Not that I’m aware of. Unless you’re thinking of 2 strokes?
I’m sure I had a discussion with my BIL about race/super bikes using cam less valves. Not 100% certain though.
This might have been what he was talking about. Still has a cam but no valve springs.
Ducatis don’t use springs, either. They have “desmodromic” valves which use followers to actively close the valves and seat them. They still use cams, though. It’s supposed to reduce power loss as you don’t expend power pushing against the spring.
I’m sure I had a discussion with my BIL about race/super bikes using cam less valves. Not 100% certain though.
This might have been what he was talking about. Still has a cam but no valve springs.
Ducatis don’t use springs, either. They have “desmodromic” valves which use followers to actively close the valves and seat them. They still use cams, though. It’s supposed to reduce power loss as you don’t expend power pushing against the spring.
This might have been what he was talking about. Still has a cam but no valve springs.
Ducatis don’t use springs, either. They have “desmodromic” valves which use followers to actively close the valves and seat them. They still use cams, though. It’s supposed to reduce power loss as you don’t expend power pushing against the spring.
Rotary valves perhaps?
I don’t believe there’s any ever been used in any production or actual series race bike.
Re: Cone-eggsegg Gamora
Posted: Wed Mar 04, 2020 9:30 pm
by integrale_evo
The problem with any entirely camless engine based on existing cylinder head layout is that whatever method you use, pneumatic, hydraulic or electrical has to be 100% reliable over millions of activations. One slight blip and a valve smacks a piston and its game over, hard to ensure a failsafe system with no mechanical link between the top and bottom of the engine.
Look at how massive the setup for the lotus engine was, they proved the technology worked but how on earth are you going to shrink something like than down to package it whilst keeping costs reasonable and ensuring reliability over many tens of thousands of miles?
The fiat multiair system is quite neat, barely any bigger than a normal cylinder head setup, but detaches the motion of the intake valves from the camshaft with what's effectively an on the fly adjustable hydraulic link.
Because it still has conventional valves and springs, if it fails and the unit doesn't maintain oil pressure then the link between the car and valve is broken, the valve doesn't open and the engine doesn't run. If it fails the other way and jams pressurised the valve just follows the profile of the cam, there is no way it can leave a valve dangling in the cylinder ready for the piston to say hello.
Re: Cone-eggsegg Gamora
Posted: Wed Mar 04, 2020 10:41 pm
by Mito Man
Probably why it’s ideal for something like this car. The average one won’t do more than 100 miles a year and a service starts from £30,000 so they can check it all over yearly
Mito Man wrote: Tue Mar 03, 2020 7:15 pm
I went from want to do not want faster than that thing accelerates as I read the specs.
Imagine what the Victorians thought when someone came up with the steamlesss engine.
What was it like back then, Paul?
Just noticed this you cheeky young scamp! As for how things were back then, I can't say because I was always kept in the dark as a result of my chimney cleaning apprenticeship.
Re: Cone-eggsegg Gamora
Posted: Sat Mar 07, 2020 2:01 pm
by NotoriousREV
Re: Cone-eggsegg Gamora
Posted: Tue Mar 10, 2020 4:27 am
by unzippy
integrale_evo wrote: Wed Mar 04, 2020 9:30 pm
The problem with any entirely camless engine based on existing cylinder head layout is that whatever method you use, pneumatic, hydraulic or electrical has to be 100% reliable over millions of activations. One slight blip and a valve smacks a piston and its game over, hard to ensure a failsafe system with no mechanical link between the top and bottom of the engine.
Look at how massive the setup for the lotus engine was, they proved the technology worked but how on earth are you going to shrink something like than down to package it whilst keeping costs reasonable and ensuring reliability over many tens of thousands of miles?
The fiat multiair system is quite neat, barely any bigger than a normal cylinder head setup, but detaches the motion of the intake valves from the camshaft with what's effectively an on the fly adjustable hydraulic link.
Because it still has conventional valves and springs, if it fails and the unit doesn't maintain oil pressure then the link between the car and valve is broken, the valve doesn't open and the engine doesn't run. If it fails the other way and jams pressurised the valve just follows the profile of the cam, there is no way it can leave a valve dangling in the cylinder ready for the piston to say hello.
Konigsegg/Freevalve have been running it in a Saab 9-5 since 2009..
integrale_evo wrote: Wed Mar 04, 2020 9:30 pm
The problem with any entirely camless engine based on existing cylinder head layout is that whatever method you use, pneumatic, hydraulic or electrical has to be 100% reliable over millions of activations. One slight blip and a valve smacks a piston and its game over, hard to ensure a failsafe system with no mechanical link between the top and bottom of the engine.
Look at how massive the setup for the lotus engine was, they proved the technology worked but how on earth are you going to shrink something like than down to package it whilst keeping costs reasonable and ensuring reliability over many tens of thousands of miles?
The fiat multiair system is quite neat, barely any bigger than a normal cylinder head setup, but detaches the motion of the intake valves from the camshaft with what's effectively an on the fly adjustable hydraulic link.
Because it still has conventional valves and springs, if it fails and the unit doesn't maintain oil pressure then the link between the car and valve is broken, the valve doesn't open and the engine doesn't run. If it fails the other way and jams pressurised the valve just follows the profile of the cam, there is no way it can leave a valve dangling in the cylinder ready for the piston to say hello.
I have a collection of bent Multiair valves alongside a broken Multiair unit.
Re: Cone-eggsegg Gamora
Posted: Tue Mar 10, 2020 9:24 am
by integrale_evo
Ok, 'should' be failsafe
Must admit, I've heard of plenty of unit failures but never of bent valves.
Re: Cone-eggsegg Gamora
Posted: Tue Mar 10, 2020 9:25 am
by V8Granite
Amazing packaging but the engines cleverness does nothing for me wanting one. Ooh half a GT2, hmm, not exactly a selling point when it’s a million pound car.
It does look absolutely fantastic though.
Dave!
Re: Cone-eggsegg Gamora
Posted: Tue Mar 10, 2020 9:38 am
by integrale_evo
unzippy wrote: Tue Mar 10, 2020 4:27 am
Konigsegg/Freevalve have been running it in a Saab 9-5 since 2009..
It's not quite how it reads to me, they did 6000 miles with it in an engine between 2009 and 2011, so if it was as perfect as they thought why has it taken another 9 years to be put into a simpler ( 3 cylinder) very expensive, very limited production vehicle?
Don't get me wrong, it would be wonderful if all production cars had it, the benefits would be huge, and I hope they succeed in it, but if it was that easy it would have been done by now and people wouldn't keep thinking up other ways to do part of the same job.
Re: Cone-eggsegg Gamora
Posted: Tue Mar 10, 2020 10:15 am
by V8Granite
6000 miles of testing is absolutely bugger all.
We would do more testing than that on a thermostat, it’s less than 250 hours of actual test time so about 11 days on a test bed set up.
It's not quite how it reads to me, they did 6000 miles with it in an engine between 2009 and 2011, so if it was as perfect as they thought why has it taken another 9 years to be put into a simpler ( 3 cylinder) very expensive, very limited production vehicle?
Don't get me wrong, it would be wonderful if all production cars had it, the benefits would be huge, and I hope they succeed in it, but if it was that easy it would have been done by now and people wouldn't keep thinking up other ways to do part of the same job.
Dunno, I just remember being very impressed a long time ago -
We had a little discussion about it in the YouTube thread, the Hyundai system is nearly identical in the way the cam speed is altered to the Rover VVC system from the mid 90s, just using an electronic actuator and worm gear instead of a solenoid and oil pressure to rotate an eccentric journal.
