high revs engine

[roospuppet]

good point, so u reckon tvr should cum up with there own design, cos i have my own design , which is similar to the coates design, which wil lbe heavier but more efficent, but not that much heavier,

[soddy]

To maximise output from your design ... go for as few moving parts as possible ... as much capacity as feasible ... as short a stroke as the capacity will allow ... as light an assembly as is practical ... and then go and have a chat with the F1 boys! They spend billions between them trying to come up with an extra couple of horsepower .. and they are now revving to 20,000 plus. The stroke on a F1 motor is rediculously short .. which is why a 10 or 12 cylinder engine is only 3 litres(or less). Also take a look at diesel dimesions to give an idea of where Torque is gained in engine design!! Good Luck!

[roospuppet]

grahambell said: Hi roospuppet,

Considering this thread and your other about rotary engines I have to ask this - what's the obsession with high revs?

my obsession, about revs,is that revs is proportional to power, torque can be increased with a g box, so maximum torque is not so important at the engine,but at wheels where acceleration cums into play, so the high levels of torque (at wheels) can be acheived for a longer period with higher revs. so maximum acceleration, acheived through high revs, with a cleverly designed close ratio sequetial g box, that has computer controlled gear changes, which happen ina fraction of a second, the car would be extremly fast, ie f1 car fast, even though f1 cars only do 0-60 in 2.16 secs, they carry on going,
of course this car would be quite rough to drive on road at slow speeds, but u just tell the comp to choose a higher gear, for road use

>> Edited by roospuppet on Saturday 21st December 12:01

[grahambell]

roospuppet said:

my obsession, about revs,is that revs is proportional to power.

OK, so more revs = power, BUT a high revving engine is also an intractable engine, which is not good if you're using it on the road (although as you also seem to be thinking of a very light car it's not as bad as it could be).

torque can be increased with a g box, so maximum torque is not so important at the engine,but at wheels where acceleration cums into play, so the high levels of torque (at wheels) can be acheived for a longer period with higher revs. so maximum acceleration, acheived through high revs, with a cleverly designed close ratio sequetial g box, that has computer controlled gear changes, which happen ina fraction of a second, the car would be extremly fast, ie f1 car fast, even though f1 cars only do 0-60 in 2.16 secs, they carry on going,

Yes, but that's because they run on a race track where they can keep the revs up in the very high power band. Engines that need high revs to work properly tend to run like shit at low revs/low speeds. That's why variable valve timing was invented. Of course I realise you're intending to do away with the usual camshaft/poppet valves arrangement but would imagine similar problem would occur with the Coates engine unless you had variable valve timing.

of course this car would be quite rough to drive on road at slow speeds, but u just tell the comp to choose a higher gear, for road use

But further to comments made above, I doubt your very high revving engine would be tractable enough to pull in a high gear. Admittedly I'm no expert, but take a look at the 'bhp v torque' thread in this section for some info you might find interesting.

Sounds like you could ideally do with trying to get yourself a work placement with the engine design department at either Jaguar or Rover because that way you'll be able to ask the men that really know these things.

Anyway, stick in there - I admire your enthusiasm.

Edited in attempt (probably unsuccessful!) to stop text appearing in narrow column.

>> Edited by grahambell on Sunday 22 December 09:40

[roospuppet]

well basically teh high gear, ie 6th gear in the high revving engine would be roughly the same ratio as a standard ford escort's second gear, becuase of teh such high revs, and this engine will still ahve alot of torque due to the 12 cylinder and possibly a turbo, not sure bout turbo yet, but still the (2nd gear ratio) 6th gear in this car, would still be at 200 mph, full revs, on a rolling road,

[roospuppet]

so basically teh very low ratio of gears will increse teh toque, plus the point about wil lhave very poor low rev performance, say u was doing 30 mph, u get the comp to put it in 1st gear, and bam ur away, cos of teh light weight, it will just fly, buti need a cleverly designed computer controlled clutch and gear selector, although clutch will onyl be used to pull away initially and driving at low throttle, the computer will take it out of gear let teh revs fall to teh level at which he engine revs are the same as teh speed of the new gear, for teh road speed, (cor im confusing myself, but hopefully u will inderstand)then pop it into gear, and for change downs, the comp will increase revs, to the rite speed,and pop it into gear,


will need quite a good set of phematics for this,

[bigrumbly]

Hi Roo
I think you should start somewhere else. !!!
Do you want a 500Kg car to acelerate to 60 MPH in 3secs with a top speed of 70 MPH. Or a car that does 120MPH.
Does it weigh 700Kg or 1100Kg do you wish to accelerate when its dry or wet.
Cos sure as eggs is eggs if you decide what car, what acceleration and what top speed, some ones done it, so copy them. You will still be one of only a hand full who have done it.

