rxspeed87

just out of curiousity I took a vac readong of my car today and it said about 15 at idle

is this normal low or what?

Scott 89t2

turbo or non turbo?

it's ok... either the engine is a bit tired or you might have a small vac leak. mines around 15 with 100k miles on it.

BlackRx7

I get between 18-14............depending on the day......

Sandmeister

So....just wondering....what is good? Higher vac, or lower vac?

TheAnalogKiddd

iTrader: (2)

higher, around 16-18 at idle is good, any lower and it's either a vacuum leak or engine going bad.. make sure your boost gauge line is tight if you're using one

Aaron Cake

iTrader: (1)

I read about -18 on my engine @ 750 RPM idle. Of course, mine is an NA block. Normal readings for a TII are between 15 and 18. Lower than 15 may indicate problems (as already mentioned).

RETed

For turbo...

16 - 18, stock port
12 - 16, street port
10 - 12, bridge port
8 and under, peripheral port

This is assuming NO leaks in the intake tract.


-Ted

rxspeed87

it is an 87 sport with 181k miles on it

compression is around 105 for the front
95-100 for the rear

not sure if I have an intake leak or not right now
I know the idle is a little rough some times but seems to settle down into a smooth idle after I get on it a little bit



and is it normal for the vac reading to hit about 2 when I go WOT

I never though I would come that close to hitting 0

RETed

Yes, WOT should push vacuum readings to "0".

The numbers I gave were for idle vacuum.


-Ted

rxspeed87

ok

well motor is going soon anywhoo just curious about it

goodspeed

I can vouch for the street port. A ported rotary will give you a lot lower vacuum reading. I have a very large street port and typically see about 12 maybe 13. And my engine has perfect compression, 3,000 miles on it.