It is the same with the newest Quattro technology. I don't think it is possible in Rally cars without central diff and electronics, but I'm not that familiar anyway. Let the experts tell.Quote:
Originally Posted by Rallyper
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It is the same with the newest Quattro technology. I don't think it is possible in Rally cars without central diff and electronics, but I'm not that familiar anyway. Let the experts tell.Quote:
Originally Posted by Rallyper
I think that no carmaker has yet found a non-permanent 4WD system useful for competitions but that's partly because of the rules. Where rules allow hi-tech stuff it might be different. Just one example. My brother was heavily involved in SAE Formula competition (worldwide university cup for small combustion and electric formula cars). The best electric car of all (from Dutch University of Delft) uses full-active 4WD system with four small but powerful engines mounted in wheel hubs. Each engine has maximum output around 30 kW but weights only 4 kg. Maximum allowed power available from batteries is 85 kW so that there is plenty of space to play with torque distribution. But here we speak about car which weights only 170 kg (its power make it able to do 0-100 km/h in 2,5 secs)...Quote:
Originally Posted by Rallyper
Of course there are differences but I doubt You can see them by eye on the video as was pointed at the start of this discussion. I bet what is possible to see comes much more from suspension, diff setup, geometry etc. while the differences given by bodyshell and it's weigh distribution although sure important for the very best performance must be marginal or impossible to see for outside observer. Currently used cars are too similar to each other...Quote:
Originally Posted by makinen_fan
I have no values, sorry. I'm just writing what comes to my mind ;)
Probably it was. With rules of 2.0 WRC cars it was possible to achieve that. But it's not everything. You know dumbbell has also 50/50 weight distribution but an awful moment of inertia :) That was the case of Audi Quattro. The S1 had perfect 50/50 weight balance but most of the mass was in front of front axle and to compensate it another big mass was at the back. That's what makes the car slow and hard to turn. The 205 T16 had awful weight balance but it was very nimble as most of the weight was concentrated close to the center of gravity between axles. If I remember right with Focus they tried to make also the center of gravity as low as possible and also the ideal balance by putting the spare wheel behind the rear axle under the floor (among other things). That's what goes against the previous point. I remember Pentti Airikkala was a loud critic of the Ford solution here on the forum.Quote:
Originally Posted by TyPat107
It is the most important if it is active one like in Subarus and Mitsubishis or even more sophisticated like in old WRC cars. But when You are limited to simple clutchpacks or other dumb mechanical things it's all different. With the S2000 they first use center diff - for example Abarth had it. Peugeot discovered that it brings very little advantage but serious disadvantages - car was heavier with it (in that time S2000 rules allowed cars to be only 1100 kg heavy and nobody was able to achieve the limit) and it consumed power. Especially the second point was very valid because the S2000 with just naturally aspirated engines were a bit underpowered. The problem of releasing rear axle when using handbrake was solved by a clutch in rear diff body. I am pretty sure Škoda largely tested both variants - with and without center diff and decided to go Peugeot way although with different supplier (X-Trac instead of Sadev). Abarth later switched for X-Trac system without center diff too. Later when rules for 1.6T cars were created they decided to ban the center diff at all.Quote:
Originally Posted by TyPat107
As makinen_fan explained, in chassis I meant the hardware you can't change in a few minutes. If it was suspension and diff preload, VW would have easily done it as they did so many thousands of test kilometers with factory drivers and engineers. Even we fans here saw that problem from short clips some months ago. Maybe this is why VW had been so conservative about their future performance in real competition. Note that masking "chassis" problem with various small setup tweaks conflicts with drivers' driving style and harms their ultimate confidence.Quote:
Originally Posted by dimviii
So I want to repeat the question, when VW is allowed to introduce (homologate) big changes?
also at wrc are sensitive about wd front -rear and left-right.Quote:
Originally Posted by makinen_fan
Slowson maybe driver liked the slight understeer of polo,is not bad thing when driver can pushes with this.Also dont take Latvalas words by rule,he has setup problems for many years.Its better to see Ogier,or he has a different chassis?Quote:
Originally Posted by SlowSon
Yes it is.Quote:
Originally Posted by Mirek
"Old" chain driven 1.2TSI was designed and manufactured by Skoda, new belt driven 1.2TSI is also produced by Skoda but I don't know whether it was developed by them too.
