Stock Boost Questions - 280zxt

[phil280zxt]

I've already posted this on Zcar, but I thought I'd also pass it by here. I'm wondering if other people have experienced these pressure levels from their stock zxt.

 

I recently installed an aftermarket boost gauge (Autometer)and an electronic boost controller (Greddy) on my 81 280zxt. Since I like to walk before I run, I installed the boost gauge first and watched it carefully for several days to understand what the stock boost level was and how the wastegate operated. To my surprise the stock boost was 7 pounds!! My understanding based on following this forum was that stock boost should be more in the 5.5 - 6 pound range.

 

I then finished the installation of the Greddy boost controller and carefully started increasing the boost. As expected, the popoff valve vented, but at 9 PSI not the 7 PSI I had read on the forum.

 

Is it possible that my boost gauge is not correctly calibrated? When the car is not running the gauge needle is slightly off center (to the right side of the box which marks zero for those with an Autometer boost gauge).

 

I was hoping to get more bang for the buck by increasing the boost 4 or so pounds from the stock 5.5 PSI. If my stock numbers are correct, I'll only able to add two or so pounds to my setup.

 

What have you guys experienced when you started messing with the stock boost?

 

Phil

1981 280zxt

5-speed conversion, Eibach springs, Tokico struts, Dynomax Superturbo, Falken tires, K&N CAI, AutoMeter A/F and Boost Gauges, Cusco Strut Bar, Greddy B Spec II boost control

[SleeperZ]

Those numbers sound perfectly reasonable. 7 psi factory boost, and I've never heard of a popoff venting under 9 psi. Really, 1 to 1.5 psi difference in one engine to another is quite common. So crank up the boost!

[Guest fatherkares]

basically the problem ive run into, after becoming a fan of these car's and buying one myself, is that the wastegate in my 1981 280zx turbo i think may be busted or just not working proberly.

 

Issue is, " when i really step on the peddle to take off, a clicking sound will reoccur many times aslong as my foot will stay accelerator". i would say, right when i step on it, all u will hear is : click, click, click, click, click.

 

so any suggestions on where i could find a new wastegate and what type, or what could be done if you know what the problem might be

[MJLamberson]

basically the problem ive run into, after becoming a fan of these car's and buying one myself, is that the wastegate in my 1981 280zx turbo i think may be busted or just not working proberly.

 

Issue is, " when i really step on the peddle to take off, a clicking sound will reoccur many times aslong as my foot will stay accelerator". i would say, right when i step on it, all u will hear is : click, click, click, click, click.

 

so any suggestions on where i could find a new wastegate and what type, or what could be done if you know what the problem might be

 

That is an entirely different question and I suggest starting a new thread about it

[GrayZee]

I am thinking that the info you previously read was correct, but for the wrong vehicle. It has been my experience that 300zxt's run lower boost and their pop off valves blow off sooner. For a 280zxt 7psi is normal with stockish exhaust. Around 9psi with a nice 3" mandrel system. The pop off should blow around 10 or so.

My buddy's z31 only gave around 5 or 6psi, I thought that was rather lame so we put on a manual boost controller only to find that we were blowing the pop off valve right away. I no longer used mine as I was running about 14 so I gave him my 280zx valve, it worked like a charm.