I have a dream...

[threep]

...that one day I'll be able to drive my yet to be built Stratos like the one at 28 secs in this video...



http://youtu.be/Ahhkmb0Qolo


Serious question, what do I need (apart from developing some talent ;) ) to power slide a Stratos out of a corner? I'm talking about power/ torque, LSD etc


Will a bog standard 2.5 Alfa V6 have enough grunt? Do I need a 3.0, a 3.2? Will it need to be breathed on (different cams, bottom end etc)?

Does a Stratos have too much traction in dry conditions to power slide?


The Stratos has a reputation for swapping ends quite quickly, is that deserved when talking about driving on dry Tarmac? I defer to my learned Forum friends.

I'm building a Stratos to have some fun and what could be more fun than power sliding a Stratos ? :D

[john]

Probably a good start would be to not shoot yourself in the foot by opting for a tyre and wheel combination which puts over 300mm of modern rubber on the road at the back.
This why I like the idea of Craig's wheels so much. You can choose a rim and tyre width.
My theory is yet to be tested though......
For my money a 2.5 V6 is plenty power enough provided the car is set up properly.

[monoposto]

Many factors contribute to this, but the short and simple of it is, weight distribution over a short wheel base depending on the % front/rear weight balance, can cause a car to have an unusually high yaw acceleration. Yaw is the rotation about the Z-axis of the vehicle. To alleviate this you may tune your suspension to have less oversteer and more Understeer so that the acceleration around a turn is not so substantial.

Also, it does not take much skill to slide the rear end around ;)

[threep]

Probably a good start would be to not shoot yourself in the foot by opting for a tyre and wheel combination which puts over 300mm of modern rubber on the road at the back.
This why I like the idea of Craig's wheels so much. You can choose a rim and tyre width.
My theory is yet to be tested though......
For my money a 2.5 V6 is plenty power enough provided the car is set up properly.

Instinctively that was my thought too, it would be all too easy to over tyre the rear. I'm very open to using alternative wheel diameters and widths, and frankly anything which gives me a well sorted car which is rewarding to drive, reliable and easy to live with. To me that's more important than originality.

[Fingers]

Don't try it that close to a concrete wall for a start!

[threep]

Many factors contribute to this, but the short and simple of it is, weight distribution over a short wheel base depending on the % front/rear weight balance, can cause a car to have an unusually high yaw acceleration. Yaw is the rotation about the Z-axis of the vehicle. To alleviate this you may tune your suspension to have less oversteer and more Understeer so that the acceleration around a turn is not so substantial.

Also, it does not take much skill to slide the rear end around ;)

So is there an accepted front/rear mass ratio to aim for which will help achieve a well handling package? There are a number of V6 engines and transmissions combinations possible, I'm guessing some are preferable to others from purely a mass distribution standpoint.

I think sliding it won't be the biggest challenge, how to control it and not damaging the bodywork is ! ;)

[threep]

Don't try it that close to a concrete for a start!

That sounds like voice of experience.

[ChrisCar6]

The difference between power slide and 180 is infinitesimal..........

[turbonutter]

The difference between power slide and 180 is infinitesimal..........


I didnt realise there was such a big difference ;)

[strat24v]

If you had two cars almost identical in equipment, power output, tyres etc, one that was more mass centralised than the weight hanging out the back would in theory be less likely to get out of shape. Powersliding can be done if the car is built and set up correctly, has a good power output to spin the wheels, room to do it and plenty cash to fix it when you get it wrong.

[Strat Fan]

For the power slide experience you can do what they do at Silverstone for the driver training, fit the cheap knackered tyres on the back & the good ones on the front, not so good for general road use though.
For a powerslide on a well set up car then plenty of power will be required, a Stratos replica should generate plenty of traction due to its weight distribution & the fact that the engine & box is firmly planted over the rear axle. Its probably easier in a Stradale due to the reduced contact patch from the narrower tyres.
The better the grip the better the clutch you will require.

[StruanR]

For autotesting you pump up the rear tyre pressures too, gets them sliding nicely...;)
The reverse flick helps as well...
Struan

[strat24v]

Or invest in some drifting tyres.

[threep]

The reverse flick helps as well...
Struan

Does it? This article is saying otherwise... http://www.sportingfiatsclub.co.uk/models/Lancia%20037%20Abarth/LanciaStratos.asp

[StruanR]

Not easy in a Stratos, the short wheelbase makes it tricky, but it's the best way to change direction quickly on a stage...
Plenty of illustrations here (http://www.youtube.com/watch?v=vcdHoyzzNRU)

[Sando]

The reverse flick helps as well...
Struan

I agree with Struan on the flick. It does work but you need to be aggressive and get the car unstuck. Obviously the person on sporting fiats who drove a road car 40 years ago wasn't trying hard enough:p

Balls, Talent an understanding is what you need, even a two litre stratos can be made to "power slide" or oversteer with stiff set up and heavy right foot.
LSD makes big difference for rear end steering

[threep]

I agree with Struan on the flick. It does work but you need to be aggressive and get the car unstuck. Obviously the person on sporting fiats who drove a road car 40 years ago wasn't trying hard enough:p

Balls, Talent an understanding is what you need, even a two litre stratos can be made to "power slide" or oversteer with stiff set up and heavy right foot.
LSD makes big difference for rear end steering

So that's three extra things I need to find, and a LSD ;)

So what options are there for the LSD? A quick google shows that Quaife offer an alternative to the Q2. Maybe I should start a new thread...

