MattR32 Posted October 31, 2005 Report Share Posted October 31, 2005 I was being a total dullard last night (as usual) checking on power/weight ratios but also having a look at torque/weight ratios. Now my Ashtray has identical power/weight ratio of an Audi 1.8T and an A6 2.4 (114bhp/tonne)- Not a lot, but not too shabby. However the torque/weight ratio (if such a thing exists) is way more than my old R32, more than an M3, Boxster S and Impreza STI and the same as an S4 saloon! This leads me to wonder how much high torque actually contributes to performance? The car is fairly quick but no road burner except maybe between the usual fast diesel power band of 2500-2500.000001 rpm. I also noticed how many cars fail to get above 100bhp/tonne these days - Seems the top end of motoring gets ever faster but the mid range and bottom end just gets slower and slower! Link to comment Share on other sites More sharing options...
Soapsuds Posted October 31, 2005 Report Share Posted October 31, 2005 Its all down to driving style really - if you want a car with a mega quick PUNCH of power, for overtaking etc. or accelleration in 1 gear, then torque is your be all and end all! It also helps you go up hills quicker when you are 5-up and wanting to go fast!!! This is why diesels excel for 'everyday' driving. Power is there throughout most of the rev band and you can kepp on accellerating, past most diesels when the torque dissapers! So, in essence, you need a bit of both. My starion has about 2ib/ft of torque below 3500rpm (and im not kidding) and then all 225bhp / 260ish lb/ft torque comes in at 3500rpm - and it hurts!!! Link to comment Share on other sites More sharing options...
silentandy Posted October 31, 2005 Report Share Posted October 31, 2005 Surely it's down to power curves rather than peak figures. Petrol engines will generally have a much wider more usable power band than diesels so it's getting more performance per rev in comparison. Link to comment Share on other sites More sharing options...
MattR32 Posted October 31, 2005 Author Report Share Posted October 31, 2005 Diesels party trick is definitely on hills - They fly up them! I've now got used to the power band of my car (I really wasn't keen at first) and it's a pretty narrow but work the gears well and it really does fly along. However, it still only gets to 60 in 8.6 seconds mostly because NOTHING happens under 2k rpm. I found the R32 a joy because there simply wasn't a single gap from idle to redline - You could get away with anything! I'm realistic with the diesel though - It's quick at the right time, but get it wrong and old ladies overtake in wheelchairs. What you need is big bhp and torque and an oil well in your back garden. Link to comment Share on other sites More sharing options...
shark_90 Posted October 31, 2005 Report Share Posted October 31, 2005 Sounds like the new 4.2 V8 diesel from VAG might be the answer then Matt? Link to comment Share on other sites More sharing options...
Chris_B Posted October 31, 2005 Report Share Posted October 31, 2005 Yes, it's far more to do with the overall shape of the torque curve than anything else. As power output is a function of torque and rpm, the higher the torque across the range, the higher the power output at any given rpm. Torque lower down the rev range provides better response to throttle inputs and allows the engine to gain rpms quicker. if the torque doesn't drop off as rpms rise, the power output will rise correspondingly. Howstuffworks.com has an interesting article that gives some of the maths involved. Of course, then there's the effects of ancilliary drives, gearing ratios and drivetrain losses to consider... Link to comment Share on other sites More sharing options...
activa Posted October 31, 2005 Report Share Posted October 31, 2005 If you look at modern 150bhp petrol hatches you'll find the 0-60 isn't that far away from your diesel. I think one of the reasons the figure isn't better is due to the fact(if it's the same as the Golf in this respect)that it won't hit 60 in second,so you have an extra cog swap taking up some of that time. Link to comment Share on other sites More sharing options...
MattR32 Posted October 31, 2005 Author Report Share Posted October 31, 2005 Will be under consideration when I'm a middle aged exec...(!) The 4.2TDi that is - Sound great but not my thing at the moment. Anyway, my dullard "research" shows that the Ashtray is actually quicker than I thought compared to "the competition" but that torque plays a smaller part in performance than bhp - Look at any fast Honda with big bhp, tiny torque but good performance figures. Link to comment Share on other sites More sharing options...
