Rail pressure on idle

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Re: Rail pressure on idle

Postby McarM » Thu Feb 18, 2016 3:54 pm

Rail Pressure Limiter 3D
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Re: Rail pressure on idle

Postby ecuedit » Tue Feb 23, 2016 11:37 pm

majsterx wrote:Sure can increase, if idle no needed modify all, only for lower IQ.
50bar increase is fine, don't increase more because more fuel will be injected. And that's value should be fine for CR pomp exploitation

Can upgrade by 100bar from 50mg bigger IQ value. But only if tune and don't change much duration


hi there,
just wanted to come to little chat. I do not agree with the statement that if you increase rail pressure that you will get more fuel.
I will explain for better understanding:

When you increase rail pressureA to rail pressureB at some point for sample at RpmX and IqY, ecu "goes" to look at the injection duration map and checks rail pressureB and iqY to see duration that is needed at specific rail presssure to achieve iqY,
so for sample for rail pressureA it was 1000microseconds for rail pressureB it is 950microseconds...

so ecu actually injects less time but gives same ammount fuel....just take a look injection duration map.

and also that affects to end of injection position....it will end earlyer so soi adjustments can be done...

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Re: Rail pressure on idle

Postby michass » Wed Feb 24, 2016 2:50 pm

ecuedit wrote:
majsterx wrote:just wanted to come to little chat. I do not agree with the statement that if you increase rail pressure that you will get more fuel.



But when you increase rail pressure on some rpm, then fuel pump consume more power. Bigger pressure - more efficient and more advanced SOI, it should be more power, but do you know point, where pumps consume more, than efficient can do?

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Re: Rail pressure on idle

Postby ecuedit » Wed Feb 24, 2016 10:20 pm

hi,
this depends on engine construction, rail system. At diesel engine you need to measure pressure inside the cylinder with spark plugs that can measure pressure in the cylinder thru full pre injection, injection and burning cycle. Depend on pressure increase and speed of pressure decrease you can get point where diesel knocking accures. Best theoretical efficiency is if all fuel burns around TDC, but there are also other limitations.

there is no generic formula for engines, it has to be done for each single engine - measurements (Hydria glow plugs can do that).

About fuel pump power consuption, what i can say that we tested the range up to 600bars rail increase (we made hybrit fuel pump with stronger elements and larger excenter) and we also turned on 3rd piston to run all the time - there was no noticable fuel consuption due to more stress and pump work.

if you increase rail pressure you get different output but it affects to fuel burning pretty much. we make lab measurements in the institute so we are obligated not to post any measurements except our measurements.

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