BenB
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| posted on 1/11/08 at 01:08 PM |
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Engine design for a miserable Saturday
What does anyone reckon is going to be the big new things in engine design?
Materials and accuracy are presumably unlikely to suddenly change (I can't see any manafacturer suddenly making titanium conrods standard), so
how can engine designer squeeze more power out of the internal combustion engine? And although computerised design has improved flow etc through
manifolds there's presumably been as much improvement there as there's going to be....
More valves? Presumably 5 valves is physically the most you can cram in before you end up with stupidly small valves
Different fuels? Higher CRs could be used if we all go to bio-ethanol (though the green lobby might squash BE yet!!!)
Direct fuel injection (ie into the cylinder not the inlet manifold)
Electromechanical valves? Totally variable timing and quick actuation....
any other ideas?
I suspect manafacturers might also go for petrol turbos in a similar way that it's almost impossible to get a non turbo diesel now!!! A VV turbo
with totally variable electromechical valves would be a bundle of fun to tune.
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MikeRJ
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| posted on 1/11/08 at 01:11 PM |
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The new 2 cylinder turbocharged fiat engine has hydraulically actuated valves (albeit, the "pump" is driven by a cam) which allows the
engine to be throttled just by valve timing, which reduces pumping losses.
[Edited on 1/11/08 by MikeRJ]
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matnrach
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| posted on 1/11/08 at 01:21 PM |
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Downsizing and turbocharging to minimise CO2
This is already happening but there will be more of it so that higher BMEP's will be used at WOT i.e more boost so greater specific power.
This will involve strategies to improve knock limits.
Better materials will have to be used to allow higher pre-turbine temps.
Also friction management will be important for CO2 reduction by reduced component masses/ coatings etc etc
Also as mentioned non engine driven valves to reduce part throttle pumping losses.
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MikeRJ
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| posted on 1/11/08 at 01:37 PM |
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I'm quite surprised nothing seems to have come of the variable compression designs that were being researched a few years back.
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matnrach
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| posted on 1/11/08 at 01:53 PM |
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A sensible thing to do but I guess expensive. Might see a comeback though
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mr henderson
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| posted on 1/11/08 at 02:17 PM |
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Could be that the most significant advances will be in transmissions. If a contiuously variable transmission could be developed then the engine could
be held at whatever was its most powerful, or its most efficient speed, while the transmission allowed the car's speed to vary according to
requirements. No longer needing to accelerate the engine whenever the car was being acclerated could be beneficial
I'm aware that such devices exist, but are in their early stages yet
John
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liam.mccaffrey
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| posted on 1/11/08 at 02:22 PM |
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I thought there were a lot of cars with CVT's, nissan and ford offer them on some models in the states.
Benneton successfully tested an F1 CVT in the early 90's before they were banned.
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mr henderson
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| posted on 1/11/08 at 02:29 PM |
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quote:
Originally posted by liam.mccaffrey
I thought there were a lot of cars with CVT's, nissan and ford offer them on some models in the states.
But I'm not aware of anybody using them in the way in which I have described (not in a production car anyway) although I may well be wrong
John
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MikeRJ
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| posted on 1/11/08 at 02:45 PM |
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quote:
Originally posted by liam.mccaffrey
I thought there were a lot of cars with CVT's, nissan and ford offer them on some models in the states.
They are fairly inefficient though, and have limited torque capacity.
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liam.mccaffrey
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| posted on 1/11/08 at 02:49 PM |
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Nissan Altima and Murano
Subaru Justy
Ford Fiesta
Fiat Uno
BMW Mini
Audi A4
Dodge Caliber
Jeep Compass and Patriot
Mitsi Lancer
from wikipedia, most as options admittedly.
I'm no fan of them btw, just find them interesting
[Edited on 1/11/08 by liam.mccaffrey]
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matnrach
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| posted on 1/11/08 at 02:52 PM |
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There are plenty of CVT's around now. I have driven a Merc B class with one which normally uses 'virtual' gears around town but
stays at max power speed when max accel is demanded.
