TR Forums

I agree, 100hp isn't enough for a full-size sedan. The torque looks nice though, justs needs a bit more out of the high end.

Umm, it's not all about speed, Synchromesh...

And, 11-11.5 seconds is more than enough speed for the average driver.

I'll admit, an engine like mine, where you MUST wind it out to 4500 in each gear if traffic is busy, to not get run over, is slow.

11-11.5 seconds is not slow. The Prius is in the same territory, FWIW.

Oh, and once a modern turbodiesel car is at speed, you usually don't have to even downshift for hills. Try that in a gasser.

Hell, in my car, on one hill, to maintain 60 MPH, I downshift into 4th. Fair enough.

Then, in a friend's Mazda3 2.3 with a 5-speed Sport AT, I was taking that same hill at the same speed. I push down on the go pedal to compensate for it slowing down. It drops into 4th, and is STILL losing speed. So, I push further. It gets into 3rd gear before it stops losing speed. Yes, I know, I wasn't pushing it into the floor like I do my car.

Also, passing is ridiculously easy - these TDIs pull like a freight train on the freeway.

Oh, and a chip will cure ANY slowness problems cheaply.

How about you have a nice tall glass of STFU, and realize that diesels have their strengths - even on performance?

Edit: SpotTheCat, the flame wasn't intended towards you, BTW. I started writing it before you posted. You might consider coming to a get together or something, and seeing what 100hp is like when it comes to power.

bhtooefr wrote:

11-11.5 seconds is not slow.

Yes it is.

bhtooefr wrote:

Oh, and once a modern turbodiesel car is at speed, you usually don't have to even downshift for hills. Try that in a gasser.

It'd take a pretty steep hill for me to have to downshift at cruising speed. *any* sufficiently powerful car doesn't make you downshift on hills. That sort of thing's largely the domain of underpowered cars or specific instances where you're in a gear that barely works for your speed.

bhtooefr wrote:

Hell, in my car, on one hill, to maintain 60 MPH, I downshift into 4th. Fair enough.

Then, in a friend's Mazda3 2.3 with a 5-speed Sport AT, I was taking that same hill at the same speed. I push down on the go pedal to compensate for it slowing down. It drops into 4th, and is STILL losing speed. So, I push further. It gets into 3rd gear before it stops losing speed. Yes, I know, I wasn't pushing it into the floor like I do my car.

You were also driving an automatic transmission. You'd have to shift it into manual mode to make a valid comparison.

bhtooefr wrote:

Also, passing is ridiculously easy - these TDIs pull like a freight train on the freeway.

So does pretty much any adequately powered vehicle.

Yeah, but you've got a VR6.

2.8L 6-cylinder vs. a 1.9L 4-cylinder? Another unfair comparison... (I'll admit, the Mazda comparison was poor...) Doesn't the VR have more torque than the TDI, stock?

Another thing is, many people won't take their engines above 4,000. On a TDI, you've got more power AVAILABLE without having to rev the engine out far. (Yes, there's exceptions to the rule - the Americans and Germans are both well known for torque even on gassers, and Honda's not as bad on torque as everyone says they are. But, even then, the diesels usually have more torque, and lower-end torque.)

Oh, and do you agree that in normal driving, the 1.9 TDI is MORE than powerful enough?

bhtooefr wrote:

2.8L 6-cylinder vs. a 1.9L 4-cylinder? Another unfair comparison... (I'll admit, the Mazda comparison was poor...)

Yeah, you really need to lock it in gear if you're interested in necessity, or test with an AT diesel. FWIW I don't remember needing to downshift for hills with my old saturn either, although aggressive passing was another matter. Appropriate gearing goes a long way.

bhtooefr wrote:

Doesn't the VR have more torque than the TDI, stock?

Yes, by a bit.

bhtooefr wrote:

Another thing is, many people won't take their engines above 4,000. On a TDI, you've got more power AVAILABLE without having to rev the engine out far. (Yes, there's exceptions to the rule - the Americans and Germans are both well known for torque even on gassers, and Honda's not as bad on torque as everyone says they are. But, even then, the diesels usually have more torque, and lower-end torque.)

