my 20b serial number is 53 (yes, very early). I hear that old 20bs have a problem with the eshaft that tends to flex excessively under boost. My question is, what did Mazda do to fix it, and at what engine revision? I also heard that changes were made to the intermediate and rear housings. What were the changes? Thanks.

 

http://www.dmrh.com.au/jc_series2.htm





-Ted

 

thanks for the good read

 

an_juan I've got you beat I have a #042 as far as the flex in the e-shaft, this is what DMRH told me today:



G'day from DMRH



Thanks for the PM regarding the 20B issues. As you have a first batch run engine, you may have issues with the shaft run-out depending on the engine KM. They where prone to flexing due to the "snap torque" of the twin turbo's around the 2000rpm area when the engine is under high lateral load.



If you are going to use the twin turbo's in a sequential operation then be aware of this factor.



If you intend to use the engine with a large single turbo (suspected) then this problem may never arise. The high load of the shaft will not cause a proble at high RPM were the single turbo is making power as the rotating inertia will counter any lateral forces.



All this is true as long as the shaft is perfect to start with. If the shaft is already out of spec, then you will destroy the engine every time you try to make power no matter how many times you rebuild with the same shaft.



If shaft issues are apparent, then a new one can be obtained via "Precision engineering" in NZ or contact Alec Bell from "KiwiRE" also in NZ. Do a search for there contacts.



REgards

Dave Morris

 

sweet ! I have a single turbo (gt42r). This is what I wanted to hear. Thanks 20b 3rd gen.