Some ungodly force is separating my turbo and manifold please help
08-15-2018, 09:50 PM
#11
That - you're not using the Nordlocks correctly. Your studs are also yielding like was stated.
If you're using M8 stuff like on a T25 turbine, then you are already on the backfoot, as they're *EXTREMELY* marginal on strength compared to the M10 fasteners on T3/T4 turbines. That's probably the biggest downside to T25 turbines in general.
The popular Miata aftermarket M8 Inconel studs will fix it, but they're pricey. OEM Nissan turbo studs are Inconel and go for about $7-8/ea and might fix it. You can also try stock SR20DET turbine nuts and locking plates. Those mild steel nuts won't last at all, nor will off the shelf stainless hardware.
Run no gasket as was mentioned. The tiny tiny amount of leakage is nothing to be concerned with, and it'll help keep things together and not let the gasket blow out. Also make sure you have a large flex section in your downpipe and bracing on the turbo side of the flex to the block or trans.
I ended up just welding my turbine housing to my stock SR20DET turbo manifold after pulling the thing about 5 times and losing track time after blowing it out. It never went on the street because I used pretty exotic materials (tried all sorts of A286, Inconel, Grade 19 Beta phase Titanium locknuts etc.), but at the end of the day, driving the shit out of the car on track would have things starting to fail after 1 day, then the next day on track it'd let go and nuts would start going and studs would be stretched. A few minutes with the MIG welder and it was all good to go! I couldn't TIG the two without cracking, probably due to the high carbon since it was a cast steel turbo manifold and a Ni-resist turbine housing.
Proper fastener materials will probably get you good for street usage, but M8 is really really difficult to make last on track if you push it. It's one of the main reasons I'm going T4 on the EFR I'm going to buy for my MR2 project.
If you're using M8 stuff like on a T25 turbine, then you are already on the backfoot, as they're *EXTREMELY* marginal on strength compared to the M10 fasteners on T3/T4 turbines. That's probably the biggest downside to T25 turbines in general.
The popular Miata aftermarket M8 Inconel studs will fix it, but they're pricey. OEM Nissan turbo studs are Inconel and go for about $7-8/ea and might fix it. You can also try stock SR20DET turbine nuts and locking plates. Those mild steel nuts won't last at all, nor will off the shelf stainless hardware.
Run no gasket as was mentioned. The tiny tiny amount of leakage is nothing to be concerned with, and it'll help keep things together and not let the gasket blow out. Also make sure you have a large flex section in your downpipe and bracing on the turbo side of the flex to the block or trans.
I ended up just welding my turbine housing to my stock SR20DET turbo manifold after pulling the thing about 5 times and losing track time after blowing it out. It never went on the street because I used pretty exotic materials (tried all sorts of A286, Inconel, Grade 19 Beta phase Titanium locknuts etc.), but at the end of the day, driving the shit out of the car on track would have things starting to fail after 1 day, then the next day on track it'd let go and nuts would start going and studs would be stretched. A few minutes with the MIG welder and it was all good to go! I couldn't TIG the two without cracking, probably due to the high carbon since it was a cast steel turbo manifold and a Ni-resist turbine housing.
Proper fastener materials will probably get you good for street usage, but M8 is really really difficult to make last on track if you push it. It's one of the main reasons I'm going T4 on the EFR I'm going to buy for my MR2 project.
08-16-2018, 11:24 AM
#12
I will tell you this. You have holes through the studs and nuts and a piece of safety wire running through that hole. There is too much slop here to hold them tight. You need to have the safety wire setup going through just holes in the nuts and put on in a tightening fashion and ending on another nut, both tightening against each other with the safety wire. Or you could also try this same concept with the way you have the holes through both the stud and nut and the wire being pulled in the tightening direction over to the other nut should help. Look up how safety wire is run on aircraft nuts/bolts and you will see what I'm talking about. No way in hell should they ever come loose with safety wire if done properly. I worked in aerospace for 9 years and know all to well on this subject.
You also need to be using either M10 or grade 8 hardware, depending on if it is metric or standard.
You also need to be using either M10 or grade 8 hardware, depending on if it is metric or standard.
