75-80 mph in second gear !?!
Discussion
Morning Chaps,
Managed to take my Chimaera 4.0 out for a bit of a blat yesterday.
Once warm and happy, I had a bit of sport around the dual carriageways in Milton Keynes with a new F type jag, and at one point I looked down to see the speedo in between the 70 and 80 marker whilst I was in second gear.
After myself and the F Type were done I tried again to see if I had confused matters in my head, and lo and behold 70 was easily acheivable in 2nd gear, more if you wanted too.
I don't know if it's the gearing, or if the speedo is hugely out, but thought I would ask on here until I can get the oppertunity to try again with a tom tom in the car.
I borrowed the wifes Cayenne S to come to work this morning, and at 80 on the M1, i tried to shift down to see what sort of gear that would sit at 80 in, and by the time I'd put it in third it was getting very shouty (near 7000 rpm) and that's a 4.5 V8.
So, do these cars just have huge gear ratios, or is my speedo well out?
Managed to take my Chimaera 4.0 out for a bit of a blat yesterday.
Once warm and happy, I had a bit of sport around the dual carriageways in Milton Keynes with a new F type jag, and at one point I looked down to see the speedo in between the 70 and 80 marker whilst I was in second gear.
After myself and the F Type were done I tried again to see if I had confused matters in my head, and lo and behold 70 was easily acheivable in 2nd gear, more if you wanted too.
I don't know if it's the gearing, or if the speedo is hugely out, but thought I would ask on here until I can get the oppertunity to try again with a tom tom in the car.
I borrowed the wifes Cayenne S to come to work this morning, and at 80 on the M1, i tried to shift down to see what sort of gear that would sit at 80 in, and by the time I'd put it in third it was getting very shouty (near 7000 rpm) and that's a 4.5 V8.
So, do these cars just have huge gear ratios, or is my speedo well out?
Thanks for the heads up, although for me 80 really is the limit for me in the Tiv on dual carriageways anyway.
Also given the nature of the beast, and the respect I have for the car, hoofing it in a bend or a roundabout is not on my agenda. Straight line drag I think if the torque would break the traction it would be fairly early on 1000-2500rpm, I'd have thought that by the time it was 4000 plus if the wheels weren't already spinning (lost traction) it's not likely too unless you hit ice or diesel etc.
I do understand that coming off the power in a bend can also induce balance issues as a result of hefty engine breaking, however once again, lifting off at high speeds for me is mostly done in a straight line.
Also given the nature of the beast, and the respect I have for the car, hoofing it in a bend or a roundabout is not on my agenda. Straight line drag I think if the torque would break the traction it would be fairly early on 1000-2500rpm, I'd have thought that by the time it was 4000 plus if the wheels weren't already spinning (lost traction) it's not likely too unless you hit ice or diesel etc.
I do understand that coming off the power in a bend can also induce balance issues as a result of hefty engine breaking, however once again, lifting off at high speeds for me is mostly done in a straight line.
PorscheFreak said:
Morning Chaps,
Managed to take my Chimaera 4.0 out for a bit of a blat yesterday.
Once warm and happy, I had a bit of sport around the dual carriageways in Milton Keynes with a new F type jag, and at one point I looked down to see the speedo in between the 70 and 80 marker whilst I was in second gear.
After myself and the F Type were done I tried again to see if I had confused matters in my head, and lo and behold 70 was easily acheivable in 2nd gear, more if you wanted too.
I don't know if it's the gearing, or if the speedo is hugely out, but thought I would ask on here until I can get the oppertunity to try again with a tom tom in the car.
I borrowed the wifes Cayenne S to come to work this morning, and at 80 on the M1, i tried to shift down to see what sort of gear that would sit at 80 in, and by the time I'd put it in third it was getting very shouty (near 7000 rpm) and that's a 4.5 V8.
So, do these cars just have huge gear ratios, or is my speedo well out?
These cars do have fairly big gearing.Managed to take my Chimaera 4.0 out for a bit of a blat yesterday.
Once warm and happy, I had a bit of sport around the dual carriageways in Milton Keynes with a new F type jag, and at one point I looked down to see the speedo in between the 70 and 80 marker whilst I was in second gear.
After myself and the F Type were done I tried again to see if I had confused matters in my head, and lo and behold 70 was easily acheivable in 2nd gear, more if you wanted too.
I don't know if it's the gearing, or if the speedo is hugely out, but thought I would ask on here until I can get the oppertunity to try again with a tom tom in the car.
I borrowed the wifes Cayenne S to come to work this morning, and at 80 on the M1, i tried to shift down to see what sort of gear that would sit at 80 in, and by the time I'd put it in third it was getting very shouty (near 7000 rpm) and that's a 4.5 V8.
So, do these cars just have huge gear ratios, or is my speedo well out?
Find the gear ratios and use these to see what it can do.
http://www.apexgarage.com/tech/gear_ratios.shtml
msmith0592 said:
I assume the Chim and Cerbera use the same gear ratio and diff ratio.
I've put the Cerb in and at 7500 RPM in 2nd the car is doing 83.
3rd tops out at 121, 4th is 162 and 5th is 202.
In the real world you hit the top of the rev limiter at around 40mph per gear. GPS registered speeds and also with timing gear, I've seen 156mph in 4th with the rev limiter beeping and 188 in 5th just starting to hit the beeps. I've also found myself changing from 3rd to 4th at 115 at castle Coombe.I've put the Cerb in and at 7500 RPM in 2nd the car is doing 83.
