A 3.8 pulley should produce at around 5 psi. If you eliminate any vacuum leak, blockages or other restriction between the blower and intake as well as belt slippage, the only thing it could be is could be is a bad compressor.

I know it is a little late, but I have posted here numerous times than a complete log should be made of all sensors before any mod for comparison. Even tho you don't have those readings (assumption), you need to get them now. Hook up your durametric and log each sensor at idle and WOT near readline.

Throttle position
Load
MAF
both before and after cat O2 sensors
LTFT and STFT


Also, check the boost you get at half your redline. i.e. 3600 rpm. The amount of boost should be the square of the boost you should get at redline. Somewhere around 2.3 psi. If you are getting close to that at half redline, it may point to a failing compressor or a vacuum leak that occurs only at higher rpm's such as a disconnected or leaking changeover valve. Also check to be sure your hose to the secondary air injector valve is good and tight.
Post these readings and something might jump out.

 

YEP, I allows say "Mustangs will make ya cry".....What do the stock 997's make at the wheels?

Check out our Mustang's......

 

Jim Thanks yet again...!
I owe you HUGE.....
Thanks for helping me read the durametric readings and explaining a few things to me as well as helping me perform some of the 'checks'.
I am starting to think that my install is fine!
I am going to order that other pulley tomorrow!



What do you figure the difference in % between your Mustang and a Dynojet?
I have been hearing as much as 15%......?!


Stacy

 

Stacy,

8%-15% is what you have to factor! What is the power at the crank stock and what is it crank supercharger power?

Did you post any pics of your beast?

 

Do a search on my name or the two links at the bottom of each post I have made.....I have posted the crap out of my car!
There are so many projects/documentation done to this thing I hate lookin' at pics myself,LOL!!!!

As far as power at the crank....I do not know forsure,I only know what the factory claims(355 bhp) and VF supercharger claims (475 bhp)
We made 329rwhp off of 3.8 psi with 12.5 afr.

Stacy

 

Confirmed today with a smoke machine check.....

That 'MY' install was good,phew!

No vacuum leaks,no boost leaks......
So we are going back to the dyno and check a few high rpm pulls with durametric.
Seems Nik @ VF wants me to check the superchargers output by plumbing in a nipple to hook a boost gauge into the charge cooler.

I WILL post the results.....


Stacy

 

Not to rock any boats here!

Just to clarify with those following this thread.I have the version 1 supercharger with a 3.8" pulley.
Not sure if the newer version (V2) is different or not ?!

My numbers are a bit low on the dyno as I forgot to disconnect my battery before the final run.To make a long story short,the first test run was cut short due to the AFR's being way lean.We diagnosed that I was only making 2.1 psi at 6000 rpm.
We adjusted a hose at that point and managed the boost to get to 3.8 psi.
However with running the car lean it may have triggered the knock sensor thus pulling timing out...even for the second run!
No timing....no power!
I should have done a quick disconnect of the battery but for no better reason than "I had NO idea" that this could happen!
I have talked to a few very well know FI'ers(6peed members and not) and learnt a ton and for that,yet again,I am thankful of this site!

After hours and hours of chasing what appears to be a ghost boost/vacuum leak because it is only making 3.8 psi and I was told it should be 5psi,I needed some more info.

So I asked a very reputable person about this and they said that the supercharger with the 3.8" pulley is only good for 4 psi,so at 3.8 psi....I am satisfied that my install is good and the car runs great!

So what I am doing NOW is....I ordered some **cough,cough** smaller pulleys (3.6" and 3.48").

The info I received says that a 3.8"=4psi,3.66"=5.5psi and the
3.48"= 6+ psi.....

I will need to confirm all of this however and address the necessary things to make MORE power!
Not sure what I will need to change yet,but definately workin' on it!

I am just glad that my install is good and sorry for posting that I may have had a problem when in reality I did not!
So for all of you who are considering installing a supercharger yourselves....do it!
As posted by 1999porsche911...before and after dyno's ARE A MUST !
Even spend a few bucks for the Durametric program and record ALL of the engines info.

Just hope ALL of the info I have been gathering is true!

I should have the 3.6" pulley late next week!!!
Let the boosting begin,LOL!!!


Stacy

PS took the wife for a drive yesterday and she loved every minute of it.....from the pull of the added power to the exhaust note at RPM she was grinning like a joker(borrowed that saying)

 

SEE! That's what I'm talking about.....Numbers are numbers, it's all about how it drives and how it makes you feel! Please post some video's for us!!!

 

Videos....I hope of the car,LOL!!!!

Anyway,I will do my best to get some videos.Especially if/when we add bigger boost!
I had a vidoe of the dyno but after thinking we were having problems(which we weren't) I erased them.

I gotta say,I so enjoy modding cars,rather than driving them....makes NO sense!!!

 

Stacy, you made me !!!!

Great to hear you finally figured out! Why not just put on the 3.48'' pulley?

 

Because...." I am a go-fast-junkie" !
Once I get bored of the 3.60" I then "feed my habit" with the 3.48"! '
Then we get you hooked Nigel......I have another charger for YOU!

Stacy

 

Stacy, I haven't been following this thread as I have been "abusing" my car on the track again. Maybe you should find some one with a stock set up to see what kind of gains your car has over the other.

 

Ed: Maybe yours should be dyno'd too!

 

Stacy: PS took the wife for a drive yesterday and she loved every minute of it.....from the pull of the added power to the exhaust note at RPM she was grinning like a joker(borrowed that saying)

Videos....I hope of the car,LOL!!!!

Stacy: That must have been some ride! What kind of videos did YOU assume he was talking about?

 

Nah, then I would find out that my mode don't provide any gains