Hey guys, I am ruined, so so tired and aching all over, this can mean only one thing, my first practice day!
The past couple of weeks have been fun with the project moving along well, so well I did not get a huge amount of pictures, most of it was cleaning and tidying which is quite frankly pretty boring!
One amusing incident occurred after the first heat cycle of the engine, it became apparent that the fuel pump was not really pumping, at all infact! Initially I thought that the vacuum line was not in the best position resulting in a weak signal to the diaphragm. I found another nickel brass fitting that was vaccum rated, then picked a good position on the inlet manifold to situate said fitting.
Tidy install -
I plumbed it all up and started the engine, and thought “the fuel is a bit foamy in the pipe, why did the engine just stop? Ahhhh the pump is emptying the flat chamber and filling the tank!” Oh yes, I am a certified plank, swap inlet / outlet and off she goes :-D This however will come back to bite me later, keep reading to see how.
There were a few other highlights, the best of which was the fitting of my tuning device, I am no master of the dark art of plug cuts and maps of Australia on piston CROWNs, so I need electronic devices to tell me what is going on.
This is what I have used to tell me exactly what is going on post combustion – www.innovatemotorsports.com/products/lc1.php
An innovate LC-1 wide band lambda controller combined with a Bosch sensor, this outputs a nice linear signal from 10:1 – 18:1 air to fuel ratio as a voltage.
The sensor needs a boss putting into the exhaust, preferably quite a distance from the port to ensure it is only reading burnt gasses not transfer from the inlet charge, so I picked a point half way along the expansion chamber and the only disadvantage was the lack of heat to keep the sensor clean (like a spark plug it needs to run hot to prevent carbon sooting it up). The section selected was also double skinned to suppot the weight of sensor and boss combined, it should help prevent fatigue fractures.
Hole drilled –
Boss ready –
Various plans were cooked up on how to rear / log the data whilst on track, finally I remembered that I had one of these sitting in a cupboard for a rainy day –www.14point7.com/UAFC.php
Now the main feature of interest to me was the fact that it can log two 0 – 5v channels for 27 mins, ideal for a track session followed by digesting numbers and deciding on jetting.
This was all hooked up and ready to go, unfortunately when I tried to download the first log the file was corrupt I tried a couple of times, but it would appear that my very early unit (it was part of the beta testing) has some firmware issues. The solution was simple and in fact worked very well -
Yep, a multimeter, 0-5 volts in, if it is at 2.8 then we are happy, over 3 and the world will end, under 2.5 and a milkfloat will have the legs on me!
By this point is was 12pm the night before the test day, the kart was ready, tools selected and boxed ready, time for a fitful nights sleep and dreams of soft ceased engines!
6am today I was up for my run, Michelle my wife was up and packing lunch before her run, both ready to take on the world, ish.
The citroen was prepared –
And filled –
On the way to the track we picked up a set of micro drills for jetting, and 10 litres of BP ultimate.
We arrived at 9.30am, unpacked and re-assembled the minor items removed for transport, Michelle cooked bacon sandwiches, the kart was warmed up and after a chat with the nice old chap running the show (I cant remember his name, but he made me laugh!) we were ready to go.
Now before you laugh at the following pictures, I really did not care what colour my suit was, I wanted a good quality item that fitted well, the result was this little number –
Yes, from now on I shall be known as ‘the golden boy’
From then on it was a steep learning curve, keeping out the way of the much faster people (yes there was a girl on track and she was much
faster than me!), keeping an eye on the engine, running it in well, checking the fuelling, and oh yeah, learning how to drive the bloody thing!
We tried different starting techniques too, the best so far is a push from someone, I tried myself, but I have not got the smooth transition hop into the seat down yet –
Fuelling was pretty damn good from the off really, seeing around 2.8 – 2.9V under hard acceleration, which is around 12.5:1.
Then after a particularly punishing 15mins the engine died, in fact it felt like a soft cease, power dropping off steeply and the engine reluctant to rev. balls, balls balls balls.
I let it coast onto the grass just after the first hairpin and retreated to a safe distance, the marshall called me over after 20 mins nearing the end of the session, he said that I could have one go at push starting it between this session and the next cadet session, if it was a no go the I would have to push it back to the pits
Michelle ran back to the car and collected the can of ‘start ya curse word’ and I gave it my best shot, nothing, then I realised I had not switched it on, I gave it a cheeky second try and bang, straight into life!
For the next 3 sessions this happened, I was watching the AFR’s and it would run full lean just before dieing, if I could keep the motor running it would recover after ½ a lap and resume progress as normal.
The it dawned on me, the pump, it was not running enough fuel to keep the engine running at full tilt along the two straights before that hairpin, so it was emptying the float chamber and would quit. Slowing down would let the pump catch back up and then back to normal!
Over the day I did 5 sessions of around 15-20mins, and I can tell you now I am shattered! Michelle decided against running today, it was just too daunting learning now to drive a gearbox kart like this, whilst other more seasoned racers were lapping a lot faster. We have a plan up our sleeve so that she can get some seat time and settle in a bit.
So the whole day without any mechanicals, I was happy! And I cant wait to get to the next one, a bit fitter and a whole lot more confident.
Parting shot, a little video of the kart in action, short but sweet, and a couple of arty shots
(click on the picture)
I hope I have not wittered on too much.