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  1. Wow... what I gained most out of that quote from Quad is that they just go the max on timing and they haven't put a whole lot of thought into how that works everyday driving/mileage, but only for max power. It's hard to say from the information there, but when he says "There is a too low and a too high number. If the IAT drops too low the ECU retards the timing just like too hot due to fears of detonation and stabilitiy of combustion in diesel fuels"... I would venture to say that "too low" is probably in the -degrees.
  2. I was thinking about this again this morning... my DD ('93 Toyota pickup) is parked for the next couple mornings so I actually had to drive the Dodge again today. It was about 38 degrees here this morning and when I cranked the ol' gal up, she was just as clattery as usual. I was thinking about the attributes of advancing timing for a cold startup. 1) Cold air decreases flame speed which would require a little extra timing from the get-go. Hence "some" of the extra noise on a cold startup? 2) If an engineer were interested in getting an engine up to operating temperature
  3. I'm not familiar with Singh grooves... But yeah, I'm talking similar things to the super squish pistons/heads.
  4. CSM, I agree 100% with your post. I didn't know that diesel burned that much slower than gasoline, even when artificially pressurized (turbo or super boost). Many VW gas engines run 30-32 degrees total advance when cruising under part throttle conditions. If we can increase the burn speed - whether by compression, smaller droplets, or more swirl - we can pull out more of the timing and create a more efficient engine. I was thinking about the difference in piston/head design between the 12v and 24v. I know that both engines have a more or less flat top piston with a combustion bowl built i
  5. As most of ya'll know, Crazy Carl "Turbolver" put a supercharger on his P-pumped 24v. I've followed it very closely with great curiousity but haven't seen any talk about the timing. I read where he bumped timing from 15 degrees to 24 degrees, but he never reported back with results. How would a supercharger affect timing, and how could you maximize efficiency using one?My thoughts are: since extra boost (especially down low) increases flame speed of diesel, you might actually be able to retard timing and maintain similar EGT's and increase torque. Am I way off?
  6. How interesting... I wonder where the extra injection events fall on those maps?
  7. Absolutely. Peak pressure BTDC is not good at all. The CR injection system should theoretically be able to inject just about anywhere to get peak pressure wherever needed. Low boost levels + high RPM (where you would normally be during a cruising situation) should have the highest amount of advance, which is probably the majority of injection BTDC.
  8. Have you optimized for fuel mileage yet? What mpg are you seeing?
  9. Well, I haven't revisited this in a while, but it's way past time to stop back by. I've been reading a lot about one of my other hobbies - VW aircooled engines. I built my own dune buggy a few years back and have helped work on numerous others. About a year ago, I converted mine to run on propane like many rock crawlers do, and ever since then I have been on a quest to make it run on the least amount of fuel possible. In doing so, I've read and read about how to make a VW engine more efficient and have stumbled on lots of good information about timing. Granted, this is on a gasoline engi
  10. Funny how these old threads get dug up! I'm curious as well. I'm getting ready to adjust my valves (never been adjusted and I'm at 230k miles) Yikes! My two cents: First - when you were asking about the necessity for valve lash - On Volkswagen motors, the rockers are designed such that everytime the lifter comes down to contact the valve, it actually causes the valve to rotate ever so slightly so that the valve is contantly rotating during operation. This keeps it from wearing abnormally. Cummins valves may have a similar design. Second - when talking about intake valve vs boost, don't forget
  11. Then I guess the next logical question is - how does the VP, or any of the pumps for that matter, vary injection pressure if pump displacement is fixed?
  12. Well... I think that the VP44 can do something very similarly to the CR by varying max injection pressure... but I don't have any evidence to back that up.
  13. Is the pressure actually always the same in the rail of a CR? I thought that it fluctuated quite a bit with fueling requirements? Where it should be low at idle and higher at RPM's.
  14. Taken off the Cummins Forum (NOT MY WORK!) This is actually a tuning "how-to" for the Quadzilla Adrenaline: _________________________________________________________________________________________________________ Pump Stretch. This will make the biggest difference in overall power and smoke. This is the amount of time the injector is actually opened and spraying fuel into the cylinder. I have this set pretty low on the 1000 tune that I sent you. The COMP file is set to 1800. More than 1800 creates more torque and a lot more smoke but, actually makes less power on the upper end
  15. Boost, more often than not, also increases as RPM increases, which would additionally advance effective timing. So to get back to our VP-44 conundrum... what is it that makes the VP burn more fuel when it's cold. Obviously it's something computer controlled, so what all parameters can the VP-44 control/manipulate to make power? 1 - Timing Advance/Retard 2 - Event duration 3 - Injection Pressure? How does the VP vary the amount of fuel injected if not by duration? Pressure?
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