Boost Spike

[quick xr6]

hi I have a bf xr6 turbo flashed custom tune sieman injector 2 half exhaust dual cat back typoon cold air intake boost is spiking from 15 to 11 psi thay told me maybe it is the cat converter. what do you think I dont wont change it for no reason I also get a bad smell after a few good hit please help by the way it was spiking before the injectors and the tune shop said I need bigger injector go them done same sh*t ?????????????????

[quick xr6]

  quick xr6 said:

hi I have a bf xr6 turbo flashed custom tune sieman injector 2 half exhaust dual cat back typoon cold air intake boost is spiking from 15 to 11 psi thay told me maybe it is the cat converter. what do you think I dont wont change it for no reason I also get a bad smell after a few good hit please help by the way it was spiking before the injectors and the tune shop said I need bigger injector go them done same sh*t ?????????????????

thanks for the info not. Sic forum?. Yea thanks for the help.

[Trish]

I am sure someone that can answer that question, will as soon as they can.

Edited 24/07/08 09:48 PM by Trish

[Trish]

  quick xr6 said:

thanks for the info not. Sic forum?. Yea thanks for the help.

I have spoken with the Team at Tuehouse and have posted the reply below.

I hope this helps.

Boost spiking is very normal on most turbo cars and the XR6T is no exception. Its not so much spiking but the boost dropping so at the top end caused by a flow restriction .

A simply way to look at this is that flow = horse power, so 15 psi boost at 3000 rpm will be like 7.5 psi boost at 6000 rpm. Approximately. Double the rpm halve the boost, same air flow.

So if there is a restriction in the system that will only allow X amount of air flow the boost pressure will drop accordingly

Now this is caused by many parameters and included, exhaust system, intake system and turbo charger flow capacity. It can be cause also by the waste gate valve being forced open by backpressure in the exhaust manifold. This is why people fit a larger “pound” waste gate actuator, as mechanically this helps hold the waste gate shut. However it is best simply to lower the backpressure.

So injectors were never going to help this problem, a new cat will help but will not eliminate it if you are looking for 15 psi across the board. It is important to know what other parts are fitted, If the intercooler and piping are poor this will also cause the problem. Eventually no matter what you do you will come up against the turbocharger itself simply not being able to flow enough air and the same will happen.

[tab]

Isn't your car tuned by CV?

Why wouldn't you either ask them or post it in their forum as they know what has been done to the vehicle?

to Tunehouse for trying to help the ungrateful bastard though!

[Ralph Wiggum]

thread cleaned up at the request of the sponsor.....

Guys please try and keep it on topic....(even IF it is unclear what the topic is.....)