That's a much better location than on the floor where mine is, but I already had a bunch of switches there. See if you can find additional cfm vs delta P restriction data on the 6637. I can't find it now, but some where I read that a WIX 6637 is only rated for 450 cfm max! It doesn't look from the pic like that's a compression fitting which is good, because the one Strokin used for my oil cap CC gauge leaked just a little, and I only discovered that after I switched to a one piece one and got a little higher CC pressure readings.


BTW, did you see (and agree with) my HP vs RPM curves, and how I answered your question about which engine is best. It's the lower HP, higher TQ one, which is the answer you seemed to be favoring.

Check out these links, this guy tore up the front of his nice car, all in the name of science! At least I did it to an old beat up pickup. I've got a lot of new analyses in the works on the RAM air effect, and what it means, which I'll post on the Genedad thread when it's done.

http://autospeed.drive.com.au/cms/A_0629/article.html?popularArticle Part #1

http://autospeed.drive.com.au/cms/article.html?&A=0637 Part #2

There's a godd write up on the The Dwyer Magnehelic Differential Pressure Gauge in Part #2

http://autospeed.drive.com.au/cms/article.html?&A=0646 Part #3

http://autospeed.drive.com.au/cms/article.html?&A=0652 Part #4

http://autospeed.drive.com.au/cms/article.html?&A=0663 Part #5

 

I will look those over in a few Gene. I made a run to the dump today with some pine tree trimmings. Well, some=a truckload. That gauge did move some but not enough to write home about. It looks like I am going to have to go out to a big hill and maybe even hook up the boat to really make the truck work.

Yeah, I hit about 27psi and about 3k standing on it a few times but no real hill or load, so no real workout for the truck. I might have moved it 1 1/2 on the scale at most. No real restriction.

I actually then went on to change my oil and install the Fumoto as all of that was long overdue. Trip to Smokin and dyno pulls, 11 runs on dragstrip, then 2k plus trip to New Hampshire. I am not into extended OICs and that was actually beyond mine despite having only been 4 months and only 3100 miles.

 

At 27 psi and 3000 RPM the model for my truck gives about 482 CFM, but that CFM # assumes a steady state pull that's of long enough duration for all gauges to stabilize their readings. Having a load to tow up a nice long grade helps in this regard. However, I suspect you have a leak or possibly a pinched or restricted hose. Right now, I've got my vacuum port going to the air box fitting, and the pressure port is vented to the cab in still air away from the A/C ducts etc. A quick test is to gently blow and suck on the hose at the air filter end an watch the gauge move using a mirror, or have someone watch. It doesn't take much suck or blow to hit full scale in each direction, as the gauge is plus and minus 0.54 psi full scale. I can see from your pic you got the same gauge as mine, and I can even make out the label that says the gauge can take up to 15 psi without hurting it.

For my AIS, The Donaldson filter (7.3 L AIS) at 700 CFM gives 16 inches of H2O a 482 CFM would read (482/700)16=11.0" H20 on the gauge, in the vacuum direction. With your 6637, if this Baldwin data applies...

The Baldwin filter at 350 CFM gives 5.75 inches of H2O
The Baldwin filter at 500 CFM gives 16 inches of H2O

... you should be seeing something like (482/500)16=15.4" in the vacuum direction, which is almost full scale. So there appears to be a problem some where. At 15 psi and 2400 RPM I get 351 CFM which should be 5.8" H20 on your gauge, and 8.0" on mine. I can get mine to read up to 8" or so by doing a hard WOT acceleration run in 3rd gear, and I've had it up to a about 10" towing a mountain. The 1.5" that you mentioned is what I measure in a positive direction, just due to the boost air pressure from the Genedad mod when I coast at idle in gear with the TC locked which keeps the revs up and the engine is still trying to suck some air, and if I shift to neutral and let the revs drop to 600 RPM and coast that way, I see up to 3" H20 in the pressure direction. Sitting stopped at idle, I see about 0.5" in the vacuum direction.

I'm still looking for better restriction data on both filters, as you can see from the Baldwin data above, the restriction follows somewhat a U shaped curve, so the calculations I did above need to be refined with additional data points of CFM vs restriction.

 

Ok, I read his entire article to this point and have several issues that I will not bore everyone with. My biggest concern is his observation that the gauge was responsible for 63% of his drop???? Did I read that correctly and can you explain that? The rest of his stuff does not concern me, well for now anyway.

If I were to say anything, it would be to put his MAF screens back in, at least the one in front. They are there for a reason, and that is probably a big part of his programming problem. A MAF screen is not a debris collector, it is an air straightener that is built into the programming. At least that is what I recall. Luckily, nobody here gives a darn because we don't have that.

 

My observations were not taken in third gear. This was accellerating from a stop. I did get some gauge flutter on the shift whoosh, but again, minor, I was only showing just under 2. The needle seems to move with temps which tells me the gauge is very sensitive to atmos press. By move, I mean less than .5 but still, makes me want to reset it as it is no longer at zero, and that is not running..

I did test the gauge as you described. It is working. Perhaps I installed it wrong but I hooked the hose to the low pressure port, and plugged the other. I even used teflon for a good seal. I can aussure you that there is no kink in the hose but I will relook the firewall passthrough on the grommet for a pinch. Only place it could be.

