0 to 60 times, kit car owner delusion??!

0 to 60 times, kit car owner delusion??!

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e8_pack

1,384 posts

180 months

Saturday 22nd August 2015
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I doubt any turbo seven would put down a decent time, they just can't transmit the aggressive torque into anything but wheelspin.

That charged fury seems to have the best of both though, nice linear delivery and plenty of it.

N/A for me though, with less weight. Mine was 570 but I know it's shed a bit since then. Xoomspeed shifter is a good bit of kit though, I bought their old engine too and modified it.

jeffw

845 posts

227 months

Saturday 22nd August 2015
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FuryCossieSteve said:
Exactly, not the same at all!
"Foot-pound" is sometimes also used as a unit of torque (see Pound-foot (torque)). In the United States this unit is often used to specify, for example, the tightness of a bolt or the output of an engine. Although they are dimensionally equivalent, energy (a scalar), and torque (a vector) are distinct physical quantities. Both energy and torque can be expressed as a product of a force vector with a displacement vector (hence pounds and feet); energy is the scalar product of the two, and torque is the vector product.

We should stick to Nm.

jeffw

845 posts

227 months

Saturday 22nd August 2015
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e8_pack said:
That charged fury seems to have the best of both though, nice linear delivery and plenty of it.
Which Fury are you talking about?

And here is a video of aggressive, F1 Turboed, torque being turned into forward motion by one Duncan Cowper

https://www.youtube.com/watch?v=XLKFecIphPk

Duncan is way faster than I am in the Phoenix, he has over 550BHP out of his motor.



FuryCossieSteve

Original Poster:

426 posts

118 months

Sunday 23rd August 2015
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jeffw said:
"Foot-pound" is sometimes also used as a unit of torque (see Pound-foot (torque)). In the United States this unit is often used to specify, for example, the tightness of a bolt or the output of an engine. Although they are dimensionally equivalent, energy (a scalar), and torque (a vector) are distinct physical quantities. Both energy and torque can be expressed as a product of a force vector with a displacement vector (hence pounds and feet); energy is the scalar product of the two, and torque is the vector product.

We should stick to Nm.
Well it would simplify things I guess. Until some numpty like me goes and puts N/m or sumfin equally incorrect and starts world war 3! jester

Re; the video you postd jeffw. That car looks a real handful but I guess you get used to dealing with something like that with practice? There are some mad mad mad machines around in the UK that is for sure!


Edited by FuryCossieSteve on Sunday 23 August 10:29

e8_pack

1,384 posts

180 months

Monday 24th August 2015
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jeffw said:
e8_pack said:
That charged fury seems to have the best of both though, nice linear delivery and plenty of it.
Which Fury are you talking about?

And here is a video of aggressive, F1 Turboed, torque being turned into forward motion by one Duncan Cowper

https://www.youtube.com/watch?v=XLKFecIphPk

Duncan is way faster than I am in the Phoenix, he has over 550BHP out of his motor.
Horses for courses. How many straights! Big power car sure to make done time up on those.

FuryCossieSteve

Original Poster:

426 posts

118 months

Monday 24th August 2015
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jeffw said:
Cough....lb ft or ft lb but never, ever lbs/ft
Double cough, in my defence I would say I am slighlty dyslexic (not even sure if that is how to spell it!!) and get my slashes and dashes mixed up at times. As I understand it it should actually be ft-lbs or lbs-ft, ie WITH dashes?? rolleyes

andygtt

8,344 posts

263 months

Wednesday 26th August 2015
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mikeveal said:
FuryCossieSteve said:
I saw a guy selling a properly sorted Cosworth Turbo Westie with 505bhp, launch control, flatshifter and all the kit, it was officially timed at 3.2secs. 1.4 secs quicker than your Westie but it took more than 3 times the power plus all sorts of expensive trick kit to do it!

Not as quick as all those on ebay with 200bhp who can do it faster of course!! rolleyes
(Proper)Launch control reduces the available power to keep the wheels spinning with ~10% slip, since that's the point of peak traction. If you have enough power to keep the wheels spinning all the way to 60mph, adding more power won't decrease the acceleration time. So dependant on gearing and weight, it's perfectly possible for the 200Hp car to be quicker than the 505Hp car.

Theory says my car should be in the low 3s (150bhp, 350Kg, 60mph in 1st gear). In practice I don't drive well enough to accelerate hard in first, I just get a lot of wheel spin.
Not entirely correct, you are referring to production car launch control... I suspect what is being used above is the same as on my car and is an entirely different system altogether.

