Quote, originally posted by enginerd » regardless of pressure ratio the bearing sections on the turbos are not designed to run these high temperatures and will suffer a seal or bearing failure prematurely compared to a borg warner or garret turbo designed for 1850 - 1900F temperatures.
You guys can try to build cheap turbo kits with massively oversized and mis matched turbos but you will end up with mediocre setups hitting boost 1000 rpm later than desired, and top ends limited by the balance of your setup. It's worth the extra money for a better matching turbo. You will enjoy driving it more.
UPDATE: Limit Engineering, a Garrett performance distributer, returned my inquiry about the maximum operating temperature of Garrett ball bearing turbos. He states:
Quote, originally posted by John C. Craig » There is not a pat answer to your question. There are many variables. The material that the turbine wheel and turbine housing are made, is it water cooled, the application. As a rule of thumb, for continuous operation with a GMR235 turbine wheel, we do not recommend that you exceed 1400 F.
John C. Craig
Limit Engineering, Inc.
Garrett Performance Distributor
So, accoring to John at Limit Engineering, you should not exceed 1400 degr. F while using a Garrett turbo. This happens to be the same maximum operating temp. advised by Holset for their diesel turbos:
Quote, originally posted by James Moorhouse » The maximum operating temperature of our turbochargers varies but they should not under any circumstances exceed 760° Celsius.
If you have any further questions, please do not hesitate to ask
Cummins Turbo Technologies Ltd
St Andrew's Road
Tel +44 1484 832637
Fax +44 1484 440385
760 degr. C is 1400 degr. F. So, based on the above statements, there is no difference in the recommended maximum operating temperature between the Holset and Garrett turbos. Therefore, the concerns you raised about using a diesel turbo on the 1.8T are a non-issue as far as bearing failure, etc. due to the high temps. that the 1.8T generates. Also, it is not true that Garrett turbos are designed for 1850 - 1900F temperatures, as the above statement makes clear.
Quote, originally posted by enginerd » Diesel engines run 400F lower EGT's. They don't like the 1700 - 1800F EGT's that the 1.8T can generate. The burn takes place in the cylinder rather than partially in the exhaust. Generous EGR (water cooled on new tier 4 engines), and excessive airflow cool the egt's on a diesel.
I regularly see 1750 EGT's pre turbo on my stg III+ at the track and even touched over 1800 when running a bit lean. Water / meth does little for exhaust temps (I have an aquamist kit), high concentrations of methanol can actually increase EGT's.
EGT logs, please. Would like to verify.