I'm still getting this strange problem:

1st gear to redline - 8-9PSI
2nd Gear to redline - 7PSI
3rd gear to redline - 6 PSI

from a roll (20mph) in 1st to redline - 7PSI
from a roll (40mph) in 2nd to redline - 5PSI
from a roll (65-70MPH) in 3rd to redline - 5PSI

Any ideas? I thought the SC would boost the same at the same RPMs no matter what speed or from a roll or stop.....

Seems like a boost leak, as the longer I'm in redline, the more PSI I lose, but I've never found any real boost leaks.

I mean I've heard a 3-4 PSI leak before - it's VERY obvious....(PSHHHHHHHHHHHHHHHHHHHHHHHHHH)

None of that under my hood.....even with it running on the Dyno and a mechanic with a stethascope under the hood....can't find any leaks.

I thought maybe it was the gauge. However, I've tried 4 so far, all located at different points on the manifold.....same results. 15Hg vacuum max and the boost problem.

Could this be an engine problem?

I know I've brought this up before, and I keep thinking it's fixed, then find out it's not.

As for the vacuum, I've never been able to figure that out. I've resealed the entire manifold with new gaskets and RTV twice, checked and rechecked every hose, connection, and valve....I did find a small vacuum leak once, but it only helped 1-2Hg (I used to never get above 13).

 

For one minute I thought you had the V2 but looked at your sig and saw you had the V1, your not going to boost 10 with the V1 and the 3.25 pulley, I have not seen anyone push 10. 9-9.5 will be the highest. Now you should be hitting 9 specially in 2nd and third and so on. I know I do but for me is 10.

your belt is it properly tightened? If is not is not going to boost properly

 

Good idea on the belts, but I've checked and even replaced and rechecked the belt.....many times now.

I've also had 3 or 4 different mechanics look at it, as well as a whole lot of friends....everyone is scratching their heads. I even tightened the belt to only a 45 degree deflection once to test...no luck.

Also, without the VI, I Dyno at 237hp in 3rd Gear.....I don't know if that's normal or not - seems pretty low.....

With the VI, I'm at 277, however....so I dunno what's up....

Also, I never said I should be hitting 10....where'd that come from?

Any other ideas?

IanS

 

hmmmm....my 0.02$

have you try to hook up another boost gauge(or just relocate your current one) right after the blower? There is a port on the blower that you can attach a connector to it. I would try to see if it is getting same amount of boost at that spot. If the reading is consistent thru out the rpm range after the blower. Then your blower is doing ok and you can at least eliminate the belt/blower as the cause of this problem.

277whp with VI is a pretty good number.

I hit 273whp on my 5th gen with 10psi.

 

I never noticed this port before...anyone have a pic? I suppose I will look at it when I get home tonight.

Good suggesstion.

The comparison you gave is pretty good, as the 5th Gen has a VI already.....Makes me think maybe I've just got a small leak somewhere after the engine, but before the Boost Gauge. But I've tried several spots on tha manifold, and 3 gauges, so that just confuses me further.

Hmmm.

IanS

 

http://home.earthlink.net/~doctorkiwi/SC/vortech1.jpg

I believe it is a hex bolt. I was told that the psi reading will be higher than what we see near the throttle.

 

I was told a great way for me to check where vaccuum leaks occur yesterday from a friend who runs a speed shop locally....

take a propane torch and WITHOUT LIGHTING , open slightly to allow gas to come out just a small amount...

hold the end near each significant conection point where you have vaccuum ends...if the RPM's go up,,,that is where you are sucking air cause the gas will go in and make the engine seem like it is revving just slightly.

that sounds like something I am going to do tomorrow to make certain all mine are straight...obviously a well-ventilated area is a must....

 

I've seen the test port on V2's only. No V1 I've ever seen has the port.

Here's a link to a thread that clearly shows the test port:
http://forums.maxima.org/showthread....super+AND+bowl

 

that will work, but its alot easier to get a can of starting fluid (ether) and spray each joint with the liquid and see if the engine revs/stutters at all. Same concept.

 

Yep - done that 5 or 6 times now.....

 

10PSI sorry bout that

about the boost gauge when you Dynoed dont they have a boost gauge they can hook up to? it will read your boost on a computer screen etc..

 

No - they duck - they don't have an electronic gauge....

Also, I don't have that little port on my SC - must be a V2 thing.