 Poster: A snowHead
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| Raceplate wrote: |
| LaForet wrote: |
| Re the 300 BHP thing - This is more of a side-effect of the trend towards adding a turbo to petrol engines to give them the torque needed to compete with diesels. My car is 330 BHP, but I didn't buy it because I needed that much power, I bought it because I wanted an engine that's smooth and capable of cruising down to the Alps and Alpine ascents without any bother, but in petrol form. To get that in petrol it needs a turbocharger for low-down revs, otherwise I'd be changing gear all the time going up/down hill. The turbo probably gives me another 100BHP, but I never use it to hit top speed of 160mph. And nowadays, even my car is out-accelerated by a mainstream electric vehicle, so if I wanted pure speed and acceleration, an EV would be better anyway. |
I've never understood why so many brands have spent 30-40 years trying to make petrol turbos effective instead of just fitting a supercharger in the first place. I think it's German engineering stubbornness (I'm looking at you, VAG group & BMW) - they simply won't admit that the entire concept of turbos is crap (too peaky and inconsistent power, turbo lag, crap boost in hot weather, too much wheelspin in cold weather, generally a PITA to drive) and are determined to prove that their engineering skills can overcome the inherent deficiencies of the design. Give me a consistent supercharged Jag (or Merc) any day. |
you have no idea what you are talking about. SC is driven by a belt, using engine power. Turbo spins from exhaust gas, which is a waste of an engine anyways. SC has excellent instant torque, no turbo lag, however, with a fuel consumption penalty.
All this downsizing of engines with reduced displacement and less cylinders, but turbocharger is because of CO2 emmissions. A small turbo engine can drive with exceptional efficiency at low RPM, which is very good for passing EPA test, how it is designed. Start driving normally or a bit harder, and economy goes out the window. And reliability is a non existant thing, with engines pushed to 100+ bhp from liter of displacement and everything beeing as light as possible and high operating temperatures.
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Obviously A snowHead isn't a real person
Obviously A snowHead isn't a real person
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| kosmoz wrote: |
| Raceplate wrote: |
| LaForet wrote: |
| Re the 300 BHP thing - This is more of a side-effect of the trend towards adding a turbo to petrol engines to give them the torque needed to compete with diesels. My car is 330 BHP, but I didn't buy it because I needed that much power, I bought it because I wanted an engine that's smooth and capable of cruising down to the Alps and Alpine ascents without any bother, but in petrol form. To get that in petrol it needs a turbocharger for low-down revs, otherwise I'd be changing gear all the time going up/down hill. The turbo probably gives me another 100BHP, but I never use it to hit top speed of 160mph. And nowadays, even my car is out-accelerated by a mainstream electric vehicle, so if I wanted pure speed and acceleration, an EV would be better anyway. |
I've never understood why so many brands have spent 30-40 years trying to make petrol turbos effective instead of just fitting a supercharger in the first place. I think it's German engineering stubbornness (I'm looking at you, VAG group & BMW) - they simply won't admit that the entire concept of turbos is crap (too peaky and inconsistent power, turbo lag, crap boost in hot weather, too much wheelspin in cold weather, generally a PITA to drive) and are determined to prove that their engineering skills can overcome the inherent deficiencies of the design. Give me a consistent supercharged Jag (or Merc) any day. |
you have no idea what you are talking about. SC is driven by a belt, using engine power. Turbo spins from exhaust gas, which is a waste of an engine anyways. SC has excellent instant torque, no turbo lag, however, with a fuel consumption penalty.
All this downsizing of engines with reduced displacement and less cylinders, but turbocharger is because of CO2 emmissions. A small turbo engine can drive with exceptional efficiency at low RPM, which is very good for passing EPA test, how it is designed. Start driving normally or a bit harder, and economy goes out the window. And reliability is a non existant thing, with engines pushed to 100+ bhp from liter of displacement and everything beeing as light as possible and high operating temperatures. |
I was also under the impression, that small turbo engines was a product of carmakers needing to cut emissions. A turbo roughly have two functions to my understanding:
1. Low rev torque for consumption
2. Extra power higher up the revs
This is the exact reason you now see 1.0 liter engines with turbo’s.
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Well, the person's real but it's just a made up name, see?
Well, the person's real but it's just a made up name, see?
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| Idris wrote: |
| damanpunk wrote: |
| Narrow tyres, half decent ground clearance and a bulletproof 4wd system. Ideal winter car! |
Er no. Had one as a work runablut in Meribel. Yes better than a regular panda in the snow. Otherwise a nasty, unreliable, underpowered, death trap. Suspension and the very basic nature of the 4wd system means you are regularily beeten in slipery conditions by a wel thought out fwd with good tyres and traction control/LSD. |
Honestly everything you've said makes me want one more.
