Over Boosting?

[R33silverS2]

Recently i fitted my 33 with a 3" turbo back exhaust and a hybrid fmic. up until then the car was running standard boost, about 5psi till 5000rpm then jumped to about 7. Now with the exhaust and cooler on, the boost is about 7psi till 5000 then it jumps to about 13. I am getting this reading off the standard boost gauge, where after 5000rpm the needle is just before the +7. I am aware that there should be a slight increase in boost after a zorst and cooler, but does this seem to high? If so, what do you think the problem could be? Ps there is no boost controller on the car.

[d00dz]

The jump from 5PSI to 7PSI is normal, this is the two stage boost < 4.5krpm = 5PSI (or is it 4?) > 4.5krpm it's ~7PSI.

As for your overboosting, might wanna check that the turbo back exhaust is not being restricted from the turbo. One of the NSW members on the forums had this similar problem of overboosting see what they say.

[Liz]

What Victor said - I also recommend a mechanical boost guage so you can see exactly what the boost is doing.

I had a similiar situation recently and was boosting till well over 14psi and the cause was a combination of my cat converter and dump pipe.

I would say that given you recently changed the exhaust, this would be the root of your problem!

Start by comparing the dump pipe you put on to your stock dump pipe and go from there. I found that the bit that joined on to the back of hte turbo and wastegate was actually smaller htan my stock dump pipe but larger else where in the system.

Hope this helps.

[R33silverS2]

thanks guys ill check it out, i think the mechnical boost gauge will be my next step.