Go Back   EcoModder Forum > EcoModding > Instrumentation
Register Now
 Register Now
 

Reply  Post New Thread
 
Submit Tools LinkBack Thread Tools
Old 05-03-2010, 01:31 PM   #1 (permalink)
Banned
 
Join Date: Feb 2008
Location: maine
Posts: 758

oldscoob - '87 subaru wagon gl/dr
90 day: 47.06 mpg (US)
Thanks: 21
Thanked 18 Times in 14 Posts
my primitive vac guage

I glanced over at my pile of junk and spotted the hand controlled vacuum pump, I kept it to bleed brakes.

on the top was a guage... I did not need it to pump brakes. Moving guage by hand something was sticking and I took it apart to clean. here is what it looks like (simply wanted to share). I calibrated it back to zero, and will use it soon enough. I have never checked my old sube, but do remember a comment on the carb versions, having one of the highest readings ever..will find out soon enough.


that copper flat curve seems to be an airtight channel, it responds to vacuum pressure...


and this is where it shows a reading.

cheap.. and now have two useful tools from one.

maybe get an LED light in there somehow, run a hardline into the car. so I can monitor...


Last edited by bgd73; 05-03-2010 at 02:00 PM..
  Reply With Quote
Alt Today
Popular topics

Other popular topics in this forum...

   
Old 05-03-2010, 01:59 PM   #2 (permalink)
Banned
 
Join Date: Feb 2008
Location: maine
Posts: 758

oldscoob - '87 subaru wagon gl/dr
90 day: 47.06 mpg (US)
Thanks: 21
Thanked 18 Times in 14 Posts
here is the readings for a 1987 carbed subaru



250 rpm (not 2500.. this is really 250, and even less)



this is maximum, 22 in Hg of vacuum. I first saw this in the 80s.. waddya know, it is still there. Super Stoich... gotta love the real thing

and on another note, one to learn safe max psi for boost for an old sube, can learn it from converting inches of mercury to psi (psi because I am american)

22*.4912=10.8064 psi
In the little sube world I am in, this was a safe rule of thumb I never got to. (never ran a turbo)
and 10.8 psi is .744 bar
interesting.
of course today and boost and max is like a crack addiction to many, but above is the rule I would follow...I never learned if that worked, but it sounded smart enough. Simply to stay safe within oem mechanical setups.

Last edited by bgd73; 05-03-2010 at 02:20 PM..
  Reply With Quote
Old 05-03-2010, 09:36 PM   #3 (permalink)
Master Novice
 
elhigh's Avatar
 
Join Date: Jan 2008
Location: SE USA - East Tennessee
Posts: 2,314

Josie - '87 Toyota Pickup
90 day: 40.02 mpg (US)

Felicia - '09 Toyota Prius Base
90 day: 49.01 mpg (US)
Thanks: 427
Thanked 616 Times in 450 Posts
That's about where my Toyota 22r idles - inches Hg, not revs. 250rpm? Srsly?

Dang.
__________________




Lead or follow. Either is fine.
  Reply With Quote
Old 05-03-2010, 11:57 PM   #4 (permalink)
Master EcoModder
 
mwebb's Avatar
 
Join Date: Jul 2009
Location: New York
Posts: 513

no nickname , it's just a car - '04 volkswagen golf tdi
Thanks: 2
Thanked 101 Times in 74 Posts
at idle ,intake vacuum flutter is bad .

at hot idle
any flutter in the vacuum gauge needle is bad

it may be related to the engine speed of 250 rpm ?

retest ;
at around 700 rpm , if there is still flutter you have a valve sealing problem

does your car have EGR ? if yes , have a look with your eyeballs and make sure it opens around 2k rpm , if it does , your intake vacuum should be
lower than 22"
if EGR does open , your passages are clogged .
disregard this if you do not have EGR

and quick quick
translation of inches of mercury to PSI is 2 to 1
30"hg = 15psi , more or less so
15"hg = 7.5 psi more or less
  Reply With Quote
Old 05-05-2010, 02:52 AM   #5 (permalink)
Banned
 
Join Date: Feb 2008
Location: maine
Posts: 758

oldscoob - '87 subaru wagon gl/dr
90 day: 47.06 mpg (US)
Thanks: 21
Thanked 18 Times in 14 Posts
Quote:
Originally Posted by elhigh View Post
That's about where my Toyota 22r idles - inches Hg, not revs. 250rpm? Srsly?

Dang.
I can't keep it there because of a common alternator, but in the summer, during the day, it is quite alright (the lights dim below 500 rpm)
it is a HUGE fuel save on the old carb.

I only got a quick read on specs typical throughout downdraft vac readings, (all cars) 22 inches HG is a maximum typical for gassers. I do not know what happens beyond that.

Getting too much could be as bad as not enough for the range of stoichial decency. 22 is the high end.
  Reply With Quote
Old 05-09-2010, 10:26 PM   #6 (permalink)
Master EcoModder
 
mwebb's Avatar
 
Join Date: Jul 2009
Location: New York
Posts: 513

no nickname , it's just a car - '04 volkswagen golf tdi
Thanks: 2
Thanked 101 Times in 74 Posts
intake vacuum flutter is bad at any rpm


expect
18 to 21 " at hot idle
18 to 22" at 2k rpm
18" with EGR open
22" with no EGR or EGR not open

0" at WOT 25" at decel following WOT snap .

but
the single most important intake vacuum measured value is
steadiness / smoothness , if there is flutter in the intake vacuum
you have a leaking valve and that is never good

sometimes
at low RPM valve overlap will cause flutter
so
what is your intake vacuum value at 750 rpm , is there flutter or is it smooth
the answer
will let you know if your engine has problems , or not .

  Reply With Quote
Reply  Post New Thread


Thread Tools


Similar Threads
Thread Thread Starter Forum Replies Last Post
Scanguage IGN guage, what is good? 40 either is really bad or really good rmay635703 Instrumentation 20 02-06-2010 10:39 AM
Priorities: RPMs vs VAC luvit Instrumentation 47 02-05-2010 08:36 AM
Any advice for driving by vacuum guage? video Chris D. Instrumentation 33 02-21-2009 11:54 PM
97 ranger not compatible with scan guage easy Instrumentation 6 02-15-2009 12:02 AM
09 corolla scan guage results mercury7 General Efficiency Discussion 6 08-29-2008 12:20 PM



Powered by vBulletin® Version 3.8.11
Copyright ©2000 - 2024, vBulletin Solutions Inc.
Content Relevant URLs by vBSEO 3.5.2
All content copyright EcoModder.com