Experimenting with a larger pre-rad

23/1/2006

Yet more testing, I think I'm becoming obsessed with this!. I thought I would try a bigger pre-rad. This is actually an intercooler core, which i've hastily completed and added the water pipe fittings. Must admit I love being able to weld aluminium - you can knock things up like this in no time.

Here's the results; A slight improvement - temps are slower to increase and recover quicker (even though I've got several extra litres of water in the system). The two lines are a comparison of last weeks run on this weeks run, the ambient was almost identical. So might play around with some more rads, as the one above looks stupid!.

At the end of the day, I think i can improve it a little - but I'm not going to get very far. My chargecooler isn't very efficient (got a few ideas about that) and the pre rad needs to be larger. I think adding more water to the system is pointless; although it will heat up slower it will take longer to cool down again plus all that extra weight.

11/2/2006

This graphs shows the water coming out of the chargecooler (Yellow) and out of the radiator (Blue). You can see under boost the water rises, then they converge again off-boost. This is with the big intercooler rad on the front

26/03/2006

Custom chargecooler radiators.

Having tried a larger pre-rad with some success, Ive decided to make something a little better and not quite so chav looking. I struggled to get much meaningful design advise (one big rad or a longer path through narrower rads), so I decided to go with the maximum flow distance by connecting two cores in series - the thinking being that its exposed to the air for longer. I'm using 2 row 12.7mm cores (40mm overall thickness) which were custom made to fit the available space by Pace Products.

Work starts by creating a steel buck to form the end tanks from. Then it's just a case of gently hitting it with a rubber mallet.

When clean just isn't good enough. As I found out from bitter experience last time, the rads must be very clean. Even though they are new and shiny, I still ground them again with a brand new sanding disk. The welds are better this time, because I butt-welded the tanks rather than overlapping them like last time.

The result of a couple of hours of welding. I'm quite pleased with the results and I saved £150 fabricating the tanks myself.

Not quite Bugatti Veyron territory, but I think 5 radiators are enough...

04/04/2006

Despite some good fun baiting scooby's out on the road, my spanky new pre-rads haven't made much if any difference.

Graph shows boosted sections only, Ambient temp was about 13'c

The big water tank experiment

Idea was to have a massive tank of water, so see if it slows down the rise in temperature - apart from have a bit of fun, it didn't work. My pump isn't powerful enough to cope.

Next steps

I want to modify the internals of the chargecooler to make sure the water flows round all the cores - as i'm pretty sure that it goes up the first core and then just takes the shortest path across the top of the other two cores to the outlet. This is because the tanks are made as one, then segmented but cutting a slot down them to create a compartment - which isn't going to be very water tight due to the un-even surface of the welded tanks.

If you are thinking of making a core, I would recommend making all the water compartments separate and then using external plumbing to connect them - it's much easier to experiment with different coolant paths then.

6/8/2006 Modified chargecooler internals

Finally got the courage up to cut apart the chargecooler and modify the coolant passages. I used a nibbler to cut holes in the water tanks to expose the compartment dividers. I had to remove both charge hoses (on each side) and I cut the front of the charge compartment off to access the cores - as i wanted block the gap top and bottom of the cores.

(Click on photo to see harrowed section) - this gap I blocked to prevent hot air bypassing the cores completely.

I cut the charge pipes off to allow me to cut holes in the water jacket to get to the dividers.

The gaps between the compartments wasn't as big as I had imagined - I filled it up with water and water came through the gap, so I decided to weld it up as best as possible (no photo's it wasn't worthy!)

Whilst it was off the car and now that I have a mill & lathe I could sort out a few other issues, I made a proper ally bung for the temperature sensor and also I could machine the flange flat as it warped considerably when it was welded (this was 6mm thick ally!!).

Poor old cooler looks like a patchwork quilt now, although considering I removed both charge pipes, the front and cut holes in both sides I'm fairly pleased with the fact that it all went back together.

And here's the results: (Ambient temp 26'c)

Off-boost efficiency is about 60% which it always has been, but on-boost efficiency actually climbs rather than falls - it averages out at around 65% - which is a good improvement over the graphs above, which typically resulted in 50% efficiency. So overall I'm now happy with the setup, I might play around with a large water reservoir as a little experiment - perhaps with some ICE inside it for some fun.