I follow some guys on instagram who have some of the most wild car collections you can think of, yet they're often driving 4x4 pandas in Italy 
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Anyway, snowHeads is much more fun if you do.
Anyway, snowHeads is much more fun if you do.
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| Quote: |
you just want not to be afraid to brake some plastics
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Or perhaps break some. I think you may still want to stop the plastic.
Going back to turbo versus supercharging. I wonder why electric powered turbochargers haven't been implemented. They would be simpler than the variable pitch systems in conventional turbochargers an probably more reliable and not consume energy to the extent of superchargers when not required.
I read somewhere that turbocharged cars were rather bad at implementing their supposed fuel consumption in the real world. No where near as bad as hybrids but still significant.
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Really comes down to how you drive them, one of my cars previously mentioned is a twin turbo 3 litre with over 400bhp. If you take it easy and drive at low rpms it'll do 40mpg. Put your foot down and it's a totally different story
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@johnE, Some of the Volvos have a small pressure chamber that gives the turbo a 'kick' to spin it up when needed. Nice, simple idea. Mine doesn't have it so I dunno if it works, but I see no reason why not.
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You'll get to see more forums and be part of the best ski club on the net.
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| johnE wrote: |
I wonder why electric powered turbochargers haven't been implemented. They would be simpler than the variable pitch systems in conventional turbochargers an probably more reliable and not consume energy to the extent of superchargers when not required.
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Electric superchargers (effectively the same as an electric turbocharger, since what you're talking about is forced induction powered by something) have been tried. In the end, you're taking power from the engine, via an alternator, to an electric motor, to spin a turbine/fan. Turns out to be easier to connect that turbine direct to the engine and cut out the electrical gubbins.
If you put the supercharger on a clutch, as my car does, you get the supercharging benefits without parasitic power loss.
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Audi SQ7/SQ8 tdi has a small electric supercharger, which helps at the lowest RPM, then conventional turbos kicks in. Same engine in VW Toureg didn't have this feature. And yes, volvo D5 has a compressed air chamber, which is released to spool up the turbo faster, however lazy calibrated gearbox does not allow to feel that much sporty.
Too bad dieselgate happened, that made so much diesels dissapear. Petrol alternatives are real alternatives only if driven carefully. Relax a bit, add some load or speed, and it's no longer comparable to diesel fuel consumption.
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snowHeads are a friendly bunch.
snowHeads are a friendly bunch.
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| Quote: |
If you put the supercharger on a clutch, as my car does, you get the supercharging benefits without parasitic power loss.
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Thats not true.
A supercharger has to draw power from somewhere, if its on a disengaged clutch then fine; its not doing anything until it engages and starts taking power off the main drive.
A staged Turbo system - a small one powered from a compressor charge or electric blower, followed by a proper gas flowed one then thats different - although any electric blower will need a 48v with some pretty hefty batteries and charging circuit to spin for long. Its the system they were going to use on the R35 until they dumped it for being overly complicated and heavy.
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And love to help out and answer questions and of course, read each other's snow reports.
And love to help out and answer questions and of course, read each other's snow reports.
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You know it makes sense.
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@Judwin, Calibra? Cavalier 4x4? or something a bit more "lotusey"? Some very under appreciated cars of that era ...
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Otherwise you'll just go on seeing the one name:
Otherwise you'll just go on seeing the one name:
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| under a new name wrote: |
| @Judwin, Calibra? Cavalier 4x4? or something a bit more "lotusey"? Some very under appreciated cars of that era ... |
Loads of trouble, usually serious.
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Poster: A snowHead
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@Judwin, how lovely! 
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Obviously A snowHead isn't a real person
Obviously A snowHead isn't a real person
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Unfortunately massive turbo lag still exists; my 2021 rig will be my last turbo vehicle. Overall great car but they should have tamed this by now. I heard higher voltage electrical systems will make electric turbos/supers viable; hope so. I had and liked a supercharged car, no lag but yeah it used almost as much fuel as the V8 it replaced. Though nothing will really replace a V8! The sound......
"Home made snow chains"? Wow, that's a new one. Did you start from scratch or modify? How long before they exploded? 
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Well, the person's real but it's just a made up name, see?
Well, the person's real but it's just a made up name, see?
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| Judwin wrote: |
| under a new name wrote: |
| @Judwin, Calibra? Cavalier 4x4? or something a bit more "lotusey"? Some very under appreciated cars of that era ... |
Loads of trouble, usually serious. |
Think we're going along the lines of Lotus Carlton, which is a Vauxhall with Lotus suspension tuning.
On the subject of turbo/supercharger, forget them both and just go for a bigger engine. Nothing works better thank more CC's
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@Richard_Sideways,
| Quote: |
starts taking power off the main drive
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But how much power? I mean, if you're already at 4k rpm and putting out 250 bhp, a wee fan won't be that noticeable will it?
