 180 degrees off but it was showing zero.
Started working on the updated dash, inspired by what you see in touring cars I wanted something simple that would still be there when upside down.
Concerned with the low power I did a quick compression test (cold) and was greeted with 150psi across each cylinder, jumped up to 170ish with oil. Concerning but the engine had only done 15 miles so the rings still needed time, chatting with Andy and Alex the plan was to just send it.
Brands Hatch Track day
Very busy, the briefing room was full and must have been about 50% race teams. Spent the morning taking things slow, plan was to just run the engine in and see what falls off. Once I got to about 70 miles down I started pushing things, at this point it was obvious the engine wasn’t performing.
Looking at the data my top speed into paddock was about 4 mph down, 106 vs 110 before braking, this is with a difference of around 70kg+ factoring in fuel and not even including the engine changes. Obviously I have a big wing which will be impacting things but I was expecting to be considerably faster. Interestingly its at the higher speeds the engine struggles vs before, once into 5th there is just nothing. To put this into context I was struggling to overtake MX5's, it felt like the power was around 190..
The day was full of red flags, must have been at least 3 cars that had engine issues resulting in 1/3 of the track being covered in oil each time. My favourite was the blue 1*2 that decided to finish the lap after a very obvious engine failure into Graham Hill.
Oil temp was steady at 100 degrees and pressure of around 4.6-4.7 bar under load, not sure how this compares to others?
Niggles
- Minor rubbing on front/rear bumper
- Bonnet likes to flap about in the wind, solved with some cable ties but might need to fix this properly
- Need door pulls
- Impossible to see clocks due to wheel / dash
- Seat needs to be slightly higher
- Gear knob likes to fly off
- Brakes are potentially over cooled, air temp was low and I wasn’t pushing things so might leave for now
- Low battery warning, expected as this is my old alternator however starting to think the regulator issues is directly related to high RPM, might look at a larger pulley for the alternator
- Brake/throttle pedals are way to close together, will either modify or switch back to my old as I had zero confidence on what pedals my feet where actually on
- It’s really loud (inside)
- High air intake temps 31 deg+ on track, this is with the airbag behind the light, wanted to test flipped but didn’t get time
- Intermittent EPS fault and I am not 100% sure ABS is working, I think this is a connection issue as revving the car seems to flick it on/off
Positives
- Nothing fell off or overheated
- Gearbox / diff survived the crash and feel great
- Handling
- Lowered the damping on the rear and the car felt a lot more balanced on the curbs/various bumps BH has
- Weight, needed to recalibrate when on the brakes as you can leave it so so so late, once I have some power this will be fun
- Direzzas are so much better than AR1’s, expected but they behave more like AO48’s by letting go progressively when they reach the limit. AR1’s like to just let go and screech you off the track, with the Dunlops you still have some grip to fix things. Combined with the frontend the limit has been raised and driver needs to catch up.
Engine
Compression test after the track day showed worse results, did a leak down test and it’s all pointing to piston rings / bores.
I measured everything when building and looking at my spec sheet both bores and pistons were right on the limit of spec with a slight taper on the bores (something I decided to ignore). It looks like when combined the spec limit isn’t workable. It’s not using any noticeable amounts of oil from the track day but the leak down / compression is obviously a problem under load.
Time to bore to 83mm and bite the bullet on some high comp pistons, engine rebuild #3 inbound…
