I'm just curious how to relate vacuum guage readings with fuel economy. From what Ive read you can use this guage to judge fuel economy and somehow translate these reading into MPG. My current normal driving measurement is 12in with the new cam and idles @ 15. I know the more vacuum the better economy but is there a straight line way to compare these readings with MPG?
12in =XX MPG.

Thanks!

Lol edited for brainfade.

 

If you have 12/15 psi you must have a blower/turbo--it's giving boost at idle too. No accurate method of comparing vacuum with mileage. More vacuum does mean better mileage on the same engine though. Back in the day, some cars had 'economy' guages that showed when the engine was getting the best mileage. The idea was you could drive around trying to keep the guage as high as possible--maximum fuel economy. The guage was merely a vacuum guage.

 

Lol I need alot more sleep. IN not PSI.

I got interested in this when reading a Chiltons "55 Ways to inprove fuel economy." According to thier picture my vaccum readings indicate fair economy yet Ive had the guage on a couple of my cars and they all seem to run in the bottem "fair" area.


Thanks for the reply.