It's normal even in a lot of old production engines.
I understand. I would also love to hear about the harnessable benefits for turbocharging. With shorter exhaust duration, the exhaust speed would need to increase. Obviously, longer intake stroke then improves cylinder packing, especially under boost.
It just seems like a dream combination for turbocharger efficiency.
Re: Offset cylinder explained.
Posted: 29 Mar 2023, 04:33
by gruntguru
You don't think "getting the exhaust out" is important to turbo engines?
Re: Offset cylinder explained.
Posted: 29 Mar 2023, 05:13
by saviour stivala
Getting exhaust out is important, It is easer done on a turbocharged engine then on an NA engine. BUT. On the present day F1 turbocharged engine with such a high risk of misfire by trying to ignite a mixture at ^-1.4 it is super-important.
Re: Offset cylinder explained.
Posted: 29 Mar 2023, 08:04
by Greg Locock
It's called Desaxe. If you mess about with a timing diagram you'll see the results are subtle to say the least, for sensible amounts.
Re: Offset cylinder explained.
Posted: 29 Mar 2023, 08:40
by saviour stivala
Were and when there is a gain to be had no matter how subtle those in F1 will dive head first for it as they are not going to let the competition gain a subtle advantage while they don't.
Re: Offset cylinder explained.
Posted: 29 Mar 2023, 22:07
by Greg Locock
Indeed. Now consider the disadvantages. Very few modifications have no disadvantages.
You don't think "getting the exhaust out" is important to turbo engines?
I know it is. My point is that lessening the time will increase the speed of the exhaust. I believe that to be turbo beneficial.
Hmmmm . . . making the exhaust valves and ports smaller will increase the speed too . . . but they don't do that!
I'm sure there are a million trade offs. I guess the pumping losses increase of the exhaust stroke then as the piston forces the exhaust out the valve?
Or maybe just upsize the exhaust valve to compensate for shorter duration?
Interesting that upsizing the exhaust valve then may then restrict the size of the intake valve. It's all trade-offs.
Re: Offset cylinder explained.
Posted: 30 Mar 2023, 08:33
by saviour stivala
Valve overlap on a turbo engine allows not only a cooling effect on combustion chamber but also help 'flush' the top of cylinder including exhaust valve ports of exhaust gasses.
Re: Offset cylinder explained.
Posted: 31 Mar 2023, 00:57
by gruntguru
Providing the design has achieved a positive pressure differential during overlap.
It's all trade-offs.