Home made barometer?

[mashaffer]

Anyone ever make a home made barometer to measure pressure at the cowl v.s. radiator at speed? might be interesting.

[GM_Guy]

Already been done by the pro's. TLDR version: Ain't going to make a lick of difference until you hit nearly triple digit speeds when the airflow will actually start affecting things. In the case of "ram air", 70mph was the magic number where air would actually start having a ram effect.
Googling things like hood scoop tests, cowl induction hood test, ram air test, along with Hot Rod, Car Craft, Hi Performance Chevy, Popular Hot Rodding and any other main magazine of the 70's, 80's and 90's.

Mother Mopar did a lot of test on hood scoops, the 6 pack hood scoop was the one that actually did something vs the other variations, which where more cosmetic than functional. 6 pack scoop being the one whose opening was an inch or two higher than the hood should get you some info.

Main thing to keep in mind with anything dealing with cowl induction or scoops is they = water into the engine bay, and dripping all over your ignition system.

Alex.

[gadget73]

Manometers are dirt simple. Its a U shaped length of tube with water in it. The difference between the height of water in one tube vs the other is the pressure in inches of water. You can make one out of clear plastic tubing, and add a bit of food color to the water for contrast if you'd like. Not the most convenient device in the world, but its an extremely accurate and inexpensive way of comparing pressures. Just make sure you mark it before trying to use it. Attempting to operate a tape measure to figure the pressure while driving is probably not a wise idea.

[sly]

The redneck ram air on my 88 takes affect on the vacuum system of the car at 60mph (vacuum starts to drop out). Lower speed if in a head wind. (drops below what is needed for the vent actuators that is) Not sure exactly since I don't have a vacuum gauge. Would be interesting to see what the baro readings would actually be on that intake vs under the hood. Maybe I'll install some meters one of these days for giggles. Sparkfun or Adafruit probably have something useful.

[gadget73]

just have to watch sensitivity. I suspect you'll need readings in inches water column vs inches mercury to get enough resolution. You'd also want either a differential sensor, or a pair of them and a means of doing the math to figure out the differential.

[sly]

Right now, I probably just need a vacuum gauge on my dash to see if it really comes up from -17inHg at cruise like I think it's doing. But yeah... I'd love to put all kinds of sensors all over the place to read random data for giggles.

[gadget73]

I thought about fitting something to read the air temperature of what gets sucked past the air filter. I've got that temp sensor in the box that does nothing. No reason to actually do that, and I don't think it would tell me anything useful, but maybe if I decided I needed to know what the rise in temperature was between the MAF inlet and the lower intake I could work that out. Or I could continue ignoring instruments like I do most of the time.

[knucklehead0202]

I occasionally think I'd like gauges to monitor everything but the more I look at it, I don't want to muddy up my classy dash with a bunch of bullshit. Long as no idiot lights are on and no funny noises, I'm happy and that's the way I plan to keep it. May get a tasteful tach, one of those kinda old-school full-sweep numbers. That way it matches the speedo, sort of.

[sly]

oh... it would be for datalogging and looking at later (except for maybe a vacuum gauge) as far as I'm concerned.