Wish you lots of luck.
David

[roospuppet]

500 kg car
revs 16k rpm plus
turbo
0-60 in summit stupid,
over 1000bhp,
v12 probly, very short stroke, around a 3 ltr,
top speed around 180 mph is sufficent, it depends on teh aroedynamics,

basically, i have never heard of a car like this, if anyone has done a car like this, then i wanna shake there hand, then go for a drive in it,

one problem i will face is sound emmisions, maybe a bit of trickery will help, only tuning the car to bout 6k rpm, with a silencer on, get it through the test, then take it all of, reprogram the computer, and wow, 0-60 in summit stupid time, under 3 secs,


not sure whether to consider carbon fibre the frame, which wont be very safe, but it will be light, or to make it out of steel and crygenasise it and turn it into a marsenite,

[ultimaandy]

How about

0-60 3.2second (in 1st gear)
212mph
1010kgs
526Bhp
6.3 V8
7000rpm redline

Hang on... thats my car!

But seriously, my engine only cost around 10k the one you are talking about would cost a fortune and have a limited life.

You would also need an incredably sofisticated chasis to cope with 1000bhp when it only weighs 500kgs, thats masivelly beter than a F1 car (5-600kgs & 800bhp?)!

[accident]

who is this engine/car for?
massive cost = very few can afford it
of these few only a small number will want to have one.
even fewer will be able to fit in it.
and the rich kids want a sound system,leather,climate control,room for the trophy blonde,need to be seen with aformentioned blonde,sat nav,and many more unusable toys.this all adds to the weight of the finished project.
if you are proposing a road project a big v10 or v12 doing moderate rpm would be more than adequate.
turbos suck just an oxymoron that sums up my thoughts on exhaust driven forced induction.
crank driven forced induction is fine as is chemical supercharging(nos)

[grahambell]

Hi Roospuppet,

I guess you've never heard of the KISS principle - Keep It Simple Stupid.

Making things unnecessarily complicated as you seem intent on doing is a sure recipe for problems. Happened with the post-war BRM Grand Prix car I mentioned earlier. Very complicated car, V16 engine, cost a bloody fortune to design and build - and hardly ever ran because something or other always went wrong. By comparison its more simple competitors kept going and won races.

Look at race car designers with all the technology available today and I bet you'll find they never make anything more complicated than they need to.

The other thing is - 1,000+bhp high revving engine plus 500kg car equals major traction problem, especially with 2 wheel drive. Unless of course you intend fit traction/launch control, which in turn adds more complications. Just look at the problems the McClaren team had with theirs - and then consider all their experience and resources.

As mentioned earlier, I admire your (obviously youthful) enthusiasm, but think you'd be better aiming for something simpler, at least to start with. Have to learn to walk before you can run and all that.

[JonGwynne]

roospuppet said: good point, so u reckon tvr should cum up with there own design, cos i have my own design , which is similar to the coates design, which wil lbe heavier but more efficent, but not that much heavier,

Interesting! Have you built it or is your design still on paper? You say it is heavier? How much?

I first heard about this idea about three or four years ago. A guy I did a job with said his neighbor had modified a Ford V8 to use ball valves rather than poppet valves and had both lightened the engine and dramatically increased power (and reliability) in the process. I never got a chance to talk to the guy but I started thinking that poppet valves did seem to be a rather silly way of controlling intake/exhaust flow through the engine.

I've never seen it in practice though and I'd be interested in speaking to someone whose actually done it about the "pros and cons" of the alternate method.

I understand that some luxury cars back in the 30s used sleeve valves because they were quieter.

I wonder, for example, what using ball valves would do for the exhaust note. I also wonder if it is possible (or even necessary) to incorporate variable timing in a ball-valve system since there is no cam shaft.

[JonGwynne]

grahambell said: Hi Roospuppet,

I guess you've never heard of the KISS principle - Keep It Simple Stupid.

Making things unnecessarily complicated as you seem intent on doing is a sure recipe for problems. Happened with the post-war BRM Grand Prix car I mentioned earlier. Very complicated car, V16 engine, cost a bloody fortune to design and build - and hardly ever ran because something or other always went wrong. By comparison its more simple competitors kept going and won races.

Look at race car designers with all the technology available today and I bet you'll find they never make anything more complicated than they need to.

The other thing is - 1,000+bhp high revving engine plus 500kg car equals major traction problem, especially with 2 wheel drive. Unless of course you intend fit traction/launch control, which in turn adds more complications. Just look at the problems the McClaren team had with theirs - and then consider all their experience and resources.

As mentioned earlier, I admire your (obviously youthful) enthusiasm, but think you'd be better aiming for something simpler, at least to start with. Have to learn to walk before you can run and all that.

I like your questions about traction. But aren't most traction problems encountered when launching from a standing start? Don't they stem from too much torque being applied to stationary wheels? Doesn't the amount of torque the wheels can take without slipping dramatically increase as the speed of the vehicle increases? Wouldn't a high-revving (i.e. low torque at low revs) almost automatically address this problem?

