Quote:
Originally Posted by werminghausen
Thanks Tom,
Higher prop pressure resulted in delay of injection start of fuel delivery (because the pump needs more time in order to increase the pressure level?)
If you say 617 engine (was it a 115bar non turbo injector or a 135bar turbo injector?) then what was the difference in pop pressure relative to the 2.5 - 3 degrees delay? Did you test both situations (both sides pop pressure and timing?)
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617 a (=Turbo), I went from 140 up to 150 bar pop pressure and could see the 2.5 -3 deg retard. Both tested with clamp and strobe light dynamically.
Quote:
Originally Posted by werminghausen
Did you then advance your timing by the 2.5- 3 degrees in order to offset the greater pressure?
okay I assume you have a turbo and spec pressure id 135bar...if you increase by 15 bar and have 3 degrees of retard...so this makes 0.2degrees per 1 bar pressure differential?
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At that time I advanced the timing to 26 deg with 150 bar and I was happy.
1 bar steps on pop pressure is way too small, think in approx. 5 bar steps.
Quote:
Originally Posted by werminghausen
I am using the DN 0 SD 265 nozzles from Monark and the spec of new nozzles for the 603 is at 135-145bar...140bar medium pressure. So let's say I increased by 10 bars. I also turned up the IP a bit (my EGTs are very high if I hit the gas).
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265 Monark is a good choice. Turning up the IP will compensate for the shorter injection time to get the same amount of fuel.
Quote:
Originally Posted by werminghausen
I adjusted injection time with RIV method..the 2 lights... at 14 degrees ATDC (vs spec of 15 degrees)...[I don't know what 14 degrees translate to as the 'real' injection timing...should be way before TDC.]
10 bars pressure differential would retard my timing by 2 degrees according your formula?
This means I should advance my timing to 13 degrees ATDC?
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RIV method 15 deg (after TDC) means 24 deg before TDC physically but only for pop pressure within spec. This is why I use the clamp and strobe light to get real life data independent from pop pressure. I.e. just putting the clamp on the IP side of the hard line (instead of the injector side) will show one full deg "late" (=hydraulic delay of injection). Next: The RIV method follows the notch on the fly weights. The fly weights are fixed on the pump cam just on a cone and it depends how accurate the pump was assembled...
Assuming the RIV method conditions are o.k. and you now have 150 bar pop pressure you can easily go to 11 -12 deg (RIV). During the first 800-1000 miles the injector/nozzles will "loose" some bars in pop pressure, therefore timing will retard and the noise will decrease.
Quote:
Originally Posted by werminghausen
Someone also mentioned that : Higher pop pressure will end up injecting just a smudge less fuel, the injection will take place later (retarded timing), and the injection pulse will be shorter (but more intense and better atomization)
if you just boost the pop-off pressure without changing anything else it is gong to hurt things.
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this is why you advance and compensate with more fuel adjusted on the IP.
Why should this hurt??
Quote:
Originally Posted by werminghausen
however if you are willing to do some work tinkering with the injector pump (timing, turn it up a smudge, etc) you may be able to improve the power and efficiency a bit.
I seem to remember reading that higher pop-off pressures will also result in sharper noise at ignition and therefor a higher overall noise level, but I can't remember details.
Martin
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noise level will be higher but it should not be hard nailing when warmed up.
As long as you are able to balance the injectors within some few bars or even better all this makes sense. But imagine you have a delta of 5 bar on one injector this means injection on this cylinder is different by one deg. Doing so you did not gain anything at the end of the day.
Tom