Just a little more . . . . .

How to make it go fast

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Re: Just a little more . . . . .

Postby BC847 » Wed Oct 04, 2017 7:16 pm

To further complicate matters, my timing advance widget spring is custom, and mounted in a custom adjustable preload cover (in place of the KSB cover). That, with appropriate case-pressure, allows me to dial-in something of a dynamic injection-event curve, that's appropriate for a given engine RPM/load.

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

1993 12mm VE Fueled W250 CC, Green
12.67 @ 103.35
Your basic farm truck ;)
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Re: Just a little more . . . . .

Postby BC847 » Sat Oct 07, 2017 5:21 pm

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?
David

1993 12mm VE Fueled W250 CC, Green
12.67 @ 103.35
Your basic farm truck ;)
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Re: Just a little more . . . . .

Postby fatty » Sat Oct 07, 2017 8:57 pm

Wait a minute? You turned down the fuel? Have you wife come check you for a fever.
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Re: Just a little more . . . . .

Postby oldestof11 » Sun Oct 08, 2017 7:35 pm

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?

Yes.

Is it more of an injector issue or an RPM issue?

Now I have read your last post. Something to think about... Is the fuel collar on the rotor advancing too far forward so it is uncovering the spill port at WOT and max fulcrum vs WOT and fulcrum retarded a little?

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?


Quicker ET with less MPH? Ok, overall power is down but your accelerating quicker? Any suspension changes?
Jon
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Re: Just a little more . . . . .

Postby stuffy » Mon Oct 09, 2017 11:25 am

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
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Re: Just a little more . . . . .

Postby BC847 » Mon Oct 09, 2017 2:21 pm

oldestof11 wrote: Is the fuel collar on the rotor advancing too far forward so it is uncovering the spill port at WOT


:shock: 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????


That last little uptick in power just as the plot ends, is where I took my foot off the fuel. See it turn up? That's what I want to move back into the power-band . . .
Image

It's a regular thing to well feel in the seat-of-the-pants, a noticeable increase in "pull" when coming off the throttle, while well wound up.



oldestof11 wrote:Quicker ET with less MPH? Ok, overall power is down but your accelerating quicker? Any suspension changes?

None since before all the above test-n-tune passes.

Some months ago, I went from the BFG All-Terian radials to the Nittos 420s. HUGE improvement in overall traction, ride quality, cost, etc.

I think the difference is in the 60' and 330' times.
Went from . . .
1.763 60', 5.308 330' and 1.799 60', 5.350 330'

to

1.745 60', 5.304 and 1.758 60', 5.289 330' (now leaned-out and a little more advance).

Just plain quicker out of the hole. . . . ?





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

I used to. I removed the KSB stuff in its entirety some time ago.

As you may well know, the KSBs effect on timing is more prominent in the lower engine rpm.
Image


Here's how it impacted my mess back then (ignore the peaks in power, look at the overall plots) . . .
Image


With the KSB ON, there's a trade-off of less lower rpm power, for more higher rpm power.
David

1993 12mm VE Fueled W250 CC, Green
12.67 @ 103.35
Your basic farm truck ;)
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Re: Just a little more . . . . .

Postby BC847 » Mon Oct 09, 2017 3:27 pm

Oh, before I forget again . . . The obligatory BS excuse for running slower with the new mess.

I gained right at 200lbs with all the additional iron/aluminum, etc.


That's good for at least a tenth of a second in the 8th, isn't it? :lol:
David

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Re: Just a little more . . . . .

Postby oldestof11 » Mon Oct 09, 2017 3:54 pm

BC847 wrote:
oldestof11 wrote: Is the fuel collar on the rotor advancing too far forward so it is uncovering the spill port at WOT


:shock: 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????


Maybe put the full throttle travel screw back in to limit throttle movement and see it if helps.

Then put the power screw in fully
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Re: Just a little more . . . . .

Postby PToombs » Mon Oct 09, 2017 3:55 pm

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. :mrgreen:
pete

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Re: Just a little more . . . . .

