I was driving home tonight. Flat road, 75 mph, 5th gear, cruise control, lights on. Vacuum held at 10 solid. Just wondering if that's what every-ones car does?

 

It should be around 14-15 at idle on a stock motor.

 

I have a street port and my vacuum today at 900rpm idle was 13

 

Yeah, that's about what I get at a 75-80mph cruise (10in). At idle I'm between 14-16in. vacuum, depending on how warm the engine is/idle speed.

 

my defi gauge reads between 18-20hg at 900rpms

peter farrell ecu reads 21-23hg at 900

reman, 3in dp intakes

 

My boost gauge reads about 18inHg and about 450-460mmHg on the PFC, at about 750rpms.

 

vacuum changes with the throttle plates, adam c, so asking everyone what their vacuum is during cruising is a very relative and broad question: relative to how far they have the gas pedal pressed down.
i guess if the cruise control is on at 75mph everyone is going to have around 10 inHg on flat pavement at 75mph. lol.

FWIW, my vacuum at idle (850-900rpm) is about 17inHg.

 

Idle vacuum also changes depending on how high your idle is set. My idle is around 600 rpm (I know it's a little low), and vacuum at about 12.

However, this thread wasn't asking about idle vacuum. More curious about cruising speeds.

 

yeah but i'm saying thats going to change with wind, incline of the road, etc.

i was just being difficult, they'll all be around 10.

 

large street port, my vacuum reads around 8-10 @ idle.

 

I have a Dirt Devil Extreme Carpet Cleaner. Has the wand attachment and everything.

Had to throw that in there...

Level surface and 75ish, 10 inches sounds about right. Fun experiment - draft a large semi, and your vacuum will increase, as you need less load to push the car through the air. The more vacuum you're pulling, in general, the less fuel you're using.

Dale