No, it was Capito or some other chief saying that, not Latvala.Quote:
Originally Posted by dimviii
And I dont think Ogier set that understeer on purpose. In Monte it was making him so angry that he was applying the exit-throttle so early. There was a perfect clip (I should have mentioned it back then :( ) showing a tight corner where the two Polos almost stalled versus all the Citroens smooth as trains on rails. Also the flatout clip from Sweden you posted - I know Ogier and JML are not the tidiest drivers but they threw the rear so early while everybody else including Neuville Novikov etc were smooth and clean. But lets better wait for typical dusty events.
The Nissan R32 GTR's ATTESSA system also ran in RWD initially, moving forward based on wheel slip and G forces. This was very effective in Group A touring cars, with the rules being changed in both Japan and Australia to effectively outlaw 4WD as it had such a significant advantage. The idea of it of course was to help on turn in/mid corner, without the front diff causing understeer, then on throttle application the 4WD kicked in, allowing full grip on corner exit.Quote:
Originally Posted by Mirek
As a road car it made for a quite tail happy drive as the sensors were a bit slow to react (this improved considerably in later models). However I don't think it would be much use on loose surfaces.
Active Centre diffs in production cars such as late model Subarus and Mitsubishis and then the ultimate in the WRC 2L formula of course were the evolution of this. But they add a lot of complexity and cost... I believe most modern cars with a performance 4WD setup would have some form of electronic adjustment?
In the book I have about suspension etc, there's a summary what cause different behaviours of a car.
Some of the below are obvious and others apply better to a formula racer but I listed all of them.
Understeer:
Rear anti-roll-bar too soft.
Front anti-roll-bar too stiff.
Toe-in too big.
Wrong camber angle (usually too positive at the front and too negative at the rear.
Front tyre pressure too low.
Rear tyre pressure too high.
Too soft tyre compound at the rear.
Too hard tyre compound at the front.
Too little down force at the front.
Too much downforce at the rear.
Too much weight at the front.
Here is an web site about AWD / 4WD systems and different makes AWD / 4WD systems.
Racing engine technology artcile on Ford Fiesta WRC engine
Race Engine Technology - Dec/Jan 2012
Highly recommended article for anyone interested engine technology
Automotive pornQuote:
Originally Posted by makinen_fan
Does anyone know if any of the current WRC cars use any form of TVC (Torque vectoring control)? Obviously front and rear active diffs were banned a couple of years ago but would the simpler, slightly less effective systems that simply brake individual wheels (limiting torque transfer to around 50%) as used on some the latest road cars be legal ?
I'd be interested to know the actual wording of the FIA's ban on these devices if anyone has any ideas on where to find it.
Some articles on the subject:
Torque-ing up for the corners - Torque Vectoring Control - Cars Bikes Trucks
Torque Vectoring and Active Differential
In my opinion they don't use it.
they use electronics and sensors so they cant be used.
Dimvi, am i correct to assume that brakes are kept purely mechanical without any form of electronic support?
exactly, only two pumps - one for front, one for rear, plus handbrake pump... everything purely mechanical.Quote:
Originally Posted by makinen_fan
Is there any specific item on the FIA regulations (including regional championships) that won't enable a car with lower cubic capacity to run in a 'bigger' class.
For example: a R2 car run in the R3 class.
R2 and R3 are not classes. One is class 5 and the other class 6. And I think it is not possible because if You enter wrong class the stewards of the meeting will put You in the correct one during scrutineering. Classes are no longer created purely according to the engine capacity.
