Vaccum should read what ? At idle on s13 red top

[Keefs240sx]

What should sr20 vacuum read at idle I've seen post an stuff say -18,-20 not really sure. I am doing a boost leak test and trying to see if this fixes the jumpy idle after revving.

[e1_griego]

Yeah, -18 to -20 inHg with stock cams and everything else.

[jr_ss]

Yep, healthy motor should be around 20", could be more. Larger cams can drop that roughly 2-3".

[Keefs240sx]

Alright thanks for the help guess was doing boost leak test an trying see if I got them all fixed

[Dima1127]

Yep, healthy motor should be around 20", could be more. Larger cams can drop that roughly 2-3".
so your saying i might have larger cams? i idle at -23 to -25 with a gt2871r

time to rip of the valve cover!

[jr_ss]

No, you'd have less vacuum if you have larger cams.

[Dima1127]

just to be clear, noob here.
so larger cams would be more like -16 to -18 or so? not in the -20 to -25?

[jr_ss]

Exactly. Larger cams have bigger lifts and durations, which cut down on created vacuum.

[AWD260R]

Uhm mine is like 7-8" vac on 280 degree 11.5mm lift with full ported head and 1mm over sized valves. I had to check with the Head shop and mine is normal for ITB's at that vacuum. Lucky I can still stop with my brakes(barely).

[e1_griego]

My car pulls -14 or -15 with HKS 264 step 1s.

[anti tyler]

Uhm mine is like 7-8" vac on 280 degree 11.5mm lift with full ported head and 1mm over sized valves. I had to check with the Head shop and mine is normal for ITB's at that vacuum. Lucky I can still stop with my brakes(barely).


barely stopping? Even when pumping the brakes? Are you sure you don't have a leak though, it wouldn't hurt to boost leak test just to be safe. Also a good idea to inspect that check valve in your booster line. Never a bad thing to blow out your vacuum booster diaphragm

[AWD260R]

barely stopping? Even when pumping the brakes? Are you sure you don't have a leak though, it wouldn't hurt to boost leak test just to be safe. Also a good idea to inspect that check valve in your booster line. Never a bad thing to blow out your vacuum booster diaphragm

All has been check trust me it's low vacuum for a brake booster to assist when that low, it helps when I decel since that puts the engine in a vacuum but only works while in gear, it's manageable to stop and all I was exaggerating a bit. I have a great brake system new lines and the works, all high end ish.

[Vegass13]

my blacktop idles about -22-24 and likes to almost die after revving, I could have a boost leak but I assume it's cuz the vta bov since my car seems to hold boost fine

[cotbu]

Idle vacuum needs to be read from a standard rpm idle, for anyone to begin to compare. You guys idling at 1100rpm ...http://proplayerinsiders.com/wp-content/uploads/2014/06/but-thats-none-of-my2.jpg