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Anyway, snowHeads is much more fun if you do.
Anyway, snowHeads is much more fun if you do.
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@Scooter in Seattle, Maybe on US vehicles, but on 'smaller' engined Euro models it's pretty much gone - certainly not massive.
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| Scooter in Seattle wrote: |
| "Home made snow chains"? Wow, that's a new one. Did you start from scratch or modify? How long before they exploded? |
Couldn't get them for 265-45-R19 in the 1990's. So took a set for something smaller, bought some square section chain from the local hardware shop, and set about it with the tools at hand. Did a few test fits, and they were Ok. I think they'd have got me past the rozzers at the bottom of the hill in France. Thankfully never had to use them in anger to test their robustness.
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| Scooter in Seattle wrote: |
| Unfortunately massive turbo lag still exists; my 2021 rig will be my last turbo vehicle. Overall great car but they should have tamed this by now. ... I had and liked a supercharged car, no lag but yeah it used almost as much fuel as the V8 it replaced. Though nothing will really replace a V8! The sound...... |
Rather like skis/ snowboards, I think the trick is to try before you buy.
My car has turbine assistance and it feels seamless - some of them very much have tamed it.
When buying this I also tested a supercharged V8, and to me at least that did have a kind of lag in it.
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The only lag in my 5 litre V8 is between my brain and right foot.
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You'll get to see more forums and be part of the best ski club on the net.
You'll get to see more forums and be part of the best ski club on the net.
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@under a new name, if you're using the supercharger to get you over the turbo lag hump, then it'll have disengaged by 4k RPM and be just sitting doing nothing, and they turbo will be spinning happily away on your exhaust gasses. The problem with small superchargers is that they really aren't very efficient for the complexity, weight and space they take up in the car - its why anti-lag systems traditionally either use a compressor to pre-spool the turbo or a pressure recirculation system like in the old Lancias, or more antisocially, just dump more fuel into the exhaust manifold and ignite it there and kick the impeller that way.
You're probably better off as a manufacturer adding a bit more to the engine capacity and/or shrinking the Turbo to reduce the spooltime - and playing with the map to tune it out.. seeing most modern cars are auto anyway now, you can play with the RPM change settings to keep the turbo happily on song in sport mode.
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| under a new name wrote: |
@Richard_Sideways,
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starts taking power off the main drive
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But how much power? I mean, if you're already at 4k rpm and putting out 250 bhp, a wee fan won't be that noticeable will it? |
It's not a wee fan though. It can take between 10% and 20% of the engines power to run the supercharger. http://fepower.net/Dyno%20Results/dyno_results_14.html
And power isn't really how it works anyway. You need to think in terms of torque not power. Torque is directly related to the amount of air you can get into the cylinder. Double the air means double the torque. There is no use having 250bhp at 4K RPM if the torque curve is so peaky that the power drops off rapidly either side of 4K.
The efficiency of the inlet manifold and head design affect the amount of the air entering the combustion chamber. At low revs there is lots of time to fill the cylinder. At high revs there isn't. That's why torque tails off above a given RPM - typically around 4500 RPM - you just can't get all the air into the cylinder in time. What you want is flat torque from tick-over to red line. If you could achieve this, then max power would be at red-line too. It never is.
A Normally aspirated engine - like Scooters V8 - will have good low end torque, which will probably tail off above 5000 RPM.
A forced induction car can have the same performance using fewer CC's - if (IF) it can supply high pressure air at low revs. If you can get 2 bar air (1 bar boost) into a 2.5L engine at low revs, then it'll have similar torque output to a 5L normally aspirated engine. So the trick is to get the boost air pressure up as quickly as possible at low RPM. The engine may also be capable of higher RPM than a big V8 due to the lower rotating masses. By the time you get to 4K things will be fully spun up and pressurised.
It's not uncommon for high performance cars to disengage various electrical and mechanical loads on the engine whilst being ragged so that more power is available for traction. A/C compressors for example. My windscreen wipers stop working above 150MPH. 
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snowHeads are a friendly bunch.
snowHeads are a friendly bunch.
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| kosmoz wrote: |
Audi SQ7/SQ8 tdi has a small electric supercharger, which helps at the lowest RPM, then conventional turbos kicks in. Same engine in VW Toureg didn't have this feature. And yes, volvo D5 has a compressed air chamber, which is released to spool up the turbo faster, however lazy calibrated gearbox does not allow to feel that much sporty.
Too bad dieselgate happened, that made so much diesels dissapear. Petrol alternatives are real alternatives only if driven carefully. Relax a bit, add some load or speed, and it's no longer comparable to diesel fuel consumption. |
Polestar upgrade - Made wonders for my gearbox on my V60.
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And love to help out and answer questions and of course, read each other's snow reports.
