JLee's 1991 Toyota MR2 Turbo build thread - part 2

[lsd]

I would strongly disagree with this statement.

Any sort of prevailing torque nut cannot maintain a significant portion of their initial preload. See: http://www.boltscience.com/pages/the-loosening-of-prevailing-torque-nuts.pdf
Furthermore, these nuts must be replaced with every use (or every few uses) to ensure proper performance. Metal locknuts can also damage the threads that they're spun onto, limiting the useful life of their associated fasteners.

Safety wire is more difficult to use than most other locking options and isn't strong enough to retain a significant amount of torque in the fastener. Put differently, there's no way a human is getting enough tension in the wire to support any appreciable torque in the fastener, and there's no way the wire would support that tension were it applied. And, frankly, if you've already put distorted nuts on there, the safety wire becomes redundant. I know that safety wire is used in practice, especially in the aerospace applications, but that doesn't make it the best solution for automotive applications.

Both lock nuts and safety wire are really 'loss prevention' solutions, not 'torque retention' solutions. They will do a good job of keeping the nut on the stud, but if any sort of motion occurs between the two parts being fastened then they won't hold the fastener preload very well, if at all.

It is worth noting that any locking technique isn't needed if relative motion between the two clamped parts never happens. Thus a vast majority of automotive fasteners need no locking in order to stay tight for an indefinite period of time.

Please don't take this as a personal attack, it's not. I would love to hear a sound technical argument as to why deformed nuts and safety wire would be the best solution, but lets skip the anecdotal evidence, there's plenty of that on both sides.

I don't have any empirical evidence to back it up anything other than my working day in and out on aircraft. I understand safety wire was't intended to retain torque, but I know from experience .032" ss wire is plenty strong.
I'll give you that using safety wired lock nuts is extreme but with to the quality of consumer level automotive hardware I wouldn't call it crazy.
The pdf you posted refers to lock nuts in only transverse movements. The problem is 1) It gives no mention of metal expansion and contraction due to extreme heat cycling 2)Using a Ni-lock. That study is not suitable at all in this situation.
Consider this: Most aircraft engines are bolted together and mounted on the aircraft with lock nuts, and lock nuts alone. They can remain on the engine for thousands of hours before overhaul.
Yes they need to be tossed when removed but it's a small price to pay for reliability.

 

[JCH13]

I don't have any empirical evidence to back it up anything other than my working day in and out on aircraft. I understand safety wire was't intended to retain torque, but I know from experience .032" ss wire is plenty strong.
I'll give you that using safety wired lock nuts is extreme but with to the quality of consumer level automotive hardware I wouldn't call it crazy.
The pdf you posted refers to lock nuts in only transverse movements. The problem is 1) It gives no mention of metal expansion and contraction due to extreme heat cycling 2)Using a Ni-lock. That study is not suitable at all in this situation.
Consider this: Most aircraft engines are bolted together and mounted on the aircraft with lock nuts, and lock nuts alone. They can remain on the engine for thousands of hours before overhaul.
Yes they need to be tossed when removed but it's a small price to pay for reliability.

Safety wire's strength is very small in the context of holding torque. Typical .032in diameter 302/304 safety wire has a tensile breaking load of about 60lbf given a strength of 75ksi. Multiplied by the radius of a nut in JLee's application, about .25in, it could hold 2*.25in*60lbf=30in*lb of torque (assuming the use of two twisted safety wires). The torque needed for this situation is on the order of 30-50ft-lb, at least an order of magnitude higher.

1) It does not, but if critical thinking is applied one can draw the appropriate conclusions. Re-read the segment on the hydraulic junker test. 2) The paper is done on prevailing torque nuts, not just ny-locks. Yes, there is a picture of a ny-lock, but if one reads the paper carefully it becomes obvious that ny-locks and distorted thread nuts act in the same way.

