Tony

Any use one of these...any input?
Im going to get one to check for intake restriction from my filter to the inlet lobes of my Supercharger. I think my intake is choking a bit at the higher airlfows.

http://www.dwyer-inst.com/Products/P...ame=Highlights

atb

I don't get it Tony, why on earth would you need one of those anyway?

hacker-pschorr

Excellent idea - another somewhat simple test most people skip over (including measuring intake temperature and exhaust pressure).

Keep up the excellent work Tony. Cannot wait to see the results.

dr bob

Tony, the science is critical in how you measure the pressure drops. Any probes will be in flow areas, so alignment and size and profile will all affect the readings. I'm not saying it's not worth a shot, just suggesting that you take measurements at several places, and ad a few grains of salt to your results.

If you don't already have one of those gauges in your toolbox I can share one with you.

Tony

Thanks for the offer Bob! Ill probably pick one up any way. Im really not out to split the atom with it, im just curious to see if there is too much of a pressure drop at WOT across my intake. Actually, im not sure what to expect but I think there is. After the boost pegs immediately it tapers off noticabley as the rpm builds. When i check under the hood there is ZERO evidence of belt slip...unless my new gatorback belt is somehow "dustless". I have never ran this brand before. Im more interested in seeing if there is a restriction then having an accurate device to measure any improvements i can make to the setup if needed.

Tony

You know how it is Adam!
need to be be prepared for all enimies foreign and domestic...

oh how Id love to have TT like that ..in silver of course

Z

I have one of the Dwyer gauges that looks like the one pictured, only the measurement range is 0-25 inches of water. It doesn't take too much for the gauge to hit it's maximum, so I have a different vacuum/pressure gauge that I end up using more often for various things. If that one isn't sensitive enough or doesn't have a small enough resolution, I go to the Dwyer gauge. The LMA-3 is also handy for meauring and logging various things by just connecting a length of tubing from what it is you want to measure to it's vacuum/pressure port.

There are two ports on the Dwyer gauge. One is for pressure and the other for vacuum. The gauge measures the differential between the two ports. If you want to measure the pressure difference across something like an air filter, the best way to do it is to connect one port to each side of the filter. If you only connect the vacuum port to the back side of the filter, and leave the other port of the gauge just open, you'll be measuring relative to the pressure of where the gauge is. The pressure where the open port of the gauge is may be different than what the pressure on the front side of the filter is, so you might end up with an inaccurate or misleading reading. If you have the gauge in the car while doing full throttle runs, that's exactly what's going to happen, because the pressure in the moving car will be different than the pressure directly ahead of the filter.

Tony

As usual, good stuff. I guess my plan is to have one port in the filter...the other at the inlet plenum to the supercharger. Along this path the air goes through the filter...makes a 90' turn in a tube...to a straight section...to the MAF..to the throttle...to the SC plenum. My plenum is VERY basic compared ot what DR has. The air goes in and then just gets sucked into the supercharher...there is nothing in side to guide it. (somehting i am goign to look into eventually) It litterally goes in...hits a wall and has to turn a sharp 90 to the rotor inlet.....I know it can be done better (see DR's setup) but it would be one of those slippery slopes you know....one thing leads to somehting else and all of a sudden i have a 4 inch pipe on Ford 104mm throttle body and a MAF sensor in a 4 inch PVC pipe

So i will need one that goes upto 25 to 30 inches of water then?

Its an annoying read but this is an artcle a guy did on an Audi S4
http://autospeed.com/cms/A_109217/ar...popularArticle

Z

Since you probably have no idea of how much of a restriction there is, you really won't know which the best gauge would be until after you've measured it. I'd just use what you already have initially, like the the LMA-3, to at least maybe give you an idea of where you're at.

Set the LMA-3 channel #4 to function #1, and it will be a one bar MAP sensor. That will give you better resolution than the way you have it set to measure your boost now. Connect a hose from your test point to the LMA-3 port, and it will measure relative to an absolute vacuum, so won't be affected by changes in pressure inside the car while testing, like the Dwyer gauge would be if you only had one of it's ports connected. Selecting the units of measure to something like kPa instead of PSI when you configure the channel in Logworks could help give better resolution too. The lower the reading, the lower the pressure, and the greater the restriction up to that point. Take a reading with the engine off, to give you a value for what zero restriction would be that you can reference to.

Don't be surprised if your restriction is way, way higher than any of the numbers mentioned in that article you linked to.

SharkSkin

If you end up with a gauge that pegs full scale in your test, you can add a needle valve to one port or the other to compensate and bring the differential into range. Since all you seem to be after is a set of relative readings to find the restriction, this should work well enough.

Louie928

Good plan Tony. I don't know about the max range of the gauge though. I use an airspeed instrument to do about the same thing. It measures the pressure differential between the pitot and static ports. When you insert the pressure probes in the intake system, you need to use probes that won't respond to the air velocity. That's a static probe. Use a closed ended tube with small holes in the side of the tube arranged every 90 deg around the circumference. There are intake losses for sure. The inlet to the TS isn't good, but I'm not sure if a basic pressure measurement would show much of the loss there. It's more of a flow, turbulence, thing. I do know that the difference between Andy's cone K&N filter at the inlet to the MAF and the larger intake I used with smooth flow into the MAF with the stock 928 air filter gave 15 hp more on Jim's car.

I noticed a boost reduction at the upper end of the RPM range on Jim's car too. I think the peak boost was around 4500 or 5000 rpm. I took that to be a reduction in the pump efficiency at higher rpm. Could be some from flow problems too. I sure don't know for sure. The positive displacement SC behaves completely different than a centrifugal which keeps making more boost as the rpm goes higher.

mark kibort

just get a real sunx sensor. much more accurate and a wider range.
you are only going to 15" of water? 14.7psi , 1 bar is 29" of mercury. I forgot how many FEET of water that is . I think I remember it being 30+ feet!

This is a picture of it running 9psi measurement. Its a gauge with a very accurate range of +/- 1 bar. (ie 14.7psi positive and negative, vacuum/pressure)

Ive used it for measuring body air flow at different sensing spots, intake air pressure based on ram, and wing pressure values at speed.

www.sunx.com
http://pewa.panasonic.com/acsd/sunx-...oducts/dp5.php

DPH-A07 Compound Pressure -14.7 14.7 M5 Male Thread Gauge Non-Corrosive Gas
DPH-A17 Compound Pressure -14.7 14.7 R(PT) 1/8 Male + M5 Female Threads Gauge Non-Corrosive Gas
DPH-A27 Compound Pressure -14.7 14.7 NPT 1/8 Male + 10-32UNF Female Threads Gauge Non-Corrosive Gas



mk