Last edited by Spoolin; 08-16-2018 at 11:28 AM.
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ryiin2 (08-16-2018)
08-16-2018, 12:47 PM
#13
I will tell you this. You have holes through the studs and nuts and a piece of safety wire running through that hole. There is too much slop here to hold them tight. You need to have the safety wire setup going through just holes in the nuts and put on in a tightening fashion and ending on another nut, both tightening against each other with the safety wire. Or you could also try this same concept with the way you have the holes through both the stud and nut and the wire being pulled in the tightening direction over to the other nut should help. Look up how safety wire is run on aircraft nuts/bolts and you will see what I'm talking about. No way in hell should they ever come loose with safety wire if done properly. I worked in aerospace for 9 years and know all to well on this subject.
You also need to be using either M10 or grade 8 hardware, depending on if it is metric or standard.
You also need to be using either M10 or grade 8 hardware, depending on if it is metric or standard.
08-16-2018, 06:20 PM
#14
The shop I took the setup to said this is what they could do, I should have taken my money elsewhere. It's M8, but as other has stated M8 is vastly inferior to M10, however, that's what fits on the flange so I must work with it. People have suggested stronger alloys like that in inconel studs. I don't know what nuts to use that can put up with the heat, regular stainless steel doesn't seem to be enough.
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ryiin2 (08-27-2018)
08-17-2018, 09:52 AM
#15
www.full-race.com has both 8mm and 10mm inconel studs with silver plated A4-70 nuts ( https://www.fullerfasteners.com/tech...ss-steel-data/ ) Inconel is 718, but if you know the sizes, ARP and others also make hardware from Carr custom aged 625+ that's a little tougher than 718.
As mentioned above, the only job of the studs should be to hold the manifold and turbo together, The exhaust manifold and turbo should be braced to the engine and each other, and the exhaust system should allow for flex downstream.
Running without a gasket eliminates a source of flex, but if you do run a gasket, an MLS gasket will allow less flex and will hold up better than anything with graphite or other fillers.
If the studs grow more than the housings, you can use cupped "belleville" washers (in inconel) to maintain tension on the gasket. Use washers spec'd to flatten at 80% of yield on the studs. If the studs grow more than the housings, the washers will "stand up" and keep tension on the gasket or (flange faces) This is even more important if you're running without a gasket. When you torque fasteners, they generate a clamping load by stretching. The "torque" value is an approximation of the clamping load, but accurate measurement of clamping loads require a dial indicator to measure the amount of fastener stretch directly. On a long fastener like a 5" head stud, they may stretch several thousandths of an inch to reach the target clamp load, but on a short stud it may only stretch a few ten-thousandths to get the same clamping load. That means a short fastener's clamping load will change much more drastically than a long fastener as a result of differential expansion between the fastener and the objects being fastened.
As mentioned above, the only job of the studs should be to hold the manifold and turbo together, The exhaust manifold and turbo should be braced to the engine and each other, and the exhaust system should allow for flex downstream.
Running without a gasket eliminates a source of flex, but if you do run a gasket, an MLS gasket will allow less flex and will hold up better than anything with graphite or other fillers.
If the studs grow more than the housings, you can use cupped "belleville" washers (in inconel) to maintain tension on the gasket. Use washers spec'd to flatten at 80% of yield on the studs. If the studs grow more than the housings, the washers will "stand up" and keep tension on the gasket or (flange faces) This is even more important if you're running without a gasket. When you torque fasteners, they generate a clamping load by stretching. The "torque" value is an approximation of the clamping load, but accurate measurement of clamping loads require a dial indicator to measure the amount of fastener stretch directly. On a long fastener like a 5" head stud, they may stretch several thousandths of an inch to reach the target clamp load, but on a short stud it may only stretch a few ten-thousandths to get the same clamping load. That means a short fastener's clamping load will change much more drastically than a long fastener as a result of differential expansion between the fastener and the objects being fastened.
Last edited by djsilverjohnson; 08-17-2018 at 10:08 AM. Reason: clarification
The following users liked this post:
ryiin2 (08-27-2018)
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