Basically this launch control simply works as a rev limiter at varying speeds until traction control takes over.... So you sit stationary and floor the throttle and it hits the limiter for 0mph (5000rpm and over 600ftlb on my car), the ignition is retarded randomly to maintain the revs and it spits fuel into the exhaust that ignites and spools the car to full loads (and thus full power at that rpm is instantly available).... Then when you drop the clutch it's allowed to make absolutely full power and the rev limit is simply dictated by speed.
So you wheelspin, but not by much and effectively have maximum acceleration as the slip is controlled.

This couldn't be used on production cars as it would kill cats etc and flames coming out the back are generally frowned upon.... However watch a rally car launch with masses of power and supposedly zero traction due to being on gravel and you will see what I mean.

I'm pretty good at launching cars and I can say It's almost impossible to match the launch of a turbo car without this on... My mind was properly blown.

mikeveal

4,558 posts

249 months

Thursday 27th August 2015
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andygtt said:
mikeveal said:
(Proper)Launch control reduces the available power to keep the wheels spinning with ~10% slip, since that's the point of peak traction. If you have enough power to keep the wheels spinning all the way to 60mph, adding more power won't decrease the acceleration time. So dependant on gearing and weight, it's perfectly possible for the 200Hp car to be quicker than the 505Hp car.

Theory says my car should be in the low 3s (150bhp, 350Kg, 60mph in 1st gear). In practice I don't drive well enough to accelerate hard in first, I just get a lot of wheel spin.
Not entirely correct, you are referring to production car launch control... I suspect what is being used above is the same as on my car and is an entirely different system altogether.

Basically this launch control simply works as a rev limiter at varying speeds until traction control takes over.... So you sit stationary and floor the throttle and it hits the limiter for 0mph (5000rpm and over 600ftlb on my car), the ignition is retarded randomly to maintain the revs and it spits fuel into the exhaust that ignites and spools the car to full loads (and thus full power at that rpm is instantly available).... Then when you drop the clutch it's allowed to make absolutely full power and the rev limit is simply dictated by speed.
So you wheelspin, but not by much and effectively have maximum acceleration as the slip is controlled.

This couldn't be used on production cars as it would kill cats etc and flames coming out the back are generally frowned upon.... However watch a rally car launch with masses of power and supposedly zero traction due to being on gravel and you will see what I mean.

I'm pretty good at launching cars and I can say It's almost impossible to match the launch of a turbo car without this on... My mind was properly blown.
No, not quite. But you're right I didn't make the distinction between launch control and traction control.

Launch control is used to limit the revs whilst you're sitting stationary, with your foot hard on the accelerator, before you engage the clutch.

Traction control is used to limit wheelspin after you've engaged the clutch and whilst you're moving.

The traction control system fitted to production cars limits wheel spin by braking the spinning wheel (or axle). It doesn't attempt to reduce engine power output, it increases the engine load.
Production car traction control doesn't generally allow any wheelspin. In the dry & on tarmac, you get the best acceleration from your tyre when you have roughly 10% wheel spin.

After market launch and traction systems work reducing engine power output. Yes, I'm talking about Race Logic. This is best achieved by skipping injector pulses, but can also be achieved by skipping ignition pulses, or by doing both. Both methods have pro's and cons.

If you skip an injector pulse, that cylinder becomes a load on the engine for that cycle. There is a risk that if you don't mask the ECUs fuel pulse properly a small amount of fuel being allowed into the cylinder could cause a lean mix and detonation.

If you skip a ignition pulse, the cylinder still gets fuel but the spark plugs don't ignite the fuel. Unburnt fuel could detonate in the cylinder as cylinder pressure increases. If this doesn't happen unburnt fuel could detonate in the exhaust. This may be sold as an advantage to turbo owners as it gives some anti lag. In reality this isn't useful because the engine is already generating too much power (or you wouldn't be cutting an ignition pulse), so extra power from anti-lag isn't needed. Anti lag is also bad for turbo longevity.


I designed my own traction / launch system a few years ago. Still have the prototype. It works on the lab bench with simulated rpm, wheel sensor and ECU pulses. Unfortunately my laptop HDD died and I lost the 2000 odd lines of assembler code that drove the project. I'll get back to it one day. The maths was pretty simple and modern day embedded chips like the PSoC make a single chip solution pretty easy to implement.