Considering your example: (1) it provides no evidence that prevailing torque nuts maintain fastener pre-load (2) cars have a tougher vibration environment yet do not use prevailing torque fasteners on engine mounts (3) an aircraft has a different penalty of failure than a car. Prevailing torque nuts and safety wire are popular retaining solutions in aircraft because falling apart in the air leads to death. These methods are simply back-ups to the correct solution: proper fastener tension/torque. This is much easier to get right in an aircraft, which receives considerably more engineering attention and has a considerably better defined vibration spectrum than an aftermarket turbocharger in a car. Simply put - the reason fasteners stay tight in an aircraft is because they are better designed and have properly understood loads with matching torque specs. The prevailing torque nuts and safety wire are there as a backup because of the high cost of failure, not because they improve the torque retention of the fasteners in those joints - they can't.

When JLee had the stock turbo, or even just a smaller aftermarket turbo, these fasteners all stayed tight. I would know, I've taken the turbo off of his car almost as much as he has. The reason nord-locks are needed in this case is because he's way past the original design space for these bolted connections. Nord-locks effectively preserve fastener pre-load, and require a bump in torque to 'un-lock' them, which is why they perform better than anything else in junker tests. Clearly these turbo/exhaust joints are experiencing some level of transverse motion (this is the only motion that loosens bolted connections) because its loosening fasteners. This is because the joints' existing torque spec no longer provides an appropriate clamping force for the added loading of the bigger turbo. Prevailing torque nuts and safety wire would keep the fasteners connected, but would allow for exhaust leaks to develop just like the stage 8 hardware did because neither solution can maintain tension during transverse motion.

I hope I've explained the apples v oranges comparison here...

 

[jlee]

It doesn't leak anymore!

 

[lsd]

Safety wire's strength is very small in the context of holding torque. Typical .032in diameter 302/304 safety wire has a tensile breaking load of about 60lbf given a strength of 75ksi. Multiplied by the radius of a nut in JLee's application, about .25in, it could hold 2*.25in*60lbf=30in*lb of torque (assuming the use of two twisted safety wires). The torque needed for this situation is on the order of 30-50ft-lb, at least an order of magnitude higher.

1) It does not, but if critical thinking is applied one can draw the appropriate conclusions. Re-read the segment on the hydraulic junker test. 2) The paper is done on prevailing torque nuts, not just ny-locks. Yes, there is a picture of a ny-lock, but if one reads the paper carefully it becomes obvious that ny-locks and distorted thread nuts act in the same way.

Considering your example: (1) it provides no evidence that prevailing torque nuts maintain fastener pre-load (2) cars have a tougher vibration environment yet do not use prevailing torque fasteners on engine mounts (3) an aircraft has a different penalty of failure than a car. Prevailing torque nuts and safety wire are popular retaining solutions in aircraft because falling apart in the air leads to death. These methods are simply back-ups to the correct solution: proper fastener tension/torque. This is much easier to get right in an aircraft, which receives considerably more engineering attention and has a considerably better defined vibration spectrum than an aftermarket turbocharger in a car. Simply put - the reason fasteners stay tight in an aircraft is because they are better designed and have properly understood loads with matching torque specs. The prevailing torque nuts and safety wire are there as a backup because of the high cost of failure, not because they improve the torque retention of the fasteners in those joints - they can't.

I hope I've explained the apples v oranges comparison here...

I think we shall agree to disagree.
But I will leave you with this: Nissan uses lock nuts on their exhaust headers, if that study was relevant nissan forums would be filled with posts about nuts backing off. But that's not the case, most issues are related to sheared studs or due to reusing lock nuts. Nissan specifically states to discard removed nuts in their fsm.

 

[JCH13]

I think we shall agree to disagree.
But I will leave you with this: Nissan uses lock nuts on their exhaust headers, if that study was relevant nissan forums would be filled with posts about nuts backing off. But that's not the case, most issues are related to sheared studs or due to reusing lock nuts. Nissan specifically states to discard removed nuts in their fsm.

