I'm wondering what (if any) benefits there are to installing a vacuum guage. Has anyone installed one (Lightning's not included)?

I thought in the olden days, a vacuum guage gave you an indication of the mileage (MPG) your vehicle was getting. Is this still the case?


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1998 F-150 XLT 4x4 SC/SB 4.6L, Auto., 3.55LS, TTP, blah, blah, blah
All the info is at http://www.fordf150.net

 

Kelly,
I recently installed a vacuum/boost gauge on my truck to check for boost out of a supercharger (of which I had none). Don't really know or remember how to use it to check mileage. Got mine from Summit for $38, I think (an Autometer). A vacuum only gauge would probably be a good bit cheaper. Good luck!

 

Well I bought an Equus vacuum gauge. Here's some insight on how to "read" it: http://www.ghg.net/fastlaw/vacuum.html

The problem know is that I can't figure out which hose I need to tap into. Which one is the intake manifold vacuum line???


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1998 F-150 XLT 4x4 SC/SB 4.6L, Auto., 3.55LS, TTP, blah, blah, blah
All the info is at http://www.fordf150.net

 

HI!... KELLY : I insalled a small AUTOMETER vacuum guage in my engine compartment, just to see what kind of vacuum my truck was running. MAN! It's high. I rum about 25-26 at idle! Most of the other vehicles I have had had about 9-12. I taped my guage right into the vacuum hose coming out of thr top of the TB elbow. Hope this helps you out.

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NEAL " THE H.P FREAK" E-MAIL :nnewman@sympatico.ca
'99' F-150 XLT SPORT, oxford white, reg cab shortbox stepside,5.4, auto, 4.10L.S, captain's chairs, bedliner, GTS carbon fiber headlight covers, ***** CEPECK clear halogen driving lights, GTS slotted tailight covers (painted oxford white), fiberglass smooth wiper cowl (painted OXFORD WHITE), FORD locking lug nuts, tinted windows,true duel exhaust with 2.5 inch mandrel bent pipes and FLOWMASTER 3 chamber mufflers with 3' tailpipes exiting before the rear wheel like the LIGHTNING, HELLWIG rear stabalizer bar, 3 AUTOMETER guage pods, filled with tranny temp, engine temp, and oil preasure AUTOMETER "PHANTOM" guages,custom fabricated air intake trac and huge K/N filter, TPS mod, BELLTECH 2-inch rear drop, custom programed SUPERCHIP "FLIP-CHIP", BAUMANN ENGINEERING shift kit (on stage 5 setting)BYPASS CLUTCH CONTROL VALVE/PREASURE REGULATOR VALVE, ASP POWER PULLEYS, custom tig welded and ported JBA "JET BLACK coated headers, twin DERALE 16 INCH ELECTRIC FANS, PERMA COOL 14"/10" tranny cooler with 10" electric fan, PERMA-COOL external tranny filter, custom ported (STOCK) throttle body, custom digital air intake temp sensor, custom ported TB intake elbow, relocated ATS, FORD RACING 24LB injectors, RUSSELL stainless steel braided tranny lines with fittings.


FUTURE MODS : BBK 75MM THROTTLE BODY, 80MM PRO-M MASS AIR METER, AADI F1 RAM AIR HOOD WITH CUSTOM FABRICATED RAM AIR SET-UP, CAL-TRAC TRACTION BARS, EXTRUDE HONED INTAKE MANIFOLD, SHM CUSTOM FUEL RAILS, 90/10 FRONT CE SHOCKS, 70/30 REAR CE SHOCKS, BELL TECH 2/4 DROP, EXPEDITION CENTER CONSOLE, HARLEY DAVISON F-150 LOWER FRONT VALANCE (painted oxford white) and a KENNE BELL BLOWZILLA SUPERCHARGER.

ESTIMATED H.P TO DATE : 340H.P / 425ft/lbs of torque.

