Discussion
Inspired by a thread on the Cerbera forum...
Now I realise that the Sag's aren't designed for top speed runs (the air brake, errr... spoiler, sees to that), and I know TVR said that they were 'over 180mph' - but who has been anywhere near that in a Sag?
And are the T350's (in 4 litre spec) faster than Sag's - due to them being slippier through the air?
What are peoples thoughts and experiences?
Now I realise that the Sag's aren't designed for top speed runs (the air brake, errr... spoiler, sees to that), and I know TVR said that they were 'over 180mph' - but who has been anywhere near that in a Sag?
And are the T350's (in 4 litre spec) faster than Sag's - due to them being slippier through the air?
What are peoples thoughts and experiences?
I would have thought a strong engined Sag would get to 180mph (perhaps with the rear spolier removed though). I have a 3.6 RR T350c which will hit over 155mph in 4th gear and should comfortably exceed 180mph in 5th. People get too focussed on top speed - 0-60mph, 0-100mph, 1/4 mile and in-gear acceleration times are a far better measure of a cars performance. The 4.5 Cerbs may have the higher top speed, but they often struggle to get the power down particularly from standing starts.
S5TVR said:
I would have thought a strong engined Sag would get to 180mph (perhaps with the rear spolier removed though). I have a 3.6 RR T350c which will hit over 155mph in 4th gear and should comfortably exceed 180mph in 5th. People get too focussed on top speed - 0-60mph, 0-100mph, 1/4 mile and in-gear acceleration times are a far better measure of a cars performance. The 4.5 Cerbs may have the higher top speed, but they often struggle to get the power down particularly from standing starts.
You won't hear them admitting it though 
Have managed low 170s (172-174) in each of the Cerbera, Tuscan S, and T350t. Comparison:
Tuscan was lethal at this point. Complete and utter hedge-seeking missile and took balls of not just brass but... um... something way denser. Osmium, perhaps? It got there quicker than I'd have expected given the 4l S6 (albeit S spec, remapped, de-catted, etc)
Cerbera was actually VERY impressive. Utterly planted, MUCH more stable, and clearly had more grunt than the S6s once you got past 130/140. It did have Nitrons on, though, which I can't help but think made a significant difference (the wheel base and aerodynamics counting for the rest of the handling)
T350 was waaaaaaay more planted than the Tuscan. It was also significantly noisier - the Targa panels on that get a lot more wind-rush than the T-top on the Tuscan.
As for what they had left:
- The Tuscan was slowly adding the MPHs. I think it would have probably hit about 182/183. The front and rear spoilers will have been giving it a LOT of extra work to do over a standard one. The front one in particular - before I had this remounted MUCH more sturdily it once ripped off at 130mph it was creating that much downforce
- The Cerbera still seemed quite happy to keep clocking up the digits on the speedo. Not MUCH faster than the Tuscan, but noticeable. I'd have expected about 185/186, perhaps?
- The T350 was starting to hit a wall - it was sloooowly creeping up; I'm expecting the targa panels were knocking a couple of MPH off what a T350C might manage. I'd guess that it'd probably have done 178 or so.
Given the difference in tune between the T350 and the Tuscan, I'm VERY impressed with the T350; especially given how much safer it felt, and more driveable/fun on a daily basis. The Cerb's just a different kind of car.
Those were all GPSd speeds.
For comparison, I got 183 out of the DB7 Vantage, and 181 out of the XKR. Of all of the cars, the XKR wins hands down for utter composure, near silence, and a general perception that you were "only just going over a ton". Apart from the great blur of things either side of you.
In *all* of these cars I opted for discretion rather than dismemberment - none of them had hit their absolute peak speed.
Forgot to add: reckon a standard Sag without the rear spoiler would top a T350 in a top-speed shoot out. Reckon a T350 with equivalent engine spec would beat the Sag, though... but the Sag would likely feel noticeably more planted, especially if all the vents were "operational". Both with a 4l engine should break 180 without an issue, other than the prerequisite change of underwear.
Tuscan was lethal at this point. Complete and utter hedge-seeking missile and took balls of not just brass but... um... something way denser. Osmium, perhaps?
It got there quicker than I'd have expected given the 4l S6 (albeit S spec, remapped, de-catted, etc)Cerbera was actually VERY impressive. Utterly planted, MUCH more stable, and clearly had more grunt than the S6s once you got past 130/140. It did have Nitrons on, though, which I can't help but think made a significant difference (the wheel base and aerodynamics counting for the rest of the handling)
T350 was waaaaaaay more planted than the Tuscan. It was also significantly noisier - the Targa panels on that get a lot more wind-rush than the T-top on the Tuscan.
As for what they had left:
- The Tuscan was slowly adding the MPHs. I think it would have probably hit about 182/183. The front and rear spoilers will have been giving it a LOT of extra work to do over a standard one. The front one in particular - before I had this remounted MUCH more sturdily it once ripped off at 130mph it was creating that much downforce
- The Cerbera still seemed quite happy to keep clocking up the digits on the speedo. Not MUCH faster than the Tuscan, but noticeable. I'd have expected about 185/186, perhaps?
- The T350 was starting to hit a wall - it was sloooowly creeping up; I'm expecting the targa panels were knocking a couple of MPH off what a T350C might manage. I'd guess that it'd probably have done 178 or so.