I don't think it is of any geat advantage as the min BSFC point is not hugely better than other speeds under normal operation.
The gearbox is expensive and inefficient.
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Dick Axtell
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| posted on 1/11/08 at 03:18 PM |
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quote:
Originally posted by liam.mccaffrey
Nissan Altima and Murano
Subaru Justy
Ford Fiesta
Fiat Uno
BMW Mini
Audi A4
Dodge Caliber
Jeep Compass and Patriot
Mitsi Lancer
from wikipedia, most as options admittedly.
I'm no fan of them btw, just find them interesting.
Add the Honda Civic Hybrid to this list. BTW - This model uses the N American saloon bodied version, and is totally unlike the latest Civic model.
Work-in-Progress: Changed to Zetec + T9. Still trying!!
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britishtrident
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| posted on 1/11/08 at 03:39 PM |
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quote:
Originally posted by liam.mccaffrey
I thought there were a lot of cars with CVT's, nissan and ford offer them on some models in the states.
Benneton successfully tested an F1 CVT in the early 90's before they were banned.
CVT has been around since Austin offered in on the Austin 10 in the late 1920s it has never been reliable in car applications.
The CVT transmision Ford used for the late Escort MK3 onwards had a dreadful reputation if it rarely lasted to 40,000 without a complete rebuild.
The more recent Jatco CVT used by Nissan and other many manufacturers in smaller models has an equally bad or even worse reptation.
[Edited on 1/11/08 by britishtrident]
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Simon
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| posted on 1/11/08 at 03:42 PM |
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I read an article the other day about the possibility of very high compression petrol engines, with direct injection and thus a dieselling petrol
engine.
Prob was pump and required pressures iirc.
For me, I think (unfortunately, as I like them) the int comb engine, while it'll be around for a while and will be developed for a few more
years, may well be past its sell by date.
Once battery technology has developed - and I think that'll take the time of computer evolution rather than the slow i/c development, then I
reckon we'll be driving them sooner rather than later.
Even though I still laugh at Prius owners
ATB
Simon
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liam.mccaffrey
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| posted on 1/11/08 at 03:47 PM |
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i think the tesla roadster proved that lecky cars didn't have to look like crap, like the prius
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minitici
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| posted on 1/11/08 at 05:15 PM |
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The Future
Graeme Wight Jr will be using this for 2009 Hillclimb Championship.
He previously used his Arrows V10 powered Predator....
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matnrach
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| posted on 1/11/08 at 05:20 PM |
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Whatever happened to the V10 car?
I don't remember it competing a full season
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minitici
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| posted on 1/11/08 at 05:24 PM |
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Graeme got the V10 running for the last few events of the season (2008) and managed one outright win at Doune.
He has had a few problems with the gearbox and spat a gear out of the carbon fibre gearbox on his last run.
He is currently trying to sell the car OIRO £100K 
Video of Doune Predator V10
[Edited on 1/11/08 by minitici]
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matnrach
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| posted on 1/11/08 at 05:35 PM |
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What gearbox control did he use?
I think the Arrows used TAG with hydraulic control. I doubt GWR used this.
It is very difficult to get the change right.
If you demand a change at the wrong instant its game over fo the gears.
Also the mapping sounds a bit rough on the video.
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smart51
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| posted on 1/11/08 at 06:00 PM |
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As soon as there is a good way of storing or generating electricity in vehicle, IC engines will die. Electric propulsion is by far the best way of
moving a vehicle.