Anecdotal evidence like that doesn't really count for much. Mazda, Honda, etc. don't use locking nuts on their exhaust and everything is fine until the design space is changed (i.e. a large turbo is added).

As I've explained before: a prevailing torque nut doesn't prevent torque loss. It can't. The torque needed to spin a prevailing torque nut isn't remotely close to the 'tightened' torque of the fastener. You'll note that a nord-lock washer needs to exceed its tightened torque in order to be loosened, which is why they're the most effective solution outside of preventing transverse motion.

We will agree to disagree, acknowledging that you've provided no empirical evidence (as you stated above) or technical evidence to substantiate your claim. I guess there's nothing I could show you that would cause you to change your mind...

 

[slag]

my son and I are looking at a local 1991 mr2 with a blown engine. It has the 2.2 though, so if we get it, we will have to explore options on what to put in it.

 

[JCH13]

my son and I are looking at a local 1991 mr2 with a blown engine. It has the 2.2 though, so if we get it, we will have to explore options on what to put in it.

That'll give you a lot of options, especially is the s54 trans is still good!

 

[jlee]

I installed the intercooler piping in such a way that it didn't interfere with anything (previously it was hitting itself or assorted other things in the engine bay) and thought I was good, then discovered I have a sticky/hanging throttle. The cold pipe is pushing against the throttle cable just forward of the cruise control box, so it's putting enough pressure on it to obstruct movement. It's really difficult to tweak pipe orientation because the clamp on the low side of the intercooler really likes to slip off the coupler unless it's perfectly straight (which makes it difficult to adjust anything). I ordered a 6" long silicone coupler, which should be here today - I am hoping with a little bit of extra length available, the clamp won't slip off and I'll have a little more leeway in adjustment.

my son and I are looking at a local 1991 mr2 with a blown engine. It has the 2.2 though, so if we get it, we will have to explore options on what to put in it.

Gen4 3SGTE swap with the S54 transmission would be a lot of fun!

 

[FuzzyDunlop]

my son and I are looking at a local 1991 mr2 with a blown engine. It has the 2.2 though, so if we get it, we will have to explore options on what to put in it.

Gen4 3SGTE swap with the S54 transmission would be a lot of fun!

Agreed. Gen 4 (Toyota Caldina) is the way to go. If you want info feel free to send me message.

 

[slag]

Does it require an entirely new wiring harness along with the ECU? Sounds like probably a new engine cover as well as wiring, exhaust, etc. Could be expensive.

 

[FuzzyDunlop]

Does it require an entirely new wiring harness along with the ECU? Sounds like probably a new engine cover as well as wiring, exhaust, etc. Could be expensive.

Uses the gen4 ECU. Engine harnesses can be done for around $400 by wiregapinc (highly recommended). Go to www.primemr2.com to see what its all about. Also check my 91MR2 build thread in my signature. If you do all the work yourself its maybe a $1500 - $2000 conversion. The Gen4 is incredible and worth it though. If you want to go full retard you could look into a 2GR-FE Supercharged conversion... do eet... doooo eeeet!

 

[XavierMace]

my son and I are looking at a local 1991 mr2 with a blown engine. It has the 2.2 though, so if we get it, we will have to explore options on what to put in it.

Asking JLee and Fuzzy what they think about buying an MR2 is like asking a coke dealer what he thinks about buying coke.

 

[slag]

So I'm curious. I need to make my decision today on this car. It's a 1991, but I'm not sure if this is the correct engine for the car that's in it. Here are pics.

This is the engine in the car currently that is shot. Notice the distributor coming off the engine at 90 degrees. Obviously he's done some stuff to the engine with a different intake, exhaust, and possibly ignition components.

Here's a stock 2001 5SFE 2.2 cylinder engine that should be identical to what's in the car. Is the distributor turned/mounted differently, or is it just me not being able to fully see the orientation in the first pic?

