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Discussion in '2006 Audi R10' started by ging, Jan 9, 2006.
ok, im not stupid you know.
Everybody that know anything about cars, know that Diesel engines Develope more torque than a equal Gas engine.
// Krillmeister the wise has spoken ! .
Did you even read the post that you quoted? That is true that diesels produce more torque but they can't use it as well as a gasoline engine. Would you rather have 500 lb ft reached at 2,000 (diesel) RPM or 300 lb ft at 5,000 RPM (gasoline)? Besides gas engines get more hp and with peak torque achieved at higher RPMs, the curve is much better and you are able to GO FASTER.
I'm new to the forum - registered specifically for this discussion as i'm currently debating TDi vs turbo charged petrol. I live in the UK and while i appreciate diesels in the states havent really taken off, over the pond we get some pretty spirited engines.
The specific diesel i've been looking at is the TDi PD 150 VAG engine (in a Seat leon cupra tdi) which (you guessed it) generates up to 150 bhp. Doesnt sound THAT impressive does it? however it also produces a peak torque of 235 lbft. Which is a lot for a small hatchback <A BORDER="0" HREF="http://www.supercars.net/PitLane?displayFAQ=y"><IMG BORDER="0" SRC="pitlane/emoticons/smile.gif"></A>
I think the debate of "which is better, diesel or petrol" is rather pointless. They both have their advantages and disadvantages. There is however a really simple fact that cant be ignored: the acceleration that a car can achieve is a product of it's torque at the flywheel and it's ratio's. The simple fact of the matter is, that at any given speed (in the optimum gear) a typical diesel engine will produce more torque than its hp equivalent patrol cousin. Theres no way around that, and torque = acceleration. Acceleration is not related directly to horsepower like it is to torque. Torque is quite litterally "turning force", force is directly propertional to accel (mass being the factor that connects them). There are other plus points as well, diesels are much more effecient, the fuel is a natural lubricant (more so than petrol) so engine wear is reduced
The diesel also has its disadvantages tho too. Its much harder to get the diesel fuel into the cylinders so the rpm is capped much lower. However, a couple of decades ago petrols only revved up to 5k, so i hope this might simply be an engineering challenge.
Someone also made a point earlier about the greater boost pressure in TDi's. Diesels can have higher boost pressures than equivalent petrols because of their already greater compression ratio. Plus the diesel engine is ignited by compression rather than sparking, therefore the benefit of the turbo is two fold.
Someone mentioned that the calorific content of diesel is less than petrol fuel. This is only half right <A BORDER="0" HREF="http://www.supercars.net/PitLane?displayFAQ=y"><IMG BORDER="0" SRC="pitlane/emoticons/smile.gif"></A> PER KG petrol does better 45.8 MJ/kg versus 45.3 MJ/kg......But Diesel fuel WEIGHS More than petrol. Therefore, by volume diesel fuel contains 30% more energy than petrol. And fuel is used typically by volume measure, not mass
However, ultimately over large ranges of speed the diesel doesnt keep up. The rev limit ultimately means that you'll be changing gear more often than your petrol cousins and your top speed will be lower. And although the petrol torque peak will be lower, the curve will be spread over a greater rev range, so it will produce that amount of torque for longer.
The implications are reflected in a "top gear" program screened towards to end of last summer. They raced a bmw 545i and a 535d. Out of the corners the diesels superior torque pulled it away from its petrol cousin and on the straights the petrols extended rev range and gentler torque curve meant it caught up. Ultimately their lap times were 3 seconds different (and thats accounting for the slower driver) in around a 1:30 lap time. The petrol won, but by a very small margin.
I've read a lot of reviews from people that have gone between engine types. Once people get used to the diesel torque, they just dont want to go back. I mean your talking about an off the shelf car that can spin its wheels in 3rd gear at 30 mph.
Theres another advantage too, you can get so much out of a chipped diesel it's not funny. Revo technic offer engine remaps for VW group cars (i'm sure many have heard of them), they can boost the TDi PD 150 from 150 to 190 bhp and from 235 to 290 ftlbs.
The stock leon TDi 150 gets from 0-60 in 7.5 (as fast as many of its petrol GTI cousins) and it has in gear accel which would hammer them. So it's as fast off the line (through the gears) and has much more instantaneous torque avaliable for overtaking.
I'm happy to debate these points in a mature and adult fashion, and am really interested to see what people make of these new funky performance diesels.
I was dead agaisnt a diesel btw ("i'm not driving a sodding tractor" etc) until i drove one!
Oh and i should also warn anyone that wants to start quoting wonky physics at me (especially when its the sort of physics that says that torque has nothing to do with accel and really its all about hp which i read earlier) that i have a masters degree in theoretical physics <A BORDER="0" HREF="http://www.supercars.net/PitLane?displayFAQ=y"><IMG BORDER="0" SRC="pitlane/emoticons/wink.gif"></A>
Thanks for your time!
