Car – Good idea or mechanical stupidity?
Turbo lag on a modern engine is minimal such that if you’re experiencing it you”re not driving properly. If you’re in too high a gear you’ll get lag, if you’re in the right gear then lag is negligible. Turbocharged engines are far more efficient as they’re utilising energy that would otherwise be wasted.
Modern cars are less leggy cause the use smaller turbos. This is possible due to modern electronic engine management systems that enable the use of turbos with higher compression ratio engines while the engine management system can control knock (exploding air/fuel mix rather than burning air/fuel mix). Even later development is direct injection, a technology that suddenly pulled Diesel engines out of the Stone Age, is now starting to be introduced which will further enable lag to be defeated. Back in the ’80’s when engine management systems were quite basic you had to reduce the engines compression ratio to avoid knock meaning larger turbos to increase the flow rate, which meant very leggy turbos.
Also turbos generate more torque, and it is torque that is more important as it means you can push bigger gears, hence better efficiency and acceleration.
The anti lag mechanisms work in various ways, but the best is the variable vane set up which is better than a complicated, heavy and expensive twin sequential turbo set up. Other methods include introducing fuel into the exhaust manifold which is burned to increase exhaust manifold pressure, but clearly this requires some pretty advanced materials in both the turbos and the exhaust manifold to handle the high temperatures and is prohibitively expensive for normal road cars.
Contrary to popular belief a turbo does not act like a windmill. You’re not trying to ‘blow’ gas through it as high speed. Turbos use the expansion of a hot gas to extract the heat energy out of the exhaust gas. The hot exhaust gas is at a high temperature and pressure at the turbo inlet with a very slow speed -almost zero. The hot gas then expands as it passes through the turbo and cools as it does so. It is the expansion and acceleration of the gas from almost zero to a very high velocity as it expands that drives the turbo. So minimising turbo lag is not not about ‘keeping the turbo spinning’, it’s about maintaining gas pressure and temperature in the exhaust manifold.
I suspect the F1 cars will be using direct injection engines with variable vane turbos and some form of fuel injection into the exhaust manifold – but they’re less concerned about lag as they are keeping the engine speed high which maintains exhaust gas flow which in turn maintains exhaust gas pressure.
So in answer to the original question, turbos are a very elegant solution. Normally aspirated is just inefficient and superchargers are plain stupid as they take more energy out of the engine rather than utilising energy that would otherwise be wasted, thus further reducing efficiency.Posted 4 years agodjgloverMember
This is what twin turbos do isnt it?
Turbo lag on a new car is almost un-noticable, plus with a NA engine you have to wait for peak power and torque to arrive, whereas with the turbo the power is just so accessible.
I love the NA straight 6 in my car, but you have to rev the balls off it to get the performance, but in the turbo straight 6 I have just ordered the peak torque is 1300 rpm, so its moving urgently throughout the rev range
🙂 😉Posted 4 years agoWorldClassAccidentMember
Manufacturers seem to be moving to turbos to get the fuel economy figures without losing the power. I am not a big fan of forced induction based on experience (despite loving my supercharged V8 SLK).
I will start with a slightly clichéd description of the options at the moment.
Turbo chargers = good power, good economy, driving experience compromised through lag
Super charging = good power, constant mechanical drag effecting economy, good driving experience
Natural Aspiration = okay power, poorer economy, best engine response
Now imagine having an ‘always on’ turbo charged engine. Still the good economy and power but with normally aspirated like engine response.
I know Lancia and VW have done supercharged and turbocharged engine but this is a very mechanically complex system with lots of extra gubbins to fit into the engine bay.
What about this then – fit an electric motor into the turbo charger. The electric motor keeps the turbo spinning while it is ‘off boost’ and can be switched off once the turbo is up to speed. Less weight and complexity that a supercharger and wouldn’t need massive batteries (weight) as it would only need to work at low revs. It could even recharge on overrun.
Any engineers want to shoot this idea down before I run off to the patent office?Posted 4 years ago
Electronic compound turbos – pretty much lag free.
They are going to be released by the VW group next year I think. Also the next BMW M3/4 has a new induction system with extremely low inertia.
Modern turbo diesel and petrols are pretty lag free with high torque in the 1200-1800rpm rangePosted 4 years agoallthegearMember
I drive one of these VW twincharger engines and it is really weird how quick it is to pick up once the accelerator is pressed.
