Engine/Transmission (1998.5 - 2002) HTBG 12cm vs. 14cm Test results

[Clmsnow]

Well, after talking with many people here on the forum and the guys at HTT, I decided to try the 12cm housing. I was bothered with the lag the turbo had when I first put it on and wanted to gain some of that low end back. Some suggested bigger and better injectors to help the light up the turbo quicker. This is still an option and will happen some day(sooner thn later) but for now I wanted to maximize what I have and try the 12cm to answer the question myslef. I just put it on last night so I only have a few miles on it. So far it seems to spool quikcer, which I expected, and seems to smoke a little less. With the Comp on 2x2 I hit 1077* EGT and 33. 6psi boost. The highest I had hit for boost before with the 14cm on 5x5 was 35. 5psi. I checked over things at lunch and will crank it up a little more this afternoon to see what it does. So far so happy... we'll see how the gauges look on 5x5 this afternoon. I kind of use 5x5 as my number to know what my max can be... and I have it recored already for the 14cm. I really noticed the probelm a few weeks ago at elevation. Lag was very noticeable, EGT's were high and boost was low. I will be at the same location(7000ft) this weekend to see how it compares. I will hang onto the 14cm until I decide which I like. HTT also said should I like the 12cm and add more fule later, I could trade into the larger compressor of the HTB2. I will report back with more results this afternoon.

 

[Clmsnow]

Ran it on 5x5 for a little on the freeway. Exact numbers from before with the 14cm for the same outside temps and driving conditions were..... 1315* EGT, 34. 5 psi. Just right now, with the 12cm... . 1303* EGT, 34. 3psi. I was surprised I didn't get higer boost readings then 34. 3. I use to get over 40 with the stock turbo; granted different animal. I may have turned the actuator rod the wrong direction when I was installing it last night... I had to flip it over to allow the air line to the compressor to reach... but I think that just affects the wastagate. I also thought the boost would be higher compared to the 2x2 setting from 5x5. I'll report more back tonight after I really have a chance to lay into it.

 

[PC12Driver]

Sounds like you're hitting the wastegate if your numbers are that close between levels 2 and 5. Check with HTT and see what they suggest for a few more PSIs (adjusting the actuator rod?). That turbo should be good to the low 40's. But then again, since your temps are safe, you may not want the extra psi's yet. The extra boost would just be extra wear and tear on the components (specifically the headbolts, headgasket, and turbo). Save the extra psi's for the M4's...

 

[Clmsnow]

Still seeing the same thing... only about a 2-3psi boost difference between 3 and 5 on the Comp. I'll try more in the morning. I can still make it smoke the same from a stop is I try... however, if I really lay into it... there's a big cloud of smoke but it seems to clear faster then before. Seems to build boost quicker, just not that high of numbers.

 

[Clmsnow]

Here are some more numbers. On 5x5 this morning I was hitting 1289* EGT and 35. 8* psi boost. Seems to be quicker then the 14cm from what I am gathering. Still figured boost would be a little higher, but outside temps have been well over 100* lately. I spoke with HTT this morning and they told me the turbo would be better closer to 40psi. They told me how to adjust the actuator to get anohter 4-5psi out of it. They seemed to think the turbo would be more effecient at that range.

 

[BDR]

Sounds like your getting it all figured out. Congrats man, glad it's working out for you. So what do you think of the 12cm housing so far?

 

[Clmsnow]

So far I like the 12cm housing. It seems much easier to drive around town. I think the smoke is the same on the bottom, but does clear up sooner when you get on it. I think when I get the boost up a little more it should run even better. The big test is this weekend at elevation... it was very noticeable there before with the 14cm(lag).

 

[Clmsnow]

I ma continuing to get more and more time on the 12cm. As of now I can't find anything about it that is worse then the 14cm. So far everything seems to be better. It defintately spools quicker and is much easier driving. I was concerned that tmep smay be a problem, but tonight, on 5x5 on the freeway I hit it at about 45mph and ran it up to 95mph. Never got much over 1230* EGT... boost was right about 32-34. Pulled pretty good. So far much happier. I'll report more after this weekend and then I'll look into bigger sticks.

 

[BDR]

That's great! I can't wait to upgrade my turbo, definitely goin the HTB route.

 

[Clmsnow]

I was able to put some miles onthe 12cm this weekend. I took the truck up above 7000ft to see how it did compared to the 14cm. The long of the short of it is that the 12cm got about . 5-1psi more boost at elevation and EGT's were nearly identical, if not a little lower. Basically I was pretty happy. It still has some lag to it up there but not as bad as the 14cm. I notice the truck runs pretty good with the Comp on lower settings... 2x2 at elevation. On 5x5 it takes awhile to spool. Overall happy with the 12cm and sending the 14cm back.

 

[BDR]

Glad you got it figured out, congrats man.