Would like to see the cross section because most post about this and do not account for the variability of idle speed.

Post your vacuum level at idle and your best guess at what RPM you are at.
Also, include a comment on your engine health too.

New Rebuild - 16 inHg at 650 RPM

 

50k on motor. -12 inHg at idle 750 rpm at cold start up. -18 inHG at idle 750 rpm when warmed up. -22inHG when cruising on the freeway. motor pulls strong with a 10-8-10 boost pattern. no smoke at all. vacuum went up a little after adding pettit racing protek-R premix to the fuel. "anyone else have this happen"?
Jeff

 

Rebuild on break in tune, -11 inHg @1050 RPM. 340 miles on the motor.

 

I get 11-12 inHG at around 850 RPMs on my recently rebuilt Street Port

 

It all depends on how aggressive the porting is. I have race port and pull about 14 inHg at about 950 rpm.

 

I have street port and pull 16 inhg @1000-950 rpm... about 5 k on rebuild w/ 2mm atkins seals.

 

Idle: 19-20 in at 800 rpm

53K miles motor.

 

~350mm of hg with a pretty large port at around 900rpm. Some of these 11 and 12s would worry me.

 

18.5-19, somtimes 20 at 182F water temp and 850rpm idle...with radiator fan switch on vac drops to 16...cruising it drops to 28

 

16hg at 780rpm. Was told the motor was a regular reman with about 15 to 20k miles.

 

490 mmhg at 950 rpm.Stock motor with 28k miles. can anyone convert this to inhg?

 

Yes... unless there is extensive port work, otherwise .

 

im at 12 with a ~950 rpm idle, stage 2 streetport by rotorsports racing with 3mm seals

normal or should I worry?

 

I'm not worried that I only get 11-12 inches of vacuum at 850 RPMs

I am on a street port, live in las vegas with dry *** air at 2000+ ft above sea level, and I only have the engine idling at 850 RPMs


If I bump the idle to 950-1000 it pulls 14-15 inches of vacuum no problem.

 

~19.2

 

Tons more

https://www.rx7club.com/showthread.p...ht=idle+vacuum

 

I pull around 10-12 at 1000 rpms, with an aggressive port with overlap. On the PFC commander it's about -300 to -320. I recently checked my compression and it was fine, 104 psi across all 6 rotor faces.

If you guys have a serious street port (not just polishing of the runners like some 'street ports' i've seen) with altered port timing it is going to affect the vacuum. In this case 12 inches mercury is fine BUT on a stock port engine I would be worried with anything less than 15 inches at ~900 rpm.

 

I just installed my original motor again after my ported motor blew the rear seal. This is the original motor that came in the car in 93, completely stock 32k, pulls 21in@750rpm, 122-125psi. My ported motor when I last built it pulled about 17in@850rpm, 117-119psi, it had the intakes ported (exhaust side stock but smoothed out) and 9.0:1 rotors.

For you guys with the 12in@800+, I'd check compression if your not race ported. Also don't just rely on your $350 RE Amemiya dash mounted guage...hookup that $45 Craftsman and compare....might have a kink in the hose...lol

 

Stock Mazda reman with ~6k miles on it. With the PowerFC set to 720RPM I pull about 19" Hg. That is, when something under the hood doesn't get too hot and the engine tries to stall.

Heck, with the ISC pulled it was idling at ~600RPM and still held 17" vacuum.

 

16-17in @ 750ish rpm warm or hot. reman 60k. stock porting.

 

3mm seals seal less. , street port even less. but 12... il let everyone else decided.

 

19-20 in hg @ 850rpm

67K on the orginal motor.

 

yes, this is the word. actual porting will pull much less, us with the "real" porting, not just smoothing need another thread. for the rest, 14-15 or less. go to your dealership and get tested. like going to the free clinic. you play, theres a chance you might pay.

 

Thank you Rich, I was hoping someone else would back up what I said.

I'm seriously getting tired of the massive paranoya posts that run rampant on this forum. No wonder people get a negative connotation about how un-reliable the rotary motor is.

 

19.3 inHg