Thanks for the answer.Quote:
Originally Posted by Mirek
But in a hypothetical situation, a driver can enter in, for example, Class 3 with a Class 6? Or stewards aren't going to allow it?
somebody here asked some time ago about weight distribution of S2000 car.
it's around 360 kgs each front wheel, 320kgs each rear wheel, with crew, spare wheel and some fuel
Hard to believe that M-Sport would reveal such detailed information about the engine.Quote:
Originally Posted by makinen_fan
Interesting reading, especially the section about the development of the DI engine. By this 30 million $ is used for the development of the Ford EcoBoost engine.
Referring to the few examples below both power and torque increases of a DI engine with the same or even less fuel (= air) consumption but that doesn't seems to be the case with the WRC cars. Can someone explain why?
“Mercedes-Benz is introducing new V6 and V8 gasoline direct injection engines for the CL and S Class that increase output by as much as 12.5% and decrease gasoline consumption by as much as 24%.”
“The design highlights of the 3.5-liter V6 in the S 350 BlueEFFICIENCY include a completely new air intake and exhaust system in conjunction with a variable resonance intake manifold and optimized inflow and backflow. Result: with the same displacement, the output compared with the previous 200 kW (272 hp) model rose by 12.5% to 225 kW (306 hp), while maximum torque has increased by 5.7 percent to 370 N·m (273 lb-ft) (predecessor: 350 N·m) and now is available over a broad engine speed range from 3500 to 5250 rpm.”
Green Car Congress: New Gasoline Direct Injection Engines in Mercedes-Benz CL- and S-Class Vehicles Cut Fuel Consumption By Up to 24%, Increase Output by Up to 12.5%
“Cadillac sells the CTS with both indirect and direct injection versions of its 3.6 liter V6 engine. The indirect engine produces 263 horsepower and 253 lb-ft of torque, while the direct version develop 304 hp and 274 lb-ft. Despite the additional power, EPA fuel economy estimates for the direct injection engine are 1 MPG higher in the city (18 MPG vs 17 MPG) and equal on the highway.”
Direct fuel injection - What it is, how it works - Direct fuel injection
“The advantage of direct injection is a more efficient engine. For example, Hyundai claims its 2.4 Theta II GDI gets 7 to 12 percent better torque than an equivalent port injection engine, while at the same time getting 10 percent better fuel economy.”
“The engine makes 198 horsepower and 184 pound-feet of torque. The current, port-injected 2.4-liter engine in the Sonata makes only 175 horsepower and 168 pound-feet of torque.”
Hyundai increases power, fuel economy with direct injection | The Car Tech blog - CNET Reviews
I'm no expert but in my opinion the biggest advantage of DI is that it allows the engine to run with high air-fuel ratio. That is good for the economy under low load but not that useful for racing engine where for maximum output You need richer AFR. I guess DI is somewhat more effective for WRC engine as well but I have no idea how much compared to usual way. Maybe Dimviii or someone else can educate us?
It would indeed be intresting to get an explanation to the engine issue.
The WRC and S2000 cars have and R5 will have three-way damapers (adjustable slow & fast compression + adjustable rebound). I don’t know if it’s the regulations that says that the dampers have to be three-way dampers or isn’t there any need for slow & fast rebound?
In the previous issue of “Vauhdin Maailma” JML told that the VW is more sensitive to changes in the set-up. As an example he said that with Ford he could do quirte a lot of “clicks” to the dampers before he could feel the difference.
