Pre Le Mans cooling

The two Spal fans arrived at SP Automotive yesterday, so with three days to go before leaving for Le Mans 24 hour, I headed over there this afternoon with the car & some 50A Maxi-fuses to get the overheating sorted out. The plan was to swap out the single Spal straight blade fan for the two curved blade models, fit the additional in-line fan controller & remove the blanking plates from the rear bonnet vents to give somewhere else for the hot air in the engine bay to escape through.

Ryan talked me out of replacing the shaped vent grills with the less aesthetically pleasing (but more more efficient) grill that matches the front vents – so the originals have been retained. We agreed to locate the two new Spal fans in parallel at the top of the radiator rather than offset them; this required some minor grinding of one of the fan frames to squeeze them both in side-by-side, but the end result looked very good (below). The offside fan would continue to be controlled by the ECU (kicking in at 95 degrees), whilst the nearside fan would be controlled by the new Revotec in-line controller, set to about 99 degrees. I left the team to it while I went for a stroll down the country lanes of Cheshire with my daughter, ending up in an Ice Cream farm (not entirely by accident, to be fair!). There was a steady drizzle by this point, but we had a couple of hours to kill so got on with the very British family activity of playing in the rain. Upon returning to SP Automotive, Ryan had finished removing the blanking plates (I can’t watch people with chisels attack my car!), & was sealing the vents back in. In the meantime the fans were fitted & the wired up but I was surprised & a bit annoyed to see a standard 30A fuse fitted, despite my supplying parts & specification for a 50A fuse. The justification for this was that the fan controller was only rated to 30A, and the fan itself was only showing as drawing 2A, but upon pointing out that Spal’s data sheet showed max draw around 33A, I was informed ‘they must be wrong’. Given the time available we agreed to disagree, but I have since found out that SP err on the side of caution in this area, having encountered several fire damaged TVRs, arising from under-specced wiring combined with high amp fuses which have overheated & ignited.

The engine was run to fine tune the point at which the second fan kicked in, with airflow judiciously managed by Ryan armed with a large sheet of cardboard to limit throughput. Cunning! Who needs a wind tunnel or computer simulation eh?… Finally with work finished the car was all set to go; bonnet down & a 50 minute run back home to see how things went. No standing traffic encountered, so natural airflow kept the engine temperature down & the fans weren’t triggered. Despite this, the rear grills were extremely hot to touch which goes to show how much hot air there is in the engine bay. I may yet need to get some circular vents drilled into the rear bonnet face. Le Mans of course will be the big test.