Car – Good idea or mechanical stupidity?

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  • Car – Good idea or mechanical stupidity?
  • orangeboy
    Member

    Do rally cars not have an anti lag system that keeps the turbo spinning anyway

    Premier Icon richmars
    Subscriber

    I think this is called a compound turbo, coming to f1 next year.

    Sui
    Member

    It already exists, can’t remember who, but one of my clients has it.

    nicko74
    Member

    Would this not be redundant-ish because of the idea of sequential turbos? Obviously they’re not the same thing, but that idea of a small turbo that spins up rapidly, leading into a larger one with more boost, into a third potentially (as with BMW’s 550d engine)?

    Beveled Edge
    Member

    Pretty sure Audi do/are going to do this on their diesels?

    wobbliscott
    Member

    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.

    djglover
    Member

    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

    🙂 😉

    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?

    oldnick
    Member

    Turbo = easy to drive quickly
    NA = nice to drive quickly

    IMO of course.

    oldnick – hit it on the head!

    I understand turbos work etc but I want them as nice as NA engines. For fun driving not just race courses

    b r
    Member

    Turbo lag on a modern engine is minimal such that if you’re experiencing it you”re not driving properly.

    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.

    Premier Icon tonyg2003
    Subscriber

    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 range

    Premier Icon Northwind
    Subscriber

    oldnick – Member

    Turbo = easy to drive quickly
    NA = nice to drive quickly

    Turbodiesel- easy and nice to drive quickly. While leaving satisfying clouds of smoke, like a rocket.

    allthegear
    Member

    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…

    Rachel

    Premier Icon flap_jack
    Subscriber

    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.

    Are you trolling STW and PH?

    Both places have their recurring topics and this is a common one on PH.

    TuckerUK
    Member

    superchargers are plain stupid

    😯

    FunkyDunc
    Member

    I’ve not driven any turbo engine that gives the same crisp throttle control of a good normally aspirated engine.

    Premier Icon garage-dweller
    Subscriber

    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.

    b r
    Member

    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.

    Premier Icon flap_jack
    Subscriber

    My wife’s 1.9 turbo diesel golf has one helluva crisper response than my normally aspirated diesel 3 litre Merc. But then it weighs half what the Merc does. Think there’s more to it than just the turbo, as garage-dweller says…

    Premier Icon tonyg2003
    Subscriber

    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?

    Premier Icon takisawa2
    Subscriber

    I mull over this very same issue every time I fire up the mighty Mondeo. 🙂

    Premier Icon Northwind
    Subscriber

    There’s no such thing as a “better” engine, people like different things- I love the surfing, effortless feel of a decent sized turbodiesel, I rode v-twin bikes for the same reason.

    singlecrack
    Member

    ‘ there’s no substitute for cubic inches ‘ 😉

    Premier Icon tonyg2003
    Subscriber

    No replacement for displacement!

    Usually said by F150 drivers I know 🙂

    Premier Icon paladin
    Subscriber

    Merchant ships have electric auxiliary blowers in their diesel engines for low speed running when the turbos won’t be operating.

    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.

    Premier Icon PePPeR
    Subscriber

    I’ve got an old Transit sat outside with a variable nozzle turbo and even though it’s got 220,000 miles on it, it still impresses me with how little lag it has!

    oldnick
    Member

    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.
    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 🙂

    Premier Icon Daffy
    Subscriber

    Triple scroll concentric turbo chargers are in a completely different league to most conventional and even variable vane turbochargers. Sadly even these tend to run out of puff toward the top end of the measly rev range.

    northernmatt
    Member

    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.

    Premier Icon tthew
    Subscriber

    I’m sorry, is this a thread about cars, or a game of top trumps?

    My Tornado GR4, well basically the engine is one bloody big turbocharger and it’ll reach a ceiling of 50,000ft in about 3 minutes.

    sweepy
    Member

    Can you get a bike in the back?

    JulianA
    Member

    @tthew Your Tornado is bloody slow… A Lightning would get to 58000 ft in one minute. See ya! Do try to keep up…

    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?

    Premier Icon benji
    Subscriber

    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.

    mikertroid
    Member

    A GR4 getting to 50000?! In three minutes?! Good gag!

    Lol! I used to have to reduce my climb speed so the F3 could hang on to my wing and that had engines ‘optimised’ for high level…

    Premier Icon bearnecessities
    Subscriber

    Pitched thrust vectoring turbofans.

    *waves*

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