Mojocvh

16,837 posts

261 months

Friday 28th August 2015
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FuryCossieSteve said:
alspeed said:
Most of the 0-60 times quoted in forums are based on peoples distorted perception of how quick they are going or the results taken from a variety of mickey mouse timing methods.

I've done a few run what you brung events at York raceway, where they have had the 0-60 times recorded along side the normal drag times, reaction, 60ft 1/4 mile ET etc

Its a bit of an eye opener really, cars that you would naturally expect to do well simply dont

Not much road legal stuff drops below 4 seconds, 3 second cars are rare, the problem is not power or even power to weight ratio, its traction or rather lack of traction.

Think the best road going car I've seen at York was a twin engined 4 wheel drive golf which IIRC did a genuine 2.8 secs. It bloody looked fast too, simply hooking up and taking off the line with very little loss of

traction.
Yep, totally agree. Watch the really quick stuff off the line at the Goodwood hillclimb and the difference is very noticeable. A small squeak from the tyres and they are gone!
Yep! A nice mojo showing just that!

https://www.youtube.com/watch?v=hsKUSl5MRRw

V8 Fettler

7,019 posts

131 months

Tuesday 1st September 2015
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Didn't rallycross cars from many years ago achieve 2 sec 0-60 (on tarmac) with AWD, light weight, lots of power and a brutal approach?

jeffw

845 posts

227 months

Tuesday 1st September 2015
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https://www.youtube.com/watch?v=yVCAN-b-upY

Makes you realise how hard it is....

andygtt

8,344 posts

263 months

Wednesday 2nd September 2015
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mikeveal said:
If you skip an injector pulse, that cylinder becomes a load on the engine for that cycle. There is a risk that if you don't mask the ECUs fuel pulse properly a small amount of fuel being allowed into the cylinder could cause a lean mix and detonation.

If you skip a ignition pulse, the cylinder still gets fuel but the spark plugs don't ignite the fuel. Unburnt fuel could detonate in the cylinder as cylinder pressure increases. If this doesn't happen unburnt fuel could detonate in the exhaust. This may be sold as an advantage to turbo owners as it gives some anti lag. In reality this isn't useful because the engine is already generating too much power (or you wouldn't be cutting an ignition pulse), so extra power from anti-lag isn't needed. Anti lag is also bad for turbo longevity.
The Motec launch control changes the ignition timing rather than slip pulses to maintain the rev limit and thus deliberately spools the turbo by igniting the unburnt fuel, unlike traction control it does not monitor slip speed at all, it simply looks at actual speed and sets a rev limit for that so you don't over rev it and thus have loads of wheelspin.

Unlike traction control it isn't specifically trying to restrict power (even though it will to a certain extent), its matching the engine speed to the road speed within your given parameters... I run 2 stages of ignition retard to maintain the rev limits on my launch control up to a set road speed and then the ecu switches to traction control which works as you describe.... they are VERY different and traction control couldn't launch the car as hard as the launch control.... in fact for a turbo car you can't replicate launch control on the throttle, were as you could get close for traction control IMO.

I know its all very bad for the turbo, but I have never cared and after 3 years mines still fine smile

My launch control remains active until around 40-50mph were it transitions to traction control as thats how I have set it... additionally it only becomes active if I keep the throttle above above 80% or something like that... its almost impossible to accidentally activate it lol


edited because now I have properly read all your post I see you did differentiate between launch and traction and I only quoted part of your post lol


Edited by andygtt on Wednesday 2nd September 12:14

jeffw

845 posts

227 months

Wednesday 2nd September 2015
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The Racelogic TCS uses injector pulse turn off in a specific sequence depending on the severity of the Traction incident or during the launch control element. As I don't have a turbo I'm OK with this wink

jeffw

845 posts

227 months

Sunday 6th September 2015
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Yesterday at the Brighton Speed Trials I did a 11.46sec 1/4 mile at 131.5 MPH....10th overall


Kawasicki

13,041 posts

234 months

Sunday 6th September 2015
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mikeveal said:
Production car traction control doesn't generally allow any wheelspin.
This is just wrong.

Johnny5hoods

499 posts

118 months

Sunday 6th September 2015
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FuryCossieSteve said:
Why is it that almost every time I see a kit car for sale on ebay or PH I see ridiculous, unproven and most likely unattainable 0 to 60mph times quoted?

Seriously, do people really think their 180bhp (car engined) 7 style car can do 0 to 60 in 3.1 seconds??? I think even a 180bhp BEC would struggle?