If there were electric motors and controllers available at eBay prices, I would already be building an electric vehicle. This is how I would do
it:
Have electric motors sized so that the vehicle has the desired performance. Have a small battery, say 10 or 20 miles range. Have a small but very
efficient generator, maybe 20 BHP. A 0-60 sprint may use, lets say 150 BHP but only for 5 seconds. The battery takes the hit. Once you get to 60 on
your nice B road, you stay there, using maybe 15 BHP. The generator gives you that and tops up the battery. 20 seconds later, your battery charge is
back where you started. On average, a car may only use about 10 BHP, taking the times at red lights and things into account. You only have brief
bursts of power. an IC engine is very inefficient at low power, which is most of the time. They are sized for max acceleration, which only happens
occasionally.
A carefully designed system like this need not weigh any more than a conventional car yet would be as fast as you like with exceptional MPG.
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MikeRJ
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| posted on 1/11/08 at 06:18 PM |
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quote:
Originally posted by smart51
Have a small but very efficient generator, maybe 20 BHP.
What does this generator run on? Now you have introduced an extra stage of energy conversion efficiency is already compromised.
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matnrach
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| posted on 1/11/08 at 06:19 PM |
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The main problem with battery/electric vehicles is the energy density.
The chemical energy stored in fuel is enormous even if you only are around 30-32% thermally efficient its way better than anything else (at the
moment)
Overall CO2 production in generating the electrical energy in the first place is way worse. This is usually ignored for political reasons!
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smart51
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| posted on 1/11/08 at 07:01 PM |
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quote:
Originally posted by MikeRJ
quote:
Originally posted by smart51
Have a small but very efficient generator, maybe 20 BHP.
What does this generator run on? Now you have introduced an extra stage of energy conversion efficiency is already compromised.
Generator runs on Petrol or Diesel until a better alternative is made. Efficiency is not compromised at all, in fact it is better overall.
In internal combustion engine has a theoretical efficiency of around 50%, more or less depending on various factors, , not least the fuel you use.
Car engines don't even get half that because they are designed to run at a wide range of speeds and loads. The engine in your generator need
only run a 1 speed, its most efficient speed, and it need only run at 1 load, its most efficient load. When your battery is charges, switch the
engine off. Your car engine's quoted efficiency (if you can find such a figure) is at its most efficient operating point. Most cars may never
be operated at that point, or only briefly if they do.
So, your generator runs at maybe 400% or 600% more efficient than a normal car. The generator motor, if you buy a good one, will be easily over 90%
efficient, as will the motors in the wheels, as will the electronics that control them. Lead acid batteries charge at 13.8V and give 12V back under
light load and as little as 8V under massive load. That's between 58% and 87% efficient. Total power train efficiency at low speeds, then is
about twice that of a normal engine and at higher speeds about three times more efficient. In town, where there is lots of stop start and idling, the
system's efficiency is higher still.
You are right that the extra conversions make the system less efficient than it could be, but your engine is way more efficient so that you can afford
to lose some and still be better.
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twybrow
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| posted on 1/11/08 at 09:29 PM |
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So why don't we see this type of system being used? It can't be down to cost, as the big manufacturers have plenty of wonga. My bet would
be it is not nearly as efficient as you are hoping. And you sit next to an annoying buzzing generator. Give it a go and let us know!
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smart51
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| posted on 2/11/08 at 08:06 AM |
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quote:
Originally posted by twybrow
So why don't we see this type of system being used?
My guess is that car makers are so focused on the existing idea of hybrid cars that no-one has taken the time to stand back and re-think it.
Car makers are very inert, very scared of change, desperately concerned with cost but terrified of being left out. Left alone, they would still be
using carburettors and selling AM radios. Only when forced to change do they do anything. That is either by legislation or by their competitors
doing something new. Remember the Rover 200 with higher ride height and "off road" styling? Even though it was a terrible idea, several
companies made similar versions of their own cars because they were scared of being left out.
Their inertia, fear and lack of imagination is why we still have still have cars made of iron, with 19th century power trains. Its why we don't
have cars that can drive themselves, even though technology could easily delivery it. Its why we only have 1 type of Hybrid technology. Honda
invented it with the insight and so everyone else has to have the same thing.
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