Im new ere 2 so go ez on me. but aint most of u missin da original point of ch1c4n3's post. da fact dat it has a unfair advantage. havnt u guys noticed how da diesel equivalents of petrol engines r generally a lil bigga n r turbocharged. a non aspirated petrol engine in da same car is fasta dan dan da same car wiv a diesel motor. 4 diesel 2 match da power output it must hav mor displacement n turbo's. surely da argument ends here
learn to write properly if you decide to post here again, but yes you are right, everyone is missing the point that to achieve the same hp a much higher turbo boost pressure is needed and usually a larger displacemnent as well.
It is true. For a diesel engine to produce the same HP figures, you will usually have heavily boosted engine compared to the petrol. This is normal. I think the point here in Audi knows they can dominate in Petrol..so why not try Diesel. Diesel I believe has a higher BTU, which means you can get that much more bang out of it. Correct me if I am wrong any where here...but Audi in Europe has developed a new Diesel injection system where it directly injects the fuel into the cylinders under high pressure and stratisfies (dun remmeber if they used this term) the fuel atoms to ensure better burning.
Well it's interesting how most of you are debating on acceleration/top speed. Those two are very important, but I don't think the engineers @ Audi will be willing to waste time and risk their reputations on developing a racing car that cannot compete. There is an aspect you must remeber in LeMans series is that the races are usually very very very very long. Petrol cars maybe a bit faster, but you also have the remember that Diesels of similar performance are more efficient. This is proven by a comparison of a BMW 535i Petrol Vs. BWM 535Di (don't remember the designation of Diesel).
So in this case, in LeMans, the rules stipulate that you cannot change tires and fuel at the same time correct? I believe Audi wants to prove that they can be competitive using a different type of power plant. If the TDI is much more efficient, and the tuning of the engine is well done, and the gears are properly set, then this R10 might be extremely competitive as it might get more distance per tank than the Petrols, stopping only to change tires regularly, and fueling probably 1.5 to 2x less than the competition..but this is all for us to wait and see.
Maybe you guys should think about the fact that you dont have to refuel as often with a diesel. Thats gonna make up for alot in a 12 or 24 hour race. Road and Track states that the R10 is slower than the R8. However....The rules changed. The cars are 55lbs heavier and have 15% more downforce. Longer wheelbase due to weight of the engine. There are loads of factors that go into a race car.
excuse me? "carbon dioxide which is harmless"... you sir. are one of the most retarded people i have ever heard try to shut some1 down... the funny thing is, i totally respected what you had to say right up until the end. where u ruined it all. do tell me, if carbon dioxide which is harmless, then y the hell does it #$%# up our atmosphere and kill people when givin in large enough doses? HOW ABOUT YOU DO SOME RESEARCH BEFORE EVER SPEAKING AGAIN, YOU LOW LIFE PIECE OF DOG SHIT... and dont start with that, anything will kill u in high enough doses bullshit, that argument is meaningless, its not the lack of oxygen that kills u, its the gases.
i have to agree with the guy from england. most of what you typed up i read in an old edition of MAX POWER. there they compared a golf tdi to a golf gti. thanks for the info. much appreciated
Well Carbon Dioxide if I remember correctly is quite harmless. Ok so it does contribute to green house gases and if you replaced all the air in a room with CO2 you will die. But CO is more deadly in a way that you will die quicker if you fill the same room as the CO2 with CO.
I don't think he is wrong. Just maybe hard to interpret. Pretty much all gases are kinda harmful besides Oxygen..but too much of it doesn't work well either..haha
6dia6blo6, I must congratulate you for having the education of a 4 year old. Do my previous posts not suggest that I know what I'm talking about? Don't debate me on science matters, I'll tear you apart.
Why does carbon dioxide effect the atmosphere? Well it's not because it's bloody poisonous is it you idiot, the atmosphere isn't a living thing, you can't kill it. The reason why CO2 is damaging the ozone layer is because it reacts with the O3 molecules which reflect certain wavelengths of the sun's radiation, turning them into O2, which doesn't reflect as much. Methane (CH4) is also a greenhouse gas, as is water vapour, which you'll probably say is harmful as well.
Why does CO2 kill people in large enough doses? BECAUSE IT ROBS YOU OF OXYGEN!!
Why the hell do they use CO2 in fire extinguishers numbnuts? Because it takes oxygen away from the damn flames.
You are a complete moron, and as I continually (and unfortunately) have to keep on saying on this website...DO SOME GOD DAMN RESEARCH!!