Put another way, a TVR Tuscan 3.6 is a more user-friendly vehicle than the old Griffith 5.0 even though they both weight about the same and the Tuscan is more powerful at the top end. Why? Because the Speed Six engine is peakier than the Rover V8.

I'm not saying that's going to solve the problems for a vehicle with 2bhp/kilo(!) but it might help mitigate them, especially if the throttle control is nice and linear and the travel is quite long.

Besides, it might be fun to have a car where not only is it inadvisable to floor it in 1st but actually dangerous.

[grahambell]

JonGwynne said I like your questions about traction. But aren't most traction problems encountered when launching from a standing start?

Yes they are, but that's what I had in mind. If you have an engine that designed to run at such high revs that it requires 5,000 rpm to idle, what chance do you think you have of setting off smoothly without wheelspin?

What roospuppet is proposing - 3 litres, 16,000+rpm - is effectively an F1 engine, and without traction control we've often seen how fine the balance is between too few revs off the line and bogging the engine down and too many revs and lighting up the tyres. And don't forget those are big sticky racing tyres not road tyres. Think you could drive an F1 car in stop start traffic? No way.

Don't forget too that even when you are moving, having lots of power (and I'm talking around 300bhp not 1,000) can result in wheelspin, especially in a light car. That's how you get sideways accelerating out of roundabouts or even giving it full throttle in a straight line if the road's slippery.

Also, look at all the problems the best engine design brains in F1 have getting engines that rev to 17,000 rpm to run reliably (or even stay together)for just 90 minutes. And consider that they use all the top space age (read highly expensive) materials and that the engines are completely rebuilt every few hundred miles.

It's nice to have big dreams, but sadly life has an annoying habit of shrinking the reality.

[Captain Muppet]

JonGwynne said: A guy I did a job with said his neighbor had modified a Ford V8 to use ball valves rather than poppet valves and had both lightened the engine and dramatically increased power (and reliability) in the process.

This wouldn't have been a push rod engine would it?

...I also wonder if it is possible (or even necessary) to incorporate variable timing in a ball-valve system since there is no cam shaft.

Variable phasing would be possible but timing would require remachining the valve.

[MEMSDesign]

Don't be too quick to dismiss the idea of building an engine from scratch. It is possible, and has been done before by small teams of determined students. I remember a US team making a small V8, which was very pretty and sounded great. Don't know what it revved to, but I'm sure you can find out.

http://dot.etec.wwu.edu/fsae/viking30.htm

You'll need a lot of cash and full backing from the department to go this route though.

If you want to talk to other students about this type of thing, the FSAE has some good forums, with a bit more of a 'can do' attitude than you'll find here. I'm sure you'll be able to dig them up with google.

[Captain Muppet]

grahambell said: ...Also, look at all the problems the best engine design brains in F1 have getting engines that rev to 17,000 rpm to run reliably (or even stay together)for just 90 minutes. And consider that they use all the top space age (read highly expensive) materials and that the engines are completely rebuilt every few hundred miles.

Kawasaki produced a 250cc four that reved to 22000rpm, although that was a good ten years ago, I'm sure it could be improved on. This would be a good place to start if you like the idea of a 1.0 V16 producing 200bhp @ 22000rpm.

[Captain Muppet]

roospuppet said: ...not sure whether to consider carbon fibre the frame, which wont be very safe, but it will be light, or to make it out of steel and crygenasise it and turn it into a marsenite,

yes - carbon chassis are notoriously unsafe - look at the recent deaths in F1. Oh hang on, they are safe! silly me.

Isn't Martensite brittle?

[grahambell]

Don't think we're trying to dismiss the idea of building an engine from scratch here MEMSDesign (I'm certainly not) just trying to advise roospuppet that he'd be better off aiming for something less ambitious than what virtually amounts to a F1 engine.

Getting 16,000 rpm out of a 3 litre engine IS difficult for a variety of reasons including material strength and valve train problems (although rotary valves could solve the latter).

Captain Muppet quotes 22,000rpm from a 250cc Kawasaki engine 10 years ago. Well it's always going to be easier to get high revs out of a smaller engine because all the parts are smaller and lighter and therefore have lower inertia which in turn causes lower stresses.

Also, was that engine a four stroke or a two stroke? Two strokes have no valves and therefore no valve train problems to worry about and do tend to rev higher - helped by the fact two strokes are always small capicity engines. Don't know what those piddly little engines in model planes rev to, but I bet it's something silly.

I hope roospuppet does get to build an engine from scratch, but he'll stand a better chance if he aims for a more realistic specification.

Anyway, I'm sure he'll keep us informed.

[roospuppet]

[quote
yes - carbon chassis are notoriously unsafe - look at the recent deaths in F1. Oh hang on, they are safe! silly me.

---

but wot about side impact protection, isnt carbon fibre only strong in one direction, so a very clever chassis would be designed, weighing a bit more, but probly still less than a steel or other metallic chassis