I'm in the process of aquiring an 18cm housing to replace my current 21cm unit. How noticeable will the difference be?

Yes, I couldn've just gone with the 16cm but I don't want to loose any power on tap at highway speeds or loose any towing power or get higher EGT's.

 

don't pay more than $50 for the 18. 16 isn't going to lose you any top end over the 21 and will actually give you lower egts. the 18 will be an improvement over the 21 not sure how much you will feel. do you have a 5spd or an auto?

 

Auto-OD, 3.73s, and the price, well I won't disclose the exact amount but it's less than $20-shipped.

 

16 will spool quicker and run cooler than an 18 and will have better top end.

 

Dan Man,

Not trying to swoop, but where oh where did you find this housing? I am interested in going with a 16, but can't seem to locate one.
.. The 18 would be cool if I could find one for 20 bucks... Good find...

All other guys... How are you searching for these housings? I have looked on ebay and craigs with no luck... Help? Thanks...Jake

 

I think the 16cm is the "magic" housing. I wouldn't waste your time with an 18.5cm.
What's your altitude, about 2k?

 

I don't see how a 16 will outflow an 18 or 21. I understand the boost and spool up side of things but I don't think a 16cm will outflow an 18 or 21 on the top end. Turbos are obviously restrictive by nature so the bigger the housing, the better it will breathe in high RPM's and high boost. And pulling a load, an 18 or 21 would keep EGT's cooler on the top end than something more restrictive. Peak boost numbers arent far apart between 16, 18, and 21 so the few extra boost #'s wont make much of a difference. Obviously the spool up keeps things cooler down low but not the case on a hard pull

 

Good score dan!

 

The 16cfm will get goin quicker. The larger cfm will cool better on the long tow cause your flowing more available air. The smaller you go, the quicker the spool, the less air to get going to get boostin (smaller cavity to fill). Smaller means hotter egts, unless you have a very efficient turbo in conjuntion with a larger intercooler.

 

I'll give up some spool time for lower egt's=more lengevity, especially with 258,000 on the ticker. As for where I found it, well, I ain't talkin.... yet!!

 

well i just recently changed mine from a 21 to a 16, love the difference, and i didnt lose any noticible top end, and any i gained some it seems. but its a good thing to do, dont know about the 18 though, but if its cheep go for it

 

I just changed mine from a 21 to a 18.5. And yes, i got it cheap, less than 20$ shipped. i have a 5 spd but i did notice a diference in boost #s at hiway speed and all around driveability. Yes, a 16 would have been nice but i don't have the 150$ to spare!! I think the 21 to 18.5 swap is worth it. A 16 might be on the horizon someday but this is good too. Good luck ez

 

I suppose if you were turning 6K RPM the 16cm might restrict a bit more. 18.5's don't start making boost until much higher in the RPM band and or at a higher fueling rate (coal train) which raises exhaust temps like crazy in my experience.
Please note that I haven't done a thourough test on this, just watched the difference on my own truck.

 

does the wastegate off a 1994-1998.5 ctd fit on our trucks, do you know what size it is, will the new wastegate help lower egt's, will i have all the sma epower

 

I noticed a difference when we put the 18 on Mom's 92. My 92 came with one, and after running the 14 for a while, I am selling it (already spoken for, so I am not advertising, merely stating a fact). I didnt notice an appreciable gain in boost or spool up with the 14 vs the 18. But, I did notice EGts climbed quicker with the 14 once I got past the mid 20s boost. I imagine the 18 will do the same, as I will be on the upper end of the turbo's efficiency map. When I went back to the 18, I MIGHT have gained 50deg EGT, dropped 4psi cruise boost, and the peak boost is still the same- 34-35ish. In-town drivability is not affected, nor is there any more smoke than before. Keep in mind, boost is nothing more than resistance to flow, so just because you peg a 40psi gauge doesnt in itself mean you are making more power than somene who is only making 35psi peak boost.

If you have a stock truck, and intend to keep it under 250RWHP, and dont do any towing, then a 12 may work for you. It will bolt up to the turbo, you will have to move/ cut the downpipe back about an inch and a half. I wouldnt give more than $30 for a 12 or 14 housing.

Daniel