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Leon FR TDI blew me away
- Thread starter daveyonthemove
- Start date
Bet you popped out for a quick GPS/speedo comparison run between your last two posts... wish there were 100mph roads around where I live
Interestingly I've measured 3 cars (a Z3, a CTR and a WRX) against GPS and they all read 10-12% over on the speedo... so hats off to Seat for calibrating their speedos well.When I can be bothered I'll put together an spreadsheet that'll calculate theoretical acceleration at any speed etc. given a torque plot and gear ratios, final drive, wheel & tyre sizes. Will be a useful tool for showing ideal shift-up points for both smokers and greenhousers and may put an end to the arguments over which will accelerate quicker, there's no doubt oil burners are getting better all the time, but I still don't think they can overcome the tall gearing needed for lack of RPMs.
Irrespective of fuel type, car designers should ideally make the redline the best shift-up point for every gear, but they sometimes get it wrong and if you are chipped it may also be different. Many people change up when acceleration (i.e. torque) starts falling off, but this is usually too soon since you're better off (i.e. more torque at the wheels) with less engine torque and shorter gearing than more engine torque but taller gearing.
Is this thread still going?
can i make it a bit simpler for everyone here?
I help run a diesel related car site, so i would obviously be the first to shout about how good diesels are (and i do), BUT as i've admitted (more than once) the car who was following me was MUCH quicker, and it does appear that it was a petrol variant. Torque or no torque, i would not have beat that car!
Can we leave it at that and stop bickering and sniping now?
can i make it a bit simpler for everyone here?
I help run a diesel related car site, so i would obviously be the first to shout about how good diesels are (and i do), BUT as i've admitted (more than once) the car who was following me was MUCH quicker, and it does appear that it was a petrol variant. Torque or no torque, i would not have beat that car!
Can we leave it at that and stop bickering and sniping now?
I was that car following you! I have an 1986 Mini Clubman in Red with tin foil coloured wing mirrors. I was probably just a blur due to my mini's pure speed because it has a 1.2 DIESEL engine. I CAN TAKE ON THE WORLD!!!!
if you say so mate.
You nasty cider drinking apple scrumping tractor driving farmer
but obviously if you have a car with 236lb/ft at 2000rpm and another one with 236lb/ft at 1000rpm, the later will be slower to accelerate because it has less power because the revs are lower
NO
! It's TORQUE (at the wheels, NOT engine torque) and only TORQUE that determines acceleration. Unless you want to argue with Sir Isaac 
!F=ma
acceleration = Force (i.e. Torque) / Mass (i.e. mass of your car)
POWER is not something that is measured, only calculated. A dyno or rolling road is measuring TORQUE at various RPMs.
(assuming bhp and lbft units...)
POWER = (TORQUE * RPM ) / 5250
Look at ANY Power/Torque plot. POWER is always equal to TORQUE at 5250rpm for this reason.
BUT and it's a BIG BUTT... It's torque at the wheels that determines your acceleration and this takes into account the gearing between engine and wheels. So, an engine that can rev higher can still produce more torque at the wheels than an engine with more torque but lower RPM limit, since the gearing can be shorter to provide any given speed.
POWER can therefore be a useful indicator that an engine can rev, particularly if it doesn't have much torque (think vtec) and so benefit from shorter gearing providing greater acceleration.
How many tour-de-france cyclists do you see with big Arnie Swarzenegger legs... they don't have strong (i.e. TORQUEY) legs, but, they can peddle like the proverbial clappers (i.e. high RPM) and therefore use a lower gear and thus still have more TORQUE at the wheels.
Again good point, torque at the wheels is not advertised in all the sales brochures misleading some people on here. However torque at the engine, particularly at low engine speeds (diesel) is a good selling point (and therefore advertised) as it is an indicator of how well the car picks up well from low revs and is hence easier to drive quickly than a car with less power at the engine (Although not neccesarily quicker overall as explained by yell_oh). Although I'm sure that others will still argue otherwise...
....and that's what makes threads like these amusing to read, keep it up guys.
we have 2 bora's in the car pool at work, a 150TDI and a 130TDI.
The PD130 version feels so much more urgent in its mid range acceleration, and was wondering whether the PD150 had a bigger turbo and hence more lag (rather than just a different mapping). The PD150 feels like it has more top end power at higher speeds, but around town the PD130 certainly feels the better of the 2 cars. I've never driven a PD170 - is the 2.0L lump much heavier than the 1.9L to affect the power to weight ratio?
