Members,
I`m having an issue with my HKS 50mm wastegate (genuine). Here`s the history

FD HKS Cast iron Manifold with 50mm wastegate...Turbonetics T-66 A/R .70

I have a 10 psi spring in the wastegate and sometimes it would spike to 12/15 psi

I`ve eliminated the Greddy Profec-b and just connect the wastegate straight. (from the turbo compressor to the side of the gate) still creep to 12/15 psi

So I`ve check the diaphragm and done alot of bench test to see if its sticking and its not.

I`ve got tired of trying to figure this out so I bought an ebay replica. I installed and the same **** happends.




I can't figure out the life of me what the hell is the problem.

The dump tube is an S-bend, could this be the reason for the spiking?



Please Advise

 

your turbine might be too small and is overpowering the wastegate
the smallest you should use for any 50 trim and above turbo on a rotary is .81
running lean can also cause spikes

 

I thought this to be. However, on my 1st Gen it has the same size turbo and it doesn`t even spike at all (I`m using a 52mm innovative indy wastegate) dumping in the atmosphere.

Also, wideband says 10.8 on load.

 

hmm i had a 50mm hks knockoff with a yellow 20 pound spring
and it held my boost very steady....

what is your exhaust system?

 

Where is the WG vacuum line sourced from?


-Ted

 

The side on the WG is connected to the compressor side of the turbo and the nipped on the cap is just open.

Is this correct?

 

The HKS cast iron manifold is a poor design and known for boost spike

 

If your manifold design is poor , you will have to get a larger gate to keep the boost under control.

 

what diameter is the dump tube?

have you inspected the wastegate valve stem to make sure it isnt bent?

I have seen 500rwhp cars use the log without spikes

 

was your boost controller connected to the top of the wastegate?

 

[QUOTE=BASTARD;7700600]what diameter is the dump tube?

Dump tube is 1.5 inches

 

yes it was connected...

The compressor vacuum line from the turbo when to the IN of the Greddy profec-b stepper box.

The OUT from the box when to the top of the WG

The side of the WG went to the intake manifold.



But I`ve eliminated it all together and it still spikes.

 

I had an HKS race wg on a log mani and it never spiked but instead boost would drop off at high rpm. The smaller HKS wg would boost creep on the same mani, turbo was a t66 with 1.0 p-trim.

 

maybe I need to rin a bigger A/R size

 

sounds like your turbo is beatin the shitz out of the wastegate to me...

 

in the first post, you list a .70A/R..................if that's on the turbine, then yes - you need a bigger housing.

If thats on the compressor side, then please divulge your turbine's a/r

 

1.5" plus the fact that it has an s-bend doesn't help flow through the wastegate. 50mm is just short of 2" and you should run piping as such from the wastegate. This will likely be the source of your problems.

 

got the hks cast with a 50mm hks wg.

running a 62-1 with exhaust at 1.00 divided i think.

Keeps perfect 14.7 all the way through the power band (ebay spring no less).

The 10psi spring was all perfect (original).