Torque on it's own is useless, a human on a bike can provide more torque than a small car engine! Fortunately gearboxes were invented...
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Why is there a REV Counter in most cars?
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Posted 1 year ago #
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I found the v-tec had a 3 lobe cam profile, the third cam lobe had an oil actuated piston which locked all three followers together so it ran on the high lift option at high rpm. Simple but effective.
Posted 1 year ago # -
I look forward to the next generation of petrol engines
I've got a few ideas up my sleeve, don't worry
Btw, does varying turbo boost not have the same effect as changing the compression ratio?
Posted 1 year ago # -
diesel type engines are still where the money is. More energy per mass and with a new stream of bio mass produced "carbon like" diesel (which is also better) coming into the fold all the more reason. also Gasolines can not produce the environmental savings required by legislation getting tighter..
Posted 1 year ago # -
Cellulosic bio-ethanol has a lot more potential than biodiesel I think. So we will still need petrol style engines.
Plus, petrol-electric hybrids get around many of the disadvantages of a petrol engine as compared to diesel. And petrol is a heck of a lot cleaner in terms of other pollutants.
Posted 1 year ago # -
Torque on it's own is useless, a human on a bike can provide more torque than a small car engine! Fortunately gearboxes were invented...
Yes that's all very well but catch a v-tec engine at anything under 6k rom and nothing happens. Fine for the race track, irritating on a real road.
Posted 1 year ago # -
Cellulosic bio-ethanol has a lot more potential than biodiesel I think
with a 30% reduction in energy per mass compared to regular gasoline.. works out around 40 compared to a good diesel. You can make diesel and jet fuel out of cellulosic biomass and very good it is too
Posted 1 year ago # -
Years ago I used to drive an expensive car (no, not my own) and if for any reason the engine stalled, you could only tell by the rev counter dropping to zero. The vibrations and engine noise were so low when the car was not moving that you could not tell the engine had stopped.
Posted 1 year ago # -
It's to do with vapourising the fuel better, large openings allow the fuel to coalece which in turn means you have to pump more fuel in to compensate (
There's a whole heap of things you want to optimise, rather than larger or smaller being right. Smaller = greater pumping loss getting the air in through the valve. Smaller diam intakes mean restriction at higher revs but better gas momentum over large diameter, which means better cyl fill and so better VE. Ultimately your car would be throttled by the valves and have completely variable intake runnner and plenum sizes across the rev ranges. In reality they just pick an efficiency level at a speed, design for that and try to minimise the damage to the upper end power, I'd guess. Things like the toyota VVTI engines are horrible to drive "off cam", gutless miserable things despite being 190hp when allowed to be let loose. Vtech are the same, but it serves a purpose I suppose.
Posted 1 year ago # -
if for any reason the engine stalled, you could only tell by the rev counter dropping to zero.
And the row of red lights on the dashboard......
Posted 1 year ago # -
How are you hoping to make diesel from cellulose? That algae they recently found in the Amazon? Could be a fair way off. They are building large scale test cellulosic ethanol plants now. May even be finished.
Ethanol is a bit rubbish as a fuel when you put it in a petrol engine. But it has a high octane rating, so you can increase the compression ratio a lot which means you can get a lot of the efficiency back. Saab I think are also working on variable compression ratio engines for this reason.
Things like the toyota VVTI engines are horrible to drive "off cam"
Sounds reasonable. You only need the power when you're flogging it, so might as well set it up to appear at high revs.
Posted 1 year ago # -
hydrotreating my dear man - you change the entire structure of the molecule and hey presto a diesel/kero stream with far surperior properties to the incumbant..
edited to add, it can be made from various wastes - some commercial jets have already flown on the stuff (through waiver)..
Posted 1 year ago # -
One thing missing from many cars these days - simple engine oil and/or water temp gauges
Was oil temp ever common in road cars? Agree though, as unless the ECU is cleverer than I give it credit for if my engine read 20psi on the motorway/b-roads I'd be worried, but in town thats fine, would an ECU account for this?
Never understood water temp guages, unless its too high its not a problem (warning light would be more use), but oil temp is more important if you need/want to know when its up to being thrashed.
Posted 1 year ago # -
Ethanol is a bit rubbish as a fuel when you put it in a petrol engine. But it has a high octane rating, so you can increase the compression ratio a lot which means you can get a lot of the efficiency back
Hmm. A year or two ago, 'Bike' magazine modified a Triumph Daytona 675 sportsbike to run bio-ethanol... from apple juice! All they had to do was remap the injection, and IIRC it made a fair bit more power than on petrol
http://www.greencarsite.co.uk/GREENNEWS/apple-powered-bike.htm
Posted 1 year ago # -
Orange Light On - STOP Immediately... and not like my colleagues wife who thought it just meant 'take to dealer when you next have chance'....
oops
To be fair, orange lights are warnings, reds mean stop. If they've used an orange light for a fault that's immediately terminal if ignored it's a design fault IMHO. Many sensible cars have an orange warning lamp for mild faults and a big red STOP if it's a fatal fault like oil pressure.
Posted 1 year ago # -
ethanol is great but it's got some sever issues to contend with - water being one, 30% high consumption being the other along with material compatability issues...
Posted 1 year ago # -
you change the entire structure of the molecule
How?
