Sorry to be bombing the forum lately but here goes... I went and replaced my blown 20g with a 16g today in hopes smaller turbo/ faster spool. Well doesnt seem to spool any faster and when it does it actually feels like less power at the same boost level. Am i just used to the power or at 12psi or does the 16g just not flow as good. I figured at a low boost level like that the 16g would actually feel faster with a faster spool and have no trouble flowing the same amount as the 20g.

So the center section and hot side are identical between the two.

Should i swap the 20g housing and wheel onto the new turbo or am i just insane and should i leave it be?

 

why not? Unless the 20g compressor side is damaged, I would see no problems with that. Not a turbo guy, so my advice maybe really bad btw.

 

So the turbine and compressor housing are the same cm3 on both turbos? And the trims of both wheels are the same?

It is entirely possible to have a 20g that makes less power on a given engine than a 16g depending upon the specs of each turbo. More numbers influence the outcome than just 16 and 20.

 

they are bothe td05h turbos, as far as i know and can tell the hotsides are identical. The difference is compressor side, the 20g has a bigger compressor wheel and a larger compressor housing. As far as the exhaust side goes im not sure if the trim is the same on both turbine wheels, not sure how you tell. They looked a lil different but maybe its just cus the turbine side on the 20g was all soaked in oil while the 16g was all shiny and new. I guess ill find out this weekend cus im gona pull the turbo off cus the crappy gaskets i used blew out already and while ive got it off im gona see about making the swap along with comparing the turbine wheels on both turbos.

 

Take the housings off and measure the major and minor diameters of all four wheels and write them down. A set of cheap digital calipers from Harbor Freight or a discount parts store will do the trick. Then look around on the housings for numbers like 6cm3 or 8cm3 or similar. These numbers are often found inside the throat (inlet) of the turbine housing and inside the lip of the compressor discharge nozzle on Mitsu's. Those numbers correspond to A/R numbers and are very important to spool and flow capacity (max available power) characteristics.

Once we have these few crucial numbers we can make some determinations. It may be that combining elements of the two units together might even yield the best result, but we won't know without the measurement data.

 

all things being equal, the turbo with the larger compressor will have greater output and spool slower.


12psi is not enough boost to really compare the two. I'm sure if you were logging you'd see you are boost sooner, or should be. the 16g should be making much better mid-range torque. but there are a lot of other factors, but im not that were versed in the mitsu turbos.

 

Well i think ive decided to just run with the 16g for a lil while... i dunno if turbos have a break in period but after a couple days of boosting on it it feels way better than when i first put it on, that along with tweaking the timing. And definetly no logging going on here.. dirty turbo setup.. stock ecu msd retarded boost box and a fmu+a walbro pump. And yeah i got digital mics in my tool box.. if i get to it i need to redo the turbo to mani gasket cus i torqued the turbo a lil crooked and its leaking ill tear both turbos down and feed you all some measurements.