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Im Curious Whats Your Vacume?on Idle

cosworth1971
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cosworth1971 Community Regular

cosworth1971

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just curious! on your boost guage what does it vacume at on idle?mine is around 18-20 psi ,which would say quiet good no?and also 18-20 wud mean no leaks at all?In old motors 18 vacume was good.

If your is different please post it :P

p.s i think my cheapo boost gauge says 13 psi when it is actually around 11?

if you have wrong reading with guages please post back also :D

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cosworth1971 Community Regular

cosworth1971

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Posted (edited)
wow hold up.. 18-20psi on idle??

or am i reading your post totally wrong..

Mine is like negative 0.7 bar.. at idle.. that means its not on boost..

.7 bar is about 10 psi but that guage isnt very accurate if its the standard one?and 10 psi is weak i think?

and yes i mean 18 to 20 psi vacume at idle

Edited by cosworth1971
Rolls Grand Master

Rolls

Posted
Posted (edited)

Its actually mmHG not psi when you are talking about the negative units on your boost guage. You can't really have negative pounds per square inch if you think about it.

But yeah mine sits on ~ -20 on idle.

Edited by Rolls
WogsRus Veteran

WogsRus

Posted
Posted

well i have tested mine so much i cna't find any leaks at all anywhere, and mine still only sits at 18" mercury at idle at 650 rpm and about 19-20 at 750 rpm.

Any common leaks to look out for, did a whole heap of test break clener, carb cleaner, smoke, pressure, all good.

RBwhatever Veteran

RBwhatever

Posted
Posted
Its actually mmHG not psi when you are talking about the negative units on your boost guage. You can't really have negative pounds per square inch if you think about it.

But yeah mine sits on ~ -20 on idle.

Should be IN-HG not mmHG. Well, it is on mine anyway.

cosworth1971 Community Regular

cosworth1971

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Oh ok cheers! I was gonna fu**ing say, how the hell people were getting -18psi!!! Both mine and my mates sit on about -0.6, -0.7 bar.

but u earlier posted and said ur aftermarket said -10(in-hg)psi (whateva)

and tha factory boost guage is just there to look pretty IMO and wont give u a good reading

PM-R33 Grand Master

PM-R33

Posted
Posted
but u earlier posted and said ur aftermarket said -10(in-hg)psi (whateva)

and tha factory boost guage is just there to look pretty IMO and wont give u a good reading

Yeah aftermarket says -10psi, stock one reads about -0.7 bar which is equal to -9.8psi :thumbsup:

Nowhere near -18psi.

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