high revs engine
Discussion
You looking at modifying an existing engine or building one from scratch? I assume it's the former.
Either way, you should try and keep all rotating and reciprocating parts as light as possible and go for a short stroke design to minimise piston speeds.
You'll also need to use all top quality parts and get everything balanced.
Don't know just how high you want to rev, but bear in mind that even with all their racing experience Honda had to overcome numerous problems to get a reasonably tractable and reliable road car engine capable of revving to 9,000rpm (S2000).
Either way, you should try and keep all rotating and reciprocating parts as light as possible and go for a short stroke design to minimise piston speeds.
You'll also need to use all top quality parts and get everything balanced.
Don't know just how high you want to rev, but bear in mind that even with all their racing experience Honda had to overcome numerous problems to get a reasonably tractable and reliable road car engine capable of revving to 9,000rpm (S2000).
hi there, just wondering wot i would need to make an engine an extremely high revving one, i no u have to reduce friction, in an engine, use a dampner for the torshional vibrations on the crank, and get a dam good g box, but have i missed anything
cheers
ian
If its a four-stroker, lighten the valve train as far as possible and increase the valve spring preload. OHC would be the way to go.
would a rotary valve be the way to go, www.coatesengine.com
that would reduce valve train, and yes building an engine from scratch is teh way, thinking of tryin to do summit like teh old f1 turbo engines, really small piston, maybe 50mm bore and a 50 mm stroke only estimates, but this is similar to the f1 turbo engines, with as many pistons as possible,
>> Edited by roospuppet on Thursday 19th December 15:54
that would reduce valve train, and yes building an engine from scratch is teh way, thinking of tryin to do summit like teh old f1 turbo engines, really small piston, maybe 50mm bore and a 50 mm stroke only estimates, but this is similar to the f1 turbo engines, with as many pistons as possible,
>> Edited by roospuppet on Thursday 19th December 15:54
the point about the honda s2000, im sure they could have mad eit rev higher, but low end torque would have suffered and remeber they have variable valve timing, which is probly not as strong as the normal valve actuation system, they had to compramise with perfromance and fuel economy, and i fink they did very well , 237 bhp from a 2 ltr, and stil gets resonable mpg. thats variable valve timimg for ya,
Engine from scratch eh - obviously like making things difficult for yourself!
Lots of small pistons Ferrari V12/BRM V16 racing engine style sounds like good idea - though maybe not considering all the problems BRM had...
Know that Honda discovered new NVH patterns above 8,000rpm, but if you're looking at a race engine (which is the impression) then that probably won't bother you.
As building an engine from scratch goes rather beyond my level I can't offer any other info apart from suggesting you contact the likes of Cosworth, Hart or Judd to see if they'd be prepared to give you any (not too secret) info. Good luck!
Lots of small pistons Ferrari V12/BRM V16 racing engine style sounds like good idea - though maybe not considering all the problems BRM had...
Know that Honda discovered new NVH patterns above 8,000rpm, but if you're looking at a race engine (which is the impression) then that probably won't bother you.
As building an engine from scratch goes rather beyond my level I can't offer any other info apart from suggesting you contact the likes of Cosworth, Hart or Judd to see if they'd be prepared to give you any (not too secret) info. Good luck!
roospuppet - are you a wind up...
anyone who seriously considered building their
own engine would know that nvh - was an industry
standard term for Noise, Vibration and Harshness.
If you are at colledge or just building this in
your garage .. you will need a bit more knowledge
than you can pick up here... how about harmonics
(1st thru 7th order) for a start, engine
configurations for second, finite stress techniques..
the list goes on.
It's no easy task - that's why it's taken 100 years
or so to perfect the internal combustion engine.
anyone who seriously considered building their
own engine would know that nvh - was an industry
standard term for Noise, Vibration and Harshness.
If you are at colledge or just building this in
your garage .. you will need a bit more knowledge
than you can pick up here... how about harmonics
(1st thru 7th order) for a start, engine
configurations for second, finite stress techniques..
the list goes on.
It's no easy task - that's why it's taken 100 years
or so to perfect the internal combustion engine.
Why the need for high revs anyway?
Revs will certainly make power, but dont go expecting a faster car because of it, torque is more useful and that occurs at lower revs.
More reliable to have a lower revving engine anyway, youre gonna have all sorts of troubles, such as ring flutter, and increased big and little end loadings.
Search for a decent engine, german or japanese and turbocharge it.
Much more likely to hang together and all the design work has been done for you.
Revs will certainly make power, but dont go expecting a faster car because of it, torque is more useful and that occurs at lower revs.
