30-70mph times

30-70mph times

Author
Discussion

mattc

266 posts

237 months

Friday 26th July 2002
quotequote all
I always think that any "x-y mph in a fixed gear" test is silly, because it will advantage any car that has the exact ratio for that test*. Meanwhile, a car with the "wrong" ratios may be FAR quicker from x-y, as long as the operator can be bothered to make a gear change. Surely the total time is what matters (i.e. including any changes you have to make)?

30-70mph thru-gears seems like the best compromise. It may ignore proper top-end performance, but it also filters out the "launch-control" effects, and is a realistic useful range for A-B road overtakes.

Just MHO!

*Doesn't this sort of thing make a Superlight "faster" than a Macca?!?

philshort

8,293 posts

239 months

Friday 26th July 2002
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Acceleration in a fixed gear is a useful guide to engine flexibility though, which to many is just as important as "how fast will my car go if I thrash it through the gears".

Dropping two cogs and bouncing off the rev limiter doesn't tend to amuse the missus; deft application of torque from a flexible engine without gear changes can achieve the same result without undue comment.

Thats why I like big V8's and diesels.

kevinday

8,709 posts

242 months

Friday 26th July 2002
quotequote all
Acceleration in a fixed gear = 'grunt'! perhaps this is the easiest calculation of grunt.

mondeoman

10,125 posts

228 months

Friday 26th July 2002
quotequote all
Mines about 5 secs 30-70, thru the gears (IIRC) - not bad for a diseasel.
:mustremembertocheckitlater:


Checked it using my dahsboard grandfather clock and it was 7 secs from 30-70 and TWO gear changes.... GULP!

>> Edited by mondeoman on Friday 26th July 23:29

GavinL

47 posts

223 months

Friday 26th July 2002
quotequote all
Interesting, what Supra MK3 or MK4...modified or stock?

quote:

I'm quite chuffed at reading those times. I have an AP22 accelerometer which can tell me stuff like that.

According to my last run, in my Supra I did 30-70mph in 3.83 seconds

However, I assume all the figures don't mean starting at a steady 30mph instead of accelerating through it. Otherwise, effects like engine response and turbo-lag would come into play.


James.


JonRB

65,394 posts

234 months

Friday 26th July 2002
quotequote all
quote:
Mitsubishi Evi VII - 4.5 sec
Renault Clio Sport - 7.6 sec

quote:
Mines about 5 secs 30-70, thru the gears (IIRC) - not bad for a deisel.

Corrado VR6 - 5.7 sec

Hmmm. Just shows that BHP is all very well for speed, but its torque that gets you there!

>> Edited by JonRB on Friday 26th July 13:28

spnracing

1,554 posts

233 months

Friday 26th July 2002
quotequote all
quote:

30-70mph thru-gears seems like the best compromise. It may ignore proper top-end performance, but it also filters out the "launch-control" effects, and is a realistic useful range for A-B road overtakes.



It can also be rather misleading.

My diesel Merc (according to Autocar) does 50-70 in 4.0 secs. My Chimeara 400 did it in 6.8 secs.

The Merc is an auto so it probably kicks down. Although performance is brisk, I can assure you in real terms the TVR was faster....

spnracing

1,554 posts

233 months

Friday 26th July 2002
quotequote all
quote:

Mines about 5 secs 30-70, thru the gears (IIRC) - not bad for a diseasel.
:mustremembertocheckitlater:



7.6 seconds for a manual 330D according to Autocar, 20 Feb 2002.

Actually thats still damn impressive - only marginally behind the TVR Chimeara time and its a much heavier car. The E320 CDI is slightly more powerful than the Beemer and has more torque, so maybe it would still be as quick as the TVR if it didn't kick down.

But it is heavier than the BMW. Who knows.

spnracing

1,554 posts

233 months

Friday 26th July 2002
quotequote all
Hang on, I'm getting confused. Well, it is Friday afternoon.

I've got 30-70 and 50-70 mixed up.

According to Autocar - 30-70 is a measure of overtaking ability through the gears, 50-70 is done in top gear (or kickdown for an auto) and is a measure of a car's flexibility.

BMW 330D

30-70 - 7.9secs
50-70 - 7.6 secs

184 BHP, 288 lb/ft torque

Merc E320 CDi Auto

30-70 - 6.9 secs
50-70 - 4.0 secs

197 BHP, 347 lb/ft torque

TVR Chimaera 400

30-70 - 4.5 secs
50-70 - 6.8 secs

240 BHP, 270 lb/ft torque (well according to TVR anyway)

this showing that the overtaking abaility of the TVR is way in excess of the two diesels. So the figures do make sense. Sort of. I'll shut up now.

JamesG

128 posts

227 months

Friday 26th July 2002
quotequote all
It's a Mk4 Twin Turbo. You can see the specs on my pistonheads profile.

