pedrosixfour Posted June 13, 2014 Share Posted June 13, 2014 Most of the big number chasers get pushed by an ordinary road vehicle to about 80mph as they're geared so high they can't move from a dead stop under their own steam. Quote Link to comment Share on other sites More sharing options...
Guest Nicholas Posted June 13, 2014 Share Posted June 13, 2014 Most of the big number chasers get pushed by an ordinary road vehicle to about 80mph as they're geared so high they can't move from a dead stop under their own steam. I believe you can do around 230/240/250 with a 1300/1400/1500hp supra and not suffer any issues to 80mph Quote Link to comment Share on other sites More sharing options...
pedrosixfour Posted June 13, 2014 Share Posted June 13, 2014 And I believe I said big numbers. Quote Link to comment Share on other sites More sharing options...
Scott Posted June 14, 2014 Share Posted June 14, 2014 Well mine's an auto, and has beaten 2 400bhp + cars, 1 of which was a 6speed, the other a W58. They must have been under the quoted figure or yours must be over the quoted figure. I've never had an auto TT be able to pull harder than me on a rolling straight. I was running 1.0bar with a Mines ECU and I out pulled an auto running 1.2bar on a Mines ECU. My boost controller wasn't configured correctly, hence why I was down a little on power. The only advantage I would have had, mechanically, was that my 1st turbo would hit 1.0bar too (an anomaly with how my VSVs were setup). Fact is.... the auto saps power. There is no denying this. You will loose at least 5% to the wheels due to the additional transmission losses. This effectively means that, even with the same engine HP, an auto will have 5% less power/torque. The reason for the 6spd requirement isn't just the power sapping of an auto box though. I believe, or I should say I have read, that the ratios are much better to get you up to that speed. It makes sense too, 4 gears in an auto means that once you are in OD it's having to pull really hard to increase the speed. 6 gears makes the increase in speed easier/less torque required to actually accelerate the box. Again I could be wrong here, but I believe if the WHP is the same and the drag co-efficient is the same then the actual top speed will be the same regardless of gearbox. The time taken to get there will be significant though, due to the transmission losses. This is why auto's will generally be slower at accelerating top end than the manual equivalent. Quote Link to comment Share on other sites More sharing options...
Mcdade Posted June 14, 2014 Share Posted June 14, 2014 Well mine's an auto, and has beaten 2 400bhp + cars, 1 of which was a 6speed, the other a W58. I know this is off topic guys Nd i apologise, but could you pm me benjy, interested in your car Quote Link to comment Share on other sites More sharing options...
fastcar Posted June 14, 2014 Share Posted June 14, 2014 They must have been under the quoted figure or yours must be over the quoted figure. I've never had an auto TT be able to pull harder than me on a rolling straight. I was running 1.0bar with a Mines ECU and I out pulled an auto running 1.2bar on a Mines ECU. My boost controller wasn't configured correctly, hence why I was down a little on power. The only advantage I would have had, mechanically, was that my 1st turbo would hit 1.0bar too (an anomaly with how my VSVs were setup). Fact is.... the auto saps power. There is no denying this. You will loose at least 5% to the wheels due to the additional transmission losses. This effectively means that, even with the same engine HP, an auto will have 5% less power/torque. The reason for the 6spd requirement isn't just the power sapping of an auto box though. I believe, or I should say I have read, that the ratios are much better to get you up to that speed. It makes sense too, 4 gears in an auto means that once you are in OD it's having to pull really hard to increase the speed. 6 gears makes the increase in speed easier/less torque required to actually accelerate the box. Again I could be wrong here, but I believe if the WHP is the same and the drag co-efficient is the same then the actual top speed will be the same regardless of gearbox. The time taken to get there will be significant though, due to the transmission losses. This is why auto's will generally be slower at accelerating top end than the manual equivalent. Have to agree here my 6 speed BPU is much faster after about 120mph then a friends BPU auto running around the same power. From a standing start he has the legs on me but once into about 4th gear I pull it back and go ahead. I think once you get to 200mph in a car you then need something like another 100bhp per 10mph or something like that. I watched a documentary on the design of the veyron and they said once they broke the 230mph they had a choice of either upping the power of the engine or playing with the aero dynamics to make it slip through the atmosphere so they played with aero to achieve this! Even though the supra is quite an aero dynamic car I would think there would have to be over 3000bhp to achieve it. Then I don't think a standard bodyshell would take that sort of power and would need heavy modification to stop it twisting in half. So at some point it would stop being a supra and just become an outer shell on some kind of high tech space frame! Quote Link to comment Share on other sites More sharing options...
mellonman Posted June 15, 2014 Share Posted June 15, 2014 The reason the auto zaps the power is in the torque converter as they are fluid driven, so they are not actually mechanically connected in any way between the engine and gear box, The fluid from the engine spinning spide of the tc is forced into the gearbox side making it spin, The only reason an auto would/is quicker at drag racing is it eliminates user error and give a perfict launch everytime, ( slightly slower) but consistently perfict launch and every gear change Quote Link to comment Share on other sites More sharing options...
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