Yet again I'm a bit late posting this. I've got even less of an excuse that usual this time. I guess I've just been lazy.
As it turned out Thruxton was a bit of a pain. I didn't really drive anything like as well as I would have liked and I got absolutely soaked as it was just ridiculously wet.
However, before getting on with the report and on the off chance that there's a member of the BARC reading this...
We're all used to the idiocy of the BRDC at Silverstone but some aspects of the way Thruxton is run beggar belief. Most obviously, when it's chucking down with rain there's a good chance that people will want to go in the grandstands. Which lunatic decided that a) they should charge £7 quid for the privilege and b) installed their own member of the Palace Guard to police entry?
End result: there are 6 people in the grandstand and scores all over the mounds at the side. Why not just change a quid a time and do it with a collection box? You'd be guaranteed to get more money and you wouldn't have to post a muppet at the entrance.
Oh well, I really shouldn't be surprised at the lack of business acumen displayed at UK circuits by now.
Anyway, we left Cambridge at about 1515 and got to Thruxton at about 2030. That's right, it took over 5 hours to get there. According to the radio there was a 41 mile long queue on the M25 and I think we were in all of it. The weather was quite nice though, much better than what was forecast for the following day.
Which indeed turned out to be the case. Saturday morning was spectacularly murky and it was clearly going to rain a lot during the day. All the same, I set to and got the car scrutineered, went to the drivers' briefing, got the video approved and was ready for qualifying for the all-comers race at 0900.
The weather had been spitting all morning so I decided to soften the car a smidge before going out, especially as I only had the vaguest notion where the track went.
As it turned out it was mostly dry for the first qualifying session but the car felt horribly bungy and unstable. The track's really, really quick and you need to use the brakes exactly twice a lap, for the Club chicane and the start of the Campbell/Cobb/Segrave complex. The rest of it is eye-wateringly quick and just flat for large periods. It's also very bumpy in places. I guess in some ways it's kind of like what an oval must be like: really quick and stable if your line's right and just horribly scary if not.
They've also been very cunning in making two corners (Goodwood and Church) look almost identical from the track. Quite worrying that.
Anyway, I was very careful, sort of learnt the track and managed a whole 26th on the allcomers grid. Problem was, the car cut out a few times on the run down to Club which didn't help the lap times. Not sure why, although it has had issues on long full throttle runs at Snetterton in the past.
A hour or so later and it was RGB qualifying. It was now properly dry (although still very overcast) and this time I needed to go quicker... I stiffened the car up again which was much better, although I suspect I could have gone further at this circuit. Then I went for it, sort of... I actually set my (rather pathetic) fastest lap on lap 4 of the quali session. After that the car started cutting out more and more. What seemed to be happening was that on the run away from Church down to Club the engine just stopped working. After a few seconds it would come back but by then it had ruined the lap time. The logs show that I was losing at least 3 seconds a lap just in that part of the track. What seemed to be happening was that after 30 seconds, or whatever, of absolutely flat out running the fuel pump just wasn't keeping up with the carbs' demands and the float chambers were running dry.
End result was a pathetic 22nd on the grid, nearly two seconds slower than my usual sparring partner which is rather dispiriting.
I've had a couple of slight incidences of this problem in the past, always on Revett at Snetterton. In that case only when the tank was right down to about 3l of fuel. This time I had lots more in but I guess I'd been on the loud pedal for longer.
Back in the paddock I changed the fuel filter element which was slightly clagged up, and wondered about trying a different fuel pump. (I've got a spare!) However, I just put a little bit more fuel in.
Come the all comers race and it was now actually wet, although not exactly pouring down. I got a half decent start and headed into the melee that was Allard. Someone didn't come out the other side and parked their Global Light on the left hand side of the track in a position that said "target" all over it. Still, we carried on.
I then got stuck behind Doug Carter. Doug's got one of the Genesisiieisi and is, if anything, more tentative in the wet then me. I was way quicker than him in the twisty stuff and also through Noble where I could blast past him with ease. Problem is, we then got to the fast bit and he could just edge back ahead of me. That carried on for a few laps until I started suffering from the fuel starvation again. Until we got to the last lap and I went around the lap trying just to keep up with Doug without actually using the throttle pedal. Back to Noble and I shot up the inside into Goodwood, breathed carefully, moved in towards the apex all the time exactly at the side of Doug. We stayed like that down towards Church and here the apex line is way superior and I was away.
