Hey guys,

I am rather inexperienced with forced induction. My current setup is relatively simple. Built 16 bottom end with wiesco's and eagle rods, stock b16 head with gsr cams. It is running an hks log manifold withe gt2871r. I do not see full boost (12 psi) untill 6k. I feel as though this is a bit off. Can anyone chime in as to whether this is normal or what can be done.

The turbo is running internal wastegate with 14lb. spring.

,Matt

 

Ive read on a few boards that the actuator my not be functioning properly, and a vacuum leak is another possibility.

 

Sounds like some sort of vacuum leak. Check you hoses and lines for any misfitted parts, tears of any kind.

Also check to see if the turbo is ingesting any exhaust gasses. This usually occurs when people don't have the dumptube routed outside of the engine bay far enough. (Pointing "downward" does not help, it must be out of the engine bay completely.

And no, the manifold is fine for the car, and for its purpose is well fitted. No need for "ramhorns" or Topmounts with this setup

 

That was my first thought. If the internal wastegate flapper is not seating properly, the turbine will take much longer to spool.

 

Is it common to have to replace the Garrett internal wastegate?

 

exhaust leaks preturbo, torn coupler, boost leaks, improper sealing wastegate acctuator

 

Not from a boost leak issue, no. Usually replacement is for over 12psi of pressure (from the Honda Greddy kits, anyway) and the flapper door "enhanced" to eliminate spiking

 

I'll assume the best way to see if the wastegate is sealing is to pull off the down pipe and check it. I'll just run through everything you guys mentioned, thanks alot for the help.

 

Have you had to lengthen your actuator arm? I had to with a similar setup - GT2871 on an Edelbrock manifold and for clearance ran an arm extender. If you did the same it may be binding or preventing the wastegate flap from closing completely.

You should see your boost come on full at just about 3k - maybe a little under.

 

I bought the car like it is. It took me a while to realize that the boost was coming in pretty late. I tried moving the actuator arm and it doesn't move with ease, of course Ive never tried moving one before, so I am not sure how easily it should move.

I am going to replace all the vacuum lines, with new ones, that way I now that part is good to go, and then check couplers, and the actuator.

 

The actuator arm should move easily. See if you can easily take off the downpipe and verify that the flap is 100% closed.