Funk3h, you make some interesting (and sometimes correct) points, however you seem to have misunderstood a couple of things:
Acceleration is proportional to rear-wheel torque, not flywheel torque, and since high hp/low tq cars must rev high, they have �larger� gear ratios, that is a higher output to input ratio, which multiplies up the torque. I seem to have made this analogy about 100 times on this website but here it comes again:
Car A: 150hp/225lbft (diesel)
Car B: 150hp/150lbft (petrol)
Car B only has 2/3 of the torque so must rev 3/2 times more to make the same power since hp=tq*rpm. If the cars had the same gear ratios then Car B would achieve a speed 50% higher than Car A in every gear, which clearly isn�t practical since it would achieve its top speed with (probably) 2 gears still to go. So, you put �shorter� gears on the petrol car (funnily enough 50% shorter) which amplifies its torque by 50%, making it equal to the diesel�s torque, therefore, given the same mass, the cars will accelerate at the same rate since they have the same rear-wheel torque.
�a couple of decades ago petrols only revved to 5k��.Well that�s a load of nonsense, the Lamborghini Miura revved to 8k in 1967. Grand Prix cars revved to 8k in the THIRTIES!!
As for diesels running more boost pressure � compression ratio has got nothing to do with it, turbo boost pressure depends solely on how much exhaust gases you can squeeze through an impellor per second. F1 cars in the 1980s were running up to 4.6bar gauge with a compression ratio of only about 7:1. The benefit is not two fold with a compression ignition engine either, power is dependent on mass of oxygen being combusted with the fuel so the pressure advantage only counts once.
Diesel contains more energy that petrol? But petrol engines produce more torque per litre than diesels with the same displacement and same turbo boost. Petrol engines can burn more fuel than diesels can so you get more power/torque.
You say the 545i (332lbft) actually beat the 535d (413lbft) around the track. Well thanks for proving that quoted flywheel torque is absolutely irrelevant.
As for having a Masters degree in theoretical physics, well big guy I�ve got a Masters degree in mechanical engineering. Think we know who the winner is in that one.
Acceleration IS dependent on HORSEPOWER since rate of change of kinetic energy over time is measured in WATTS!!!
Thank you and good night Mr Physics man.
Let's try to stay on the subject of this thread which was inquiring about the engine's size in regards to LeMans' regulations.
I dont care,still owned the petrol, even tho it is deisel n smells
"I say if you can't play fair, don't play at all"
The rules say this is how it is, so i cant see no unfair play.
If so are the rules, it is very much fair play.
everyone can use a diesel and get to use a 5,5L diesel engine.
but not everyone want to as it seems.
Audi R10 will kick their asses !.
hi, just came past your forum and noticed this
The regulations say a turbo'd diesel engine can have a capacity of 5500 cc. Not many standard 1100cc road cars match the performance of my car:
Citroen AX 1.1i
0-62 in 11.9 sec
Max 105 mph
by a person called ozzzman. just a little bit of info, I had a 1994 cireon ax spree 954cc spi that I was diving down the M5 and I hit 116.2mph and the cars bog standard. I can do 0-62 in 10.9 now put that in your pipe and smoke it.lol
by the way I dont condole driving @ high speeds with a light car, if it wings on it it would have taken off so easily, scary for braking. dont ever take an ax over 95, to be safe
just wanted to say this ok bye
nobody really reads anybodys points in these forums anyway... i like electric engines the most, they are slower and sound wierd but they are clean.
holy shit, I'm impressed. You're pretty much right on everything. Diesel's a joke, except on mass transit cause them buses burn so damn much.
in 1991, the mazda 787b's 2.6L normally-aspirated quadrotor wankel developed 700+ hp while a whole 14 years later, the audi r8's 3.6l v8, turbocharged and running 1.67 bar, managed a paltry 520 hp. so, by virtue of their greater capacity for output/displacement and output/weight, rotary engines are superior to otto cycle gasoline engines, right? in fact, rotary engines are so l33t the FIA banned them outright in 1992. and don't even get me started on the superiority of the two-stroke cycle over the otto (greater hp/l and hp/lb, after all.) more evidence of the impending automotive apocalypse just for you, chicane: http://www.speedtv.com/articles/auto/alms/26588/
and yes, i'm aware that rotaries and two strokes have one combustion cycle per revolution
Buses burn so much? Umm no. Buses use Diesels cuz it has higher torque and lower revs. If gasoline engines were so efficient and create so much power, then there is no real point of diesels have such a strangle hold over transit vehicles, and even passenger vehicles in Europe. I mean...a 1.3L Disel with like 90HP making over 130mph is pretty impressive.
1.3L Gasoline engines make bout the same ore less...and struggle to accelerate with significant load in the car..like family.
Electric engines sound cool, and not particularly slow. Check on the T-Zero electric sports car. Accelerates like a Ferrari.