'Too much track isn't good either as I learnt about a dozen years ago on the old 1200.'

Hi Harry,
Could you please elaborate on this?
Love the new look.
Cheers
Dave

I should say wider track through negative offset wheels (or spacers).

My old 1200 coupe handled pretty well and won its class almost everywhere it went



But after fitting the flares and negative offset wheels, it developed a problem at Morgan Park which was the main place I raced back then. Through the fast esses at the back of the track, the fast line through there was to ride one of the kerbs with a slight dab of brakes before the the tighter RH turn at the end of the esses. Never a problem in the previous 3 years I'd been running there, but now all of a sudden it wanted to rip the wheel out of my hands if I braked with a wheel on that ripple strip! It didn't seem to be a problem at Mt Cotton or anywhere else I raced. Changing the line through the esses was slower. I knew it was costing me time, so as much as I liked the way it looked with those new fat 13x7 -7 Superlites, I changed to 14x7 +3 hotwires with a slightly taller 195/60 and the problem was gone.



Both sets of wheels had the same A032R tyres, but it now had criper turn-in and better mid corner grip as well, and was 2.6sec faster over a 3 lap supersprint (they only supplied total times, not individual lap times).

The reason is scrub radius - the distance between where SAI (Steering Axis Inclination) insects the ground and the center of the tyre's contact patch. SAi is a line drawn throught the center of the top strut mount and the balljoint pivot down to the ground. Scrub radius is positive if the tyre center is outside that SAI intersection with the ground and negative if the tyre center is inside the SAI line. Struts don't like too much '+' scrub. It makes them unstable under brakes on uneven ground, and also reduces the amount of cornering power that can be generated.

On that car the problem was also helped along by the Stanza struts with the hub face further from the balljoint, which required a more positive offset wheel to keep scrub radius acceptable.

Like the wheels and yes I have had similar issues on precious axes with neg off set on the rroads tram lining we ride vibrations on certain reads, dulled turn In with poor return to center feel and action too.
Too much pod offset I gave also found makes the car understeer (or i should say less front end grip) and a bit tippy toey under hard turn In.

Car looks the business

car looks absolutely amazing !!
quick build rate too mate.
any videos of this car performing on track?

cheers

Thanks. It's only done 1 hillclimb so far - a few months ago before the diff was welded, just as a bit of a shakedown run. It handled surprisingly well considering the lack of camber and castor at this stage.



here's a video of it single pegging around Mt Cotton hillclimb: https://www.youtube.com/watch?v=Ajc-dps1-t0&feature=youtu.be

It will be seeing alot more track time this year, as soon as events start up again. :)

Enjoyed the video.Looks like alot of fun.

What is the powerband of the car? From what i could hear of the engine revs,Are u letting go of the gas pedal to avoid loss of traction or is that to drop back to the powerband rev range to accelerate when exiting corners?

yeah just because of wheelspin really. Powerband is from almost nothing to about 6500rpm where it starts to nose over in taller gears. I was using about 7000 at the hillclimb in 1st and 2nd.
Boost threshold varies depending on what gear you're in. 1st and 2nd gear it only gets to full boost fairly high in the rev range, but it's still very torquey right down low thanks to the stock L20, so it doesn't really matter too much. My old worked L18 1200 coupe with big cam and 4.3 diff needed 1st gear in the first corner and hairpin at Mt Cotton, whereas this thing pulls out of there strongly in 2nd with a taller 3.9 diff despite being a slightly heavier car (driver is a bit heavier than he was back then too lol) so it's got good low down grunt.

Looks like the first event this year will be at Lakeside on the 1st of February. Can't wait to see how it goes on a fast flowing track. It will be a good test of the engine and handling. might try and get some more camber & castor before then...

Looks good. Go the 2-door.

Sounds like pure torque, much like a revvy turbo tractor!.
I wonder what this turbo setup would be like with your
ported revvier lighter L18 engine? what are your views of
using the same cc but L20b vs L18 stroke w/ longer rods?
Also would this setup benefit in the future when you
have sorted the handling and brakes for a bigger turbo?
say for 2000-8000rpm rev range or are you content just
putting up the wick within reason>

The L20B has a decent rod to stroke ratio of 1.7. Pretty much what my old L18 with L16 rods had. Not much need to mess with that with a turbo on the side of the engine :)

For the power levels I want this turbo will be fine. I'm only at 7psi at the moment according to the digital gauge - the old analog one was hard to read accurately. I'm sure I'll eventually turn the boost up a bit, but the most I'd want in one of these is around 150rwbhp, and I'm pretty sure this turbo could produce that.
For now I'm very happy with the power. The original plan was for something that went like my old L18 1200 coupe and I reckon it does - a couple of track days will soon tell for sure. The low boost should be pretty easy for the stock L20 to handle on multiple lap sprints even in Brisbane summer temps, and I don't think the Stanza 5spd would appreciate a whole lot more grunt running through it, so I'll leave it as it for a while, and like you say, get the suspension dialled in and just have fun driving it as much as I can.