[threep]

Not easy in a Stratos, the short wheelbase makes it tricky, but it's the best way to change direction quickly on a stage...
Plenty of illustrations here (http://www.youtube.com/watch?v=vcdHoyzzNRU)

If I had the money I would love to go forest rallying..... but to start a stage rally career in the forests in a Stratos sounds a bit adventurous to me.

There's some nice footage in that video. The sequence starting at 0:41 is pretty impressive and I like the way guy in the Alitalia car shortly after has it dancing on the loose. A couple of reminders too how quickly they can end up pointing in the wrong direction......

[Fingers]

That sounds like voice of experience.

Luckily not, just going by the reputation the Stratos has for swapping ends. I'll be taking it very easy in mine until I'm comfortable with it. It was very easy to do in my Fiat 124 sport in the wet though. But as has been said I think the weight distribution has a lot to do with it.

[StruanR]

An LSD on a rear or mid-engined is not always helpful on loose surfaces. You end up with too much grip at the rear and not enough on the front, a recipe for terminal understeer.... :mad:
It's a question of weight distribution, driving style, suspension setup etc, etc .....
Struan

[StruanR]

Does it? This article is saying otherwise... http://www.sportingfiatsclub.co.uk/models/Lancia%20037%20Abarth/LanciaStratos.asp
Of course, most of the cars in the pictures are not Lancias.... article was written about a stradale, not shown.

[monoposto]

So is there an accepted front/rear mass ratio to aim for which will help achieve a well handling package? There are a number of V6 engines and transmissions combinations possible, I'm guessing some are preferable to others from purely a mass distribution standpoint.

I think sliding it won't be the biggest challenge, how to control it and not damaging the bodywork is ! ;)

Yes and no. Say you put tire "A" on your car. This tire has specific properties which allow it to handle and produce a certain amount of lateral force/G-force with a given amount of normal load on that tire. (normal load=vertical force pushing down) going around a 30m radius turn. Your front/rear weight dist. is 50/50. Tire "A" gives you oversteer. Switch to tire "B" now, all things being equal, same chassis set-up, wheels, etc... Now you are getting less oversteer on that same 30m turn. Put simply your tires are the most effective part on any car, without them you wouldn't go anywhere. They create all of the forces which allow you to maneuver a car the way you want.

If you know how much normal load the tires can handle, you can determine your lateral forces, telling you where to maximize your weight distribution. A simple goal when designing a car from scratch, that I tried to do was aim for neutral steer, and design the suspension such that you can tune to over or under-steer. There's another factor and this one is "the joker". This is the driver, the biggest variable of all.... Some people like oversteer, some like understeer and also in varying levels.

So there's no golden egg you can hit. When I said aim for "neutral steer", this is what I tried to do in my FSAE/college days. Some tires may not allow you to tune for understeer, no matter how much adjust ability you have in your suspension and like-wise for oversteer. Hopefully this answers your question somewhat.... I've read LOTS of vehicle dynamics books... From Aerodynamics, all the way down to chassis/suspension design. If you want to learn more pick up a Carroll Smith book called "tune to win" and if you want to get into the crazy stuff, there is always "Race Car Vehicle Dynamics" by Milliken and Milliken.

[threep]

Thanks monoposto. There's a saying, start with the end in mind. Whilst it may take a considerable time to achieve my "dream", I want to try and tease-out at the beginning the key factors which will make it more likely to be realised. Tyres are obviously a huge factor and set up will have to be geared around the tyres, so I'll worry about that later. What I think I've learned to date is that I need sufficient power (a 2.5 may we'll be sufficient, but a 3.0 or 3.2 even in standard tune will do the job), a LSD (Q2, Quaife, Gripper), 5 speed box with roller bearings on input shafts and the strongest driveshafts I can afford!

I did wonder whether a 2.5 was preferable to a 3.0 or 3.2 (or vice versa) from a weight distribution point of view, but as no one has mentioned it I'm guessing the difference is negligible and can be dialled out in the set up.

I've got a mate who I'll be calling on to help me with the set up, he's done vehicle dynamics in F1 and has all the books! ;)

[ChrisCar6]

strongest driveshafts I can afford!

Remember something has to be the weakest link that breaks first. If it's not the driveshafts (easy to replace) is it to be the gearbox (expensive & more difficult)...

[monoposto]

Honestly, I think people get caught up too much in what "set-up" they run. When stock is probably the best and least likely to get you in trouble (im using "you in general terms here, not specifically you!). Spend your time karting and getting used to feel the tires and how things react with different inputs. You'll have much more success going that route than the "race car set-up" route.