Vaccum should read what ? At idle on s13 red top - Zilvia.net Forums | Nissan 240SX (Silvia) and Z (Fairlady) Car Forum

Keefs240sx · 09-01-2014, 08:39 PM

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 · 09-01-2014, 09:08 PM

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

jr_ss · 09-01-2014, 09:36 PM

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

Keefs240sx · 09-03-2014, 08:21 PM

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

Dima1127 · 09-04-2014, 04:00 PM

Quote:

Originally Posted by jr_ss

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 · 09-04-2014, 04:16 PM

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

Dima1127 · 09-04-2014, 04:18 PM

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 · 09-04-2014, 04:33 PM

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

AWD260R · 09-16-2014, 11:22 AM

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 · 09-16-2014, 11:27 AM

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

*anti tyler* · 09-16-2014, 01:56 PM

Quote:

Originally Posted by 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).

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 · 09-16-2014, 02:20 PM

Quote:

Originally Posted by anti tyler

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 · 09-16-2014, 03:20 PM

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 · 09-16-2014, 07:56 PM

Idle vacuum needs to be read from a standard rpm idle, for anyone to begin to compare. You guys idling at 1100rpm ...

09-01-2014, 08:39 PM	#1
Keefs240sx Zilvia Junkie Join Date: Oct 2011 Location: Nc Age: 35 Posts: 350 Trader Rating: (0) Feedback Score: 0 reviews	Vaccum should read what ? At idle on s13 red top 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.

09-01-2014, 09:36 PM	#3
jr_ss Post Whore! Join Date: Dec 2005 Location: Pa Posts: 6,410 Trader Rating: (35) Feedback Score: 35 reviews	Yep, healthy motor should be around 20", could be more. Larger cams can drop that roughly 2-3". __________________ My SR20VET Does your VTC gear rattle in your S14/15 SR? PM me.

09-04-2014, 04:16 PM	#6
jr_ss Post Whore! Join Date: Dec 2005 Location: Pa Posts: 6,410 Trader Rating: (35) Feedback Score: 35 reviews	No, you'd have less vacuum if you have larger cams. __________________ My SR20VET Does your VTC gear rattle in your S14/15 SR? PM me.

09-04-2014, 04:33 PM	#8
jr_ss Post Whore! Join Date: Dec 2005 Location: Pa Posts: 6,410 Trader Rating: (35) Feedback Score: 35 reviews	Exactly. Larger cams have bigger lifts and durations, which cut down on created vacuum. __________________ My SR20VET Does your VTC gear rattle in your S14/15 SR? PM me.

09-16-2014, 07:56 PM	#14
cotbu Post Whore! Join Date: Sep 2005 Location: SWFL Age: 49 Posts: 3,318 Trader Rating: (3) Feedback Score: 3 reviews	Idle vacuum needs to be read from a standard rpm idle, for anyone to begin to compare. You guys idling at 1100rpm ... __________________ LoverTechnologies "Half Broken Things!"

09-01-2014, 09:08 PM	#2
e1_griego Post Whore! Join Date: Sep 2004 Location: Independence, Ore. Age: 39 Posts: 2,711 Trader Rating: (24) Feedback Score: 24 reviews	Yeah, -18 to -20 inHg with stock cams and everything else.

09-03-2014, 08:21 PM	#4
Keefs240sx Zilvia Junkie Join Date: Oct 2011 Location: Nc Age: 35 Posts: 350 Trader Rating: (0) Feedback Score: 0 reviews	Alright thanks for the help guess was doing boost leak test an trying see if I got them all fixed

09-04-2014, 04:18 PM	#7
Dima1127 Leaky Injector Join Date: Aug 2012 Location: Beyond the point of no return Age: 29 Posts: 66 Trader Rating: (0) Feedback Score: 0 reviews	just to be clear, noob here. so larger cams would be more like -16 to -18 or so? not in the -20 to -25?

09-16-2014, 11:22 AM	#9
AWD260R Leaky Injector Join Date: Apr 2014 Location: Oklahoma Posts: 74 Trader Rating: (1) Feedback Score: 1 reviews	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).

09-16-2014, 11:27 AM	#10
e1_griego Post Whore! Join Date: Sep 2004 Location: Independence, Ore. Age: 39 Posts: 2,711 Trader Rating: (24) Feedback Score: 24 reviews	My car pulls -14 or -15 with HKS 264 step 1s.

09-16-2014, 03:20 PM	#13
Vegass13 Zilvia Member Join Date: Jan 2014 Location: Las Vegas Posts: 159 Trader Rating: (3) Feedback Score: 3 reviews	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