I just finished two days of towing with the recent mods that I described here...
https://www.ford-trucks.com/forums/607571-recent-mods-cc-pressure-gauge-ccv-and-dp-tuner.html

When I left Asheville it was about 50 F and I immediately encountered some grades and noticed an effect that I've observed before but not nearly as pronounced as with the new DP tunes. There's something about cooler temps (IAT, MAT, or whatever) that causes more aggressive fueling and higher EGTs with less foot pressure on the throttle. This effect gradually diminishes during the first hour of towing as the under the hood temps warm up an stabilize. Well, I started out in my DP 60 HP w/ special shifting, and part way up the first grade with a foot pressure calibrated for my old tune I noticed the EGT was continuing to climb rapidly, and to stabilize the EGT at 1100 F I had to let off to the point that I was just relaxing and letting the weight of my foot rest on the throttle.

I climbed the grade fine, but I was concerned about how just a little too much pressure on the throttle would cause the EGT to quickly approach my personal redline of 1150 F. On the next grade I switched to the DP 40 HP, and this was much more to my liking. After pulling several grades in this setting I was thinking that it had some magical property because it seemed to climb as good (or better) than the 60 HP setting and was much more tolerant to various throttle pressures, and I had to push moderately hard to get the EGT up to 1150 F. I then tried my old tune, and it required the firmer throttle pressure I'd become accustomed to, and when I tried the stock setting I had to run at near WOT to keep my speed up. I'd been towing for about an hour and then went back to DP 60 HP, and it now exhibited a much more forgiving throttle response with everything under the hood thoroughly warmed up.

I decided that the 40/60 HP combination was very useful, and it would be a good idea to start off in the AM in 40 HP, and after an hour or so I could switch to 60 HP to give my foot muscle a rest! I also decided to remove my boost limiting spring shown here Click for full size image to get a couple of extra psi of boost to see if that would help with 60 HP EGT the next day. I finally got the spring off, but I had to cut it in several places with my Dermal tool, and climbing that far into the engine compartment with my bad back and a 20K rpm cutting wheel in one hand was quite a chore.

The next day was considerably warmer so it was hard to judge just how much the extra boost helped. On WOT runs I was holding 22.5 psi boost (no SES light) and EGTs didn't get as high as the colder day before running at 20 psi boost. During all this testing with various chip settings, I was also taking measurements of CC pressure with my new gauge.

I guess my CCV mod using RV sewer hose is a keeper, as the wife hasn't complained about the fumes and my CC pressure at WOT under full load towing grades is lower than I expected. In fact my CC pressures seem so low that if I hadn't measured several trucks at Smokin and my OEM CCV on the tow to Asheville to get my DP, I'd be questioning if the readings I'm seeing are accurate. However, I do see some anomalies that are much more easily induced with all the DP tunes than with my previous 70-HP tune or the stock tune, and I'm still trying to understand these better.

As background for my expectations, at 1200 rpm with no load, Guzzle reported measuring a positive crankcase pressure of 5" H2O with his CCV hose vented directly to the atmosphere and 7.5" H2O with the hose connected to his special canister, and Racor claims about a X4 increase from idle to WOT under full load, which would imply maximum readings of about 20" to 30" H2O.

The smallest division on my gauge is 0.5", and I can rev to 2,000 rpm in park and only see about 0.3" H2O. When I apply my US Gear exhaust brake at normal 600 rpm idle I see about 0.2" H2O, and using the fast idle setting on my DP and applying the brake I see about 0.3" H2O. Towing on the flat at 2000 rpm (65 mph in OD) I see about 0.3" H2O, and pulling a 2% grade in OD it goes up to about 0.5" H2O.

Headed north from Asheville on I-26 there are several long 6% grades, and I experimented pulling these in both 2nd and 3rd gears by starting at 2K rpm and running at WOT to 3K rpm, and then slowing down and doing it again until I reached the top. With my almost 14 K# 5er in tow, this is pretty close to a full out run on a dyno. The highest readings I saw were about 2.5" to 3" H2O, but above 2.5K the gauge would often start fluctuating rapidly as much as +/- 2" H2O or sometimes more about an average reading of 3" H2O, which complicated getting an accurate average reading. If I let off the throttle some these fluctuations diminished in amplitude, and completely stopped if I let off some more and coasted down from 3K rpm.

With a stock setting, I had to hold near WOT to get these fluctuations, in my previous 70 HP tune it took about 3/4 of WOT, and in DP 40 HP about 1/2 WOT and in DP 60 HP I could get them at less than 1/2 WOT. I'm guessing that these fluctuations are caused by spikes in combustion pressure that are leaking past the rings as blow-by into the CC, as they seem to definitely be related to the aggressiveness of fueling (and possibly timing) versus throttle position. Also, the rate of the fluctuations is about 20 Hz which is consistent with pressure spikes from each cylinder during their power strokes. At 2.5K rpm, a spike from each of 8 cylinders would give a fluctuation rate of 21 Hz. I can also induce these fluctuations with hard acceleration while running empty, and when I get the time I'm going to experiment with some different size restrictors in the hose to my CC pressure gauge to see if I can dampen the fluctuations and get some more accurate readings.