Until the sodding engine cut out again. Buggeration....! Doug snuck back up the inside into Club and I couldn't get past before the line. Actually, the exit of Club was the slippiest spot on the circuit and the opposite locks slides coming away from it were rather alarming...
Oh well, I was 18th and I could console myself that I'd have been a lot faster had I actually had a car that went.
A while later it was the RGB race which I'd prepared for by filling the tank to the brim. that means I was carrying about 10kg of additional ballast and, what's more, it was absolutely pissing down. I sat in the assembly area under an umbrella watching the rain bouncing off the bonnet. They told us it was going to be a wet race (no shit Sherlock?) and we'd get a green flag lap and please would we put our rain lights on. Finally we went out and on the way round the out lap there was a truck cleaning up debris from the previous race at the entry to Goodwood. Oh good, that means we're going to be sitting on the grid without an umbrella.
We said there for about 10 mins, getting wetter, and then the let us drive round again for a green flag lap. Problem was, my visor had misted up and didn't seem to be clearing even when I was going.
Back round to the start, 1st gear, watch the lights, away we go! I got the best start of the season and passed two complete rows of the grid before the melee at the first corner. At that point I could not see, literally, a thing, with the exception of the occasional rain light. What's more, my visor was still misted up and I could see nothing out of the right hand side and only bits out of the left. I considered stopping but carried on anyway.
Essentially that was it, I just drove around, quite enjoying myself in the wet but not able to commit myself because I just couldn't see properly. I was driving down the straights with my head turned to the right so that I could look out of the left side of the visor. I got in a bit of a dice with Neil C-B but after I got away from him at Club that was it really.
Wet and miserable we got the cars weighed at scrutineering and then packed. I went into the bathroom in the motorhome to have a shower and when I came out the sun was shining! How did that happen? More to the point, why couldn't it have happened earlier?
Ho hum. I need to sort out what's happening with the fuel feed. I also still need, after the post-race weigh-in, to get *loads* of weight out of the car. I've got precious few decent ideas about that, or ones that involve not spending vast amounts of money. I did wonder about using last years's bodywork to make some moulds from with which to make some wet layup, super lightweight, carbon bodywork. I'd need a very long time in the shed though...
So, it was back to the garage. As you will have noticed I was a bit hacked off about my performance at Thruxton. Oh well, I seem to have regained my equanimity now. With luck the next races (a double header at Brands Hatch next weekend) will take place in slightly better weather. What's more, the nature of the Brands circuit means that a return of the fuel starvation seems unlikely.
All the same, I need to do something about it. I have a spare fuel pump and I checked that that one pumps out fuel as fast as the other one does. After much testing they seemed to be exactly the same. So, after a good deal of thought, I decided to modify the fuel system so that the pump's at the front of the car, and closer to the carbs. I don't really know why this would be any better but there are definitely other cars that work like this.
With luck I can manage to do a bit of testing before the next race so I will at least know if it works like this.
Finally, I was a bit alarmed at the temperatures at Thruxton. In the one and only really dry practice the oil temperature was up to 120° which is really a bit high. In fact, it's almost as if the oil cooler isn't working?
However, one thing I've been meaning to do for a while is to increase the amount of ducting at the front of the car. So, I arranged for another sheet of Correx to be put under the radiators. In fact, the water radiator actually sticks down a bit too low so I had to cut a hole in the Correx.
In fact, the water temperature seems to stay pretty low so I've been wondering about using a smaller radiator, to save a bit of weight. It would probably mean that I could get rid of that hole too...
Carrying on the cooling theme, I decided to try shrouding the oil cooler a bit to see if that would reduce the temperature. Mind you, I'm also thinking about just taking the oil cooler out. There's a view that 120° is fine really. It's looking like the weather for the races at Brands this weekend will be pretty good to it's a good chance to see how well the cooling works.
