I've picked more T3 turbos out the junkyard than I care to remember. Pretty sure the number stands at 5. The previous 4 all dying from bearing failure. At Buttonwillow this summer, we were 18 hours into our 24 hour race and just breaking back into the top 20 when turbo number four gave out. So 7 turbo charged races, 4.5 turbos. That's 1.5 races per turbo. And pretty consistent.
Also, while tuning the MegaSquirt setup, I've noticed the motor seems to run out of steam beyond 4,750RPM. I am thinking maybe the T3 is getting maxed out. It is from a four banger after all. So, I am considering the HX35 as a viable substitute that I can realistically shoehorn into a Lemons budget. Does this sound like a good idea? I think it also gives me the breathing room to pop an 885 head on there later on and bump the redline up to 6,500RPM.
Some questions of the HX35:
1. I've read the internal WG is too small and I would have to go external. True?
2. Is the 12cm housing the right size to get? Seems to be the most common.
3. Does the oil feed need a restrictor to protect the bearings? The T3 didn't need one but the oil pressure was in the higher end of the limit.
4. Where's the best place to find them?
5. The T3 currently hits max boost at around 2,700-2,900. Would the HX35 take much longer to spool or should I expect a similar RPM range?
6. Should I consider something other than the HX35?
Upgrading to HX35
Re: Upgrading to HX35
I wouldn't doubt that the turbo is being oversped and driven into choke which is why it is both running out of steam and dying prematurely (in addition to it being a junkyard turbo).
ianwood wrote:Some questions of the HX35:
1. I've read the internal WG is too small and I would have to go external. True?
As a general rule of thumb, I have seen this to be true. IIRC the wastegate only "vents" from one volute of the twin scroll housing which is why it has problems with boost control. You are almost always better off running an external gate if you can.
2. Is the 12cm housing the right size to get? Seems to be the most common.
That seems to be pretty common with what the e30 guys are running on their m20s
3. Does the oil feed need a restrictor to protect the bearings? The T3 didn't need one but the oil pressure was in the higher end of the limit.
Your best bet is to monitor pressure to the turbo and determine max pressure near redline and then see if it needs a restrictor. Every setup is different and can will affect pressure seen at the turbo. Below is from the Holset repair manual.
The minimum oil pressure when the engine is on load must be 210 kPa (30 lbf/in2). Maximum permissible operating pressure is 500 kPa (72 lbf/in2) although 600 kPa (88 lbf/in2) is permitted during cold start up. Under idling conditions pressure should not fall below 70 kPa (10 lbf/in2).
4. Where's the best place to find them?
Ebay, Dodge forums, truck salvage yards.
5. The T3 currently hits max boost at around 2,700-2,900. Would the HX35 take much longer to spool or should I expect a similar RPM range?
From some dyno plots of an hx35 on an m20 grabbed from google, it looks like it will hit later than that.
I have no idea what housing they were running in the above plots but my guess is that it will have a boost threshold somewhere in the 3500-4k range.
6. Should I consider something other than the HX35?
There aren't a whole lot of junkyard options that are sized anywhere close to appropriate. Just keep in mind the turbo sizing that TCD uses (which is a T4 turbine and T04e compressor) which is larger than most production turbos. A Holset, while not optimal, would probably get the job done.