I used to have a really quite ‘old school’ turbo engine in my Subaru Impreza. That would need a completely different driving style than a normally aspirated engine and I can see the difference. Mind you, unlike WCA, I actually MUCH prefer a turbo engine to an NA one…
RachelPosted 4 years agoflap_jackSubscriber
Says the man that has probably not driven a decent non-turbo engine as a comparison – or a fast motorbike for something with instant acceleration at any revs.
I used to have an FZR1000 Yamaha. I find the response of a turbo diesel acceptable. It strikes me as unreasonable to expect a 1.9 Golf to go like an eXup, so I can’t really understand your point.Posted 4 years agogarage-dwellerSubscriber
If you drive a modern diesel or petrol turbo car properly you really shouldn’t notice much lag and the little there is can be made to work for you (creeping through crap traffic or slow manoeuvres).
I like turbo and na cars of both fuel types. I will happily have any solution so long as the manufacturer has sorted the car as a package. Cracking engine and bad chassis- no thanks. Wooden brakes and floppy steering would ruin a car with the most incredible engine.
I think turbo engines will dominate the future as the best compromise for road cars of performance and economy.
For a track weapon I would fancy an naturally aspirated engine and something nice and light.Posted 4 years agob rMember
I find the response of a turbo diesel acceptable. It strikes me as unreasonable to expect a 1.9 Golf to go like an eXup, so I can’t really understand your point.
The point is that a decent non-turbo car (for example; either of my last two, a 3.5i V8 or 3.0i V6) is far nicer to drive than pretty much any smaller engine turbo with the same bhp – especially when going from non-turbo petrol to a turbo diesel.
And, that a decent motorcycle really makes you appreciate non-turbo engines, for their ability to just rev from any point, with no lag.Posted 4 years ago
Well I’m sure that something like a 6.2l AMG is almost the perfect performance engine (c63 please) however given purchase, fuel and tax prices that isn’t going to happen for many. Combining a combo of fuel efficiency, little lag and high torque a big modern tdi is a good alternative. Pretty good response and performance from most normal driving situations?Posted 4 years agoThe Flying OxMember
I’ve not driven any turbo engine that gives the same crisp throttle control of a good normally aspirated engine.
I know most people won’t have had the chance, but a turbo’d rotary is about as good as it gets as far as FI goes, and certainly more enjoyable than any NA car I’ve driven (e.g. BMW 4 & 6 cyl, VTEC Hondas, Jag straight 6).
Nice, instant throttle response up to about 3500rpm, then over the next 1000-1500rpm your available power roughly doubles. There’s nothing quite like it. And none of the lack of torque nonsense. If we’re talking throttle response, that doesn’t include driving everywhere in 6th gear and still expecting effortless overtakes.Posted 4 years agooldnickMember
I must admit to not having a vast experience of different cars but I do like the way my old 16v KR GTI got more and more urgent as the revs increased. But I can’t ignore 225 (stock) BHP, so the S3 BAM lump is on its way.Posted 4 years ago
As I get older easy overtaking starts to appeal, but they do sound a bit pants compared to a revvy NA. That said my mate’s 4.2L XK seemed to be the best of both worlds, given that I wasn’t buying the petrol 🙂northernmattMember
I went from 1.0 Nissan Micra with 61bhp and about 110nm of torque to a 2.2TD Toyota Avensis with 180bhp and 400nm. I enjoyed driving the Micra fast more than I do driving the Avensis fast even though the diesel can leave quite a lot of other cars on the road in a cloud of soot.
I think in my case it’s a lot to do with being able to extract the most from a car and still stay (reasonably) within the law whereas in the faster car it’s much harder to have a bit of fun as at slower speeds it’s just not that involving. Mind you, that could be something to do with it being a Toyota Avensis.Posted 4 years agoTheArtistFormerlyKnownAsSTRSubscriber
Can’t we just assume that if you can think of any conceivable way of extracting power from an engine that
a) the Germans have either done it/are on with it – and will do a bloody good job of it
b) the Japs have either tried it/will copy it/have some batshit crazy alternative with varying results
c) the Yanks just thought fook it and increased the displacement?Posted 4 years agobenjiSubscriber
Rather than wasting all the brains on developing technology for a fuel that will run out as it is a finite resource, why not spend it making something sustainable, and then just for a change the manufacturers actually make all items serviceable, so if something needs a 5p washer/rubber widget that can be changed rather than having to junk a £100+ assembly.Posted 4 years ago
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