GMA T50 Engine Choice
Discussion
read this article in Evo about the GMA T50
https://www.evo.co.uk/gma/t50
It's incredibly light at 986kg and has a V12 made by Cosworth that makes 654bhp and 345 lb/ft and sure won't be a slouch
But the article compares it's engine with another V12 made by Cosworth that's in the Valkyrie and that engine is only 28kg heavier yet produces 1000bhp and 546 lb/ft.
Can only imagine how fast the T50 would be with another 350 bhp and 200 lb/ft
https://www.evo.co.uk/gma/t50
It's incredibly light at 986kg and has a V12 made by Cosworth that makes 654bhp and 345 lb/ft and sure won't be a slouch
But the article compares it's engine with another V12 made by Cosworth that's in the Valkyrie and that engine is only 28kg heavier yet produces 1000bhp and 546 lb/ft.
Can only imagine how fast the T50 would be with another 350 bhp and 200 lb/ft
Yes, I agree the linked article does prompt that question, by juxtaposing the two engines specs.
However, Gordon Murray began by thinking of the Ferrari 250 GTO, which had a three litre V12, and whose revviness and responsiveness he loved. He then wanted to match his F1 in some measure of mid-range response, and when doing the numbers, Cosworth came back saying 4.0 litres was the smallest capacity that would achieve that, so that's what they went with. So the engine is chosen deliberately in order to achieve the subjective effects the designer wanted.
Secondarily, the evo article may well say that the Valkyrie's 6.5L engine is only 28kg heavier than the T50's 4.0L. However, that's just the engine itself. You also have to ask
- how much physically larger is the Aston engine, and how much heavier would the car become if it was that much longer?
- how much heavier a gearbox would you need to go from 345 lb/ft to 546 lb/ft, and how would that change the shift characteristic?
- how much heavier do the diff, driveshafts, etc need to be?
- how much greater cooling requirement does the 1000hp engine have? how much heavier does the radiator need to be, and how much larger the cooling ducts for airflow for this mid-mounted powerplant?
- how much more fuel does the big engine use, and do you need a larger fuel tank?
- with the higher performance and greater weight, do you need bigger brakes, and how much unsprung weight does that add?
So the conclusion is that the '28kg' extra would probably end up imposing a lot more than that in terms of secondary knock-on changes to beefier parts. This is especially true on a Gordon Murray car, where every part is designed to be just strong enough to do it's job, and no stronger, to keep the weight down - there's less margin available for upgrades than on a more run-of-the-mill car.
Thirdly, where could you use the extra 350hp? There's a limit to how much traction you can get on normal road tyres anyway, with such low weight. If you're limited by the traction control, then any extra power is moot.
So all in all I think there are sound reasons why the T50 has 'only' a four litre engine, based around the type of car it is and what the designer is aiming to achieve.
However, Gordon Murray began by thinking of the Ferrari 250 GTO, which had a three litre V12, and whose revviness and responsiveness he loved. He then wanted to match his F1 in some measure of mid-range response, and when doing the numbers, Cosworth came back saying 4.0 litres was the smallest capacity that would achieve that, so that's what they went with. So the engine is chosen deliberately in order to achieve the subjective effects the designer wanted.
Secondarily, the evo article may well say that the Valkyrie's 6.5L engine is only 28kg heavier than the T50's 4.0L. However, that's just the engine itself. You also have to ask
- how much physically larger is the Aston engine, and how much heavier would the car become if it was that much longer?
- how much heavier a gearbox would you need to go from 345 lb/ft to 546 lb/ft, and how would that change the shift characteristic?
- how much heavier do the diff, driveshafts, etc need to be?
- how much greater cooling requirement does the 1000hp engine have? how much heavier does the radiator need to be, and how much larger the cooling ducts for airflow for this mid-mounted powerplant?
- how much more fuel does the big engine use, and do you need a larger fuel tank?
- with the higher performance and greater weight, do you need bigger brakes, and how much unsprung weight does that add?
So the conclusion is that the '28kg' extra would probably end up imposing a lot more than that in terms of secondary knock-on changes to beefier parts. This is especially true on a Gordon Murray car, where every part is designed to be just strong enough to do it's job, and no stronger, to keep the weight down - there's less margin available for upgrades than on a more run-of-the-mill car.
Thirdly, where could you use the extra 350hp? There's a limit to how much traction you can get on normal road tyres anyway, with such low weight. If you're limited by the traction control, then any extra power is moot.
So all in all I think there are sound reasons why the T50 has 'only' a four litre engine, based around the type of car it is and what the designer is aiming to achieve.
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