Peak torque location cuts both ways a bit. Steeper gear ratios are going to cut into your wheel torque. Torque band width is obviously important too

bhtooefr wrote:

Oh, and do you agree that in normal driving, the 1.9 TDI is MORE than powerful enough?

Honestly, I'd need to drive one or at least see some detailed accelleration plots and dyno charts to answer that. There's always a difference between "more than powerful enough" and "truly enjoyable" too. I mean I've driven similarly slow vehicles and they got the job done, but in less than ideal fashion, depending on driving location. Go out on empty country roads and power isn't real important, but if you're driving in crowded freeways the minimum standard goes way up.

Well, the AT diesel comparison would be even suckier, because the only ATs offered on my diesel engine were 3-speeds. (and only in Canada, too.)

The torque peak is at ~2000, with the HP peak at ~4000 on the TDIs.

And, dyno plots... you'll have to be a TDIClub member to look in here, but...

http://pics.tdiclub.com/showgallery.php?cat=532 <-- 90hp engine (lower torque) in 1996-1997 Passats, 1997-1999.0 Jettas
http://pics.tdiclub.com/showgallery.php?cat=533 <-- 90hp engine in 1998-2003 New Beetles, 1999.5-2003 Jettas/Golfs
http://pics.tdiclub.com/showgallery.php?cat=560 <-- 100hp engine in 2004-2006 Golfs and New Beetles, 2004-2005.0 Jettas, very similar (differences are in engine mounts and some electronics, power ratings are the same) to engine in 2005.5-2006 Jettas

mattsteg wrote:

bhtooefr wrote:

11-11.5 seconds is not slow.

Yes it is.

man! I've driven lots of cars with a 0-60 of 30+ seconds, THAT'S slow.

Now that said... a diesel sports car is a stupid idea. They just aren't a "fun" drive. Fast, sure if it's got a turbo, economical too but not fun. Stick your foot down, you get a surge of torque and then just when a petrol engine would start to sing... you have to change gear.

Don't get me wrong, I really like diesel cars for actual transport. That low reving torqueness does mean changing gear a lot less on motorways and the like. Even not being fun to drive is a plus for me. The roads I drive on are covered with speed cameras, I don't want a car the encourages me to loose my licence.

edit: spelling

Well, now that it's won at Sebring AND Le Mans, time for some Salt Lake City action. One two start. Where have I heard that before...

2PM eastern tomorrow on CBS, FWIW. (The race is today, though.)

It's only 2:45 long.

Oh, and...

Allan McNish said at Lime Rock Park that he is losing a longtime girlfriend, but the new girl is much quieter and sexier.

bhtooefr wrote:

Umm, it's not all about speed, Synchromesh...

And, 11-11.5 seconds is more than enough speed for the average driver.

I'll admit, an engine like mine, where you MUST wind it out to 4500 in each gear if traffic is busy, to not get run over, is slow.

11-11.5 seconds is not slow. The Prius is in the same territory, FWIW.

Oh, and once a modern turbodiesel car is at speed, you usually don't have to even downshift for hills. Try that in a gasser.

Hell, in my car, on one hill, to maintain 60 MPH, I downshift into 4th. Fair enough.

Then, in a friend's Mazda3 2.3 with a 5-speed Sport AT, I was taking that same hill at the same speed. I push down on the go pedal to compensate for it slowing down. It drops into 4th, and is STILL losing speed. So, I push further. It gets into 3rd gear before it stops losing speed. Yes, I know, I wasn't pushing it into the floor like I do my car.

Also, passing is ridiculously easy - these TDIs pull like a freight train on the freeway.

Oh, and a chip will cure ANY slowness problems cheaply.

How about you have a nice tall glass of STFU, and realize that diesels have their strengths - even on performance?

Edit: SpotTheCat, the flame wasn't intended towards you, BTW. I started writing it before you posted. You might consider coming to a get together or something, and seeing what 100hp is like when it comes to power.