Here is a link to a pdf which explains very nicely how the fast & slow compression and rebound works (8760 series beginning on page 11). I had been looking for this kind of explanation (words + pics) for a long time. :)
Btw, for newcomers. Here is the link to Antony Warmbold’s thread. In the first post a link to his blog with lot of interesting readings.
there is no such rule, that only 3 adjustments are allowed. but those are most important ones so most widely used. now there are a lot of dampers with additional - fourth adjustment - hydraulic bumpstop. most widely used is rubber bumpstop, then there is hydraulic bumpstop not adjustable and hydraulic bumpstop which is adjustable, it's common in Sachs or BOS dampers.Quote:
Originally Posted by OldF
So called "fast rebound" is not separately adjustable by a knob, it's often done by system like RCV (Reiger) or CAS (BOS) - when wheel is not touching the ground rebound "opens" fully and wheel is free to go down and touch the road again, it's good thing, but sometimes makes some trouble. Similar with for example Reiger CCV system - corner control valve - during cornering system detects which wheel is outer one and stiffens it's slow compression, giving less roll in the corner - it allows to use softer ARBs.
The problem is to create the smallest possible droplets, preferably gas before combustion begins. There is also a problem to create as equal mixture as possible in the combustion chamber. These are the problems one solve better with DI engine. (I think). These benefits should also prevails in a WRC engine.
Hope no one that really understand this, tear off his hair because of this explanation.
As far as I know, you can adjust drop-out with how much / little pressure one has before it triggers. Tein works this way in any case. Normally, a pressure of about 140 kg (or less) will be required before the drop-out occurs. This means that drop-out first occurs when the pressure is below 140 kg.Quote:
Originally Posted by br21
That is correct (if you`re reffering to RCV or CAS or whatever they name it) mostly they are spring load adjustable when the rebound needle opens, this is done in the topmount with a very small diameter spring able to withold a certain weight, by changing the spring rate you can adjust how soon/late the rebound needle opens!Quote:
Originally Posted by Coach 2
And actually the rebound doesn`t really open fully, it`s more less a certain amount/velocity of oil to run pass the shimstacks, for really fast damper speeds this small hole want be enough so something is always limited by the shimming!
yes, yes of course you are right, it was just shortcut in my thinking :)Quote:
Originally Posted by AMSS
the resume is that with direct injection you have more horsepower because you can control better the air-fuel ratio.Quote:
Originally Posted by Mirek
You can control better the timing of injection and the amount of fuel,due to the position of injector inside the combustion chamber.
Dimviii, why does DI accommodate higher compression ratios with higher boost? Is it just the control over the air fuel ratio?
allows higher compression ratios because it is prone to less detonation.Quote:
Originally Posted by TyPat107
Think you are very close to the main issue here, to avoid detonating when trying to create an explosion.Pressure changes the gas to be liquefied, or drops. Heat changes liqued back into gas.This happens in the intake manifold, intake channels and inside the engine several times in a four stroke engine. A DI engine does not take account of this issue in the intake section of the engine, but can concentrate on getting the most air to enter. Currently, this is the best way to achieve what we think is the best ratio of air and gasoline (14.5 to 1).Quote:
Originally Posted by dimviii
Again, hope whoever understands this on a different level, do not tear off his hair.
your english are much better to explain proper such tech points.Quote:
Originally Posted by Coach 2
At fuel injected engines most lean we manage with race fuel is no more than 12,2-12,4 to 1.
to understant the difference a Mitsu evo 9 with 11.8 to 1 with an identical evo with 12,2 to 1, if we accelerate from 30km/h to 220km/h the evo with 12,2 to 1, will be about 3-4 car lengths ahead.
These air fuel mixtures(12,2 to 1) are not safe at all with fuels we use (and can find at petrol stations) at our daily cars.Case of time to break.
In my daily evo i use lean mixtures of 11,9-12 to 1 but i have some gauges to monitor detonation.
WHat compression ratio do they actually use in the 1,6 DI engines? I heard from one guy what he said Ford uses but couldn`t believe it was true..
so what did you heard? 11?Quote:
Originally Posted by AMSS
By the regulations the max. compression ratio is 12,5:1.
Than what I heard was bogus, must have been the "calculated" (boost included) CRQuote:
Originally Posted by OldF
Three years before any major changes to the car. VO, ER etc. homologations possible.Quote:
Originally Posted by SlowSon
“The rules state that you should be driving the same car three years and we're going through the last season now and VW the first season.”
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