I have wondered what vacuum readings other RX8s are getting.

I recently had my vacuum go way up from premixing with a lead substitute(Catless), and actually got 27 miles a gallon with no A/C and the windows up. (it was cold for Florida) My vacuum used to hold around 16 to 18, but went to 18 to 20, and now I am even seeing 20 to 22. (These readings were at a steady speed on a level road, about 40-50Mph in 6th gear.) When I decelerate, I now get 26 inches of vacuum, up from a max of 24 in the past.

Also, can too much vacuum be a bad thing; can it be a sign of something wrong?

 

no not really. is this an idle vacuum reading? or at speed (approx 2K)?
the lead substitute --is it like a pre mix oil too? With 1/2 oz premix to the gal my idle vacuum would increase approx 1 point.
OD

 

done a little reading---very interesting. you may have something here.
olddragger

 

my vacuum readings are just about exactly like what yours were previously Rote8

 

I always have people ask questions when adding two extra things to my tank of gas!
I have always been using Protek-R and now I also add 2 Oz of the CD2 stuff.


I have been getting very good mileage for an 8.
(I still do not believe one fill up calculation)
I have wondered how much the cool fall air has to do with this.

I think it's dyno time soon....

 

Do you have a catalytic converter?

 

I never had an increase at idle with pre-mix, or I did not notice it if I did.
My idle vacuum is up the same amount too. (up to 20 and rarely to 22 on my gauge)

 

20 of vacuum at idle is damn good---great sealing, that motor could suck the chrome off a trailer hitch ball!
OD

 

im leaded--have not had time to really check her out but damn if i dont think i feel something.
lead may be better than pre mix--i am going to post that and let the stuff fly!
OD

 

I premix and have no change in vacuum with or without...Just 15 all the damn time at idle. No stalling, no powerloss. I will give the lead substitute a go. I am catless, so no issues there. Only 2oz per fill-up? I will give it a go, but need to see if the MMO I am using will cause any issues.

 

just follow the directions with whatever product you get.
OD

 

It also "sounds" smoother while idling.
It did not happen suddenly, it just slowly got better, I have ran about 5 or 6 tanks premixed with this stuff. (and Protek too)

I like the idea of lead(or substitute) lube in the rotor tip slots where the seals ride.

Can you have too much vacuum?

 

nope, mazsport dual resonated midpipe

 

what is this cd2 stuff?

beers

 

dug aroung last night and see that redline makes a lead substitute as well. Seems though that some use a sodium based substitute or some tytreblahblah stuff that I can't recall at the moment. from reading, the CD-2 and Redline seem to both be very poplular with the older engine crowd.

 

I could only find the gunk brand locally. I pulled up the MSDS charts on the CD-2 and Gunk and they are pretty similar. They use potassium, etc...

http://www.gunk.com/msds/M5012.PDF
http://www.turtlewax.com/res/msds/msds4197-1.pdf

 

i didnt think to pull those sheets--and once i saw them it just validates an old thing i remember--1 gallon kerosene + 5 gallon gas.
Ha
OD

 

Ok Rote--my vacuum reading was 18 with a slow leakdown to a 17.5. this is with a warm engine not cold. those are pretty good findings.
my 2K vacuum was 24! That aint suppose to happen!!
Centrifugal forces at work? sure is sealing better at rpm!!
Anyway it is going to take me a couple weeks to go through 2-3 tanks
please follow.
OD

 

My vacuum has stopped rising at 20 to 22 at idle and about 20 at a steady speed 6th gear at 45-55Mph. I get really good mileage with the windows down and A/C off at this speed.
(not saying what the mileage is; scared to jinx it)

 

A lead substitute I happened across in Walmart.
About 6 dollars for a quart of it, you use about two Oz per fill up.
It even has a neat way to measure the Ounces.

 

wow,

link? odd all walmarts are not the same. used to be able to find a good 2stroke syn premix in my local one. now not so much..

beers

 

My car will pull 19 inches at idle with the A/C off, 17 or so with the A/C and rad fans on. Sometimes I will see 20 inches of vacuum at idle.

I haven't paid too much attention to vacuum while cruising, it's usually around 18ish in 6th with the A/C and at a steady clip. If I play with the throttle I can get around 20-22 but it's hard to maintain speed.

Besides, vacuum is no fun, I'm usually in positive manifold pressure.

 

Here is the stuff I found at Walmart.
It seems to be more expensive online, or the price has gone up since three weeks ago.

 

I think I am going to invest in some of this stuff

 

Thread resurection!

I'm taking my 97k mile Renesis in for a precautionary compression check before the core warranty runs out. I fully expect it to pass (no problems), and I'll report my findings. I just tested my vacuum at idle and at 2k rpms. I used the popular Actron $25 gauge plugs in at the VFAD nipple:

Idle: 16-17 cm Hg
2k Rpm: 22-23 cm Hg

Car was fully warm off of a 250 mile highway road trip around 90 degrees outside.