 

[jlee]

An 01 is a Camry motor and isn't quite identical, though close.That's the normal distributor orientation, though.

 

[JCH13]

Speaking as someone who owns a 1991 5S-FE MR2... that looks like the right engine, with a typical aftermarket header and 'cold air intake.' Ignition components all look original/Toyota, or close enough. The valve cover is the only weird part.

 

[jlee]

My Amsoil order arrived and I sprayed the cruise control linkage with silicone spray. The pulleys spring back to their home position now, whereas previously the lower pulley stuck in whatever position it was left in. The throttle no longer sticks!

I also installed new silicone couplers. The piping all fits much better now with additional length on the lower hot pipe coupler and a hump coupler on the turbo -> hot pipe connection.

 

[jlee]

All good! I am, however, smoking white on cold start and blue on deceleration, which appears to be slowly getting worse over time. I'm suspicious of my valve guides, which rarely fail and were not touched during the rebuild. I may be picking up another head to go through during winter and replace it in spring.

 

[FuzzyDunlop]

Ahya, shitty news. Good call just getting a new head to work on, as they are dime-a-dozen. Allows you to work on it at your own pace and not be rushed to get it back into the car.

 

[jlee]

Ahya, shitty news. Good call just getting a new head to work on, as they are dime-a-dozen. Allows you to work on it at your own pace and not be rushed to get it back into the car.

It is going to be parked for the whole winter, though....so I'm tempted to just pull it and rebuild this one, instead of spending the money on another one that will still need a rebuild (and re-shimming for the cams).

 

[jlee]

Leakdown is good - the engine is very healthy. 8/3/2/6%.

Parked for the winter now, waiting for a head rebuild! New valve guides, 3 angle valve job, and valve springs while it's apart.

 

[jlee]

Starting on this tomorrow! Objectives for the weekend:

Remove cylinder head
Repair climate control slider
Replace passenger side window regulator
Clean/verify battery and chassis grounds
Replace front bumper beam to allow fog light install
Install fog lights
Fix off-center ignition switch (bent steering column...?)
Install new steering wheel clamshell trim

 

[jlee]

I couldn't find some of the parts I wanted to replace - they weren't stored with the car, so I have to track them down. Anyway, completed the following:

Remove cylinder head
Clean/verify battery and chassis grounds
Replace front bumper beam to allow fog light install
Fix off-center ignition switch (bent steering column...?)

I'm going to replace the metal retainer that goes at the top of the bumper cover before it gets reinstalled, so holding off on bumper/fog installation until that part comes in.

Turbo and valve cover removed:

Head and intake manifold removed:

Block looks good

There was something that looked like a fracture by the water jacket, but I cleaned it up and it looks fine:

Bumper cover removed:

Broken bolt

Drilled out and fixed, new-used bumper beam and fog light brackets installed:

The ignition switch has been off center basically forever. Black2na determined that a locating pin was missing on the large cast arm that attaches the ignition assembly to the steering column. He was able to loosen and adjust it so it's where it should be again. I dealt with this for damn near a decade...had too many other priorities to look into it!

Head:

Because organizing is good:

Shims and buckets removed:

I noticed something rather terrifying at this stage. Exhibit A:

Exhibit B:

I'm really glad my engine hasn't exploded. I missed a shift quite a while ago and I think that may have been the culprit (over rev). I was going to replace the retainers anyway, but...I'm glad I had valve stem seal failure to push me into pulling the head so I actually noticed!

 

[FuzzyDunlop]

OMG! That is rather terrifying indeed! Didnt even know that could be possible. Probably a few miles away from major disaster there... damn. Blessings in disguise!

 

[jlee]

OMG! That is rather terrifying indeed! Didnt even know that could be possible. Probably a few miles away from major disaster there... damn. Blessings in disguise!

Check your square shifter bushings so you don't miss shifts, lol. Mine was incredibly worn.

 

[JCH13]

I think that the buckets were keeping the spring retainers together, thank god.