3rd tops out at 121, 4th is 162 and 5th is 202.
msmith0592 said:
I assume the Chim and Cerbera use the same gear ratio and diff ratio.
I've put the Cerb in and at 7500 RPM in 2nd the car is doing 83.
3rd tops out at 121, 4th is 162 and 5th is 202.
You would need a 3.08 diff for those speeds, mine does 133 in third across the qtr line, but 202 in fifthI've put the Cerb in and at 7500 RPM in 2nd the car is doing 83.
3rd tops out at 121, 4th is 162 and 5th is 202.
ChilliWhizz said:
Pretty sure I'm only doing a tad over 60 at 6k rpm in second, but to be honest using WOT in second I'm too busy watching the rev counter and trying not to crap myself to watch the speedo 
Ditto. Tried to time a 0 - 60 once and really wanted to grab 3rd.Edited by ChilliWhizz on Friday 12th December 15:24
msmith0592 said:
I assume the Chim and Cerbera use the same gear ratio and diff ratio.
I've put the Cerb in and at 7500 RPM in 2nd the car is doing 83.
3rd tops out at 121, 4th is 162 and 5th is 202.
If the terminal velocity through aerodynamics and friction is more like 180, why bother gearing to an uttainable speed ? Surely would be better with lower gearing for better acceleration and the same real world top speed ? Or am I missing something and the Cerb actually was a 200 mph car ?I've put the Cerb in and at 7500 RPM in 2nd the car is doing 83.
3rd tops out at 121, 4th is 162 and 5th is 202.
According to my tom tom I have a 3 mph difference: @ 70mph on speedo tom tom indicates 67. At 60mph indicates 57mph and at 80mph it reads 77mph so all seems pretty consistent.
As already pointed out it's pretty difficult watching the clock whilst gunning it,but the times I've tried it I reckon the limiter hits at the 70-75 region,but then take off the 3mph gives 67-72 if sat nav reading is bang on of course.
Someone told me on my car that 3rd gear is 100-105 on the clock so again deduct the error on the gauge and it's probably about 100. Can't remember who it was though.
As already pointed out it's pretty difficult watching the clock whilst gunning it,but the times I've tried it I reckon the limiter hits at the 70-75 region,but then take off the 3mph gives 67-72 if sat nav reading is bang on of course.
Someone told me on my car that 3rd gear is 100-105 on the clock so again deduct the error on the gauge and it's probably about 100. Can't remember who it was though.
Speed 3 said:
msmith0592 said:
I assume the Chim and Cerbera use the same gear ratio and diff ratio.
I've put the Cerb in and at 7500 RPM in 2nd the car is doing 83.
3rd tops out at 121, 4th is 162 and 5th is 202.
If the terminal velocity through aerodynamics and friction is more like 180, why bother gearing to an uttainable speed ? Surely would be better with lower gearing for better acceleration and the same real world top speed ? Or am I missing something and the Cerb actually was a 200 mph car ?I've put the Cerb in and at 7500 RPM in 2nd the car is doing 83.
3rd tops out at 121, 4th is 162 and 5th is 202.
or am I missing something? Keeping a eye on the speedo and not the revs is waiting for a piston to appear outside the block.Oh, and Brummies IS a 200 MPH Cerb'
macdeb said:
I can't really see the point of maximum speed in a given gear or am I missing something? Keeping a eye on the speedo and not the revs is waiting for a piston to appear outside the block.
Oh, and Brummies IS a 200 MPH Cerb'
200 mph no but a few have been clocked at high 190's! or am I missing something? Keeping a eye on the speedo and not the revs is waiting for a piston to appear outside the block.Oh, and Brummies IS a 200 MPH Cerb'
TVR actually came up with a slippery shape in the Cerbera, completely by accident of course, and the engine is a thing of wonder if you have a good one.
Edit to point out I meant to quote Spped 3 not macdeb.
Edited by gruffalo on Saturday 13th December 22:38
Magic919 said:
PorscheFreak said:
I do understand that coming off the power in a bend can also induce balance issues as a result of hefty engine breaking
Engine breaking would certainly upset the balance. 
Circumference of 255/40/17 approx 2m
Diff Ratio 3.43
km per mile 1.609
Cerb red line 7500
Top Speed in Fourth Gear
2 / 3.43 / 1.609 * 7500 * 60 / 1000 = 163
Gear ratios for T5WC
1352-248 TVR WC U 2.76 2.95 1.94 1.34 1.00 0.80
http://www.britishv8.org/articles/borg-warner-t5-i...
163 / 2.95 = 55
163 / 1.94 = 84
163 / 1.34 = 122
163 / 1.00 = 163
163 / 0.80 = 203
I'm assuming that the rolling circumference is the same as the actual circumference at high speed
Also assuming a 7500 red line, I think the standard rev limit is set at 7600, with the buzzer coming in at about 7250
Diff Ratio 3.43
km per mile 1.609
Cerb red line 7500
Top Speed in Fourth Gear
2 / 3.43 / 1.609 * 7500 * 60 / 1000 = 163
Gear ratios for T5WC
1352-248 TVR WC U 2.76 2.95 1.94 1.34 1.00 0.80
http://www.britishv8.org/articles/borg-warner-t5-i...
163 / 2.95 = 55
163 / 1.94 = 84
163 / 1.34 = 122
163 / 1.00 = 163
163 / 0.80 = 203
I'm assuming that the rolling circumference is the same as the actual circumference at high speed
Also assuming a 7500 red line, I think the standard rev limit is set at 7600, with the buzzer coming in at about 7250
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