CURRENT PERFORMANCE : 1/4 MILE - 14.52E.T * MPH - 93.73 * 0-60MPH - 5.8 * 1/8 MILE - 9.2 * 60 FT - 2.0

OTHER TOYS : "83" PRO STREET FORD RANGER : 351-w stroked to 408c.i 625H.P (natural), 875H.P with 250H.P "BIG SHOT" N.O.S kit, tubbed (crome moly tubing), 12 point chrome moly roll cage, 4-link with coil overs, MUSTANG II front suspension, c-4 tranny (race prepped), 4000rpm stall converter(8 INCH), 3" chrome moly driveshaft,AUTOMETER guages, 16.50 MICKEY THOMPSON rear tires, 4" M/T front tires, CENTERLINE CON-VO PRO rims, fiberglass hood - bumper - prostock hood scoop, wishbone trac-link, two chrome moly driveshaft loops, 16 gallon JAZ fuel cell,etc

 

Hi Neal,

Thanks for the reply. I found a vacuum hose behind the battery. I know you should tap into the the vacuum hose as close to the intake as possible, but that's the best I could do.

I mounted the guage on the panel to the immediate right of the steering column. It is flush mounted, and I think it looks like it came from the factory. I'll try to post a picture as soon as I can borrow the digital camera from work.

Anyway, here are some readings I got from it (all measurements in Inches of Mercury - IN/Hg). The truck was empty:
================================================== ===========
Idle: steady 19
Cruising at 100km/h (60mp/h) with light wind behind me:
11-12 in overdrive (1900rpm)
15 in 3rd gear (2700rpm)
Cruising at 100km/h (60mp/h) against light wind:
8-9 in overdrive (1900rpm)
13 in 3rd gear (2700rpm)

So this is how I'm interpreting these results. Please let me know if I'm right or wrong:
1. The higher the vacuum level, the better the fuel efficiency.
2. In my tests, On a long trip, I would get better fuel economy in 3rd gear (even though the rpm's are higher).

Thanks.


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1998 F-150 XLT 4x4 SC/SB 4.6L, Auto., 3.55LS, TTP, blah, blah, blah
All the info is at http://www.fordf150.net


[This message has been edited by Kelly (edited 05-17-2001).]

 

I installed the gauge, and was careful on how I drove. I drove light-footed and kept an eye on the gauge. I tried to not step on it too hard or have the manifold pressure drop below 10 inches of vacuum. I got 14.0MPG in all city driving! I normally get 10 to 13, so getting 14 is pretty good.... considering all it cost me was a 1/2 hour to install the gauge, and then some patience on the road. The MPG rating for my truck is about 13.3MPG, so I'm actually doing better than a (stock) F-150 similar to mine should get.

If I can keep this up, maybe I'll even throw my Superchip back in and drive nice. Oh wait, I don't think it's possible to drive nice with a Superchip in <evil grin>.

Here's a picture of the gauge installed behind the shift lever, flush in the dash. I think it looks like it came from the factory in there.



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1998 F-150 XLT 4x4 SC/SB 4.6L, Auto., 3.55LS, TTP, etc.
All the info is at http://www.fordf150.net

[This message has been edited by Kelly (edited 06-07-2001).]

 

Man, I HAVE to do this mod. tomorrow!!! Where should I look for a guage, and how much are they? Would anyone care to give step by step instructions from start to finish? How would you "tap" into the vaccume lines, and where would be the ideal place? Thanks!!!

-AR

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2001 F-150 XLT 4x4 Off-Road, SuperCab, Flareside, Black[*] 4.6L Triton V8 HPI[*] 5 Speed / 3:55 Reg. Axle[*] Keyless[*] Premium Audio CD

Mods:[*] K&N Intake (Chopped Airbox)[*] Removed Elbow Silencer[*] 3" Cat-Back (No Muffler, Turn-Down)[*] Cranked Torsion Bars[*] APC XENON PLASMA Super Whites[*] '01 "L" Taillights[*] Bugshield[*] Bedliner[*] Ventshades[*] Taillight Covers (Slotted)[*] Removed Mudflaps[*] "Light Argent" 4x4 Off-Road Decals

Audio:[*] Clarion 6675[*] Rockford Fosgate 5x7's[*] Rockford Fosgate G360A2 Punch Amp[*] JL 12W3-D2 (Ported)[*]Viper 500 Alarm

Build Date: 8/23/00 (Kansas City Plant)

 

Hi Jackal,

You can get the gauge from most aftermarket parts stores. It would likely run you around $30.

