Do new GDI engines have throttle plate?
Do new GDI engines have throttle plate?
(OP)
A friend pointed out that a GDI engine could run w/o a throttle plate like a diesel and be governed by the fuel/ignition controller. This would reduce backwork and improve fuel economy except at WOT.
Is anyone doing this?
Is anyone doing this?





RE: Do new GDI engines have throttle plate?
Running without a throttle plate would increase pumping losses because the engine would always be running at 100pct air flow.
If it ran, it wouldn't be running an Otto cycle. I'm not sure it would run at all with that much excess air.
If the ECU were not set up to compensate somehow (and I'm not convinced it could be), the engine would most likely IMHO detonate, overheat, and self-destruct, while running like crap.
You are welcome to try it on _your_ engine.
Mike Halloran
Pembroke Pines, FL, USA
RE: Do new GDI engines have throttle plate?
Briefly, no they don't, yes it matters.
http
http://cit
Neat reading.
RE: Do new GDI engines have throttle plate?
I'm still fuzzy on how they can get a stoich or rich mixture without throttling the intake. ... unless they're throttling by diddling the valve timing or lift.
Mike Halloran
Pembroke Pines, FL, USA
RE: Do new GDI engines have throttle plate?
- Steve
RE: Do new GDI engines have throttle plate?
RE: Do new GDI engines have throttle plate?
Thanks all for the education.
I think I'll wait a while to do it to my lawnmower...
Mike Halloran
Pembroke Pines, FL, USA
RE: Do new GDI engines have throttle plate?
VW/Audi (T-)FSI has a throttle and also runs at lambda one with a TWC. Ditto Mercedes-Benz and GDI systems from GM, Ford, Hyundai, etc.
All the above implementations could also run in lean/stratified mode, but the ineffectiveness of a TWC (and the high tailpipe NOx that would result) in that regime and the need for a lean-NOx trap catalyst (more complex, more expensive) results that nobody is currently implementing it where Euro 5 / Tier 2 Bin 5 regs need to be met.
All the above are still considered Otto engines.
RE: Do new GDI engines have throttle plate?
RE: Do new GDI engines have throttle plate?
For the purposes of most discussions I use the convention that the Miller cycle refers to late intake valve closing causing some of the cylinder charge to flow back into the intake ports, while Atkinson denotes very early intake valve closing before BDC resulting in a pre-expansion before the compression stroke proper.
RE: Do new GDI engines have throttle plate?
The modern equivalent of this I would have thought would have to be the high geometrical CR/LIVC approach.
The Miller Cycle is never as clear to me but I think to be classed as "Miller" it must involve a supercharger plus an element of Atkinson Cycle. Just why the supercharger is a better method of cylinder-filling I have never quite been able to picture.
The EIVC approach I don't think has a cycle name and is much less effective than Atkinson (especially) or Miller.
RE: Do new GDI engines have throttle plate?
Schutting, E. et al. Miller- and Atkinson-Cycle on a Turbocharged Diesel Engine. MTZ 06I2007 Volume 68.
RE: Do new GDI engines have throttle plate?
RE: Do new GDI engines have throttle plate?
I'd think because your exhaust energy availability is relatively lower.
RE: Do new GDI engines have throttle plate?
RE: Do new GDI engines have throttle plate?
I don't see how this can be construed as Atkinson by anbody's definition.
RE: Do new GDI engines have throttle plate?
RE: Do new GDI engines have throttle plate?
I can see how late or early IVC on a piston engine could give you a miller or atkinson cycle.
I found the article in german, looked for it in english, not a member of MTZ.
RE: Do new GDI engines have throttle plate?
-Agreed.
RE: Do new GDI engines have throttle plate?
RE: Do new GDI engines have throttle plate?
High PR turbocharging implies a diesel application. I'm not aware of any production diesel engines that actually use the Miller cycle, although since it is only a camshaft profile change away, it's possible that it is present but not advertised as such.
RE: Do new GDI engines have throttle plate?
RE: Do new GDI engines have throttle plate?
I am afraid I take a somewhat simplistic and less "scholarly" view of the Atkinson Cycle. I regard any engine which has a high CR (too high for "normal" use) combined with any strategy to reduce the combustion chamber pressure after compression as "Atkinson". Whether this strategy is LIVC, EIVC, automatic throttle plate control or any other method of limiting the pressure - it is still Atkinson.
I can see why you favour EIVC as being closest to "true" Atkinson but I think it still needs the CR component to be called Atkijnson.
Without the high CR component, LIVC and EIVC I think should be regarded as engine load control/reduced pumping loss strategies. I have found from personal experience that LIVC is more effective than EIVC.
The following is probably less "scholarly" than Schutting et al but I agree with their views - which I think are expressed very clearly.
http://www.mechadyne-int.com/vva-reference/
I should point out that I have no connection with Mechadyne and I don't think that their variable valve strategies are very practical - but I like (and agree with) their explanations of the various part-load strategies.
RE: Do new GDI engines have throttle plate?
P-V diagram illustrates the differences.
Engineering is the art of creating things you need, from things you can get.