I recently upgraded my turbo from stock with 14cm housing to an HTT stage II with 14cm housing I was not impressed with the spool up it seems slower than before also the smoke did not clear up as much as I thought it would. I pull some fairly heavy loads with this truck about 23000 lbs GVW. Will going to a 12cm help or will I run into problems? Or is my current turbo to small? The EGTs are not much of a problem 1200 degrees preturbo. I also have a set of BD 65hp inj. to install dut would like to fix current problems first. Any help or suggestions greatly appreciated.


Richard

 

What kind of boost numbers are you seeing now and before? The stage II is slightly bigger than stock, but you went to a smaller turbo housing, this should make it spool at minimum the same rate as stock, but most likely faster. I would check for a boost leak at the short cast elbow between the turbo outlet and the intercooler pipe. You might not of gotten it lined up correctly when installing that new stage II compressor housing.

BTW I would NOT run anything smaller housing wise for what you tow. You'd burn the house down pulling that much.

 

I had a 14cm housing with the stock compressor. Before the bost was 27 now it is 30. I pressured the sysrem and didn't hear any leaks but I could always retest it.I did some mild porting on the exhaust housing, maybe I should do more agressive porting?

 

I had a 14cm housing with the stock compressor. Before the bost was 27 now it is 30. I pressured the sysrem and didn't hear any leaks but I could always retest it.I did some mild porting on the exhaust housing, maybe I should do more agressive porting?

 

Sometimes you won't hear any leaks, but you can see them (bubbles) with soapy spray water on all the connections while the system is pressurised. Porting and a smoother free flowing exhaust manifold will net less boost than a restrictive manifold and housing. More boost isn't always a good thing. I'll have to let someone more familar with the htt stage upgrades to give their input.

 

the turbo spoolup almost seems slower now than before I changed turbos.

 

If you had the same exhaust housing before (14cm) and only changed the compressor housing/wheel 56mm vs. 58 or 60 (HTT) whichever it may be, then you will see a slightly lower spool up because of the bigger compressor wheel.

You have a turbo now cabable of moving more air- if given more fuel. You can now add more fuel to it to change the spool up time. Time to install those injectors you have.

 

thanks bgilbert for the help I will recheck for air leaks and try the new injectors