Given the difference in tune between the T350 and the Tuscan, I'm VERY impressed with the T350; especially given how much safer it felt, and more driveable/fun on a daily basis. The Cerb's just a different kind of car.
Those were all GPSd speeds.
For comparison, I got 183 out of the DB7 Vantage, and 181 out of the XKR. Of all of the cars, the XKR wins hands down for utter composure, near silence, and a general perception that you were "only just going over a ton". Apart from the great blur of things either side of you.
In *all* of these cars I opted for discretion rather than dismemberment - none of them had hit their absolute peak speed.
Forgot to add: reckon a standard Sag without the rear spoiler would top a T350 in a top-speed shoot out. Reckon a T350 with equivalent engine spec would beat the Sag, though... but the Sag would likely feel noticeably more planted, especially if all the vents were "operational". Both with a 4l engine should break 180 without an issue, other than the prerequisite change of underwear.
Edited by J_S_G on Tuesday 30th December 01:58
ive had my 4.5 rr cerb clocking 190 a few years back how correct the clocks are i dont know ,i also got done at 173.96 by the local boys in blue and i think there equiptment is proberly quite accurate they gave me 2yrs ban and 10 weeks in hmp winstergreen not the most pleasant place in the world !
First, we need to understand what is being used to measure the speed. If it's the speedo then from my experience of using both a Performance Box and a Tomtom sat nav, then the dial is measuring between 5 and 10% over. So if it's an indicated 180mph you are probably doing 170mph or less real speed.
Last year I did Fighting Torque (the standing mile ended up at more like 7/8 mile but that is another story) and the top real speed I got (on the performance box) was 161mph in the Sagaris. At that point there was still a little more to go (the movement of the bonnet was getting very worrying though), but the car was still firmly planted to the tarmac. I'd estimate maximum real speed attainable with an unlimited straight would be around 170mph without any bodywork tweaks.
Last year I did Fighting Torque (the standing mile ended up at more like 7/8 mile but that is another story) and the top real speed I got (on the performance box) was 161mph in the Sagaris. At that point there was still a little more to go (the movement of the bonnet was getting very worrying though), but the car was still firmly planted to the tarmac. I'd estimate maximum real speed attainable with an unlimited straight would be around 170mph without any bodywork tweaks.
[quote=Englishman]First, we need to understand what is being used to measure the speed. If it's the speedo then from my experience of using both a Performance Box and a Tomtom sat nav, then the dial is measuring between 5 and 10% over. So if it's an indicated 180mph you are probably doing 170mph or less real speed.
Most car speedos are going to find it tough to be accurate over the entire speed range (say 0 to 170 or so). Mine seems to agree with my Road Angel GPS at about 90ish. At 30 it over registers by about 10%, by 50 it's down to 5% over and at 120 it slightly under registers. At an indicated 170 I suspect it would be under registering more. Sadly as my Road Angel isn't brilliantly attached, a couple of rubber bands, I've not tested this theory in an environment where it would be safe or legal to do so.
Most car speedos are going to find it tough to be accurate over the entire speed range (say 0 to 170 or so). Mine seems to agree with my Road Angel GPS at about 90ish. At 30 it over registers by about 10%, by 50 it's down to 5% over and at 120 it slightly under registers. At an indicated 170 I suspect it would be under registering more. Sadly as my Road Angel isn't brilliantly attached, a couple of rubber bands, I've not tested this theory in an environment where it would be safe or legal to do so.
Been there, done that.It's not that the dials "struggle" to be accurate - it's a litigious thing: cars aren't allowed to be traveling faster than the speedo indicates. Everything has manufacturing tolerances; in the case of speedos it's normally taken as +-10%. They are then designed to read +10%, that way the worst will either be reading 20% over actual speed or bang on the money. Wish my islands of knowledge were a bit bigger than this
jrb43 said:
It's not that the dials "struggle" to be accurate - it's a litigious thing: cars aren't allowed to be traveling faster than the speedo indicates. Everything has manufacturing tolerances; in the case of speedos it's normally taken as +-10%. They are then designed to read +10%, that way the worst will either be reading 20% over actual speed or bang on the money. Wish my islands of knowledge were a bit bigger than this
Yes it was also my understanding that all manufacturers err on the side of caution by design, to ensure speedos never under register. Does mean of course that to get anywhere near the advertised 185mph top speed, the Sagaris speedo would likely need to be indicating ~200mph.Like others, the computer does say I've done 220mph at some point though, but I can't can't seem to recall it.
jrb43 said:
It's not that the dials "struggle" to be accurate - it's a litigious thing: cars aren't allowed to be traveling faster than the speedo indicates. Everything has manufacturing tolerances; in the case of speedos it's normally taken as +-10%. They are then designed to read +10%, that way the worst will either be reading 20% over actual speed or bang on the money. Wish my islands of knowledge were a bit bigger than this
mine shows a speed about 1 or 2 mph slower than is showing on the sat nav.hollowpockets said:
When i had my T350 last year on the autobahns, with its 4l rr sag engine and all the fancy bits on it i couldn't get past 175mph, the car would simply not go faster.
Did you ever have the 4.0 litre RR engine dyno'd - maybe it was a bit down on power ?Edited by s5tvr on Thursday 5th February 13:37
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