I decided to do this with some more Correx. It's amazing stuff, I've just discovered a whole bunch of stuff on the 'net about using Correx for aeromodels. I did wonder whether it would get too hot but the specified melting point is OK.
In theory this shroud should help eliminate the dead zone between the two radiators. However, the gap's only about 15mm so it may not have any effect.
If not I'll probably try junking the oil cooler.
I'm just about set for the racing at the weekend now. There are two races, both on Saturday. What's more, they've separated class C from the rest which is good. The only problem is all of RGB has to qualify together so that probably means that qualifying will be even more frenetic than it usually is at Brands. As there's two races we have to set two lap times too.
Well, for all those people who moaned at me about the lateness of my last update, here's one that's actually less than a week late! Nag, nag, nag...
Anyway, we were back to Brands Hatch again and this time the weather forecast was that it was going to be hot! I was going to say that that makes a nice change. However, as it turned out it was kind of my undoing. There were two races this weekend and in a way there's not too much to say as it was not too eventful. To be honest, I didn't really go anything like as well as I would have liked: I seem to have fallen off my perch somehow or other. What I need is some more testing time as I'm sort of levelling out to some extent.
Before this meeting my fastest time around Brands was a 54.7 which was the result of just about my only serious qualifying lap. Apart from that the only times of notes have been mid 55s which isn't anything to write home about. I guess it's true, though, that in general my times were about 1 second quicker than they were earlier in the year, although that could easily be because it was such warm day and the tyres were sticking better.
Anyway, we got to the circuit at about 1900 on Friday evening and grabbed a garage and set about setting the car up. We had to sign on at 0730 on the Saturday morning in order to make scrutineering at 0745. As we were in the garages we had the odd procedure of driving the race cars across the circuit, parking them in the scrutineering queue and then signing on. Kind of the wrong way round.
Anyway, that was largely uneventful and eventually, I got to the assembly area, trying to nab a place near the front of the queue as this was bound to be a frenetic process. For some reason they held us for ages in the assembly area and then in the pitlane.
Once out on the circuit it was indeed ridiculously frenetic. What's more it was already pretty hot and the circuit was very slippy. People who had been testing the day before (I couldn't get in) said that it had got slower through the day so presumably the same thing would happen today.
I essentially spent all of qualifying trying to find a decent lap. I didn't get a single clear one although it did get a bit clearer towards the end, probably because quite a few people had left the circuit. Adrian, for example, just wanted to get some sort of time, any sort of time, and then wait for the races.
In the event my FL was 54.83, with second best lap of 55.02. I just know that I could have gone much faster than this too. Mind you, the theoretical FL was just 54.43 so perhaps there wasn't too much in it. In retrospect I'm just too nice during qualifying, and during the races too, come to that, as I make sure I don't get in other people's way and end up not setting the sort of time I can do. I shall have to fix this...
After that we sat around in the sun, trying not to get too hot and waiting for the race time to come around. Eventually, we formed up on the grid in blazing sunshine and we were off! I got past Chris and Martin R at the start and then Martin braked later into Paddock than me, no surprise there, and I was blocked by Pete Rope who was, for the 875th time this season, spinning in front of me. I dropped back a bit but managed to get up the inside of Martin into Druids. Unfortunately, I couldn't completely get past him so we went around GH bend side by side.
At that point I must have lost track of my senses as I tried to go round Surtees at his side too, albeit at the speed I would have done on the line proper. Not surprisingly I ended up on the grass and had an interesting few moments trying to avoid hurtling back onto the black stuff in front of someone else. I nearly succeeded too, although contact was avoided.
After that I set to and had a fun time passing a few people and then got into a big dice with Chris Seaman who had by this time caught up again. We spent about 3 laps passing and repassing each other which was just fantastic fun until he dropped back, apparently with something wrong with his gearbox. Chris ought to be way quicker than me, he won this race back in April, so he was obviously being held up anyway. All the same, it was fun.
After that I just concentrated with catching up the people who had passed me earlier, with not too much success. I suspect that the reason for this was that the car was getting very hot and it's a known issue with blade engines that as they get hotter they produce less power. More worrying, perhaps, was that the oil temperature was up to about 130 degrees which was rather worrying.