 

OK, went out there today to do some testing. 104*, 27% Hum, 63.9dew, 29.53press, like that made a difference except my tranny gauge.

Two fair sized hills in third pulling anywhere from 8-10 psi, traffic you know, never went above 1. OK, no problem, out to the interstate for a mile long hill run, in OD, what do you want, 65-70 and no real taxing of the truck and egts below 950, pulled 15psi while accellerating up that hill @3000rpms and gauge read 1.5???

Drove down road say a broke down early PSD on side of road, stopped to help, nobody with truck, hood up and leaking out front cover=bad. Got back onto interstate, floored it to get up to speed, not a hill, made 20 psi,revs were showing 2500, and only 2" water.

All this done in 60 tow setting. I must have a leak, but not finding it. Maybe I need a bigger load for the truck or the filter is not an obstruction. I was jerking this down the road:


So Gene (or anyone else) if you are quick with a few suggestions, I may go back out there, otherwise I will park the boat back under the carport as I go back to work tomorrow.

EDIT: BTW, I did test the gauge from the filter fitting side of the hose and it is quite easy to peg by mouth.

 

Tenn, you DO NOT want the other port cappped. The unused port needs to reference atmosheric pressures. BTW, If you connect to the "+" port, the reading will be on the negative scale. Pull the plug, and you will get higher readings.

 

I'm not so sure. The instructions call for leaving the hi press side vented to atmosphere and plugging the low side. Here's why, both ports low-low share the same or common feed opening. The only diff between them is where you tap with your fitting. One is for side, like I have, and the other is for a rear fitting. If I did not plug that rear fitting I would get nothing on the gauge. Does that make sense?

Anyway, thanks. I have put the boat up. I went out to look for a possible intake ducting leak but it was still 103* out there, it was parked right where the pic shows it. Underhood temps were way too high to fool with it. Sweating like a crackhead trying to tell the truth. I will put the truck under the carport and put a fan to it, look at it a little later. Miller time. Gonna go jump in the pool.

 

It has been miller time for awhile. Ahh, I see you actually do know what your doing. From your post, I thought you had either the high or low side completly blocked. Sorry I doubted you.

 

No worries, I don't think it was a matter of doubt so much as doublechecking. Again, I am still stymmied. Since it is well into Miller time, and I have not gone any further, (watched pre-season football) I will have another beer, button up the truck and head to bed. My weekend is over.

My concern is the sensitivity of that gauge. I should have showed something more. Perhaps this gauge has pointed out a major leak in my intake though I have yet to find it. The truck will not move for the next 4 days so no big deal now. I will get back to it when I get off, or during the evenings.

Until then, all input/ideas are welcome. Perhaps I need to move the pickup.

 

Maybe the filter is just more efficient than Gene thinks it should be.

 

That thought had occurred to me. The gauge does flutter slightly during the "whoosh".

 

I've been lost in Yellowstone Park for two days, and just found my way back to your thread. I spent 8 hours and several hundred miles on a tour in a Ford V10 powered bus/ snow cat vehicle, and when I get a chance I might put together a post on some things I learned about it, and on using a 203* stat at over 10K ft where H2O boils at well under 200 F!

My gauge had 4 ports on the back side, 2 P's and 2 V's. I installed the 2 plugs (using thread sealant) that were provided in the kit in the 1 P and 1 V port that I didn't use. What I did was to use a P port to detect the vacuum restriction, and a V port to detect RAM air pressure along with any pressure puffed back out of the turbo inlet that might occur during a surge or a whoosh. The ONLY reason I did mine this way is so my needle will move toward the right hand side of the gauge for vacuum (where I can see it better for measuring CFM), and to the left hand side when measuring pressure.

Note, that air flows through the gauge when a differential pressure exists between the ports, and it will be sucking a tiny flow of air into the vented port when the other port is hooked to the vacuum on your turbo inlet. To make sure no dust is sucked into the gauge, I inserted a VERY loose ball of cotton into the vented port. I did tests with and without this cotton ball just to make sure it provided a negligible restriction.

You should NEVER have to re-center the gauge as a function of changing temp or changing atmospheric air pressure. If your hose isn't restricted or your vented port clogged, both ports respond to changes equally, and the gauge should always read 0, unless a difference pressure occurs between the two ports. I emailed how I accidentally turned mine into a barometer when the hose got pinched in my air box lid.

Even if your 6637 had 0 restriction, at high CFM there's a measurable pressure drop across the inlet tube to the turbo itself, as the guy in the link found when he took measurements in three different locations. I'm not sure what the inches H20 restriction is for just the inlet tube (with no filter) for our trucks, but one could tap into the tube at the filter box end and at the turbo inlet end, and use the differential gauge with one port at each location to find out, all in the name of good science of course.

 

Thats funny!!!!!!!

 

Well Gene, except for the cotton stuff, that reply was of little assistance to me in figuring this out. I am certain that the gauge should be showing me more. I will likely be moving the tap to another location, and testing again

One other thought, my hose is about 10' long. I wouldn't think that makes any difference, but at this point I am reaching. It is not pinched at the firewall, as I have checked. Other than that, gonna move the darn source tap.

I just cannot believe that at 20psi of boost that the silly thing is only showing 2". That gauge is trying to tell me something, and I'm going to find out what it is. Maybe it is telling me that my filter is working better than we expected.