Frodo Posted October 31, 2005 Report Share Posted October 31, 2005 The 3.0 TDi in the Audi range looks quite good as well anywhere from 204 to 233 BHP and a good 0-60, the benefit of Quattro and still returns almost 38 mpg. Now if you chip it then 250 bhp, more torque than an RS4 and still loads of mpg. Link to comment Share on other sites More sharing options...
mooret Posted November 1, 2005 Report Share Posted November 1, 2005 Have any of you ever driven a Honda S2000? That would clearly show what a lack of torque means. 60mph in sixth.....foot to the floor........nothing Try fifth...........nothing Fourth?...........its started to pick up a little speed Third?............Wow......how fast is that? Cars without torque need the nuts reving off them to make any real progress. Fine in a sports car, but no good if you are spending all day on the motorway. For high mileage motorway work diesels win hands down every time for me. Sixth gear, 60 mph, foot to the floor and with a whoosh of the turbo and possibly a cloud of soot, 70+ (!)in no time at all. Best of all is seeing those petrol pullers busy swapping cogs to keep up! At the end of the day it depends on what you want the car for and whether you can afford to have different cars for different jobs. Link to comment Share on other sites More sharing options...
MattR32 Posted November 1, 2005 Author Report Share Posted November 1, 2005 Not driven an S2000 but had a mk3 GTi 16v for three years and tested a CTR - Both with very little torque but good performance if you caned it. The Ashtray is actually very easy to live with and has genuine back of the seat shove at the right revs but I guess my favourite power delivery, the one that drinks fuel alarmingly and costs a packet to insure, is the big block petrol engine shove of something like an R32. Link to comment Share on other sites More sharing options...
Ian_C Posted November 1, 2005 Report Share Posted November 1, 2005 Torque is more important than bhp in everyday driving. Agreed. With our tractors, the 'meat' is right there at the bottom end. Good economy and instantaneous torque should it be required. Petrols like the S2000 do nothing for me. Although I have never driven one, it would frustrate the f--- out of me unless I was screaming around a track. The Ferrari 355, which doesn't get out of bed below four grand, is forgiven due to the screaming orgasm it offers at double this engine speed. Still don't understand why manufacturers and magazines don't demonstrate torque output. E90 320d with 163 bhp. Who gives a monkeys - 163 bhp is nothing - it's the monster 250 lb ft that makes it into a driftdays special around an airfield on its piddly 16s should you disengage the electronics. Reference the short power band, remember the torque starts just stupidly low. Well, it does with the modern French offerings - pulls smoothly from 40 mph town limits in 4th from 1500 rpm. Gather the heavier Audi & Volkswagens with PD 130 just won't do this. What is the Vauxhaul like at 1250-2000 rpm Matt? Certainly agree there is no point in going much higher than 3k - better to grab another gear and trust the torque. Ian Link to comment Share on other sites More sharing options...
shark_90 Posted November 2, 2005 Report Share Posted November 2, 2005 [ QUOTE ] Reference the short power band, remember the torque starts just stupidly low. Well, it does with the modern French offerings - pulls smoothly from 40 mph town limits in 4th from 1500 rpm. Gather the heavier Audi & Volkswagens with PD 130 just won't do this. [/ QUOTE ] You're joking aren't you? I regularly drive at ~20mph in 3rd through town and easily accelerate to 40/50 in breeze, and I'd say 4th is just as good at it's relative speeds. Ok, so mine's been remapped now, but I did drive it for a good while as standard and I can assure you it's a very flexible engine Or maybe they just don't loosen up until 135,000 miles Link to comment Share on other sites More sharing options...
MattR32 Posted November 2, 2005 Author Report Share Posted November 2, 2005 Ian - The turbo kicks in at just over 2k rpm. Below this, I'd say the it's relatively "normal" in power delivery but I try and keep it between 2 and 4k rpm to really get motoring. Once the turbo gets whistling, it really goes well. The car is pretty light at under 1300kg (for an estate) so the bhp and torque go a long way. Link to comment Share on other sites More sharing options...