 

As always, very informative. Thanks for the post and keep it up.

 

Good info ernest.

 

I must apoligize to everyone ernest as the decimal point on the text in my webpage was misplaced.

If you look at the picture, the water manometer actually reads .5" W.C. and .75" W.C. respectfully. That would give you a max 4x of 2" to 3" W.C. at the CCV doghouse which I believe is what you experienced.

Doing a recent test, empty weight, WOT, 3000RPM pulling a 3% grade at 4500 ft altitude, I could only get a max of 1.6" W.C. at the doghouse using an actual water manometer.

Sorry for the confusion; the web page has been edited.

 

Well, I'm glad to see that the scientific method (same experiment giving same results) still works. This makes me think of the saying by Mark Twain about being careful not to die from a typographical error! I would've done a CCV mod long ago (well at least 6 months ago), but when I scaled your results at idle to WOT, I was afraid of blowing some seals that would be much more trouble to fix that reconnecting an oily boot once in awhile.

What do you think about the fluctuations I described? I guess your water manometer has enough natural damping that you don't see them. I can't tell for sure if the fluctuations are at 20 Hz implying I'm seeing spikes from all 8 cylinders, or maybe they're at 10 Hz and I'm seeing something from the injectors (or blow by past the valve seals) on just the side with my gauge. I also saw these fluctuations when I measured my OEM CCV, but they were fluctuations about an average of -5" H20, and with the CCV mod to the atmosphere, they're about an average of 2" to 3" H2O.

I just finished installing a restrictor in the vent hose from my oil cap, and it did dampen them some, but I still get them. This is a pic of my new setup Click for full size image First I tried the new nipple fitting with a much smaller hole than the angled compression fitting, and that helped only a little. Then I cut the tip off of one of my water pick tools which has a 3/64" hole, and inserted it in the hose. Even with that small hole just blowing across the oil cap with my mouth and having my wife watch the gauge caused it to bounce all over the place. I'll try inserting some kind of porous plug into the hose and see how that does for providing more damping.

 

Gene, I guess you weren't kidding about the duct tape were you?

 

 

With the manometer I did not see any fluctuations at all. As soon as the boost kicked up, the manometer came up smoothly and held solid at 1.6" until I backed off the floorboard.

I did a few other tests in the shop @ 2000 RPM with various lengths of 3/4" hose. Doghouse pressure with a 7' piece of 3/4" measured .2" @ 2000rpm; 23' of 3/4 hose yeilded .6" @ 2000rpm (Both tests were with an open hose end).

One test was done on the open road with a 7' piece of clear hose (like home depot and lowes sells.) I would advise that no one use this for CCV venting because after just a few miles, the hose was so soft from the heat, it would easily kink down and severly restrict CCV gas flow that would cause excessive backpressures.

 

If you get a chance, read again my description of the fluctuations and give me your guesstimate of what might be causing them. I'm hoping for a benign explanation so that I can stop worrying that there might be something wrong with my engine.

The above seems to imply that the flow is Laminar since the delta P is proportional to the length, and that most of the residual CC pressure is due to the pressure drop through the length of CCV hose.

I looked at just that very type of hose at a Lowes in Asheville, but thought it was too flimsy and went with the 10' length of 13/16" ID special sewer hose I already had on hand. I don't know if you read the description and saw the pics of my hose, but I ran it straight out the inverted doghouse and down the firewall in as straight a run as possible and it reached to about midway along the fuel tank. The hose is very tough, as I can't even begin to pinch it closed with my fingers and thumb, but I'll definitely keep an eye on it. I'm going keep my CC pressure gauge as a permanent feature so I should notice right away is my pressure starts increasing for whatever reason.

 

Holy duct tape hell batman!

 

I don't have a good explanation ernest other than mechanical gauges are prone to erratic readings under these type of applications. That's why most will use liquid filled gauges to dampen the shocks in fuel pressure measurements. WIth the pulsations going on in the crankcase, your readings are not alarming to me using a mehanical guage. I doubt if there is a problem there.

But such is life, it would be difficult to mount a bunch of manometers in your cab filled with water and mercury.

 

This is a pic of the final version of the fitting for my CC pressure gauge. The previous one on the oil cap required messing with the hose every time the cap was removed.

 

How did you manage to do that without duct tape???

 

Look to the left of the oil fill tube .. IC tube is wrapped with it

 

Damn that was a good one. LOL