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  #11  
Old 08-04-2014, 02:25 AM
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Just so were all on the same page here, this is my most recent cut to the hood vents:
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While my first cut that Jim pictured in post #2 probably had a greater low pressure zone at the vent, the newer opening should allow for more airflow, but likely has no low pressure zone.
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  #12  
Old 08-04-2014, 02:34 AM
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Originally Posted by vette427sbc View Post
Just so were all on the same page here, this is my most recent cut to the hood vents:
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While my first cut that Jim pictured in post #2 probably had a greater low pressure zone at the vent, the newer opening should allow for more airflow, but likely has no low pressure zone.
I like the design of the screen. What is it, and how are you attaching it?
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  #13  
Old 08-04-2014, 03:38 PM
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While my first cut that Jim pictured in post #2 probably had a greater low pressure zone at the vent, the newer opening should allow for more airflow, but likely has no low pressure zone.
Looks good.
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  #14  
Old 08-04-2014, 04:16 PM
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What's the story on those hood latches? I've never seen any quite like them.
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  #15  
Old 08-04-2014, 11:58 PM
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so does the tube connect to the gauge at both ends and then as it gets squeezed produce a movement on the meter? I guess I have to do some reading up on this it sounds interesting.



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Nice set up.
I wonder how many of us "aero-kooks" have a Magnehelic Gauge?
[should we ask for a show of hands?]
Just a few questions, if I may:
Are you using a multi-tube setup, and pulling "taps" or reset/retape after each run?
Have a recorder with you to take data?
Or, using a camera?

Just a few things I've been thinking about as I get closer.

Cheers - Jim
I'm just a one man, low budget operation. I've got a couple of ten foot lengths of tubing (plugged into the Magnehelic) that I move around and tape onto body locations or plug into pressure/vacuum taps. No data recorder or anything, I just take a glance at the gauge(s) during the long straights on test & tune track days. Would be nice to have a printout of pressure versus speed or RPM, but I'm happy to just get whatever info I can however I can.
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Old 08-05-2014, 01:34 AM
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so does the tube connect to the gauge at both ends and then as it gets squeezed produce a movement on the meter? I guess I have to do some reading up on this it sounds interesting.
............................
I'm not sure I understand your question (but I'll throw out a response). The Magnehelic gauge is a differential pressure gauge. It just gives you a reading of the difference in pressure between the two ports in the back of the gauge. I hook up a couple hoses to the two ports (and say, tape one hose to the top of the hood, and the other hose to the bottom of the hood)and I can then measure the difference in air pressure between the top and bottom surface of the hood. I can also do this to check the pressure drop across an air filter, or the pressure drop across the carburetor at WOT, or any of a number of other things.
If you leave one gauge port open (to atmospheric pressure), then the gauge just acts like a common gauge where the reading is gauge pressure (as opposed to differential pressure or absolute pressure).
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Old 08-08-2014, 11:13 AM
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Here is another question, if I may:
Are you using/getting full swing on the 4.0 gauge- or way less? Haven't tried mine yet - its a 1.0 full scale.

I note there are a lot of digital versions on eBay for about 30 bucks. Some with data hold. Could be nice for a one man operation - or use a "voice" recorder to "announce your data". I'm sure Pappy will recall that "method."

Quote:
I'm just a one man, low budget operation. I've got a couple of ten foot lengths of tubing (plugged into the Magnehelic) that I move around and tape onto body locations or plug into pressure/vacuum taps. No data recorder or anything, I just take a glance at the gauge(s) during the long straights on test & tune track days. Would be nice to have a printout of pressure versus speed or RPM, but I'm happy to just get whatever info I can however I can.
BTW - I've added a few more of Simon McBeath articles in the Chassis/Suspension Downloads section for those interested. These are from "Aerobytes" in Racecar Engineering. More to follow.

Cheers - Jim
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  #18  
Old 08-08-2014, 01:39 PM
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Default Magnahelic gauges

Quick point on your Magnahelic; these gauges are designed to operate in the vertical position. With yours in the passenger footwell at nearly horizontal the operation and calibration may be affected.
Very good gauges though. Being a pesky European, I like mine in Pascals.
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  #19  
Old 08-08-2014, 03:13 PM
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Originally Posted by Blue Juice View Post
Quick point on your Magnahelic; these gauges are designed to operate in the vertical position. With yours in the passenger footwell at nearly horizontal the operation and calibration may be affected.
Very good gauges though. Being a pesky European, I like mine in Pascals.
Thanks for the advice. I greatly appreciate it. I had it angled so that I could see it while I was driving, but I'll make a change to the bracket.

In most of my career I was using Pascals (kPa) for engine test load points and calibrations, but now that I'm retired, for some reason, I tend to gravitate towards the old English and American units of measure.
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  #20  
Old 08-08-2014, 03:22 PM
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Quote:
Originally Posted by phantomjock View Post
Here is another question, if I may:
Are you using/getting full swing on the 4.0 gauge- or way less? Haven't tried mine yet - its a 1.0 full scale.

I note there are a lot of digital versions on eBay for about 30 bucks. Some with data hold. Could be nice for a one man operation - or use a "voice" recorder to "announce your data". I'm sure Pappy will recall that "method."

Quote:
I'm just a one man, low budget operation. I've got a couple of ten foot lengths of tubing (plugged into the Magnehelic) that I move around and tape onto body locations or plug into pressure/vacuum taps. No data recorder or anything, I just take a glance at the gauge(s) during the long straights on test & tune track days. Would be nice to have a printout of pressure versus speed or RPM, but I'm happy to just get whatever info I can however I can.
BTW - I've added a few more of Simon McBeath articles in the Chassis/Suspension Downloads section for those interested. These are from "Aerobytes" in Racecar Engineering. More to follow.

Cheers - Jim
This Magnelic gauge is a 0-40 inches H2O (about 1.5 psi). Measuring different exhaust system backpressures will move the dial significantly, while measuring air filter pressure drops don't cause much movement at all. I still need to measure my carb pressure drop at WOT to see what numbers I get.

I gotta check out those digital meters you mentioned. They sound rather interesting.
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