mattyb Donating Members 1,097 Member For: 16y 9m 23d Gender: Male Location: Gold Coast, QLD Posted 12/03/10 02:24 PM Share Posted 12/03/10 02:24 PM Hey guys,Sitting here with a mate drinking and we're talking about tuning in 4th gear with a zf 6 speed compared to tuning in 3rd gear with a zf 6 speed.I am running 360rwkw in my car, tuned in third.My mate checked up on the net and apparently 3rd gear runs a ratio of 1.52:1 compared with 4th gear running 1.14:1can anyone out there please explain the differences. I'm going to continue using my tuner as I am extremely confident in what he has done with my car. My mate is confused as back in the day he said cars used to be tuned as close to a 1:1 ratio as possible. Does this mean my car was actually putting ont more power at the wheels than I thought? if so cool! it's just something I'm not educated on so I thought I'd ask.Cheers, look forward to some of the reputable tuners giving their explanations. Link to comment Share on other sites More sharing options...
Adam Here since the start... Lifetime Members 10,282 Member For: 21y 11m 11d Gender: Male Location: Victoria Posted 12/03/10 10:59 PM Share Posted 12/03/10 10:59 PM It makes no difference to power.Torque at the wheels, wheel speed and therefore dyno speed will be different because of the different ratios. Link to comment Share on other sites More sharing options...
ratter Member 6,793 Member For: 18y 10m 10d Gender: Male Location: @ my laptop Posted 12/03/10 11:44 PM Share Posted 12/03/10 11:44 PM I have had this discussion several times with my dyno manufacturer.Ther gear ratio is not important as most think when it comes to doing a dyno run, power should remain constant although torque will go up with the lower gears.Running in a 2nd as opposed to 4th for example will create issues with traction because of the higher torque and quicker acceleration rate.Some dynos may be maxed out speed wise if a car is run in 4th gear due to the higher road speed, my dyno will spin uo to 240 kmh, some will only go to 200 kmh and 4th gear may exceed that.Now what we have found in these 6 speeds is they normally make more power in 3rd than they do in 4th, when stock or slightly modded.I have asked my dyno guy about this one also and he puts it down to windage loss from the higher speeds, as the wheels turn they are acting partially like a fan and push air, the faster they turn the more they push, a standard'ish type car will start to show this loss in 4th gear, so 3rd gear may show they make more power than in 4th even though nothing is different on the car. when the car is making some decent power it can make enough power for this windage loss to not show as a problem so the results will be closer beteween 3rd and 4th gears although there will still be a torque difference.We normally dyno these 6 speeds in 4th gear Link to comment Share on other sites More sharing options...
Wenier Donating Members 1,736 Member For: 15y 2m 19d Gender: Male Location: Christchurch, New Zealand Posted 13/03/10 02:27 AM Share Posted 13/03/10 02:27 AM The main thing is if you are going to compare results you should compare them with the same gear. So say he decides to use 4th this time get a base run first so you know the difference between 3rd and 4th (should only be torque) and then compare from there. Link to comment Share on other sites More sharing options...
mattyb Donating Members 1,097 Member For: 16y 9m 23d Gender: Male Location: Gold Coast, QLD Posted 13/03/10 07:20 AM Author Share Posted 13/03/10 07:20 AM cheers guys. Link to comment Share on other sites More sharing options...
icer Banned 2,335 Member For: 15y 8m 20d Gender: Male Location: Aspendale, Vic. Posted 13/03/10 08:25 AM Share Posted 13/03/10 08:25 AM 2 same car same dyno it 3rd and in 4th would be nice to see how it differs Link to comment Share on other sites More sharing options...
HI PSI Member 1,586 Member For: 18y 10m 12d Gender: Male Location: Central Queensland Posted 13/03/10 09:35 AM Share Posted 13/03/10 09:35 AM I wil be putting mine on the dyno in the next few days.. I have a 6 speed manual.. What gear should I use? I will do a comparison when it's on there... Link to comment Share on other sites More sharing options...
Wenier Donating Members 1,736 Member For: 15y 2m 19d Gender: Male Location: Christchurch, New Zealand Posted 13/03/10 12:44 PM Share Posted 13/03/10 12:44 PM Your dyno guy will decide what gear, just make sure you always use that same gear after that. Link to comment Share on other sites More sharing options...
PHANTMXR6 It's not a MKI! Member 1,742 Member For: 16y 9m 18d Gender: Male Location: Earth Posted 13/03/10 12:56 PM Share Posted 13/03/10 12:56 PM If it's a manual, 4th gear will be used. Link to comment Share on other sites More sharing options...
Rootster Just a large member member Silver Donating Members 3,125 Member For: 16y 5m 21d Gender: Male Location: sydney Posted 13/03/10 01:44 PM Share Posted 13/03/10 01:44 PM had mine on the dyno today.....4th gear was used....manual gearbox.... Link to comment Share on other sites More sharing options...
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