CHRA/turbine bolts relaxing.
#221
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The turbine bolts do NOT see exhaust, at least not on my housing. When I trashed the first CHRA, one of the bolts broke off in the housing. I passed it off to a machine shop for extraction because they weren't through-drilled - if they had been I would have just drilled straight through the broken bolt and retapped.
Nimonic is a nickel superalloy, just like Inconel - this assumption that it's going to be easier to machine is likely a pipe dream.
edit: Scratch that, it is a pipe dream. I don't have time to go through every alloy, but I just checked Nimonic 80A on the manufacturer's website and it all but says that "this **** is a bitch to machine."
Nimonic is a nickel superalloy, just like Inconel - this assumption that it's going to be easier to machine is likely a pipe dream.
edit: Scratch that, it is a pipe dream. I don't have time to go through every alloy, but I just checked Nimonic 80A on the manufacturer's website and it all but says that "this **** is a bitch to machine."
#222
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Both times the problem has cropped up for me have been at Calspeed. At Calspeed, I spend approximately 30 seconds at full boost in 5th and 6th gear, always above 5800rpm, and for ~15-18 of those seconds I am at 7300-7400rpm in 6th gear. The first time, it was very abrupt - suddenly no boost, like it had popped an IC pipe. Second time, it was VERY gradual - there was a slight metallic squeaking noise that I chalked up at the time to a loose fender bolt. I didn't realize the extent of the issue for 2-3 events after that.
Inconel for the creep resistance, safety wire for the vibration.
#223
False. If you're a faster driver, you are at higher RPM for a longer period of time. It's not just heat.
When I was working at a co-generation plant with a steam turbine, the instructions for power-up were to never dwell the RPM within certain "critical" ranges. You were supposed to ramp quickly through them.
A fast vs. a slower driver would be equally likely to dwell through resonant RPM ranges. A fast driver *will* burn through more fuel per sessions and thus will bring the hardware to higher peak temperatures.
The type of track would have a much bigger effect than the skill of the driver. A very high speed track would make the motor take much longer to climb through the rev range due to the higher gears involved, and would thus dwell at critical RPM's for much longer.
I still think the simple slowly rev it up in neutral test will show any strong resonances.
Inconel studs, resbond, Stage 8 lockers = total success.
BTW did the Resbond help by preventing the studs from backing out?
#224
I would like to postulate that, although the vibration is what causes the inconel to back out, it requires that the part and bolt in question heat up differently and expand at rates that are ideal to "loosen" the bolt before the actual "backing out"/counter-clockwise rotation of the bolt occurs. This would suggest that a street driver, driving at the same RPM range as the track driver, may never heat the turbine housing enough that the threads of the bolt loosen by thermal expansion, and therefore the bolt will not be able to actually rotate to "back out" by vibration. The street driver's bolts simply stay tight enough that they never become loose enough to actually begin turning by vibration/resonance.
#225
The turbine bolts do NOT see exhaust, at least not on my housing. When I trashed the first CHRA, one of the bolts broke off in the housing. I passed it off to a machine shop for extraction because they weren't through-drilled - if they had been I would have just drilled straight through the broken bolt and retapped.
#226
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I suspect that on some housings, the CHRA fastening bolts don't go all the way though. If you want, I can take pictures of the housing I have in the garage showing that all 6 holes go through and expost the bolts to direct contact with exhaust gases. Are you and Hustler running identical turbine housings? He did admit that his see direct contact as well.
#229
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lol @ your old .64 paperweight still floating around on a delivery truck or a shelf, somewhere in America. I remember that fabled day, working in Little Rock, Johnwag on his way up to pull my broken car back to Dallas, calling you and finally Tim in desperation to get something reliable in my car...that's back when we were young and dumb. Look at all the wisdom we've gained since then.
#232
TiAL. They now come standard when you buy a turbo with their turbine housing too. They've made a few different styles the first of which did come predrilled for safety wire. I've taken a sample of each and ran 'em thru Jesel's SEM/EDS xray detector gizmo to get the alloy content, results posted in this thread. 30Rc.
#233
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I wouldn't be surprised if tial changed the bolts again. They've done it a few times already. Would black oxide bolts be an improvement over stainless? They certainly don't have the CTE of stainless but still don't have the temp rating of inconel.
I checked the 3 tial turbine housings I have here, two .64a/r GT30 and one .63a/r GT28, none of the holes go thru into the gas stream.
#236
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I may offer a service where you send me your bolts and I'll attempt to drill them. The price is not set yet but it will probably be $40 if you bought a setup from me and $80 if you haven't. Plus shipping, flat rate box is $5.
#237
Those look like the newest tial inconel bolts. You're good.
I may offer a service where you send me your bolts and I'll attempt to drill them. The price is not set yet but it will probably be $40 if you bought a setup from me and $80 if you haven't. Plus shipping, flat rate box is $5.
I may offer a service where you send me your bolts and I'll attempt to drill them. The price is not set yet but it will probably be $40 if you bought a setup from me and $80 if you haven't. Plus shipping, flat rate box is $5.
What are these supposed to be torqued to, and are we supposed to be using thread locker on these?
#238
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My safety wire advice you can disregard if you already know this:
This is bad:
Notice how mine is tight?
I started wire across the little flanges, another fail safe considering that if one flange loses both pieces of hardware your housing with either warp, cause turbine contact, or more likely you'll have both.
I twist more than most recommend, to snug the wire up to the outer edge of the bolt head, count the # of twists for future reference, run through the next bolt, then twist to 8-10 twists per inch to increase tension.
Wire tight, break a few to find the limit. You're working with inconel and everything you read on the interweb is about wiring soft SS in light duty applications.
#239
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I am pretty sure I will be successful. I did 4.5 the other night but they were the shorter 8mm hex versions like the one's i pictured above. So for the 10mm hex versions if I use one drill per 2 bolts I should be able to do it quickly without drilling from both sides. should...I still have to order more of that particular drill and try it.
I don't know the torque but I can guestimate if I do math. you'd need a trick torque wrench to measure it though. I'd make it as tight as any other bolt with a 10mm head on it. Inconel is pretty strong. I love that icon.
I don't know the torque but I can guestimate if I do math. you'd need a trick torque wrench to measure it though. I'd make it as tight as any other bolt with a 10mm head on it. Inconel is pretty strong. I love that icon.
Last edited by TurboTim; 02-28-2011 at 11:19 AM.
#240
Thanks for the link to the wire.
What is an EDM shop (Electrical Discharge Machining)? I'm looking around locally for a machine shop that can drill them. I'm not in this type of industry at all, so I'm not exactly sure which shop can or cannot handle them...even if they say they can.
Were those regular SS bolts that you had come loose, hustler?
What is an EDM shop (Electrical Discharge Machining)? I'm looking around locally for a machine shop that can drill them. I'm not in this type of industry at all, so I'm not exactly sure which shop can or cannot handle them...even if they say they can.
Were those regular SS bolts that you had come loose, hustler?