I see one CEC on PH atm that quotes 3.4 secs with 200bhp and 180ftlbs and yet is another very well set up car, track proven and with a well accomplished track-experienced driver quoting a more sensible 3.5 secs with 50bhp more at 250bhp and 190ftlbs (and that I know is a very quick car, full of nice top line equipment to enable it to do that kind of time). A full 50bhp less (nowhere near the level of track equipment) and yet faster? I seriously doubt that!!

I once saw a guy selling a 7 type car on ebay quote 2.6 seconds for pities sake!! I'd love to see him do it! Even if he could get the whole (less than 230bhp) down that would be a road going car world record most likely!!! Or not far off. Here are some real world times figures from just recently, not sure if I can post a link, but here goes....... http://www.telegraph.co.uk/motoring/2716549/Gone-i...

My Cossie Fury (around 320bhp and about the same in torque I believe - must check!) must be around 1.5 seconds then??? jester

Edited by FuryCossieSteve on Sunday 9th August 21:32
I remember a couple of road tests Autocar magazine did in the early 1990s.

1. A factory built Westfield ZEi: 128bhp 1.8 Zetec, brand new, and 680 KGs (another myth exploded!) - 0-60: 7.0 secs.

2. Caterham HPC: 2.0 Red top XE 16v on twin 45s, making 165 bhp, and an impressive 165 lb/ft. Weight was 627 KGs ("Caterhams are about 500KGs mate" - yeah, right!) - 0-60: 4.9 secs.

I suspect their test track was probably damp on the day they tested the ZEi, and dry when they tested the HPC. But even so, it just goes to show how far the wishful thinking has drifted from reality.

mikeveal

4,558 posts

249 months

Monday 7th September 2015
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Kawasicki said:
mikeveal said:
Production car traction control doesn't generally allow any wheelspin.
This is just wrong.
No it isn't.

Kawasicki

13,041 posts

234 months

Monday 7th September 2015
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mikeveal said:
Kawasicki said:
mikeveal said:
Production car traction control doesn't generally allow any wheelspin.
This is just wrong.
No it isn't.
Pulling away (if we ignore tail winds, downhill gradients etc.) is impossible without some wheel slip.

Why would production car traction control not be well optimised? The physics is fairly well understood. Do you think the traction control engineer will get a pat on the back when his vehicle is slower than the competition?







mikeveal

4,558 posts

249 months

Monday 7th September 2015
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No, I think that production car traction control systems are designed to keep wheelspin as close to 0% as then can manage, because that's the safest option in all conditions; dry tarmac, gravel, rain, snow, ice etc. They are not interested in maximum acceleration and indeed braking a spinning wheel doesn't give the control needed to precisely maintain (say) 10% spin. The "brake that axle" traction control systems fitted to production cars act to stop wheel spin as completely as they can.

Can I say that every production car system works like that? No. I've not studied how they all work. But the vast majority do work like this.


And yeah, at the interface between tyre and tarmac, there has to be a tiny amount of slip. But traction control systems don't attempt to measure that. They look at the difference in rotational speed of all the wheels and attempt to deduce if one wheel is breaking traction.

Kawasicki

13,041 posts

234 months

Monday 7th September 2015
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mikeveal said:
No, I think that production car traction control systems are designed to keep wheelspin as close to 0% as then can manage, because that's the safest option in all conditions; dry tarmac, gravel, rain, snow, ice etc. They are not interested in maximum acceleration and indeed braking a spinning wheel doesn't give the control needed to precisely maintain (say) 10% spin. The "brake that axle" traction control systems fitted to production cars act to stop wheel spin as completely as they can.

Can I say that every production car system works like that? No. I've not studied how they all work. But the vast majority do work like this.


And yeah, at the interface between tyre and tarmac, there has to be a tiny amount of slip. But traction control systems don't attempt to measure that. They look at the difference in rotational speed of all the wheels and attempt to deduce if one wheel is breaking traction.
To reduce wheel slip many/most production cars can close the throttle, interrupt the ignition and brake a wheel, or a mix of all three. All three strategies are used to get the actual slip as close as possible to the target slip. There are many considerations as to what mix of strategies to use. The idea that production cars used basic systems is completely false, for example there is also friction coefficient estimation, which then calls up different target slip based on what surface the car is being driven on, so the target slip is set higher on snow/gravel. That's before we even get into integration with the stability control.

The slip on all 4 tyres is being continuously measured, on pretty much every production car.