The installation itself is pretty easy. All the parts you need are included with the gauge (at least, the one I bought did). It came with the hose, and the Tee. You just use that tee to tap into an existing vacuum line. The fun part is finding the right line. What I did was connect the gauge up to different hoses until I found the right one. THEN I ran the hose back through the firewall in front of the driver's seat, and mounted the gauge in the dash. I used a 2" hole saw to make that cut you see.

It is recommended that you tap into the vacuum line as close as possible to the intake manifold. I followed the hoses out of the intake manifold, and found a vacuum block behind the battery (had to take the battery out), and just tried each hose until it worked. You can test the right hose by hooking up the gauge and starting the engine. If it goes up to 19-21 inches of vacuum, and if you rev the engine, it drops & comes back up, that's the hose you want.

I don't have any pictures, and I'm leaving town tomorrow otherwise I could get you some. When I'm back in a week and a half, I could try to get some pictures of the rest of the installation (vacuum tee, firewall grommet, etc.).

Hope this helps. Feel free to reply to this or send me an e-mail for more info. (My e-mail address can be found by using the link in my sig. I don't post it here because of spammers).

Regards.

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1998 F-150 XLT 4x4 SC/SB 4.6L, Auto., 3.55LS, TTP, etc.
All the info is at http://www.fordf150.net

 

Another nice benifit of a vacuum gauge is as a diagnostic tool. Low vacuum reading would indicate a leak in the intake manifold or a well used engine. A guage that has a needle which pules can indicate a weak cylinder. Its great to use when shopping for a used car. The guage is small and easy to attach for a quick reading. It will help in evaluating the condition of the engine.

 

Awesome...thanks guys. So you cut an existing line, and use a "T" to splice in? What does this vaccume do? Wouldn't splicing in take away from it's original task?

-AR

 

Hey, Neal, I figured out why yours runs so high... it's a metric gauge. People that run english gauges can pull no more than 14.7 PSI of vacuum (Not possible to have any more than that above sea level). Your gauge is calibrated in kPa or kilo-pascals which is one kilo-Newton per square meter.

14.7 psi = 101.352 kN/square meter (the yellow numbers)

The other side is Inches of Mercury (another pressure scale).
14.7 psi = 29.92 in Hg.

That's why everyone else is running so low... they're running psi, you're looking at in Hg... not the same scale.

Now, if they are running the same gauge, but you have a higher vacuum reading, it means that they have less of a pressure difference between the ambient pressure and the gauge pressure. Assuming they are mounted in the same place in the vacuum system, the lower reading has less restriction in the intake. The higher the restriction, the higher the vacuum reading. (actually, the higher the restriction, the more negative the pressure down-stream is, but it's the way the gauge is calibrated.)

That's why, at idle, a supercharged engine will have negative pressure (i.e. vacuum) and at WOT, it will have positive pressure. However, a normally aspirated engine will also read negative at idle, and will never quite reach zero at WOT due to flow restrictions up-stream of the reading point.

Sorry for the long-winded nature of this post... just thought I might clear up some of the confusion.

-Joe-




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98 Explorer (Lemon Law Case in Progress)

'00 F-150, X-cab, 4x4, Lariat, Off-road, Trailer Tow, Holandia Sunroof($1000), built 11/99 picked up 10/00!Clear Corners($36), Manik Stainless Steel 1-piece brush guard($700), Custom CB wiring, Uniden PC76-XLW CB radio($100) with K-40 Magna-Mount antenna (for now [$40]), 1 set of 165 watt KC Daylighters (for now... more on the way... $140) Fog Light Switch mod(free!!!), Custom switch mounting plate and overhead console, Bully Stainless Steel Trailer hitch drawbar w/ 2" stainless steel ball($80), Gray Tek Style Soft Tonneau Cover($250), Gray Line-X Bedliner ($450).
List of planned mods: Clear tails, torsion bar tweak, bug deflector, Chrome ORP rims.
93 Probe GT teal, OE rims painted to match, bone stock drivetrain, leaky exhaust.

 

"Clear it up"? HA!!! Now I'm really confused!!!

-AR

 

GIJoeCam,

FYI, my gauge also reads in InHG. And it now seems to idle anywhere from 20 to 21, but steadily (it doesn't fluctuate at idle).


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1998 F-150 XLT 4x4 SC/SB 4.6L, Auto., 3.55LS, TTP, etc.
All the info is at http://www.fordf150.net