hi all
i have a friend who asked me to put a vacum gauge in his escort rsturbo mfi he already has a boost /oil but am i right in saying he can not have a vacum gauge as i thought they where for old carb engines i have seen the vacum guage and it is one not another if someone could let me know please
many thanks
mark2

 

You can fit a vacuum gauge no problem, when off boost it will show vacuum, but as soon as it sees boost vacuum will drop to zero, most boost gauges have a negative side as well as a positive side, negative being vacuum , positive being boost, so up to your friend, if you go ahead jusdt "T" into a line to get signal on gauge.
tabetha

 

hi cheers for that quick reponse
so it just like a boost guage basical just has different scale
cheers
mark2

 

It's the OPOSITE of a boost gauge, boost is Positive pressure, ie being forced in by the big air pump(turbo), vacuum is Negative and what exists when the engine is sucking, caused by the pistons going down the bores creating a vacuum behind them which sucks in the air.
tabetha

 

i follow you
but what i ment was sitting at idle in a turbo car reads -10/15 psi so on a vacum guage it would reed idle then as postive boost comes in it will read poor on vacum guage i did understand what you ment and understand how a vacum guage works turbo positive pressure so on vacum guage it would be reading as if there was air getting into the system and indicate poor vacum on the guage but is there any benerfit in having a vacum guage on a turbo engine would it help to notice an airleak as such
mark2

 

Nope, you would be just as likely to notice it on a boost gauge, idle on mine is about 0.7 bar(10psi), if it were a more sensitive scale it might be easier to spot a leak, but a leak under boost will be felt quite easy.
tabetha

 

ok cheers
just trying to find out why he wants a vacum guage on his turbo and cant see why and any benerfit
mark2