Postby BC847 » Mon Oct 09, 2017 4:09 pm

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. 8)

Elegantly simple and easily controllable/tunable way to better see what's going on. 8)
David

1993 12mm VE Fueled W250 CC, Green
12.67 @ 103.35
Your basic farm truck ;)
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Re: Just a little more . . . . .

Postby BC847 » Mon Oct 09, 2017 4:10 pm

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. :mrgreen:

Is that perhaps where the term: "Sand-Bagging" came from? :lol:
David

1993 12mm VE Fueled W250 CC, Green
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Re: Just a little more . . . . .

Postby oldestof11 » Mon Oct 09, 2017 4:46 pm

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. 8)

Elegantly simple and easily controllable/tunable way to better see what's going on. 8)


Only time I make big bucks is in OT. Even then, it isn't quite $45/hr.

I miss my trucks but I am done racing trucks competitively. I need one to bag, drop, and tow with. The fact is have compounds, 5x16's or even 6.7L's is inconsequential to the fact it will be a tow pig
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Re: Just a little more . . . . .

Postby PToombs » Tue Oct 10, 2017 4:41 pm

BC847 wrote:Is that perhaps where the term: "Sand-Bagging" came from? :lol:


Could be! ;)
pete

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Re: Just a little more . . . . .

Postby stuffy » Tue Oct 10, 2017 8:46 pm

[quote=
As you may well know, the KSBs effect on timing is more prominent in the lower engine rpm.
Image


Here's how it impacted my mess back then (ignore the peaks in power, look at the overall plots) . . .
Image


With the KSB ON, there's a trade-off of less lower rpm power, for more higher rpm power.[/quote]

Just figure out a way to make it come on at 3k rpm and above :/
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Re: Just a little more . . . . .

Postby BC847 » Sun Oct 22, 2017 11:27 am

Went to the track this past Thursday and made a couple of passes. The second had me break traction coming out of the hole resulting in sthi jumping all around till I could get off it. The track and tires were cold so that didn't help, but it got me to thinking: That shuddering rear-end, did that actually cause it?

So, I took it apart today to have a look.

Damnit!

CSI mode ON.

I've photographed things as they came apart to see if I had inadvertently assembled something wrong . . . ..


Removing the diff and setting it on the floor shows I have the Spider-gear shafts properly seated in the proper grooves/notches of the carrier . . . .

Image



I've layed things out showing how I assembled it back then. This is looking at one of the two clutch-pacs . . .. .

Image



Understanding the clutch steels are dished / concaved, I can see where the steels come into contact with the clutch disks. (See red dots) Notice the streaks of wear on the steels, match the neighboring clutch. It's polished the steels, and heated the mating clutch area enough that one can see perhaps heat related damage to the opposite side of the clutches.

Image



The dished steels have cut into the clutches such that it cut rings into the clutch material, on both sides of the clutches, on the inner, or outter diameter, pending which side of the dished steel you're looking at.
You can clearly see the cutting of the clutch material (Green Dot). One can see where the cut-free clutch material is separating from the thing (Red Dot) . . .

Image



So, now I've got this mess floating around in the lube-oil . . .. It's strips of clutch material . . . .

Image



I figure that crap has gotten into the carrier bearings, momentarily jammed them, forcing them to spin the races in the axle-housing . . . . .

Typical of both sides . . .
Image


Typical of both sides . . .
Image



Futher, I figure that same clutch material has gotten in the gears and being abrasive in nature, has scored the gear's teeth . . . . Pinion-gear . . . .

Image



Spider-gears . . . .

Image



- How did the clutch-disks get cut up? I'm wondering if there was not enough preload on the clutch-packs? But then I don't know if such wear is common for dished clutch-pack elements. . . . . ?
What can I do to correct such so as not to have it happen again?

- That free-floating abrasive clutch material getting in the gears, has it caused fatal damage?
Is the differential housing now ruined with the carrier bearing mounts being scored/wallowed out?

Seven of the ten voices in my head are saying I'm screwed, need to look for a new rear axle.

Are the voices wrong?

Crap.
David

1993 12mm VE Fueled W250 CC, Green
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Your basic farm truck ;)
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