I don’t get it. I put on a 16cm replacing my stock 21cm. Works great around town but the reason I did it was I "though" the 16 would give me an extra boost when I was towing. WRONG this combo does not work towing where I used to tow at 80 with some pedal to spare I’m now flooring the pedal to get to 80 with the same load. I thought I would have gotten some extra UHP to get up hills now I stuck flooring it and just waiting. It’s now cruising at 70-75 instead of 80-85 WHAT Happened???? I’m ready to go back to the 21cm PS: its an automatic.91 intercooled ???

 

From what I've read on the post here, if I understand it right, the 16cm housing will peter out before the 21cm housing on the top end, but will give you more bottom end than the 21 cm housing. I have been thinking real hard about changing mine, but I don't want to smoke the tires, redlight to redlight, I want it to pull like all heck with a load on the interstate and still have some left if needed. I currently have 23lbs. boost at WOT, stock injectors, the pump turned up a little, and straight pipe. New injectors are due in on Tuesday. But running down the road at 60-70 mph, and nail it, it'll get up and go.
Have you turned up the pump, changed injectors, or anything, if not try doing these and see.
Someone will most likely correct me on the turbo housing thing, before very long.

 

Pump daddy, there definitely is something wrong. Dodge went to an 18cm housing for better towing in mid 92. If you have gauges you can tell by the numbers if something is amiss. going from a 21 to a 16 should net you 5 psi increase across the board. If your towing and you smash the throttle and dont have subtantial more boost than your 21, you have a problem.
Could there be a leak somewhere? Have you increased the fuel delivery to match the increase boost? If not your "puttin out the flame" in your diesel. The 16cm housing should not restrict your rev ability until well past 2500 rpms. Mine runs like a scalded cat until 2900 rpms which is past 100mph and that's with or without 4000 pounds of wood in the back! With the proper gauges you can pinpoint where the power went. Lower boost with the 16 over the 21 = leak. High boost; ie, 22-26psi and 8-900 degrees exhaust temp = low fuel. If you get like I get, 25 psi and 1150 exhaust temp, your trailer is in for one hell of a ride! Heat = power. With no heat pushing on the pistons there's not a lot of power. The 16 is great for towing and very good on the top end as well. You'll start strangling the breathing with a 12cm but most definitely not with a 16cm. I have friends with the 16 and the 3200 rpm spring in it and it feels like the truck has a big cam in it now!

 

I agree, there is something not right here..... the jump from a 21cm to a 16cm should be VERY noticable. You should have at least 5-6 psi more boost and you should have it alot sooner in the RPM range.
The 16cm housing is pretty much identical to the 18.5cm housing at the upper end of the band, in terms of heat reduction.
The 16 will likely run hotter once you enter the 28-30 psi range under sustained/heavy load due to some restriction. If you're towing and not making boost or temp you have either a boost leak, or a fuel issue.
Sometimes the boost tube rubbers don't like the added/sudden boost and can spring a leak. Check them all. Did you undo the metal boost elbow at the bottom of turbo and loose or pinch the square cut O-Ring??
Check all clamps, and also, if possible, do a boost check.
Pressurize the inlet to the turbo (from the aircleaner) to about 20psi and look/listen for leaks. Grab a spray bottle with soapy water and hit the intercooler/joints/rubbers etc.

More info on temps and boost numbers too. Last you may be starting to push thru your tranny if you have done alot of miles towing and working hard. Sadly the TC and Tranny can start to give way if the engine is pushing too hard on it...

bob.

 

[quote author=Bushy link=board=9;threadid=21883;start=0#msg204853 date=1067840661]
Did you undo the metal boost elbow at the bottom of turbo and loose or pinch the square cut O-Ring??

More info on temps and boost numbers too.

bob.
[/quote]
I pulled the whole turbo and replaced the Square gasket to the oil line. Your are saying that there is a square gasket in the line from the turbo on both sides? I’ll pull the lines and look for the gaskets. I’m not gauged at this time I “know” you can’t tell anything without them. I was under the impression this mod was straight forth. Pump has not been touched.

 

I think the square gasket Bob was talking about is between the turbo compressor ("cold" side) and the elbow that connects to the outlet. Mine was leaking when I replaced my housing. Definitely a place to start looking.

Hope this helps some.
Carl