Boost Gauge Behaviour - Stillen SC

ART_Auto · 07-17-2014, 05:24 PM

Hey everyone.

Im still trying to get to the bottom of what is going on with our car.

Im sure that we are getting belt slip but at the same time im wondering now if the gauge is playing up,

We have an AEM Digital gauge installed and when you go on WOT it climbs but jumps around and the higher the boost the more it drops. like 6psi to 2psi, 8 psi to 4 psi etc.

We have installed the small 2" idler pulley between the 75mm idler and the supercharger pulley up top but the problem we are now having it making a belt fit.

Does anyone else have a similar thing happen with their gauge?

ART_Auto · 07-17-2014, 05:37 PM

I just read this:

http://www.928motorsports.com/instal...0solutions.pdf

It's deffo belt slip as we had number 2:

"a dark rubber residue on the front of the supercharger near the pulley - that's rubber thrown by belt slippage. "

I both love and hate this car lol

JWillis72 · 07-17-2014, 06:02 PM

I have the AEM boost/AFR gauge and haven't seen anything like on but the first one I had the wire somehow ended up rubbing on the drive shaft and the thing went crazy. One moment it would be normal the next it was showing high boost and crazy AFRs. The shop that installed it ended up having to replace because after they fixed the wires it still acted crazy.

ANMVQ · 07-17-2014, 06:03 PM

Do you have the tensior set right ? I know every car is differnt but I didn't have any belt slip at 12 psi and I didn't have the smaller pulley you guys just installed either , the only thing I can think of is the belt is walking, either the tension is wrong or on of the pulleys don't line up right , I ran into the walking issue when trying to my cog set up

Pro4Jackster · 07-18-2014, 12:54 AM

If it's a bracket flex issue. JTran Studios builds these braces. But I didn't need it until about 15 psi.

ART_Auto · 07-18-2014, 03:10 AM

Its the one I have highlighted in red that has the slip as there was black debris round the face of the bracket. Has anyone experienced anything similar?

ANMVQ · 07-18-2014, 09:20 AM

Its hard to tell from that angle but are those pulleys even? Like I said I have mine walk but only on my cog set up, I dumped the cogs and stayed with the stock set up.

Pro4Jackster · 07-18-2014, 09:12 PM

Quote:

Originally Posted by ART_Auto

Its the one I have highlighted in red that has the slip as there was black debris round the face of the bracket. Has anyone experienced anything similar?

Yes. It should be the same for every Stillen S/C. That will be the pulley that slips. But, I don't understand why yours is slipping at such a low psi.

Pro4Jackster · 07-18-2014, 09:18 PM

Quote:

Originally Posted by ANMVQ

Its hard to tell from that angle but are those pulleys even? Like I said I have mine walk but only on my cog set up, I dumped the cogs and stayed with the stock set up.

They are not even. The 34T is a 20mm, and the 30T is a 35mm (if I remember correctly).

I had no problems with the cog setup pushing 13 psi. But you could see the bracket flex. I ran it that way for a few thousand miles and a few trips to the track.

07-17-2014, 05:24 PM	#1 (permalink)
ART_Auto Base Member Join Date: Mar 2014 Location: Glasgow, UK Posts: 43 Drives: 370z Rep Power: 11	Boost Gauge Behaviour - Stillen SC Hey everyone. Im still trying to get to the bottom of what is going on with our car. Im sure that we are getting belt slip but at the same time im wondering now if the gauge is playing up, We have an AEM Digital gauge installed and when you go on WOT it climbs but jumps around and the higher the boost the more it drops. like 6psi to 2psi, 8 psi to 4 psi etc. We have installed the small 2" idler pulley between the 75mm idler and the supercharger pulley up top but the problem we are now having it making a belt fit. Does anyone else have a similar thing happen with their gauge?

07-17-2014, 06:03 PM	#4 (permalink)
ANMVQ A True Z Fanatic Join Date: Mar 2011 Location: Framingham MA Posts: 2,732 Drives: 2014 Q50 AWD Rep Power: 19	Do you have the tensior set right ? I know every car is differnt but I didn't have any belt slip at 12 psi and I didn't have the smaller pulley you guys just installed either , the only thing I can think of is the belt is walking, either the tension is wrong or on of the pulleys don't line up right , I ran into the walking issue when trying to my cog set up DEpointfive0 likes this. __________________ 14 Q50 AWD, ARK, ECUTEK (SEB), Takda,

07-18-2014, 12:54 AM	#5 (permalink)
Pro4Jackster Base Member Join Date: Oct 2011 Location: NW Houston Posts: 130 Drives: '08 350Z Rep Power: 14	If it's a bracket flex issue. JTran Studios builds these braces. But I didn't need it until about 15 psi. __________________ Jtranbuilt '08 Z [Jtran PT7075 Single - Fujitsubo - Transgo - Wilwood - TE37SL - BC Racing]

07-18-2014, 09:20 AM	#7 (permalink)
ANMVQ A True Z Fanatic Join Date: Mar 2011 Location: Framingham MA Posts: 2,732 Drives: 2014 Q50 AWD Rep Power: 19	Its hard to tell from that angle but are those pulleys even? Like I said I have mine walk but only on my cog set up, I dumped the cogs and stayed with the stock set up. __________________ 14 Q50 AWD, ARK, ECUTEK (SEB), Takda,

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07-17-2014, 05:37 PM	#2 (permalink)
ART_Auto Base Member Join Date: Mar 2014 Location: Glasgow, UK Posts: 43 Drives: 370z Rep Power: 11	I just read this: http://www.928motorsports.com/instal...0solutions.pdf It's deffo belt slip as we had number 2: "a dark rubber residue on the front of the supercharger near the pulley - that's rubber thrown by belt slippage. " I both love and hate this car lol

07-17-2014, 06:02 PM	#3 (permalink)
JWillis72 A True Z Fanatic Join Date: Sep 2013 Location: Fort Myers FL Posts: 2,002 Drives: 2009 370Z yellow 7AT Rep Power: 45	I have the AEM boost/AFR gauge and haven't seen anything like on but the first one I had the wire somehow ended up rubbing on the drive shaft and the thing went crazy. One moment it would be normal the next it was showing high boost and crazy AFRs. The shop that installed it ended up having to replace because after they fixed the wires it still acted crazy.

07-18-2014, 03:10 AM	#6 (permalink)
ART_Auto Base Member Join Date: Mar 2014 Location: Glasgow, UK Posts: 43 Drives: 370z Rep Power: 11	Its the one I have highlighted in red that has the slip as there was black debris round the face of the bracket. Has anyone experienced anything similar?