And love to help out and answer questions and of course, read each other's snow reports.
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| ansta1 wrote: |
| On the subject of turbo/supercharger, forget them both and just go for a bigger engine. Nothing works better thank more CC's |
Don't they have a saying in the US - "there's no substitute for cubic inches" 
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@Alastair Pink, yes we do!
And @philwig, the part you (or rather I) left out from "try before you buy" is "don't let your hard-on for the car deceive you into thinking the lag ain't there when it is"!
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You know it makes sense.
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@DanishRider, I've been tempted by the Polestar u/g but it's good enough as it is!
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Otherwise you'll just go on seeing the one name:
Otherwise you'll just go on seeing the one name:
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| MorningGory wrote: |
| @DanishRider, I've been tempted by the Polestar u/g but it's good enough as it is! |
You WILL get more power, but not out of this world power.
Two reasons for getting it:
1: More torque
2: The gearbox timings
The gearbox timings is alone worth the upgrade - The original software for the Aisin gearbox is horrible, but the updated version literally changes the car to the better.
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Poster: A snowHead
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Don't know what engine you've got, but mines the T5 so pretty torquey anyway!
Also not sure about the insurance aspect.
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Obviously A snowHead isn't a real person
Obviously A snowHead isn't a real person
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| MorningGory wrote: |
Don't know what engine you've got, but mines the T5 so pretty torquey anyway!
Also not sure about the insurance aspect. |
Don’t know how it works in the UK, but the polestar upgrade has EU type approval and are supported by Volvo, so here it hasn’t any impact on insurance etc. I guess you need to ask you insurance company about it.
Had the D4 190.
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Well, the person's real but it's just a made up name, see?
Well, the person's real but it's just a made up name, see?
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@Richard_Sideways, @Judwin, thanks, every day is a schoolday 
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You need to Login to know who's really who.
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| Raceplate wrote: |
| Same as the original Audi S5 with a 4.2 V8 was a far better car than the 3.0 V6 turbo that replaced it. It's consistent power and torque. |
Better engine, not better car. I had both; the V8.....loved it; I'm considering trying to find one to rebuild for my next rig. That was also the car that taught me about summer tires and how they suck in the cold. The SC V6 was the better car overall though. More sorted, very similar straight-line performance, minus the soundtrack, of course. I called it the angry vacuum cleaner. I got an all-time compliment about that car from a football dad. He said, very seriously, "I covet your car".
Since we're talking about the number of turbos, how about Porsche calling the top model in the all-electric Taycan line a "turbo"? How does one spell "hidebound" in German?
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Anyway, snowHeads is much more fun if you do.
Anyway, snowHeads is much more fun if you do.
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So, in conclusion, two turbos and a super charger and don’t bother with chains 
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You'll need to Register first of course.
You'll need to Register first of course.
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@Judwin, "And power isn't really how it works anyway. You need to think in terms of torque not power. Torque is directly related to the amount of air you can get into the cylinder. Double the air means double the torque. There is no use having 250bhp at 4K RPM if the torque curve is so peaky that the power drops off rapidly either side of 4K."
Worth expanding for explanation......torque is the effort the motor can put out and usually stated as peak @ given rpm (eg 250 lb / ft @ 2000rpm) and so it can enact that effort in total at that running point.
Bhp is something of a notional figure that takes into account time/work rate as a component of the calculation. Effectively it takes torque and uses the rpm at which the peak occurs as a gain factor to give bhp. The M in rpm being minutes.
Two engine having torque of 250 lb/2000 rpm and 250 lb/4000 rpm produce the same "power" but with the occurrence at 4000 rpm giving a higher bhp.
Ordinarily this is fitted into real usage by having a lowered gearing for the higher rpm example which then has the output of 250lb then enacted through more power pulses over a given distance.
Pressurised intake has the ability to increase however it's delivered, turbo has more options to control over a range, how that is trimmed and generally at lower cost. Hot and cold sides of turbine can be tailored individually, most now are configured with a variable geometry to alter boost on demand via altering the internal flow of the hot side primarily to bring speed at low rpm and avoid overboost at peak, normally doesn't need a waste gate to bleed of excess pressure either. They are very neat integrated units that are fitted.
All engine will vary in combustion and power with intake air temp too, intercooling (air to air heat exchange for intake cooling) is a fundamental to making power while not detonating the engine.
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You'll get to see more forums and be part of the best ski club on the net.
You'll get to see more forums and be part of the best ski club on the net.
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FAQ
just looked it up, and it appears that the last one was the 2013 version - What a shame, because a 4x4 at that price with those capabilities, is really amazing to be honest.
I knew about the A/C cutoff on some cars at full throttle but never heard anything about windscreen wipers, any power saving must be really minimal so seems like a strange design decision.