The PD130 version feels so much more urgent in its mid range acceleration, and was wondering whether the PD150 had a bigger turbo and hence more lag (rather than just a different mapping). The PD150 feels like it has more top end power at higher speeds, but around town the PD130 certainly feels the better of the 2 cars. I've never driven a PD170 - is the 2.0L lump much heavier than the 1.9L to affect the power to weight ratio?
I would say that the FR TDI and the TFSI are almost identical in their midrange acceleration... with the TFSI being a little bit faster, but not something worth mention!
I got a TFSI sport up my self, and I have tried a FR TDI! - In comparison they really feel much the same when we talk about midrange acceleration... but they are of course pretty different to drive! - No doubt about that from 0 to 100km/h the TDI can’t keep up with the TFSI...!
I have measured my own car by recording the rev counter and speedometer on video and then measured the speed! (not the best way, I admit that... but I tried a couple of times and are pretty satisfied with the result, even though I grant its not EXCATELY accurate compared to professional equipment!)
My TFSI (not an FR so it should only produce 185hp... but as mentioned before, a lot of them produce around 200hp in reality) goes from 60 - 140km/h (3. and 4. gear) in a little less than 9 seconds, and from 65 - 145km/h (only in 4. gear) in a little more than 9 seconds!
I have seen a video of a guy (maybe girl) pulling of from 60 - 140km/h in about 9 seconds in a Leon FR TDI... (guess that it was in 3. and 4. gear) so I believe they are - as I said before - almost identical in their midrange acceleration!
If the FR TFSI really has around 15hp more than my car (I have tried one as well... but it was hard to tell a difference), then I believe it must be slightly faster than the FR TDI in the midrange acceleration... but again... I don’t think it’s much!
I got a TFSI sport up my self, and I have tried a FR TDI! - In comparison they really feel much the same when we talk about midrange acceleration... but they are of course pretty different to drive! - No doubt about that from 0 to 100km/h the TDI can’t keep up with the TFSI...!
I have measured my own car by recording the rev counter and speedometer on video and then measured the speed! (not the best way, I admit that... but I tried a couple of times and are pretty satisfied with the result, even though I grant its not EXCATELY accurate compared to professional equipment!)
My TFSI (not an FR so it should only produce 185hp... but as mentioned before, a lot of them produce around 200hp in reality) goes from 60 - 140km/h (3. and 4. gear) in a little less than 9 seconds, and from 65 - 145km/h (only in 4. gear) in a little more than 9 seconds!
I have seen a video of a guy (maybe girl) pulling of from 60 - 140km/h in about 9 seconds in a Leon FR TDI... (guess that it was in 3. and 4. gear) so I believe they are - as I said before - almost identical in their midrange acceleration!
If the FR TFSI really has around 15hp more than my car (I have tried one as well... but it was hard to tell a difference), then I believe it must be slightly faster than the FR TDI in the midrange acceleration... but again... I don’t think it’s much!
NO
F=ma
acceleration = Force (i.e. Torque) / Mass (i.e. mass of your car)
POWER is not something that is measured, only calculated. A dyno or rolling road is measuring TORQUE at various RPMs.
(assuming bhp and lbft units...)
POWER = (TORQUE * RPM ) / 5250
Look at ANY Power/Torque plot. POWER is always equal to TORQUE at 5250rpm for this reason.
BUT and it's a BIG BUTT... It's torque at the wheels that determines your acceleration and this takes into account the gearing between engine and wheels. So, an engine that can rev higher can still produce more torque at the wheels than an engine with more torque but lower RPM limit, since the gearing can be shorter to provide any given speed.
POWER can therefore be a useful indicator that an engine can rev, particularly if it doesn't have much torque (think vtec) and so benefit from shorter gearing providing greater acceleration.
How many tour-de-france cyclists do you see with big Arnie Swarzenegger legs... they don't have strong (i.e. TORQUEY) legs, but, they can peddle like the proverbial clappers (i.e. high RPM) and therefore use a lower gear and thus still have more TORQUE at the wheels.
I give up, lol, i was merely stating that a big torque figure at the fly on its own isn't enough to give any idea of how a car will accelerate as it depends at what revs the torque is and a car with relatively low torque but high revs can easily be as quick.
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