Britcar Round 7 - Snetterton
Discussion
Hi all,
We are competing this coming weekend in the 7th round of the 2011 Britcar British Endurance Championship at Snetterton near Norwich. We have stepped out of the last two rounds in order to complete some further testing on the car which we had been lacking, and to carry out some development work for this round and the Britcar Silverstone 24hr in October. We have carried out a lot of work on the car since Thruxton and have made some aero improvements as well as chassis, suspension, electrical and packaging developments since we last raced.
We will have up to the minute race updates are available on our Facebook and Twitter pages. Live timing for the event can be found at the link below. The race is 3 hours long and the race start time is 12:25 on Sunday.
Live timing:
http://www.tsl-timing.com/eerc/livetimingBritcar.h...
Full Timetable:
http://britcar24hr.co.uk/cms/e107_plugins/content/...
We have a very strong driver lineup with myself and former British GT Champion, Jamie Smyth, driving, and the car should suit the circuit well, so fingers crossed for a good result. There will also be updates and pictures on our website in due course www.macgracing.co.uk. If anyone is going to the event please come by and see us!
Jonny
We are competing this coming weekend in the 7th round of the 2011 Britcar British Endurance Championship at Snetterton near Norwich. We have stepped out of the last two rounds in order to complete some further testing on the car which we had been lacking, and to carry out some development work for this round and the Britcar Silverstone 24hr in October. We have carried out a lot of work on the car since Thruxton and have made some aero improvements as well as chassis, suspension, electrical and packaging developments since we last raced.
We will have up to the minute race updates are available on our Facebook and Twitter pages. Live timing for the event can be found at the link below. The race is 3 hours long and the race start time is 12:25 on Sunday.
Live timing:
http://www.tsl-timing.com/eerc/livetimingBritcar.h...
Full Timetable:
http://britcar24hr.co.uk/cms/e107_plugins/content/...
We have a very strong driver lineup with myself and former British GT Champion, Jamie Smyth, driving, and the car should suit the circuit well, so fingers crossed for a good result. There will also be updates and pictures on our website in due course www.macgracing.co.uk. If anyone is going to the event please come by and see us!
Jonny
ezakimak said:
We use the Winrace A with the lightweight option - like this but the centre lock version:http://www.braid.es/wheels/products/competition-wh...
Jonny
Apologies - The bad news is the video from the race was lost due to a slight technical issue with the recorder - however we will get some photos up shortly.
The good news is that we got a pretty good result - 8th overall and 3rd in class.
Testing on Saturday went well, despite a broken driveshaft at the end of practice 2. We headed out for qualifying early in the session and put down a decent benchmark time to put us P2 - we then swapped drivers as both drivers have to post time. Unfortunately just as the track started to rubber-in and get considerably quicker, we had another driveshaft failure, so despite having most of the session to go we simply didn't have enough time in the 30 minutes to get it fixed - so we ended up P6 on the grid in the end. Other than the driveshafts, the car ran faultlessly and the development work we had done over the last few weeks paid dividends as the car was a big improvement over the last few outings.
I started to the race, and slipped back to 7th from the start, but quickly got back up to 4th, when there was a safety car period - the top four runners all pitted for fuel and rejoined the procession right at the back. When the race resumed, the four Class 1 cars (a Super GT Mosler, us, Ferrari 458 GT2 and another Super GT Mosler in that order) went tearing through the field whilst trying to get past one another - great stuff for the spectators! The battle continued for a few laps, with a million pounds worth of cars dicing for position inches apart - our car was running well and we could keep pace with the Moslers comfortably, once again our race pace being very good.
Around an hour in and the car started to suffer from fuel starvation slightly, cutting out on some of the prolonged turns - we pitted for a driver change and a fuel top-up, and headed out again. Jamie took over from me, and he kept up a decent pace, despite the car continuing to suffer from what seemed like fuel starvation, cutting out intermittently during some corners. This dropped us some time each lap, but we continued and kept the fuel topped up over 6 pitstops (one was also to repair some damage after a bollard was spat out from under another car and hit the splitter and brake ducting) - this dropped us back but kept us running. As above we finished 8th overall and 3rd in class, despite the fuelling issues.
Now we just need to understand what is causing the problems - we think it is likely to be an intermittent connection on the fuel pumps or related circuitry, maybe caused by debris - there was a lot of it about! Other than that, the car ran beautifully, the braking has now been setup very well and the handling is vastly improved with our suspension modifications. Now we are looking forward to the last round at Brands Hatch in November and even possibly the 24hour in October.
Gallery to follow.
Jonny
The good news is that we got a pretty good result - 8th overall and 3rd in class.
Testing on Saturday went well, despite a broken driveshaft at the end of practice 2. We headed out for qualifying early in the session and put down a decent benchmark time to put us P2 - we then swapped drivers as both drivers have to post time. Unfortunately just as the track started to rubber-in and get considerably quicker, we had another driveshaft failure, so despite having most of the session to go we simply didn't have enough time in the 30 minutes to get it fixed - so we ended up P6 on the grid in the end. Other than the driveshafts, the car ran faultlessly and the development work we had done over the last few weeks paid dividends as the car was a big improvement over the last few outings.