The Jap Spec Mk4s are 280bhp as standard but it only takes a few modifications to put them well in excess of that.

By the way, my time was accelerating through 30mph, rather than starting at that speed.

James.


quote:

Interesting, what Supra MK3 or MK4...modified or stock?

quote:

According to my last run, in my Supra I did 30-70mph in 3.83 seconds
James.




Toffer

1,524 posts

223 months

Friday 26th July 2002
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Answer: Calculate power to weight ratio(BHP/tonne), torque, gear ratios, number of gears and speed of change.

Masses of power plus low mass plus close ratio gearbox
= very quick =

Masses of power, masses of torque plus low mass
= Griff =

Mojocvh

16,837 posts

224 months

Friday 26th July 2002
quotequote all
Hmmmm, seem to remember this subject was the (late lamented) EVO forums most popular thread.
(Not that I'd want to take any credit it was when I was "another life" so to speak.........) MoJo

Pinkney

Original Poster:

1,010 posts

226 months

Friday 26th July 2002
quotequote all
As spnracing said, the 50-70 times indicate flexibility of the engine rather than overtaking ability (which is why it is done in top gear). If the magazines did the 50-70 (not 30-70) through the gears the results would tell a different story, as most TVR's are capable of 70mph in 2nd,3rd,4th AND 5th gears. I would assume the 30-70 times would be through the gears unless the car has sufficient power (torque?) and gearing to manage it in one gear (2nd in the TVR). IMO the magazines would use the best combination for each individual car rather than a set routine (i.e gear changes) thus giving the best figure for each car. As for accelerating through 30mph rather than from a steady 30mph, a good point (never thought!). I would hope it was from a steady 30 in order to represent real-life overtaking.

Roadrunner

2,690 posts

229 months

Friday 26th July 2002
quotequote all
These stats are meaningless without a few more details in each case. For example - does the stopwatch start when the foot is depressed on the accelerator, or when the car starts accelerating past 30mph? In a turbo car with poor lag this could put the figures out by half a second. The 911 turbo 2 is bloody fast when it does start accelerating, but there is a lag time. In a real world situation this lag time will affect whether it's ok to overtake or not - if the manouver is going to be tight anyway!

The most important time for our roads is the midrange of 40-100 for dispatching numpties.

funkyboogalooo

1,844 posts

230 months

Friday 26th July 2002
quotequote all
looked everywhere for some stats on my motor, all i can find is the 0-60 of 4.8 seconds! nothing else. suppose i'll just have to do some practical tests!
Life is such a bore (sic)

hertsbiker

6,267 posts

233 months

Saturday 27th July 2002
quotequote all
Interesting posts, but in the end the real decider with overtaking is if the driver is any good! no doubt we are all quite good at "making progress"..? which would explain why even humble cars like my old Smart can get past most people!

Pinkney

Original Poster:

1,010 posts

226 months

Sunday 28th July 2002
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Managed to get my hands on an Autocar Mag and here are a few other examples.

Aston Martin Vanquish - 3.7
BMW M5 - 5.0
Caterham R500 - 2.6
Daewoo Matiz - 25.2
Ferrari 550 Maranello - 3.8
Ford Ka - 18.2
Lamborghini Diablo GT - 3.1
Jaguar XKR - 4.4
Skoda Octavia 1.8RS - 6.3
Porsche Boxster S - 5.5
Nissan Skyline - 3.9
Impreza STI 4.7
VW Lupo - 18.3
Toyota Celica 190 - 6.6
MCC Smart - 20.2
Mazda MX5 - 8.2
Mondeo 2.5 V6 - 8.8
Vectra 2.2LS - 10.0

SJobson

12,470 posts

226 months

Sunday 28th July 2002
quotequote all
The magazines quote 30-70 through the gears, with the car accelerating through 30mph. Basically all they do is take the 0-30mph and 0-70mph times from their standing start runs and subtract one from the other - it's a standing start time without the standing start variables involved. Hence why fwd cars like the Corrado VR6, Integra Type R and Civic Type R have good 30-70 times but poor(ish) 0-60mph times.

I always think 60-100mph through the gears is a real measure of power. More than that is not terribly useful on the road, but the Elise, for instance, has a good 30-70 time but a not so hot 60-100 time, indicating the reality of its acceleration being a product of low weight. Didn't concern me on 400 miles of Welsh twisties this weekend though

Pinkney

Original Poster:

1,010 posts

226 months

Monday 29th July 2002
quotequote all
Now that makes sense. Agreed 60-100 is the better formula for real-life overtaking manoeuvres. This is also an easy one to work out as the 0-60 and 0-100 times are regularly published.

Nice one!

Roadrunner

2,690 posts

229 months

Monday 29th July 2002
quotequote all
60 - 100 sounds ideal. How about some stats for our top PH beasts - 996TT (basic version), cerbera, exige.