VERY SICK OF Boost spike then fading 6 psi !

[v8killer]

Guys i have a 20g tdo5h with a bleeder boost controller setup eveyway possible and i keep getting a spike of 24 lbs falling to 17-18. it will not hold a steady number. even with the the line strait to the wastegate it will loose a couple lbs on top end. 12lbs down to 10 lbs !

can a boost leak casue this. i do have a small leak at the throttlebody.



short lines off the compressor housing
adjustable wastegate "internal gate " tight and loose "

 

[95fwdtsi18psi]

Guys i have a 20g tdo5h with a bleeder boost controller setup eveyway possible and i keep getting a spike of 24 lbs falling to 17-18. it will not hold a steady number. even with the the line strait to the wastegate it will loose a couple lbs on top end. 12lbs down to 10 lbs !

can a boost leak casue this. i do have a small leak at the throttlebody.



short lines off the compressor housing
adjustable wastegate "internal gate " tight and loose "

How small are we talking. I had 3 seals on my throttle body blown, and it wouldn't hold boost at all.

 

[v8killer]

the shaft seals, the back one i know is leaking and the biss screw barley !

 

[habitatguy187]

Just change the TB shaft seals and the BISS O-ring then see what happens.

 

[Ceddy]

Ditch the bleeder boost controller, and pick up a $10 ebay ball and spring controller.
The bleeders don't work well.

Adjust your wastegate so you have 1/4-3/8" of preload.
What pound spring is your wastegate? If it is blowing open you can add a helper spring to hold it closed.


All the TD05H turbos at high boost will taper off at higher RPMs, but I don't think you've reached that point yet.

 

[JayRolla]

Yes they will taper off but it should hold at least 20psi. Like stated its because of your MBC. The bleeders main fall back is boost spike!

 

[e85_4g63]

I'm assuming your still using the 7cm^2 ported turbine housing you have listed in your profile. My question to the OP is at what RPM do you consider "top end"? The td05h wheel doesn't flow enough to hold higher boost pressures (20psi+) in the higher RPM range (7K+ RPM's), without an ungodly amount of clipping and / or a larger turbine housing. Next question, is this an ebay special turbo or a genuine MHI unit? Sounds like you may have ported the wastegate passage and now the flapper is blowing open. Like mentioned above, ditch that POS bleeder valve.

 

[v8killer]

Just change the TB shaft seals and the BISS O-ring then see what happens.

i am waiting on the seals to get here. i know it will help it can't hurt !

 

[v8killer]

Ditch the bleeder boost controller, and pick up a $10 ebay ball and spring controller.
The bleeders don't work well.

Adjust your wastegate so you have 1/4-3/8" of preload.
What pound spring is your wastegate? If it is blowing open you can add a helper spring to hold it closed.


All the TD05H turbos at high boost will taper off at higher RPMs, but I don't think you've reached that point yet.

this turbo should have no problem holding 20+ lbs of boost till redline 7500 i'm only flowing 38lbs/min at this point ! i have had the wategate at all preloads......

 

[v8killer]

I'm assuming your still using the 7cm^2 ported turbine housing you have listed in your profile. My question to the OP is at what RPM do you consider "top end"? The td05h wheel doesn't flow enough to hold higher boost pressures (20psi+) in the higher RPM range (7K+ RPM's), without an ungodly amount of clipping and / or a larger turbine housing. Next question, is this an ebay special turbo or a genuine MHI unit? Sounds like you may have ported the wastegate passage and now the flapper is blowing open. Like mentioned above, ditch that POS bleeder valve.

its a mhi 20g tdo5h with 7cm housing w/non ported wastegate hole 28mm flapper i believe.

 

[e85_4g63]

its a mhi 20g tdo5h with 7cm housing w/non ported wastegate hole 28mm flapper i believe.

What cams, throttle body, IM, exhaust, etc. ?

 

[v8killer]

What cams, throttle body, IM, exhaust, etc. ?

Comp 101200 cams,nt 60mm tb,stock 2g intake,full 3" exhaust