Just on your hill comment... i have a 1.6 Ford Fiesta Zetec S (dont know if they exist in America) but i could comfotably take any hill at 60mph in 5th gear...

Separately i would have thought outright power or torque numbers have no meaning... at least compare power/torque per kg or something. That is a much more meaning full way of looking at it i find. This way you can not only factor in the diesel advantage but also its disadvantage... quite often diesel engines weigh more.

Peak torque numbers are meaningless. It's horsepower that moves your vehicle. What you really need is a good transmission that keeps the engine producing its maximum horsepower. The limited rpm range for diesel engines makes this even more necessary. Haven't you ever wondered why big diesel trucks have so many forward gears? This is why so many new cars are equipped with 5-speed (and 6-speed) automatic transmissions with lockup instead of the old 3-speed slushboxes.

While that is true, it's usually only 100 or 200 more poudns.

That said, in the case of the Mk5 Jetta... the TDI is often considered to be as driveable as the 2.5, due to the similar torque (although the TDI has 50 less horsepower).

However, according to this datasheet, the Jetta 2.5 manual weighs 3230 pounds vs. 3197 for the Jetta TDI manual.

That said, the 2.5 is a 5-cylinder, whereas the TDI is a 1.9L 4-cylinder.

Edit: JAE, I'll have to disagree somewhat. The horsepower does move your vehicle, but low-end torque is valuable. Low-end torque manifests as available HP at low RPMs. Which means you don't have to rev the piss out of it to get fast starts.

Torque is meaningless for automobile performance. You need a good transmission that keeps the engine producing its maximum horsepower. A good modern 5-speed or 6-speed automatic transmission will "rev the piss out of" the engine if it needs to. CVT + diesel would be even better.

Ah, but your "modern 5 or 6-speed automatic" weighs and costs more than a simpler 4-speed automatic. (or a 5-speed manual, for that matter.) More low-end torque means that you can have a simpler transmission.

It ALSO means better fuel economy, as you're NOT revving the piss out of it just to have enough power.

Actually, it means worse fuel efficiency.

Running the engine at its most efficient point all of the time is better than forcing it to run across a broad range of rpms. That's why CVT is more efficient than conventional transmissions.

But, the most efficient point (most HP per given quantity of fuel) isn't usually the point of peak HP.

As for CVT, CVT transmissions suffer from more drivetrain losses than traditional transmissions. For a comparison here:

1989 Subaru Justy, 3 cyl, 1.2 L, Man(5), (FFS), Regular, City: 34, Highway: 37
1989 Subaru Justy, 3 cyl, 1.2 L, Auto(variable), (FFS), Regular, City: 33, Highway: 34

And, for a more modern CVT...

2006 Honda Insight, 3 cyl, 1 L, Man(5), HEV, Regular, City: 60, Highway: 66
2006 Honda Insight, 3 cyl, 1 L, Auto(variable), HEV, Regular, City: 57, Highway: 56

Seems to me the more advantage you have with the manual is that you can drive it like a granny if you want to get those efficiency numbers. That and the fact that most (excepting the newer 5 and 6 gear) automatics have a smaller number of gears to work through than the comparable manual.

Dont manual trannys weigh less then auto ones? If they had the same number of gears of coarse. So wouldn't a 4speed auto maybe balance out with a 5 speed manual? Figurativily speaking, if it isn't the case, the difference in weight isn't going to be so drastic where you could actually notice a differnece in performance.

JustAnEngineer torque means ALOT for automobile performance . You put a trailer behind two pickup trucks one with a 325hp/325ftlbs gas engine and a 325hp/600ftlbs diesel and tell still tell me torque means nothing .

Hance wrote:

JustAnEngineer torque means ALOT for automobile performance . You put a trailer behind two pickup trucks one with a 325hp/325ftlbs gas engine and a 325hp/600ftlbs diesel and tell still tell me torque means nothing .

I used to use my dads chevy Duramax desiel (completely stock), torque is important especially in pulling.

Also, read this: http://www.pistonheads.com/doc.asp?c=100&i=9847

Basically, if you're NOT revving the piss out of it, the 535d is faster than the M5.