I started to the race, and slipped back to 7th from the start, but quickly got back up to 4th, when there was a safety car period - the top four runners all pitted for fuel and rejoined the procession right at the back. When the race resumed, the four Class 1 cars (a Super GT Mosler, us, Ferrari 458 GT2 and another Super GT Mosler in that order) went tearing through the field whilst trying to get past one another - great stuff for the spectators! The battle continued for a few laps, with a million pounds worth of cars dicing for position inches apart - our car was running well and we could keep pace with the Moslers comfortably, once again our race pace being very good.
Around an hour in and the car started to suffer from fuel starvation slightly, cutting out on some of the prolonged turns - we pitted for a driver change and a fuel top-up, and headed out again. Jamie took over from me, and he kept up a decent pace, despite the car continuing to suffer from what seemed like fuel starvation, cutting out intermittently during some corners. This dropped us some time each lap, but we continued and kept the fuel topped up over 6 pitstops (one was also to repair some damage after a bollard was spat out from under another car and hit the splitter and brake ducting) - this dropped us back but kept us running. As above we finished 8th overall and 3rd in class, despite the fuelling issues.
Now we just need to understand what is causing the problems - we think it is likely to be an intermittent connection on the fuel pumps or related circuitry, maybe caused by debris - there was a lot of it about! Other than that, the car ran beautifully, the braking has now been setup very well and the handling is vastly improved with our suspension modifications. Now we are looking forward to the last round at Brands Hatch in November and even possibly the 24hour in October.
Gallery to follow.
Jonny
I think they simply aren't up to the job - we got some uprated ones but they didn't last too long either. We adjusted a few things on the car for the race, fitted the fresh pair and kept out of 2nd which helped a lot. We also keep off the kerbs and are careful not to spin up the rear end to avoid stressing them.
Jonny
Jonny
MarkWebb said:
You are of course correct Ewe. If problem occurs immediately after refueling then its not overheating fuel. However Kinsler have written an article about this problem and the solution is to fit a pressure regulator in the return fuel line. This has been 100% effective in my case.
Is that return from the fuel rail or return from the swirl pot to tank?Steve
MarkWebb said:
Jommy give some thought to the possibility of overheating fuel. When it gets too hot it can cause fuel to evaporate in the suction side of the duel pump.
Funnily enough we did wonder about that - the presence of the new fuel would obviously cool down the overall temperature. It was a warm day, and the car was running slightly hotter than normal so it is something we have considered. I take it this is something you have suffered from?I never though of the regulator idea - sounds good. The data tells us we had total starvation of fuel - so either the pump was intermittently failing (unlikely) or it was fuel cavitation as you describe.
We will look into it and report back!
Either way we need more cooling to under the clam - it will protect items such as the gearbox and coils, as well as help us with performance. We are adding more ducting, courser mesh on the sides of the car and opening up the vents on top.
Jonny
Gallery here:
http://xynamic.photoshelter.com/gallery/2011-Britc...
Official race report here: http://britcar24hr.co.uk/cms/news.php?item.1142.18
http://xynamic.photoshelter.com/gallery/2011-Britc...
Official race report here: http://britcar24hr.co.uk/cms/news.php?item.1142.18
Edited by macgtech on Thursday 18th August 22:18
Paul
[/quote]
A diagram would most likely cause you more confusion as it will likely not reflect the system you have.
Your high pressure fuel system has a HP pump and HP regulator being fed from a swirl pot. Unused fuel is returned to the pot.
The system has a low pressure pump to keep the swirl pot full and replace fuel used. There may then be a valve system to decide which tank the fuel comes from and goes back too but we will ignore that for the moment.
There is no restriction on the LP return so the swirl pot is around atmospheric pressure.
When the HP pump makes a high demand there will be low pressure on the suction side of the HP pump. This low pressure could cause cavitation in the pump as it is not able to pull the fuel through from the swirl pot fast enough.
The cure is to put a pressure regulator in the return line from the swirl pot to the tank. I will use the one left over from my Holley install which will give me 6psi. This pressure in the swirl pot will force fuel into the HP pump and therefore reduce or remove the cavitation.
Steve
[/quote]
A diagram would most likely cause you more confusion as it will likely not reflect the system you have.
Your high pressure fuel system has a HP pump and HP regulator being fed from a swirl pot. Unused fuel is returned to the pot.
The system has a low pressure pump to keep the swirl pot full and replace fuel used. There may then be a valve system to decide which tank the fuel comes from and goes back too but we will ignore that for the moment.
There is no restriction on the LP return so the swirl pot is around atmospheric pressure.
When the HP pump makes a high demand there will be low pressure on the suction side of the HP pump. This low pressure could cause cavitation in the pump as it is not able to pull the fuel through from the swirl pot fast enough.
The cure is to put a pressure regulator in the return line from the swirl pot to the tank. I will use the one left over from my Holley install which will give me 6psi. This pressure in the swirl pot will force fuel into the HP pump and therefore reduce or remove the cavitation.
Steve
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