Calder Park Raceway this weekend!

[jimnielsen]

I am taking the Q4 to Calder park raceway this sunday for a club sprint event.

http://www.calderpark.com.au/tracks.html

So far I have removed 155Kgs (thats 340 lbs) from it, removed the cats & pre cat and changed the inlet to a "pod" style filter. Apart from that its still just a "standard' Q4. I have also hooked up a 2nd MAP sensor so that I can map the cars boost vs RPM curve on a datalogger. I have used the MPX4250 MAP sensor made by freescale as this is the one that the "megasquirt" systems uses so there is a lot of information about how to map its voltage output to a pressure reading. I am planning to get some video as well if things go well!

JimN~

[wrinx]

Good stuff! Looking forward to your report...

wrinx

[pavs]

Looking good Jim

[jimnielsen]

below is a video taken from inside my Q4 at Calder park raceway last weekend.

Its about 6 mins long, 64Mb and in the divx format. You wont be able to view this video unless you install the divx codec.


http://www.nielsen.org/alfa155Q4/calderq4vid.divx

Regards

JimN~

[wrinx]

Excellent!

....shame about missing that gear though :(

wrinx

[AlfaJack]

Nice vid!! Your car sounds good. Does it get on the boost particularly early? what revs and pressure do you get?

[jimnielsen]

Attached is a graph of boost / speed taken at calder this weekend. As you can see boost is mostly limited to .75 bar. It does get to .9 bar at one stage when I run it in 4th from 3750RPM. At this stage I think this is just normal operation of the pierburg valve / wastegate - but I haven't really examined it closely yet. On the track you tend to go through the gears at high revs, and as quickly as possible. The way the boost map is setup on the stock ecu chip (that I have) means that you don't get much boost!

However the car is much quicker with 155Kg less weight, and with the cats removed. Unfortunately the car is now higher (less weight on the springs..) and so it has even more body roll. The brakes worked well, but it was quite easy to push them into fade after a few laps (will have to implement some brake ducts. The car is more responsive in 2nd and 3rd gears but has very limited power in 4th gear at higher revs. Need to remap the ecu to fix this. Its fun to drive but I'm now staring to push it into so pretty heavy understeer as I get more confident at driving it. Unfortunately I find it VERY easy to miss third gear and select 5th instead. I think this may be due to the quick shift kit that is fitted - but maybe I just need to be more careful. I may put it back to "standard" in this regard. The clutch return is too slow, I may need to put in a return spring.

Its all fun..

JimN~

[cuore_sportivo_155]

did you sort the brake bias valve already? this cures a lot of (fading) issues with the 155 brakes... even the 257mm brakes perform very well with a sorted brake bias...

what pads are you using? possibly oem pads that came with the car?

[jimnielsen]

No! I didnt even know that it had a brake bias valve - where is it and what adjustment is possible? I have replaced the pads already with ones i use on my "other racecar". i have used them many times before

[wrinx]

Underneath the rear of the car....very near the right hand shock absorber. You'll see brake pipes coming out of it.

Bit of a pig to get to...need to tackle mine as the spring is all floppy!

Adjustment is by fitting a new or stronger spring...and ensuring the lever moves freely.

wrinx

[cuore_sportivo_155]

not really wrinx... adjustment is by loosening th nut on the lever, and pretensioning the spring by hanging a weight on the lever... 5kg for road use, i recommend 10 kg for track use, but you might want to find the ideal value for your liking. on my 2.0 TS this allows me to do some trailbraking into a corner without outright locking the rears.

make sure it moves freely like wrinx says, very common fault, not only on italian cars... the other end of the spring is connected to the anti-roll bar, and thus influences the brake bias according to the height of the rear end of the car.

When adjusted properly the rear brakes will get just as hot as the front ones, but no fading should occur. Up to ~25% of the braking effort can be done by the rears, so it's a very good and cheap brake upgrade...

[jimnielsen]

Thanks, I'll look at this before I take it to the track again!

JimN~

[markgq4]

However the car is much quicker with 155Kg less weight, and with the cats removed. Unfortunately the car is now higher (less weight on the springs..) and so it has even more body roll.
Its all fun..

JimN~

doesnt it make a massive difference without all that weight in !!
just wait til you get 1.4 bar boost on too :D :D then she really goes :D

as for brakes i have red-dot 40 groove discs and red-dot fast road pads on front end and 6 groove rears with std pads and this will quite happily take 20 mins round a track with no fade . . . but i did used to get it with std discs and pads

I still havent cured the understeer tho . . .
Barry waterhouse did tell me a long time ago that 2.5`deg negative camber on front cures 90% of it and it was a simple slot and re-weld of a washer on the top hole at the bottom of the strut but unfortunatley i never got it done when i had the chance and i am not brave enough to do it myself....
like you said its all fun!

[Steve Webb]

as for brakes i have red-dot 40 groove discs and red-dot fast road pads on front end and 6 groove rears with std pads and this will quite happily take 20 mins round a track with no fade . . . but i did used to get it with std discs and pads

I always bang on about the standard sized brakes, with better disks, pads and high quality fluid you can really give it some stick on track.



I still havent cured the understeer tho . . .
Barry waterhouse did tell me a long time ago that 2.5`deg negative camber on front cures 90% of it and it was a simple slot and re-weld of a washer on the top hole at the bottom of the strut but unfortunatley i never got it done when i had the chance and i am not brave enough to do it myself....
like you said its all fun!
Barry (god rest the old bugger) was a mine of information about all things track and handling related, he sorted mine out with thicker ARB, strut brace and 2mm toe in. Sounds like it shouldn't work (effectively stiffening up the front end => less grip) but it killed a lot of understeer out on track.