Alrighty, about a month ago, I installed Stillen SC Stage 2 (6psi). Reason I chose it is because it was one of the most reliable, albeit mildest mods (as far as FI goes) on the market. However, it appears I've been driving with -40 of both torque and whp, because I just took the car to be dyno-tuned, and -- low and behold -- it 'scored' only 267whp/246wtq...

WTF!!?

Can anyone even begin to explain this? I mean, this was installed by SGP, a reputable pro-shop here in Houston. Also, tuned by them, and they did richen my A/F which appears to have been too lean. In fact, first dyno showed pretty much stock numbers, or just above: 244wh/252wtq.

What's even funnier, according to SGP guys, I'm running mostly about 5psi of boost, at best 5.5psi. This is a 6psi pulley. Again, WTF!?

Possible reasons (deduced by Yours Truly and SGP):
* slipping clutch
-- but, how can clutch be slipping at below 270whp? Since I drove the car already for 4 weeks before dyno-tuning, it is possible I was making more before, and now am not able to make power. However, I cannot say I feel the diff. Nor do I feel the clutch slipping (how would I verify this?)...
* heat
-- it was around 105F. We did 7 dyno runs. Driving home, my thermo showed 111F. Humid, too (y'all know houston, of course its humid! ).
* RT cats
-- free-flowing cats reducing boost? Could be. SGP guys were not so ready to agree on this, but I'm forced to consider it. My headers are stock.
* bad dyno
-- not likely, there was a TT Z on it just before me, and it developed 400whp. That seems about right.
* bad, BAD Stillen!
-- something wrong with the SC? How would I determine that? Can anyone point me to another pro-shop in Houston, where I can get a second opinion?

Any of you guys seen anything like this? Especially, you, Stillen SC guys. Like I said, this is supposed to be most reliable, trustworthy, and mild mod for my car. But, please, not this mild!

 

Limits suck! Here are prime cuts, for the gawking! Let the freak show begin!

 

one more...

 

slipping belt? timing being pulled. I know nothing about FI but just throwing things out there.

 

your belt might be slipping, mine was slipping the first time i dynoed and i got low numbers and low boost. as soon as i tightened my belt, everything was fine...

 

What about the ECU? Have you done anything to the ECU in conjunction with your sc installation? I've heard that the stock ECU does not always play well with major modifications.

 

Weren't RT Cats the ones that get all clogged up sometimes and fail? Or is that another cat?

Go with the belt thing first for sure..if not, drop the cats and look inside.

 

Dude, it was WAYYYYY too hot.

I would bet a fair amount of cash your ECU was pulling timing.

When Crawford's has a Z on the dyno, the Consult is plugged in... Timing has been one of the WORST enemies.

 

My WAG is fuel, or the lack of. Just a guess.

 

I'm not too sober right now, but belts... that's a possibility. For ECU... well, Stillen is plug-and-play, the SAFC2 I got on is just for more leeway to play with. Without any ECU changes, no fuel adjustments (no SAFC changes), etc... you can see 243.9whp only. Ouch!

As far as temp... dude, its like this here 6-8 months out of the year. Bloody hot! Gotta get me a chiller or NOS shot...

RT cats... mine sound very nice, I don't think anything is broken, I would've heard it. Nevertheless, I'm considering placing the stocks back on.

Fuel... was running that nice Texan !Yeehaw! 93 ... lot of good it did me.

 

I would bet dollars to donuts Phoenix is right on the money...its too hot/humid to get meaningful numbers

to be safe go over the pulley and make sure its taught.

Also might want to run an ODB2 datalogger next time you do a pull so you can log the timing and fuel trims....that should give us some better insight

The cats are not reducing your boost...boost is only regulated by the pulley, not the exhaust pressure.

Where did they measure the boost from?

 

Dunno...I dynoed last month in Dallas at 101*, hit 380rwhp on standard ATI kit(plus other bolt ons of course)....the losses can be somewhat attributed to heat, but certainly not at the level he's missing.

--wes

 

Dude... our cars are ****...

On the same day, I saw one car pull timing... and another one didn't.

Wanna put a lil' wager was?

 

Check to see if everything was installed correctly and no mistakes were made?

 

well how are you holding up with other cars....i think that'll help. race a stock z

 

Sure...heat causing losses of 60-80hp ? Don't think so... there is another issue somewhere. I could see heat causing losses like that ona 800rwhp car, but not one that only puts out 235rwhp to begin with.

I've got probably 100 dyno sheets sitting in front of me for cars of mine that I've dynoed at various times of the year, mind you these are all FI'd cars (Lightning,300zxTT, 350Z) and they have seen differences in temps, but nothing compared to what he's describing.

--wes

 

I got my stock GTech numbers. I will test with this setup, before I do any changes to it. I'll also get a second opinion, but it'd be great to find a reputable pro shop in Houston (aside from SGP) that can evaluate the work.

My butt dyno is already used to any pull I might've had, so car seems slow again :-). However, it does not feel more than 20-30whp more. So far, I've accumulated following possibilities:

* slipping belt
* 7th injector may not be running
* RT cats (=lower boost)
* temp
* coolant not circulating
* slipping clutch

I think its a combination of several items, heat included. I'm 40whp/45wtq under advertised and what I've seen on other dynos: -15 for heat, -10 for 5.5psi boost, and something else...

Some of you asked me details, like how my boost was measured, etc. I'm a dumbhead when it comes to tuning, and I've never worked on my own car (don't have space for it). Hence, I'm not sure, they had diagnostic software connected. I have a boost sensor and gauge. All they had to do is connect, I'm guessing.

Wes, your pull is my goal :-) -- 380whp.

 

My guess would be either the heat or cats. I know mine didn't like hollow cats, but that only brought my stage 3 down to 320. However, you are talking a 60hp loss or so, and the heat shouldnt do that much. What you really need to do is contact Stillen and talk to the R&D department, not sales. Sales guys will give you the runaround. R&D really helped me though. Also, how hard would it be to disconnect the SAFC? that, although it would seem to not be doing it, could be causing the problems.

 

2003z, out of curiosity, what was your best dyno with stage 3? I'm estimating stage 2 at about 300-305whp/285-290wtq, and stage 3 at about 325-330 whp/300-305wtq. Are these good estimates?

 

I would guess a loose belt or the timing being pulled.

If you have a gtech, do some runs during the hot humid day and then do some at night when it cools some.

Or see if SGP will let you dyno early in the morning or late in the evening.

I think the 7th injector is kicking in, it is hard to make out but you A/F looks to be in the 11-12 range and smooth throughout.