hey
for few years already i was thinking of redesigning of the intake in a IC engine.I was thinking of a diesel engine where there is no butterfly(or how u call it
) to regulate the air flow into the engine.Engine is there feed with "all it can suck" air,only amount of fuel decides what is the power output at the specific time.Diesel operates thus on highest possible effective compression ratio at any given time instant.
Now why not to incorporate it into a standard benzine engine.No throttle ,all air it can get (best efficiency both volumetric and mechanic) at all rpm's and all load conditions.We have fuel injection as a standard ,it should be fairly easy to manipulate the amount of power needed and rpm's by feeding the right amount of fuel(just like proven diesel concept!).Nowadays the amount of fuel is in function of load,current rpm's and amount of air feeded,but in fact diesel engine goes around it and just play with fuel amount.So it can be done and it is one of the points why diesel engine is more efficient than gasoline one.
Now imagine no throttle all air u can get situation:
-u press the acceleration and this means u inject more fuel
-engine responds by going up with rpm's
-at certain level the amount of fuel is not enough to produce more power and rpm's are steady (if it went on higher rpm's the mixture would be leaned out and deliver less power=>rpm's drop back to where they were)
-u want to decelerate
-engine gets less fuel and rpm's drop(too lean mixture to sustain previous level of power production)
as i see it:
+we get better engine response(always fully open air channel)
+better volumetric efficiency
+better overall efficiency(more power for less fuel)
+self regulating system running in optimum(less parts,electronics,maintenance,cost)
+engine can be downsized
what is now in benzine engine:
-u want to accelerate u open the air restricion(throttle)
-engine reads throttle position and adds more fuel(watching the rpm's and lambda signal)
-u want to cruise,the air restricion is let's say half open,less air is going into the cylinders and effective compression ratio goes down to 5:1
(so u get less power by directly restricting the efficiency of the engine!)
It is not economical solution as u see.
OK all of this sounds a bit theoretical,but i m in the middle of an experiment with my car.It is operating on simple vacuum LPG installation,no electronics.Engine gets as much fuel as air being sucked inside.When driving with slow acceleration,barely open throttle,switching to neutral gear as much as possible,avoiding braking it used 11l of LPG per 100km in the city.Next i started to drive with only fully open throttle(hard acceleration) switching to neutral gear as much as possible,avoiding braking it used 10l of LPG per 100km in the city.I should admit i drive every week the same routes at the same times for months
and never i got 10l consumption,always 11-11,5l.This is already 400km i made so the result is consistent.In the mean time i drove 200km in "slow mode" just to verify if weather or something can play a role.Nope it was 11,2l per 100km.
Conclusion is quite obvious,my car took the benefit of volumetric efficiency i gave to it(so it run at higher effective compresion ratio).But wait all! as i stated it is a simple vacuum mechanism and it showed improvement just because the engine itself took care of amount of fuel needed to run in best conditions that were allowed at that time instant.Electronics would try to find an optimum operation point,where here engine actually found it and that makes a difference.My next step is to take out the throttle and install one on the LPG distributor.Just to taste "diesel like" operation mode.
