Help me understand the difference
Discussion
I had a 2005 BMW 645i until about a year ago when it died. I loved that car and the sound of the engine.
As it's replacement I got a 1998 Jaguar XKR.
4.4L v 4.0L Thugh the Jag is supercharged.
When I put my foot down in sport mode in the Jag, the engine sounds better, and it feels faster and the acceleration more exciting than the BMW did. It took me a long time to appreciate, but now I feel certain that the Jag is more exciting.
If they're both V8s and the cars have similar statistics/horsepower, can someone explain why the Jag seems more fun? Is it the supercharge?
As it's replacement I got a 1998 Jaguar XKR.
4.4L v 4.0L Thugh the Jag is supercharged.
When I put my foot down in sport mode in the Jag, the engine sounds better, and it feels faster and the acceleration more exciting than the BMW did. It took me a long time to appreciate, but now I feel certain that the Jag is more exciting.
If they're both V8s and the cars have similar statistics/horsepower, can someone explain why the Jag seems more fun? Is it the supercharge?
Yeah, it’s like having another couple of litres, which in effect it is.
I remember a similar discovery, two Saab 9-3s, one none turbo 2.0 and one light pressure turbo 2.0, only 15/20 bhp in alledged outright power difference but my god, night and day difference to drive. The turbo was much much nicer.
People wax lyrical about N/A engines and they are often right, if the car is light, and/or the engine is massive but forced induction has its place as you found out.
I remember a similar discovery, two Saab 9-3s, one none turbo 2.0 and one light pressure turbo 2.0, only 15/20 bhp in alledged outright power difference but my god, night and day difference to drive. The turbo was much much nicer.
People wax lyrical about N/A engines and they are often right, if the car is light, and/or the engine is massive but forced induction has its place as you found out.
In addition to the Jag's engine being more powerful and torquey, there's also the difference in the car itself.
The XKR is 10cm lower in roofline, so you probably sit closer to the road. It is also 20cm shorter in wheelbase, which tends to increase pitch under acceleration, which also increases the sense of speed and excitement. I suspect there is probably more engine, road and wind noise, which also increases the feeling of acceleration.
Overall the BMW is a fairly modern 2000s car, whereas the Jag is a 90s car based on a 70s one (the XJ-S). Thus even though both cars are rated at about 5.5 seconds 0-60, it's probably a more exciting five and a half seconds in the Jag.
As others have said, it will be the torque from the supercharger.
My 2005 Alpina B5 (E61) is based on a 545i (4.4 V8 so the same engine as your 6 series had) but with updated internals, more cooling/intercooler, but most importantly a supercharger. Boost starts about 2.5k revs and by 4k the acceleration is frankly silly with revs flying up. Superchargers rock. I've driven more powerful (bhp) cars but nothing has made me giggle like a child as this thing does.
I started out with bikes, and still have bikes, and this car is the closest I've tried that feels like the way bike revs rapidly progress, since about 15 years ago I experienced piloting a 911 Turbo with a launch from rest which was memorably mental.
My 2005 Alpina B5 (E61) is based on a 545i (4.4 V8 so the same engine as your 6 series had) but with updated internals, more cooling/intercooler, but most importantly a supercharger. Boost starts about 2.5k revs and by 4k the acceleration is frankly silly with revs flying up. Superchargers rock. I've driven more powerful (bhp) cars but nothing has made me giggle like a child as this thing does.
I started out with bikes, and still have bikes, and this car is the closest I've tried that feels like the way bike revs rapidly progress, since about 15 years ago I experienced piloting a 911 Turbo with a launch from rest which was memorably mental.
Mr E said:
At a guess, a s
t ton more torque.
This would be my guess too. Something comparable would be my CLS55 vs my CLS63, the 6.2 makes more power but less torque and that power comes in really high in the revs, so for normal driving it's a bit more wafty. The CLS55 is supercharged and that torque is far more immediate, it always feels like it ready to launch. As my mrs said as a passenger, it's either on or off. t ton more torque. So I'd probably say that the supercharger is the key. Where your old 6 series needed to be revved to really get shifting, the Jag is more immediate.
Forced induction and loads of torque is why people love turbo diesels, its like the inverse of what a lot of us were used to, you get that low down punch and not much up top, vs say an old 2 litre 16 valve which was gutless low down and you had to rev it hard to make progress.
My Jaguar is a 3 litre Turbo Diesel and it has a fair bit of shove, 450 lb/ft at 2000 rpm so if moves quite well, its never lacking but you get the feeling there is no point hoofing it like a petrol, it just doesnt go that much faster, they always feel based on the initial response like there is plenty in reserve but in reality you have had most of it.
Then electric motors come in and in terms of power delivery, just wipe the floor with everything.
My Jaguar is a 3 litre Turbo Diesel and it has a fair bit of shove, 450 lb/ft at 2000 rpm so if moves quite well, its never lacking but you get the feeling there is no point hoofing it like a petrol, it just doesnt go that much faster, they always feel based on the initial response like there is plenty in reserve but in reality you have had most of it.
Then electric motors come in and in terms of power delivery, just wipe the floor with everything.
It's all to do with Torque as others have said. BHP is a made up number. We all give it a lot of importance, but all Horsepower is, is (Torque(lb-ft) x RPM)/ 5252.
An engine with forced induction acts as if it is a bigger engine. You get more air in, therefore you can shove more fuel in and get a bigger bang. (Though to describe the combustion in the cylinder as an explosion is very wrong too!) That bigger bang, pushes down on the piston with more force. That force is turned into a rotational force by the crankshaft being pushed round by the piston movement and onwards down the gearbox and drivetrain until it hits the wheels which turn that rotational force into motion.
The other thing to think about is the gearing on the car and how that works. For example, I used to have a PH favourite of a tuned 335d. It had masses of torque on the dyno and actually had to be dialled back as the diff was grumbling about it. Yet a few years later, I replaced it with a more modern 330d (they hadn't released the 335d for that era of 3 series yet) and whilst on paper it had a lot less go, it also had the new ZF 8 speed gearbox. It felt significantly faster than the old 335d even with less torque and power which had the older 6 speed auto.
Everyone else has already answered it wit the comments about forced induction, but there are lots of reasons for cars to feel faster or slower.
An engine with forced induction acts as if it is a bigger engine. You get more air in, therefore you can shove more fuel in and get a bigger bang. (Though to describe the combustion in the cylinder as an explosion is very wrong too!) That bigger bang, pushes down on the piston with more force. That force is turned into a rotational force by the crankshaft being pushed round by the piston movement and onwards down the gearbox and drivetrain until it hits the wheels which turn that rotational force into motion.
The other thing to think about is the gearing on the car and how that works. For example, I used to have a PH favourite of a tuned 335d. It had masses of torque on the dyno and actually had to be dialled back as the diff was grumbling about it. Yet a few years later, I replaced it with a more modern 330d (they hadn't released the 335d for that era of 3 series yet) and whilst on paper it had a lot less go, it also had the new ZF 8 speed gearbox. It felt significantly faster than the old 335d even with less torque and power which had the older 6 speed auto.
Everyone else has already answered it wit the comments about forced induction, but there are lots of reasons for cars to feel faster or slower.
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