[fencekey]

I have an SPI boost guage that I installed about a month ago. My car is stock, and the guage would register 11 psi at WOT with both turbos spooled. This week, I did a couple of WOT runs and only hit like 9.5 psi. I was concerned that perhaps I had a problem with the sequential system, so I did the TTC mod. Guage still reads around 9.5 psi.

My question is this. When I turn the car off, the boost guage needle sits at just below zero, approximately 1.5 psi below (just a unit of measurement here; I realize there is only vacuum below the zero mark). Anyway, could it be that my guage is just a little off or does anybody think I have a boost leak? The car still feels strong, but I'm not capable of discerning a 1.5 psi boost leak by the seat of my pants.

My next thought is to test the guage by hooking it up to a controlled boost source (such as my front tire!) to see if it is accurate at various pressure levels.

BTW - my car is stock except for the boost guage and TTC mod. I checked the plastic "T" near the Turbo Pressure Sensor and I don't see any loose hoses or anything.

Any thoughts before I buy another guage? Do SPI guages tend to go bad with age (I bought this one used).

Thanks in advance.

 

[fencekey]

Anyone?

I just installed a RMM dp last night and this morning on the way to work I hit between 11 and 11.5 psi (call it a 2.5 psi gain). I didn't get a chance to get the rpm's up past 5,000 so I'm not sure if it is going to hit fuel-cut or not. Assuming no boost leaks anywhere, I should hit fuel-cut right? What percentage of people hit fuel-cut with a dp and a stock exhaust? If I don't, is this a sign that the guage is okay and a have a minor leak?

Thanks in advance

 

[fencekey]

Anyone home to help a fellow Supra owner?

 

[LateralusFU]

with a dp and aftermarket exhaust most people are borderline boost cut-some hit some dont. i wouldnt think that just a dp would cause boost cut-maybe on a really cold day? stock your car should be at 11psi and a 2.5psi gain sounds right for a dp-check your hose from your gauge and make sure its not leaking otherwise its probably your gauge-spi gauges are suppossedly not that accurate.

 

[burnmacs]

Yeah, I've heard the SPI is a POS. Go for a Greddy electronic, preferably a 60mm peak hold. I went for the 52mm electronic and regret not getting a peak hold.

 

[fencekey]

Thanks for the replies everyone. That is what I was looking for. I'm going to go with an electronic guage for the accuracy. I feel so blind not knowing exactly what the boost is on the car. If you can't rely on your boost gauge readings, it's difficult to diagnose problems.

Any preferences between Greddy and Blitz? Also, I want to put it in the stock clock location, so 52mm is what I need. Do peak hold's come in 52mm?

 

[LateralusFU]

pretty sure defi gauges are the only 52mm with peak hold. its gonna cost about 75 more than the greddy though. do some searches on defi gauges.