So, during the interval I took off the ducting that I'd put on recently, as perhaps that was actually making things worse. In retrospect this was a really daft decision.
When the next race came around they had combined the class A and C races because some chap in one of the Austin 7 racers had rolled it and they took a long time extricating him from the wreckage. Apparently he's "a bit mangled" but fundamentally OK. That's good as I must admit that we were all fearing the worst.
I'm not sure how many readers have seen them, but there's no way on this earth I'd get into one of those Austin 7 racers. No roll cage, no seat belts and an alarming tendency to tip over because of the high CoG don't, to me, add up to much sense. However, if that's what people want to do then it's fine by me as the alternative is legislating any even vaguely risky activity out of existence.
The second race was not that eventful. I got a decent start and then got into the inevitable dice with Colin, although I never managed to actually pass him. We got blasted past by some of the badly qualified class As and it looked like we were going to end up crossing the line just after each other when my oil temperature got up to 150°! That was clearly a bad idea and I reluctantly, as I hadn't yet caught Adrian, DNFed.
Eagle eyed readers will not that this gauge doesn't even read to 150°. However, the needle was pointing vertically downwards when I stopped which is comfortably beyond 140 and far too hot for comfort.
So, that's the first ever mechanical DNF that I've had, and that just through caution. I have to do some work though on sorting this. Not too sure how at the moment although I've got a couple of ideas.
So, next races are at Pembrey in 5 weeks time. Might have to find some other way of playing the meantime though. First thing, though, is going to be to change the oil again (I changed the current lot before this meeting) and look into what I can do to improve the cooling. My current thoughts are that I need to improve the way that the exhaust from the radiators works. It was clear at the weekend that a lot of it was going up the centre tunnel (as it got very hot) and that doesn't seem the best way to do it.
So, in the break before the next race I need to do something about the cooling. My current thoughts are that the problem is really to do with exhausting the hot air from inside the engine bay. Since I panelled in the bottom of the bay over the winter there's a lot fewer places for the hot air to go. One thing I did notice at the weekend was how hot the tunnel got. It was close to burning my leg in one of the races and that obviously means that a lot of hot air was trying to go down the tunnel, which is of course mostly blocked off by diff, propshaft and centre bearing.
So, one strategy is to reinstate the shrouding around the radiators, which in retrospect was doing something, and to arrange for a better exhaust from the engine compartment. It's not totally clear how to do this. One possibility is to cut some holes in the side of the bonnet, where the stickers are in the photo. There's all sorts of RGB regs about where holes are allowed to be in the bonnet. In many places they have to be blocked off by 1mm mesh, which would allow sod all air through. However, I think that at the side there's a chance to put some holes that are not completely obscured by super-fine mesh. I guess I ought to check the blue book first.
The other thing that may well change this is that I want to experiment with the standard Honda airbox. Using such a thing would mean that I should be able to remove the hole in the front of the scoop. To be honest I'm not entirely sure why it's there anyway, other than some notion that it might be worth it for some sort of airbox that I was thinking about at the time. It's possible that having this hole is actually pressurising the inside of the bonnet and reducing flow through the radiators anyway.
So, that sounds like more GRP fiddling and spraying coming up... I've got slightly less time than I thought though in that I've signed up for some other races at the Anglesey circuit on the weekend of July 8th. If nothing else, that'll give me a chance to try a few things out.
Not exactly an unusual state of affairs, but discomfiting anyway.
One of the things that I decided I ought to do was to change the oil, having attempted to break it at Brands. So, I drained it out the other day. Looking at it, it seemed fine really. You can tell when oil's really too old as it actually feels less "slippery". However, this was fine. Still, it seemed sensible to change it. So, I bought some new stuff and started filling the sump.
Then I noticed this.
This is the same oil temperature gauge as shown above. Since I took that photo I haven't touched the car. However, since that time the gauge has decided to move so that it's displaying 50°, rather sitting on the end stop at 40° as it is above.