Sparky Posted November 2, 2005 Report Share Posted November 2, 2005 [ QUOTE ] [ QUOTE ] Reference the short power band, remember the torque starts just stupidly low. Well, it does with the modern French offerings - pulls smoothly from 40 mph town limits in 4th from 1500 rpm. Gather the heavier Audi & Volkswagens with PD 130 just won't do this. [/ QUOTE ] You're joking aren't you? I regularly drive at ~20mph in 3rd through town and easily accelerate to 40/50 in breeze, and I'd say 4th is just as good at it's relative speeds. Ok, so mine's been remapped now, but I did drive it for a good while as standard and I can assure you it's a very flexible engine Or maybe they just don't loosen up until 135,000 miles [/ QUOTE ] Yeah, I agree mate. Not sure what Ian means. Mine pulls early, in any gear with plenty of power. Link to comment Share on other sites More sharing options...
Ian_C Posted November 3, 2005 Report Share Posted November 3, 2005 Apologies, my mistake, the lack of pull from idle was aimed at the Vauxhalls not the Audis. Strange the Vaux has a distinctive turbo 'kick in' point - most modern offerings just have a seamless surge from idle upwards. Ian Link to comment Share on other sites More sharing options...
MattR32 Posted November 4, 2005 Author Report Share Posted November 4, 2005 Ian - I've driven plenty of TDIs and the 1.9CDTi unit, as used in Saabs, Alfas and Vauxhalls is one of the most refined and smoothest sub 3.0 litre TDIs available. There's no rough turbo lag or "kick" in but a noticeable surge in power above 2k rpm. You also here the turbo whistle (and it's very noticeable) just above 2.5k rpm and, for a diesel, it actually sounds quite good. I've driven the Golf 150PD with the same power and torque (just about) and the Vauxhall unit is streets ahead. I'm also not keen on the rough as nail 2.5TDI unit used in VWs and Audis - Also very rough. Link to comment Share on other sites More sharing options...
Ian_C Posted November 4, 2005 Report Share Posted November 4, 2005 [ QUOTE ] I've driven the Golf 150PD with the same power and torque and the Vauxhall unit is streets ahead. [/ QUOTE ] Blimey - it is that good?! Ian Link to comment Share on other sites More sharing options...
shark_90 Posted November 5, 2005 Report Share Posted November 5, 2005 The 150PD engine is meant to be a bit of a dog anyway, most people I've spoken to say the 130 is the one to have. The 130 is more expensive to run with the cambelt being at the front of the engine though Link to comment Share on other sites More sharing options...
MattR32 Posted November 5, 2005 Author Report Share Posted November 5, 2005 I've heard many say the 130 is smoother and more refined than the 150PD. The GM sourced unit beats them on refinement though but rather than listening to me witter on, try one! Link to comment Share on other sites More sharing options...
R32North Posted November 5, 2005 Report Share Posted November 5, 2005 I'm keen to find out what the 170PS VAG version is like! Link to comment Share on other sites More sharing options...
mulkbear Posted November 5, 2005 Report Share Posted November 5, 2005 I love the V.A.G. TDI PD 130 and the TDI PD 150 The 150 has a loud turbo and it is a tuned engine so it loses some of its refinement. On the good side it is a great The 130 is a great all rounder with a 6 speed box it is the dogs dangleys Link to comment Share on other sites More sharing options...
activa Posted November 5, 2005 Report Share Posted November 5, 2005 I don't understand this 130 is more refined comment? They're both diesels and sound like diesels just that the 150 is quicker. I don't notice much lag,it pulls smoothly from most revs and from 40 onwards will upset a lot of petrol equivalents. Link to comment Share on other sites More sharing options...
Thorburn Posted November 5, 2005 Report Share Posted November 5, 2005 I believe by more refined he means less noisy and possibly less vibration.... Link to comment Share on other sites More sharing options...
activa Posted November 5, 2005 Report Share Posted November 5, 2005 [ QUOTE ] I believe by more refined he means less noisy and possibly less vibration.... [/ QUOTE ] Well,I can't say I've noticed any vibration whatsoever and the only time you hear it is at tickover. I can only assume that all diesels still rattle on idle execpt maybe the 535D which is probably a few light years ahead! Link to comment Share on other sites More sharing options...
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