Discussion
...after 5-6 months of development, we are pleased to reveal the 2013 specification MacG Racing Ultima GTR! We have completed a host of updates to the car, which have been focussed on reliability, with the remainder being a balance between driveability and performance.
Word of warning, this is a 'cup of tea and a biscuit' sort of post!
The first stage was to strip the car back to the chassis (we left the loom in place)and cut our the section under the dash and replace it with 1.5" T45 tubing to improve stiffness - we had issues with the screen fracturing as soon as we went round a fast corner after it was chipped. Interestingly one of the tubes we removed was very bent! Apologies for the poor quality photo, was taken with a dirty phone...
We also put in plenty more bracing round the cab and in the engine bay (ironically the engine bay bracing is very similar to the Factory updated chassis) but with some additional removable braces too.
We also cut out the lowered floor section and replaced with a flat sheet, as the old one was heavily damaged from kerbs, but although the replacement lost us 30mm of headroom, it allows us to reconfigure our flat floor to improve downforce and reduce weight. The roof was also braced too, which has the added benefit of improving GPS and radio reception!
The electronics were also updated - the Race Technology Dash has been replaced with a Motec SDL3 (provided by Nathan at Race Data Systems), which improves our logging capability and allows us to run drive by wire, map switching, autoblip on downshift and traction control along with a host of other clever systems. The dash area was also simplified, and the seat, shifter and wheel slightly repositioned to improve ergonomics.
The shift cable has been replaced with a shift rod to improve shift quality.
The front uprights have been replaced with heavier castings which significantly bigger bearings, which currently retain the standard geometry, however the next stage of development will involve adjusting the front geo and ride height to improve turn in.
The rears have been completely redesigned to house the tripod joints in the spindles themselves, allowing for longer driveshafts which will be able to absorb shock loads. The bearings are 100mm ID so the tripod joints sit inside them. The wishbones have been lengthened on the rear too. New wishbones on the production line:
Front aero has been increased too - ducting has opened up significantly at the back of the wheel arch which now drives the side skirts, and larger louvres have been fitted to the front clam above the arches.
Canards/dive plains have been added to the front - these can be easily removed to adjust aero balance:
Previously we lowered the floor level by fitting a false floor manufactured from a GRP sandwich with a foam core, based with marine ply. We have now removed this in the centre of the car and replaced under the sideskirts with a lightweight alloy frame and marine play sideskirts - this creates a tunnel in the centre of the car which should improve downforce further and drive the splitter harder. The centre section under the cab is now 35mm higher than the splitter and sidepods - there is a composite diffuser section between splitter and the tunnel to maintain attached flow. Weight saving approximately 15kg.
Larger rear wing end plates improve rear downforce with an insignificant drag penalty, and further opening up of the rear to improve cooling:
A high flow airbox was designed in house - we moved to the standard DBW throttle body from the 92mm cable throttle body we used previously, equating to around 5% reduction in airflow - highly noticeable when running the engine in the garage as the existing map ran very rich, however the increased airflow at speed will significantly increase power - and we can control/increase fuelling accordingly by compensating for airbox pressure. It also houses a filter that is over double the surface area of the standard filter to maximise flow and still allow for build up of filth in endurance races:
Rear view camera added to avoid glare during night stints, which caused a crash at last year's 24hr:
A new set of back boxes will shortly be made to increase power - the current set were specified at 102dB and are slightly restrictive to flow. We can run upto 105dB in 'normal' (not 24hr) races, so the new back boxes will allow for this, and have a larger bore as a result. The bore was reduced from the standard 3.5" to reduce the noise. The road cars do not have this problem as it runs cats which significantly reduces the noise - we had endless issues with the cats blowing out so moved away from them.
There are a host of other updates which are less significant. We have aimed to remove all the issues seen previously and we hope we have done that. We will be testing over the next few weeks, so will keep the updates coming. The next race is on 27th July at Brands Hatch GP - so we are hoping for a good one!
Word of warning, this is a 'cup of tea and a biscuit' sort of post!
The first stage was to strip the car back to the chassis (we left the loom in place)and cut our the section under the dash and replace it with 1.5" T45 tubing to improve stiffness - we had issues with the screen fracturing as soon as we went round a fast corner after it was chipped. Interestingly one of the tubes we removed was very bent! Apologies for the poor quality photo, was taken with a dirty phone...
We also put in plenty more bracing round the cab and in the engine bay (ironically the engine bay bracing is very similar to the Factory updated chassis) but with some additional removable braces too.
We also cut out the lowered floor section and replaced with a flat sheet, as the old one was heavily damaged from kerbs, but although the replacement lost us 30mm of headroom, it allows us to reconfigure our flat floor to improve downforce and reduce weight. The roof was also braced too, which has the added benefit of improving GPS and radio reception!
The electronics were also updated - the Race Technology Dash has been replaced with a Motec SDL3 (provided by Nathan at Race Data Systems), which improves our logging capability and allows us to run drive by wire, map switching, autoblip on downshift and traction control along with a host of other clever systems. The dash area was also simplified, and the seat, shifter and wheel slightly repositioned to improve ergonomics.