Presumably by making the needle go all the way around until it was pointing straight down I've broken it. Odd that it should just move. All the same, I've ordered a new one and I'll fit it soon. The annoying this is that I'll have to drain all the oil out of the sump again (as the sender's fitted in the sump). So, I need to find some sort of clean container that I can drain it into. That might be difficult in my garage...
I've bought another set of dynojets and fitted them to these carbs. This time, though, I haven't blocked off the air corrector which I think is the thing that makes the current carbs not work with the airbox. I've also fitted the throttle cable and the connector that I need for the throttle position sensor.
So, hopefully I can try this this weekend and do some minimal setup which will just be the idle mixture and balancing. I do worry that the carbs are not going to allow me to get a decent balance though.
In the meantime I've been setting up future events. I've not got the Anglesey weekend set up to include a trackday, a test day and two races. (Although I've sent off the entry form but not received anything back yet from the BARC.) I've also booked testing for the next meeting at Pembrey.
There's also an attempt being made by some of us RGBers to get a team together for the Birkett which is a six hour relay race at Silverstone which is traditionally the last race meeting of the 750 motor club year. It's handicapped in some mysterious way which means all sorts of cars are out at the same time. Don't know whether we'll get in though, the entry's always oversubscribed.
I'd ordered a new oil temperature gauge so at the weekend the first job was to take out the old one. This is pretty tricky due to the permanently fixed capillary in mechanical instruments and involved much cutting of cable ties.
I got it out though and I thought I'd check it to see if smashing the needle against the end stops had indeed done it some damage. So, I boiled up some water and dunked the sender in there.
This is what the gauge said, which looks like about 117° to me. Seems like a good call to buy a new gauge.
So, having justified the expense I plumbed in the new gauge and ran the engine for a short while to check that it did actually read something and that that was vaguely sensible.
With that done it was back to fiddling with carbs. I had this notion that it'd be nice to experiment over the Anglesey weekend with airboxes and so on. So, I finished fiddling about with throttle cables and the like and put the new (well, rather old) carbs on the engine.
Then it was time to start it. However, it didn't want to play ball. I spent ages fiddling about and finally managed to get it run very poorly. I'm not even sure what the problem was, but I suspect that there's still a lot of dried up petrol clag still sitting in various corners of the carbs and this is just making them work very poorly. Perhaps I just need to dunk them in a vat of carb cleaner and leave them there for a week?
Anyway, after some time spent faffing about I gave up and went back to the old ones, which worked fine.
So, I was back to real problem: cooling. I've been thinking about this for ages and it seems to me that the fundamentals of the problem must be that the radiators just aren't working too well. This is probably due to the way that air has to exit from the back of the radiators. Since I panelled in the floor it's clear that there's many fewer ways for the hot air to escape. The real solution is probably to duct the radiator outlet to the top of the bonnet, in much the same way that the ducted nose did on the nose of my Westfield many years ago.
However, for now I just don't have the time to do that. If nothing else there's a huge amount of suspension in the way. There are a couple of other RGBers who have done this so I'll probably try and have a more careful look at their cars when we're in Pembrey.
For now, I've decided to just chop some additional vents in the bonnet which is what these holes are. (The little yellow splodge, by the way, is where some of the paint came off when I pulled off the MDS battery sponsorship sticker that used to be here.) These holes are carefully low down in the area where you are allowed to have holes that aren't just forward facing. At least that's how I read the regs. The other thing I might do is to block up the inlet on the air scoop. When I made this I originally had a plan to make some sort of airbox to use that as the inlet. That's turned out to be a rather forlorn hope and it may be that it's just helping to pressurise the bonnet. Of course, it could be helping to provide the carbs with cool air, which is bound to be helpful. Hence I'll make up some sort of blanking plate and just try it at the Anglesey tests.
I've actually considered completely removing the oil cooler and relying on the water/oil intercooler that's in the engine as standard. The assumption is that if the water cooling is working OK (which it wasn't at Brands) then the oil must be OK. If nothing else, that would save a couple of kilograms and remove the number of places where hot oil could squirt out. Again, that'd be something to try at Anglesey if there's time as it's pretty easy to completely remove the oil cooler and the associated plumbing.