carlos8

hi, Yesterday I install a new precision 5831mfs. I just only remove my old sc34 and put this with new gasket.

Today I was street tuning (cleaning the tune). When I made a full pull the boost drop from 17 to 13-14psi at 8k-8.5k

Went to my home, take off the turbo filter and block the turbo and blow off with my hands and the car dies ( apparently no boost leak).

Any advice on what it's happen or what to check.

thanks

viper_boy403

iTrader: (1)

Where are you getting the boost reference for the wastegate? Just ran into this with my setup, moved it from the compressor housing to my vacuum block. Intake manifold would work as well

carlos8

Yeah, I have it in the compressor and never happen before, but I can give it a try in one of the manifold ports.

I'm going to this tomorrow and a smoke test on the charge pipe.

Thanks...

Muckman

iTrader: (2)

Before I blame the small turbine have you tried the basics? Running without the air filter? Trying a diffrent WG spring?

carlos8

Now that you already mentioned it: The filter is new k&n 6Wx4Wx6L inlet 3"

Taking apart: dirty or broken.

A filter can become a restriction? Inclusive new? Maybe too small?

Going to try without filter. I already test for leaks and it's free.

viper_boy403

iTrader: (1)

With the larger turbo, your intercooler could be becoming more of a restriction, causing higher pressures on the hot side and giving your wastegate a boost reference that is not the same as what is actually reaching the engine. Takes all of 30 seconds to pop the hood and run a new line

carlos8

I already put a new line from the int. Manifold.

Also prepare a DIY charge pipe tester with PVC end caps.

Waiting for the rain to stop to test the car...

carlos8

Now hold the boost fine!!

For the other side I get too excited and push the car hard from 3rd to 5th, to much in 5 gear. Apparently the head gasket get hurt, 185 psi cyl. 4, all the rest 200psi. Overflow tank boiling and coolant consuming.

Last time that this happen with a cometic HG. I just only clean well and replace the gasket with OEM.

Do you guys think this time I need to get the head to check or resurface?

I don't know if start a new thread, so I posted in the same.

viper_boy403

iTrader: (1)

When just replacing a gasket under normal circumstances (rebuild, preventative maintenance, etc), just a gasket swap is ok. If you actually blow a gasket, I would always get it resurfaced or at least checked for flatness

carlos8

Yeah, I going to take the safe route and take it to the machine shop.

Muckman

iTrader: (2)

head studs?

carlos8

Yes Sir, ARP's torqued to 80lbs with moly lube.

carlos8

Muckman, The block threads are M11 x 1.5 Right hand?

Muckman

iTrader: (2)

Correct

carlos8

ok, Bought the tap. I just screw the tap with wd-40 in the thread? I'm a little worried because the studs are 7/16" and the Tap M11 metric vs. standard.

ef92b

so after moving the boost reference line to your IM, the boost held fine at higher rpms? or both, without the filter?