I just installed an HKS downpipe and now I have a boost spike when the secondary comes online.

I have an apex'i N1 dual exhaust but still have the stock cats.

Is there anything I can do about the boost spike other than removing the turbos and porting the wastegate oriface. The boost is spiking to about 12 - 12.5 psi (damn DEFI guage). Is this too much for the stock ECU and fuel system to handle?

Please help!

 

Granted that is an accurate display of ur true boost I would say that I never lost an engine to that.

Only when I went into the 15+psi on stock ECU and fuel system was it a problem.

Start saving $$$$ to get ur turbos rebuilt and ported by a company like BNR. That fixed my boost creep along with the PFC.

 

Is it spike or creep?

 

do you guys thing having filters, intercooler, do, and cat. back would cause spikes or creeps?

thanks

-joe

 

yes

 

It's a spike...

It settles back down to about 10 psi after a short time.

 

If it's just a spike, a boost controller will take care of that.

Either manual:

https://www.rx7club.com/forum/showth...hreadid=178136

or a GReddy Profec B will do the trick.

 

Yup, buy a boost controller to govern that spike.

 

I'm not sure if an electronic boost controller will govern a transition spike properly.

Besides, do you guys really think that a transition spike of this size could kill my engine???

 

Like Mahjik suggested you could go down the manual path that Damian designed ... I've done that and it's awesome, speeds up the transition to boot.

Couldn't find any well priced valves down here so built them instead .. https://www.rx7club.com/forum/showth...hreadid=203040

 

what is/was your actual boost pattern?

 

I would just do it right and get a PFC and have the turbo wastegate ported.

That completely fixed my problems.

 

Try putting a smaller orifice in the prespool line.

 

Thanks BATMAN.

I am planning on putting in a PFC or AEM (the only good tuner we have here installs AEM!).

I will probably have to port the wastegate at the same time (or sooner).

I was just wondering if there was anything I could do in the meantime...

I read the post you referred me to, lots of good info...

Thanks

BTW, DaiOni, my boost pattern was 10-8-10 and is now 10-8-12-10. The 12 is only for a short period of time however.
Shaun I will look at your thread in a minute... looks interesting.

 

If ur 12, u'll be OK for now until the wastegate starts to wear out. Then it starts to climb up a pound or 2.

What u can do with a PFC is tune the boost down to 7PSI and that should compensate for the creep........

 

Yes.

Again, why not reduce the size of the orifice in the prespool line to reduce the amount of prespool prior to transition? You have a classic case of boost spike, not creep.

 

Thanks John,

I will try that...

Next question is how?

I am not sure which is the prespool line and how I would reduce the oriface (smaller tube?)

Thanks again for all your help!