The shift cable has been replaced with a shift rod to improve shift quality.
The front uprights have been replaced with heavier castings which significantly bigger bearings, which currently retain the standard geometry, however the next stage of development will involve adjusting the front geo and ride height to improve turn in.
The rears have been completely redesigned to house the tripod joints in the spindles themselves, allowing for longer driveshafts which will be able to absorb shock loads. The bearings are 100mm ID so the tripod joints sit inside them. The wishbones have been lengthened on the rear too. New wishbones on the production line:
Front aero has been increased too - ducting has opened up significantly at the back of the wheel arch which now drives the side skirts, and larger louvres have been fitted to the front clam above the arches.
Canards/dive plains have been added to the front - these can be easily removed to adjust aero balance:
Previously we lowered the floor level by fitting a false floor manufactured from a GRP sandwich with a foam core, based with marine ply. We have now removed this in the centre of the car and replaced under the sideskirts with a lightweight alloy frame and marine play sideskirts - this creates a tunnel in the centre of the car which should improve downforce further and drive the splitter harder. The centre section under the cab is now 35mm higher than the splitter and sidepods - there is a composite diffuser section between splitter and the tunnel to maintain attached flow. Weight saving approximately 15kg.
Larger rear wing end plates improve rear downforce with an insignificant drag penalty, and further opening up of the rear to improve cooling:
A high flow airbox was designed in house - we moved to the standard DBW throttle body from the 92mm cable throttle body we used previously, equating to around 5% reduction in airflow - highly noticeable when running the engine in the garage as the existing map ran very rich, however the increased airflow at speed will significantly increase power - and we can control/increase fuelling accordingly by compensating for airbox pressure. It also houses a filter that is over double the surface area of the standard filter to maximise flow and still allow for build up of filth in endurance races:
Rear view camera added to avoid glare during night stints, which caused a crash at last year's 24hr:
A new set of back boxes will shortly be made to increase power - the current set were specified at 102dB and are slightly restrictive to flow. We can run upto 105dB in 'normal' (not 24hr) races, so the new back boxes will allow for this, and have a larger bore as a result. The bore was reduced from the standard 3.5" to reduce the noise. The road cars do not have this problem as it runs cats which significantly reduces the noise - we had endless issues with the cats blowing out so moved away from them.
There are a host of other updates which are less significant. We have aimed to remove all the issues seen previously and we hope we have done that. We will be testing over the next few weeks, so will keep the updates coming. The next race is on 27th July at Brands Hatch GP - so we are hoping for a good one!
wow wow wow wow.. looking good.
when are you next at Oulton Park i ll come and say hello again.
interesting about your exhaust.. would like to know more about the new one.. i see the silencer still bolts straight onto 4 into 1 .. been advised so many times need at least 10inc pipe inbetween,, for hp gains.
dom
when are you next at Oulton Park i ll come and say hello again.
interesting about your exhaust.. would like to know more about the new one.. i see the silencer still bolts straight onto 4 into 1 .. been advised so many times need at least 10inc pipe inbetween,, for hp gains.
dom
Hi Guys, thanks for all the comments - there has been plenty fo effort put in all round so we are eager to see how testing goes.
Dom - the exhausts will basically be as big as we can fit in - whilst there is some 'ideal' geometry, it makes slight variations to the torque/power curves, so nothing drastic. The main reason for the loss we have is because the bore is 2.5" rather than the recommended 3.5", which makes it much quieter but loses power too. We chose this as it satisfied the 24hr regulations, but since there is no 24hr this year, we may as well get the bigger system.
Chris - we are using a pair of 100mm ID deep groove ball bearings (the same as in our diff in the Albins box) in the rear uprights - we were slightly hesitant about moving away from taper roller bearings but it is the bearing of choice in V8 supercars, and since they weight several hundred tons and have massive cornering forces they should be fine - they are designed to run with the tripod style driveshafts at the moment which we use with the ALbins ST6 transmission, however there is no reason they could not be modified to suit the Porsche CV/Lobro type joints. Pic below:
Jonny - please abide by the Ts and Cs in terms of forum advertising - thanks
Dom - the exhausts will basically be as big as we can fit in - whilst there is some 'ideal' geometry, it makes slight variations to the torque/power curves, so nothing drastic. The main reason for the loss we have is because the bore is 2.5" rather than the recommended 3.5", which makes it much quieter but loses power too. We chose this as it satisfied the 24hr regulations, but since there is no 24hr this year, we may as well get the bigger system.
Chris - we are using a pair of 100mm ID deep groove ball bearings (the same as in our diff in the Albins box) in the rear uprights - we were slightly hesitant about moving away from taper roller bearings but it is the bearing of choice in V8 supercars, and since they weight several hundred tons and have massive cornering forces they should be fine - they are designed to run with the tripod style driveshafts at the moment which we use with the ALbins ST6 transmission, however there is no reason they could not be modified to suit the Porsche CV/Lobro type joints. Pic below:
Edited by Stig on Tuesday 28th May 12:17
Jonny - please abide by the Ts and Cs in terms of forum advertising - thanks
Edited by Stig on Tuesday 28th May 12:18
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