Ok..I know this is a pretty common deal, but if we didn't keep asking questions, life would be boring!!

So, I think I have the stock 21cm housing on my truck.. Thinking about getting a 16cm housing... Will this be a pretty big improvement?? MPG up or down? How much more boost will I probably get if I keep the fueling the same.. I am hitting about 27 psi and 900 on the exhaust temp wot no smoke.. Also, could I install the 60mm compressor wheel upgrade too, or do the compressor upgrades have to go with the housings they sell..

When I chop of the throttle now at wot, the turbo is shuttering pretty bad.. Will it get worse or go away with a smaller housing.. Thanks guys..

 

Changed my housing when I first got the truck. She was a dog before putting the 16 housing on. Very good improvement in spool up speed and power feel. About equal to removing the muffler which I did a week later. Both very good mods. Miliage better. Power better. Temps came up a little still managable. Your other questions I do not know.

 

First, where is your pyro probe? If in the pipe, move it to the manifold.

Second, if your turbo is barking, fluttering, etc, it will get worse with the smaller housing.

Dont look for any MPG gains. You'll drop 50-100deg peak/ WOT manifold EGT, and gain about 4-6psi boost, not much more. I'd venture to say your cruise temps/ boost will be real similar. You're actually at the upper limits of your stock turbo's efficiency map. Most of the upgrades for the H1C have a mapwidth enhancement slot, which will alleviate the flutter/ bark.

 

I cant say how much more boost you will get because at the time, i did not have a boost guage. i can tell you a 16 will bring your truck to life! you will get power much sooner. surprisingly, my egt's dropped by 50-100 degrees. im not sure if that is a typical thing though. i got better millage i cant tell you specifically how much better either due to a broken odometer at the time.

 

there hard to compare. you wont beleve what that 16cm will do to your truck, it will be so less doggy from a dead stop.

 

Pyro probe in the outlet in the mainfold.. I got the 2nd gen intercooler and a nice 3'' intake horn, so I have some good flow goin on.. also a 2nd gen 4" dp.. the funny thing is, it seems to spool real fast now.. I mean it is like a rocket off the line... So I couldn't imagine more..


But the shudder is what worries me, if it gets worse by putting a smaller housing on that won't be good... So the only way to stop that is to??

 

eaither you can roll off the throttle easy or.....?
the mwe slot in the 60mm upgrades help with turbo bark but wont stop it completly

 

If you think its a rocket off the line now then you wont believe it with a 16cm, my opinion is our 91 with a 16cm housing and an automatic spooled up quikcker then my dads 2005 with aFe and straight exhaust.

 

Mine shutters ocasionally when you let off quick after heavy throttle, but it doesn't do it any worse than the stock 21 cm housing. My mileage went down a little, but i think it was timing more than anything, they started blending the fuel about the same time i changed it. Better low-mid power, and it spools way faster...you can hear the turbo now all the time

 

I'd go for the hole upgrade- exhaust housing and compressor wheel/housing.

You could just put a new fuel pin in the truck and an exhaust housing... my DennyT made a huge difference off the line with the truck being bone stock.

M

 

i thought the 91.5-93 intercooled trucks had an 18cm housing

 

some 92s had teh 21.

 

Is that the only difference between a '92 and '92.5 truck?

 

it seems like whatever cummins had laying around in the way of housings is what they put on , MOST 92's had the 21, its more common to see stick trucks with the 18.5 i think, all 93's had the 18.5

all 91.5's had the 21cm and late 92 they got rid of the 21 because of complaints of power. its stamped in the back of the housing.

 

It has to do with the mid-year-92 CPL change. Sometime between April and June they went from the 1351 CPL to the 1579 CPL. Besides the exhuast housing (1351= 21cm; 1579=18.5cm), you had differences in air filter housings (no through bolt on the 1579s), and the 205 VE pump with the CPL 1579.