With all the above, maintaining case-pressure that's relative to engine RPM is important.

Moderators: Greenleaf, KTA, BC847, Richie O
BC847 wrote:Look at the numbers as I'm fully-staged sitting at the line (from a similar run):
2100 engine RPM.
955* EGT (holding brakes at 25psig boost)
132psig case-pressure.
At the end of the race, just lifted foot:
3150 engine RPM (dropping from 3400ish).
1090* EGT (dropping from 1400ish)
174psig case-pressure.
That 42psig difference equates to some degrees of retarding the injection-event timing over the course of 2100rpm to 3150 @ WOT.
THAT's the issue I'm working to correct.The retarding of the timing results in a drop in power. I've seen it repeatedly on dyno-runs. The power ticks up notably as I let off the fuel. I've actually thought of turning down the main fuel-screw, just enough to have the case-pressure NOT drop with the application of WOT. If the dyno's not lieing, I should see an increase in power in the upper engine RPM. It's counter intuitive.
Or, I can reinforce the fuel supply to the case, and not have the case-pressure drop @ WOT under load and not see the timing retard with high RPM @ WOT under load.
Make sense?
BC847 wrote:So . . .
Made baseline passes of:
8.481 @ 79.03mph
8.459 @ 79.00mph
Then, the next week, advanced timing little to get:
8.341 @ 80.45mph
8.373 @ 80.72mph
Then, the following week:
Turned the fuel down 1/2 turn to get: 8.354 @ 79.97mph
A little more timing advance: 8.327 @ 80.32mph
Getting mess together to upgrade the lift-pump stuff. We'll see, huh?
oldestof11 wrote: Is the fuel collar on the rotor advancing too far forward so it is uncovering the spill port at WOT
oldestof11 wrote:Quicker ET with less MPH? Ok, overall power is down but your accelerating quicker? Any suspension changes?
stuffy wrote:Do you have your ksb on a switch? I know when I had big injectors if I flipped the ksb switch at wot I would notice a huge power increase. Like 50-100 hp as my estimates go
BC847 wrote:oldestof11 wrote: Is the fuel collar on the rotor advancing too far forward so it is uncovering the spill port at WOT
That's an excellent question! I've never considered that.
If the collar was uncovering the port, wouldn't the spilt fuel lessen the case-pressure drop? It's spilling right back into the case. Less delivered to injectors, more to maintain the case-pressure?
Hmmmm????
oldestof11 wrote:Maybe put the full throttle travel screw back in to limit throttle movement and see it if helps.
PToombs wrote:I know 100 lbs is a tenth in the 1/4, so it may be close.
I know my buddy used to put 4 or 5 100lb bags of sand in his trunk and go to the track. Everybody watches to see how fast your car is. Then he took out the bags, installed the Nitrous kit, and away we went up to the Boulevard to street race.
BC847 wrote:oldestof11 wrote:Maybe put the full throttle travel screw back in to limit throttle movement and see it if helps.
That right there, is why you make the BIG bucks, my friend.![]()
Elegantly simple and easily controllable/tunable way to better see what's going on.
BC847 wrote:Is that perhaps where the term: "Sand-Bagging" came from?
Users browsing this forum: No registered users and 55 guests