More reliable to have a lower revving engine anyway, youre gonna have all sorts of troubles, such as ring flutter, and increased big and little end loadings.
Search for a decent engine, german or japanese and turbocharge it.
Much more likely to hang together and all the design work has been done for you.
the bike industry has done the hard work for you .. just bolt together as many fireblade (ie cheap) engines as you need to make the required HP.
But if you want to DIY your engine you'll need a host of exotic components .. conrods break on the exhaust stroke because of the loading as they change direction, titanium here then.
Gas flow at high revs without compromising low down torque? .. solonoid valve operation, rotary valves or compressed air operation work well.
Stick to short length crankshafts, so you'll be using a Vee configuration not an in-line. long cranks flex.and break .. early Cerbie SP6 anyone?
A short stroke gives a lower mean piston speed for any given revs, but it's interesting to note that until very recently piston speeds had stayed pretty much static (ie shorter strokes and higher revs giving same overall mean speeds).
If you're not going forced induction you'll have to have 5 valve heads or be limited to about 170bhp/litre without throwing away lots of torque lower down.
If you can, use a twin spark plug head .. the flame front progression becomes a critical limiting factor in high revving engines so start the spark/burn at two parts in the chamber.
Building your own engine isn't unheard of, John Britten did it in new zealand (what became of his carbon framed bike?) and I remember one hilarious piece of footage where he was casting the block and hadn't filled the cooling container with enough water .. mad panic as they set about fetching more water to fill it up!! .. happens to the best ..
Joolz
But if you want to DIY your engine you'll need a host of exotic components .. conrods break on the exhaust stroke because of the loading as they change direction, titanium here then.
Gas flow at high revs without compromising low down torque? .. solonoid valve operation, rotary valves or compressed air operation work well.
Stick to short length crankshafts, so you'll be using a Vee configuration not an in-line. long cranks flex.and break .. early Cerbie SP6 anyone?
A short stroke gives a lower mean piston speed for any given revs, but it's interesting to note that until very recently piston speeds had stayed pretty much static (ie shorter strokes and higher revs giving same overall mean speeds).
If you're not going forced induction you'll have to have 5 valve heads or be limited to about 170bhp/litre without throwing away lots of torque lower down.
If you can, use a twin spark plug head .. the flame front progression becomes a critical limiting factor in high revving engines so start the spark/burn at two parts in the chamber.
Building your own engine isn't unheard of, John Britten did it in new zealand (what became of his carbon framed bike?) and I remember one hilarious piece of footage where he was casting the block and hadn't filled the cooling container with enough water .. mad panic as they set about fetching more water to fill it up!! .. happens to the best ..
Joolz
When you say 'extremly' high how high are you aiming for? most modern 4 pots will run to 9,000Rpmish reasonably reliably providing you put a decent set of rod bolts in. If you want proper revs 12,000Rpm+ then you'll have to be prepared for a short engine life and lots of rebuilds, as currently its not possible to have something that revs to 18,000Rpm and lasts 100,000 miles unless its a 25cc 2 stroke.
The main things to consider are:
Achieving the tuning speed you require, the higher the revs, the shorter the inlet and exhaust pipes will need to be.
Maintaining valve control at high revs: L/W components needed and heavy load springs preferably with no hysterisis (ie air)
Achieving the mechanical strength required, bear in mind that the loads in the reciprocating parts (piston , con-rod etc) will increase at the square of the speed. ie double the engine speed then parts need to be 4 X as strong
Bear in mind how much things will bend, flex etc at full revs
Engine development isn't for the faint hearted as whatever can go wrong and far quicker than you thought possible.
Best of luck
Matt
The main things to consider are:
Achieving the tuning speed you require, the higher the revs, the shorter the inlet and exhaust pipes will need to be.
Maintaining valve control at high revs: L/W components needed and heavy load springs preferably with no hysterisis (ie air)
Achieving the mechanical strength required, bear in mind that the loads in the reciprocating parts (piston , con-rod etc) will increase at the square of the speed. ie double the engine speed then parts need to be 4 X as strong
Bear in mind how much things will bend, flex etc at full revs
Engine development isn't for the faint hearted as whatever can go wrong and far quicker than you thought possible.
Best of luck
Matt
Hi roospuppet,
Considering this thread and your other about rotary engines I have to ask this - what's the obsession with high revs?
As mentioned earlier on this thread it's not the best way to go performance wise, at least for a road car engine.
If you really want maximum revs then why not go the whole hog and use a turbine. No reciprocating parts, just rotating and so can run at astronomical revs.
