Today we did that odd thing of moving closer to finishing the car by taking it even further apart.
First order of the day was to remove the front floor and radiator assembly. This was necessary for a couple of reasons, firstly the existing floor is broken, and needs to be replaced, but also I needed to remove the existing radiators and the mounting frame so that I can fit the new front body work.
As we took the radiator out it became apparent how very lucky we had been to finish the Birkett, my little grass cutting escapade had, it seems been very very effective. The whole radiator was covered in thick layer of grass cuttings and the airbox was absolutely stuffed full of grass. No wonder I was going around Silverstone smelling of mown lawn! It was grass everywhere, how the thing didn’t overheat with so little airflow I don’t know!
More concerning was that when we cleaned the grass out of the old radiator, it became obvious that we were even luckier. The grass was mixed with the usual tyre debris, but also there where some substantial stones and other hard sharp things mixed with it. Including this nice little pebble that is so firmly embedded that it had distorted the radiator cores. That pretty much settled the debate about trying to move the radiators to the sidepods. They are just too vulnerable up at the front.
More of that later. While we were in body prep mode we went over the new body moulding to remover the mould flash lines and key it ready for painting. This takes much much longer to do, than to describe and is one of the those jobs where one slip or accidental gouge can leave you with a lot of recovery work. Anyway after about 3 hours of scraping and sanding Duncan and I were nearly there. The flash lines are now gone and we are at the stage were we need to do a little defect filling before we can continue. So with the front floor off (gosh the car seems so much shorter when the front is removed) and the body prepped as far as we could go today (I’m out of sandpaper) we turned our efforts to the engine bay.
One of the the things that the regs mandate that we must have for 2009 is a catalytic converter in the exhaust. Cats are only really effective when running in lean cruise mode and in a race environment can be expected to have a very short usable life. Still MSA rules are MSA rules so we had to fit 1.5 KG of additional ballast. To do this we shortened the existing exhaust tube by about 6 inches and biiffed the cat onto the pipe. We’ve not welded it into place yet as I need to work out where the next stage is going. I’d quite like to add an additional silencer to help me pass the noise tests. but we haven’t quite worked out the routing yet.
So on to the re designed cooling system. I’d already sourced a Honda Vti rad which looked like it should fit in the side pod.
I chose the Honda unit as it cheap and freely available in standard form, but also because there is a bloke on ebay selling a thicker all aluminium “motorsport” version that I can upgrade to if I needs be.
IT is actually very slightly over tall, but I think we can get away with it. It also came with outlets that match my current pipe work and very handily placed mounting points and hose exits. As such it didn’t take us long to get to this stage. The rad is mounted up on the side tray and supported on the appropriate brackets. We’ve even manage to get the top hose installed, and have a plan for the header tank. The current problem is routing for the bottom hose. By now Duncan and I had been at it all day and were tired and cold so we called it a day. We’ve a few bright ideas but right now we’re losing our objectivity (Each plan seemed to have an insurmountable fault) as well as the feeling in our fingers. Once the bottom hose is routed across the engine bay,it should be a simple matter of moving some wiring to drive the relocated water pump, cutting the inlet in the right hand side pod and making an Ali shroud for the rad.
Actually while were were making the changes we chatted about how much coolant capacity we were removing from the system. The pipe runs are probably 60% shorter than the old ones and the radiator is only 2/3rds the size. I guess we’ll be using a couple of litres less water than the existing setup. This means that the system has a lower overall thermal capacity, and so will heat up quicker. Hopefully this will not mean that it boil over quicker too. It should certainly be lighter.
The questions is “Am I trading weight for reliability?”. I’ve been lucky to get way with three lots of front end damage this year… which under other circumstances would have damaged the radiator and cost me the race finish, moving the rad to the side of the car should prevent this occurrence (the oil cooler I moved there last year hasn’t a mark on it … touch wood) However if the new system is not thermally efficient, over heating will also cost me races. Also moving the weight to the rear will change the handling balance ,will I now face horrible understeer? Questions… Questions. Hmmm The big boys would have a room of aero\thermo dynamicists figuring this out before trying it. Me I’ll suck it and see! 
Good job I’m testing in February, hopefully I can answer some of these questions then. It is beginning to look awfully close now though