Now, the M5 is faster once you DO rev the piss out of it, but...

Horsepower matters.
http://auto.howstuffworks.com/question622.htm
http://auto.howstuffworks.com/question381.htm

But the point is that high RPMs aren't necessarily good.

bhtooefr wrote:

But the point is that high RPMs aren't necessarily good.

Sure they are. That's how you make more horsepower without having to increase the displacement of the engine.

But, fuel economy is another important point.

Here's a thread that might interest you. The subject is pushrods vs. OHC, but torque, RPMs, and fuel economy are all brought up: http://forums.thecarlounge.net/zerothread?id=2702833

Basically, increasing the displacement of the engine can actually help you.

bhtooefr wrote:

Also, read this: http://www.pistonheads.com/doc.asp?c=100&i=9847

Basically, if you're NOT revving the piss out of it, the 535d is faster than the M5.

Now, the M5 is faster once you DO rev the piss out of it, but...

What is the point in racing, if your not revving the piss out of anything? Thats a usless statement i believe. When racing, the M5 will murder the 535d on a track, and in a straight line, backwards or forwards.

Some numbers:
BMW 535d
0-60: 6.0 seconds
3.0 liter 272bhp
413lb-ft
15 second 1/4 mile

BMW M5
0-60: 4.2
5.0 liter 507.0 bhp
383.5 ft lbs
12.4 second 1/4 mile

Comparing these two engines is a joke really. Probably not even a fair match. Puting it up against an M3 might have been a better engine match up, but its realy hard to say what is fair and what isn't when your comparing diesel vs gas.

http://www.youtube.com/watch?v=__HpspsvRVg&search=535d

And top gear actually reviewed a 535d, and put it up against a 550i, which is a 4.8 liter, 360 hp, with 360ft-lb torque. You can watch the video for the verdict.


One thing i will agree with is BMW makes some of the nice engines.

V10 5.0-litre engine in the M5/M6: Best New Engine 2005
V10 5.0-litre engine in the M5/M6: Best Performance Engine 2005
V10 5.0-litre engine in the M5/M6: Winner in the class exceeding 4.0 litres
3.0-litre 535d Variable TwinTurbo-Diesel: Winner in the class 2.5 to 3.0 litres
3.2-litre six cylinder engine in the M3: Winner in the class 3.0 to 4.0 litres.

One thing that'll rival the M3 engine is a GT2, which is in a class of its own. But the new M3 engine should deliver the punch back.

But now I'm talking about daily driving... how many M5 owners track their cars?

JustAnEngineer its plainly obvious that you have no real experience with diesel engines . Yes horsepower matters but torque is just as important if not more important than HP when it comes to driveability and performance.

My dad has a 2006 F150 Ford with the 5.4 triton V8 (300hp 365 ftlbs ) . The curb weight of his truck is 5170 pounds according to ford . I have a 2005 Dodge Ram 2500 with the 5.9 liter cummins diesel (325 Hp 610 FtLbs ) . The curb weight of my truck is right at 7000 pounds . When my truck was still stock we raced 1/4 mile 3 times one night . I beat him by atleast 5 truck lengths every race . I am sure it was the extra 25hp that did it for me not the extra 250 ftlbs of torque . Not to mention the fact that my truck weighs an extra 1800+ pounds

I just realized that I didn't post the results!

Audi in first and third.

It was close to the very end - a Porsche RS Spyder was RIGHT on the Audi's tail through that last turn, but the Audi just walked away from the (LMP2 - so a class down from the Audi) Porsche on the straights. The Porsche was better in corners, because (by virtue of being an LMP2) it was lighter.

FWIW, this race had a bit of dirty strategy... the #7 RS Spyder was having some minor engine problems, and IMO, decided to eliminate the gap between the second place Audi and the #6 RS Spyder (the one that ended up in second)... by "breaking down" at the end of pit lane, causing a full-course caution. Extremely dirty tactics, and completely legal according to the rules.

Portland race was yesterday, televised now on CBS.

Don't know results and am not looking them up.

Audi wins!