PP - usually flex-fuel cars just change the map somehow (not sure how) and presto, you run on ethanol. However this usually results in similar performance but lower MPG - no idea if it'd be different in a motorbike. However with a turbo petrol car you can ramp up the boost no end because of the high octane rating. So some folk in the Volvo 'community' get 300bhp from their 2.0l petrol
Posted 1 year ago # -
chemical engineering - hydrotreating has been used for years to change carbon molecules to other "end products" they've relaised that a similar process can be used on biomass.. quite clever really and the only "real" contender for a "proper" renewable fuel!
Posted 1 year ago # -
some folk in the Volvo 'community' get 300bhp from their 2.0l petrol
Or just chip a T5? There's no replacement for displacement!
Posted 1 year ago # -
There's no replacement for displacement!
There is - boost!
The point is, ethanol allows much more boost than petrol. So whatever your displacement, if you have forced induction you can tweak it to get much more power than if you were on petrol.
Posted 1 year ago # -
Sui - I think you are a tad confused. I don't think you can make biodiesel from cellulose very easily...
Posted 1 year ago # -
Rev counter: in my Lotus it can be more useful than the speedo and I find myself watching that than the speedo in some situations. 4k revs in 5th = 80mph, each 500rpm is +/- 10mph. Very useful on track days to hit the sweet spot for gear changes. And isn't that what the red limiter light is for
In wifey's Audi V6 TDI 3.0 then rpm is pretty pointless. It just goes. And anything above 2,500rpm is a bonus.
I'd expect that most people would *know* when to change gear though, by engine tone or the fact that the car is labouring or not making progress at full throttle. You can just feel these things, even in lovely comfortable luxury cars. Or maybe not.
There is a whole lot of mis-information on the use of revs though. I've seen drivers who religiously change up or down at 2,000 2,500 or 3,500rpm. Why? I ask them... Because my driving instructor told me to. D'oh! No consideration for the road, the load, the speed just robotic change up / change down when at that point
As for temp and pressure gauges, I've got a water temp retro-fitted and oil pressure too. Wait until the oil temp and water temp are pretty much aligned before giving it some beans otherwise a risk of engine stress due to a huge temperature gradient. Oil pressure is there to monitor the oil condition - too low at a certain RPM and the oil is past its best, zero - and I have a major oil leak :o.
TBH I wasn't really too fussed about all this stuff until I trained to be a pilot. In the most basic aircraft you learn to control the flight using engine rpm and you have to get attuned to hearing the engine and what it is doing. From engine note you can judge airspeed and from that make a good safe landing. You also learn the importance of engine Ts & Ps.
As for most modern cars having a rev counter? I dunno. A pointless exercise really.
Posted 1 year ago # -
Epic willy wave ----------^
I drive a Lotus on a track
I can drive better than the guy who taught you
I can fly a planePosted 1 year ago # -
molgrips - Member
your correct and i've alluded to the wrong point -my bad - The biomass (of which cellulosic ethanol is produced through a catalytic process) can be changed into an 'oil' type through a pyrolysis or de-oxygenation process, then through selective cracking / catalytic stabilisation process. the end result is a synthetic parrafine. removing oxyegen from the double bonds allows you to manipulate the remaining hydrogen atoms and putting it back through a catalyist bit of propane to produce straight chain parrafines........ and this is where my chemical engineering knowledge slowly grinds to a halt... either way there are some very clever processes coming on line making the use of "waste", or true renewable (2nd Gen) feedstocks..
Sui - I think you are a tad confused. I don't think you can make biodiesel from cellulose very easily...
Posted 1 year ago # -
can be changed into an 'oil' type through a pyrolysis or de-oxygenation process
So different again from FAME/RME?
Sounds very energy intensive tho..
Given the availability and difference of various biofuels though it would seem we still need a distribution of different engine types. However, market forces would determine that over time. IE if E85 was only 60p/l then a lot of people would buy E85 cars
Posted 1 year ago # -
That was an epic willy wave indeed
Posted 1 year ago # -
So some folk in the Volvo 'community' get 300bhp from their 2.0l petrol
Well Mitsubishi get a reliable(ish) 400bhp from a 2.0 litre unit! Only driven the FQ360 (366bhp) but even that is an EPIC engine.
LOL at willy wave. Off to pose in our 1.3litre Jimny. Might even put the roof down
Posted 1 year ago # -
My point is it's a big percentage increase from using ethanol and tweaking a screw on a crappy old engine.
Posted 1 year ago # -
Ultimately your car would be throttled by the valves and have completely variable intake runnner and plenum sizes across the rev ranges.
already available in production cars...
Posted 1 year ago # -
To be fair, orange lights are warnings, reds mean stop. If they've used an orange light for a fault that's immediately terminal if ignored it's a design fault IMHO. Many sensible cars have an orange warning lamp for mild faults and a big red STOP if it's a fatal fault like oil pressure.
yes my bad, driven too many old cars - i always associate oil pressure funked with orange... moderns have red... though most clubman comp cars still have a nice big orange light..
in my last comp car i had combined big LED shift light (green for shift, red for def shift and orange for knackered... no need to look at gauges and dials them - oh apart from high water temp buzzer and light
Posted 1 year ago #
Topic Closed
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