Now that would be a real novelty in a car. Has been done before though. Rover made an experimental turbine road car (from a P4!) in the 60s and I'm pretty sure Lotus built a turbine car to race at Indianapolis the same decade.
Problem with turbines is no real performance until you get them wound up. OK when you're constantly doing 200mph round Indy but no good when accelerating out of a 30mph hairpin.
Rover also collaborated with BRM to make a turbine powered racer in the 60s which raced at Le Mans and was also road legal. If the sight of a racing car pulling into a filling station wasn't enough to amaze people, imagine their reaction when it then pulled up to the parrafin (kerosene) pump, because that's what it ran on!
Come to think of it, it might be worth building a turbine powered car if only as a way of saving on petrol taxes...
Considering this thread and your other about rotary engines I have to ask this - what's the obsession with high revs?
As mentioned earlier on this thread it's not the best way to go performance wise, at least for a road car engine.
If you really want maximum revs then why not go the whole hog and use a turbine. No reciprocating parts, just rotating and so can run at astronomical revs.
Now that would be a real novelty in a car. Has been done before though. Rover made an experimental turbine road car (from a P4!) in the 60s and I'm pretty sure Lotus built a turbine car to race at Indianapolis the same decade.
Problem with turbines is no real performance until you get them wound up. OK when you're constantly doing 200mph round Indy but no good when accelerating out of a 30mph hairpin.
Rover also collaborated with BRM to make a turbine powered racer in the 60s which raced at Le Mans and was also road legal. If the sight of a racing car pulling into a filling station wasn't enough to amaze people, imagine their reaction when it then pulled up to the parrafin (kerosene) pump, because that's what it ran on!
Come to think of it, it might be worth building a turbine powered car if only as a way of saving on petrol taxes...
im after a combination of torque and revs, lookin into various ways of makin engines, will take a long time doing, i am studying mechanical engineering at the mo, and havnt covered the full sylabus yet. so my knowlege is far from perfect, but im still learning, my aim is to have an engine perfect for a light weight kit car, ie lighter than 500 kgs, just considering, the perfect match,
roospuppet said: im after a combination of torque and revs, lookin into various ways of makin engines, will take a long time doing, i am studying mechanical engineering at the mo, and havnt covered the full sylabus yet. so my knowlege is far from perfect, but im still learning, my aim is to have an engine perfect for a light weight kit car, ie lighter than 500 kgs, just considering, the perfect match,
I think the way forward for this application is superbike engines. They are light very revvy, and powerful enough for Power to Weight ration to be gross, they lack torque but in a car that light it doesn't matter. May I suggest you read our discussion about BEC in the kit car forum (I can't remember the link, sorry). Certainly go to the kitcar shows and have a look at DAX, Westfield, MK, Fisher sportscars, and the new CorumLM (which hasn't been released yet but looks like it will be a cracker)
rev-erend said: roospuppet - are you a wind up...
anyone who seriously considered building their
own engine would know that nvh - was an industry
standard term for Noise, Vibration and Harshness.
If you are at colledge or just building this in
your garage .. you will need a bit more knowledge
than you can pick up here... how about harmonics
(1st thru 7th order) for a start, engine
configurations for second, finite stress techniques..
the list goes on.
It's no easy task - that's why it's taken 100 years
or so to perfect the internal combustion engine.
Yes, but keep in mind that building a one-off eliminates lots of the problems that huge companies have to face. The engine design is only a part of the process. The engine not only has to be designed but has to be designed to be economical to mass-produce.
roospuppet said: would a rotary valve be the way to go, www.coatesengine.com
that would reduce valve train, and yes building an engine from scratch is teh way, thinking of tryin to do summit like teh old f1 turbo engines, really small piston, maybe 50mm bore and a 50 mm stroke only estimates, but this is similar to the f1 turbo engines, with as many pistons as possible,
>> Edited by roospuppet on Thursday 19th December 15:54
Does TVR know about this? Seems to me that with a rotary valve system like this they could accomplish many good things at once with the Speed Six.
1. No more valve/follower/camshaft problems.
2. Increased power, increased efficiency, decreased emissions.
3. Cheaper to manufacture and the whole concept fits in nicely with TVR's position as automotive iconoclasts. TVR could be the first modern car manufacturer to give the poppet valve its long overdue retirement.
roospuppet said: also there are many designs for a rotary valve, but teh coates seems the best , because it seals the cylinder better than any others,
Yes, but even though the Coates design may be patented, surely the idea of a rotary valve isn't and there must be lots of options for a place with clever engineers, a well-equipped machine shop, R&D budget and a motive for doing away with poppet valved (e.g. TVR).
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