ok, what do you make of this???? HG Failure....

[jc052685]

We're waiting. . . .

 

Seriously though, I would really like to see it so I can learn something about tuning.

 

I am working on getting them off my MSnS computer. I work 14hrs a day guys. I will get them asap.

[HENRY MACIAS]

Sorry to chime in.

 

I had the same problem with my l28 turbo until a friend of mine who used

to build engines told me that under no circumstances, I should not use

oil on the bolt threads it causes a hydraulic effect on the torque, and affects

torque pounds as well. We were both looking at the pictures and he suggests

that it seems like the proper torque sequence was incorrect.

He suggested that I use a very light touch of anti seize on bolt threads.

[jc052685]

Sorry to chime in.

 

I had the same problem with my l28 turbo until a friend of mine who used

to build engines told me that under no circumstances, I should not use

oil on the bolt threads it causes a hydraulic effect on the torque, and affects

torque pounds as well. We were both looking at the pictures and he suggests

that it seems like the proper torque sequence was incorrect.

He suggested that I use a very light touch of anti seize on bolt threads.

 

Molly lube. Arp says to use it so I do. Tq sequence is corect.

[BRAAP]

My apologies if this comes across as harsh, that is not intention.

...

a friend of mine who used

to build engines told me that under no circumstances, I should not use

oil on the bolt threads ...

 

To not use oil on threaded fasteners that are to be torqued to a specific value when "oil" is the listed lube, and then advising using a different lube without that lubes matching torque value for that fastener is not sound advice. With head studs, oil under the studs resulting in any hydraulic action will not affect stretch of the stud during the torquing sequence, only how deep it gets installed in the head. Proper seating of the studs during installation should be verified and done prior to instaling the head.

 

...

I should not use oil on the bolt threads it causes a hydraulic effect on the torque...

The hydraulic lock you speak of would apply if you pumped oil down the blind bolt hole. Light oil on the threads of the bolt is acceptable and has a torque value associated with it for a reason. Anti seize can and will result in the same hyrdraulic lock issue that oil can give, if either is used inapropriately. Key here is to know what you are doing, do not guess or second guess what is known to work.

 

...

hydraulic effect on the torque, and affects

torque pounds as well...

Yes, hydraulic effect would affect the bolt stretch for a given torque value. Again, key is to know what you are doing.

Regarding bolt torque and bolt stretch. When oil is prescribed for a particular bolt with a particular torque value, then oil is the correct lube to use as its coeffecient of friction matches the torque values given to deliver a specific bolt stretch which is the end result we are after. Changing the lube is not recomended unless specified with a given torque value for that lube. ARP lists two different torque values for their hardware. One spec for oil, the other for their moly lube because each has a different coeffecient of friction which would result in different amounts of bolt/stud stretch for a given torque value. Again, knowing what you are doing is key, do NOT second guess the manufacture of the hardware in regards to the lube to be used, whether it is the OEM, ARP, or other.

 

 

...

We were both looking at the pictures and he suggests

that it seems like the proper torque sequence was incorrect.

 

Possible, but not likely. Improper torque sequence is about as likely a cause as not enough of the correct lube on the bolt threads, AND under heads of the bolts. Most likley detonation was the cause for the failure, the root of cause of the detonation is still under investigation, (awaiting ignition timing tables as that is the most likely culprit on top of the L-series already hyper sensitivity to detonation, covered earlier in this thread.)

 

Hope that helps,

Paul

Edited January 7, 2010 by BRAAP

[Zmanco]

Paul, a quick side question: for the stock turbo head bolts, is engine oil the proper lube to use when torquing to the factory torque specs? Reading your post made me question if I read that somewhere reputable, or otherwise.

 

Hopefully this isn't too big of a threadjack ...thought it was worth clarifying for all of us following this thread.

[BRAAP]

Paul, a quick side question: for the stock turbo head bolts, is engine oil the proper lube to use when torquing to the factory torque specs? Reading your post made me question if I read that somewhere reputable, or otherwise.

 

Hopefully this isn't too big of a threadjack ...thought it was worth clarifying for all of us following this thread.

 

Yes. The "How to modify your Datsun/Nissan OHC engine" book, (the L-series builders bible), by Frank Honsowetz, page 91. Head-bolt threads with oil as well as under the head of the head-bolts. It went on to say that Anti-sieze can be used under head of the head-bolt as well. It did not mention it's use on the threads, i.e. use oil.

 

I don't have a FSM handy to verify if it's mentioned in there or not.

As a professional engine builder, engine fastener torque specs are assumed to be with oil unless otherwise noted, always follow the manufacturer recomendation.

[Ben]

Without oil (or specified lube), the fastener will bind in the threads (and may not torque down properly), probably rust, and then snap off when you try to remove it.

 

I really hate pulling an engine apart that has dry, creaky head bolts...

 

(And where are those maps? It's 0530 Thursday! Get out of bed and upload them! )

[Lazeum]

Without oil (or specified lube), the fastener will bind in the threads (and may not torque down properly), probably rust, and then snap off when you try to remove it.

 

I really hate pulling an engine apart that has dry, creaky head bolts...

 

(And where are those maps? It's 0530 Thursday! Get out of bed and upload them! )

 

 

This is not particularly the reason. The biggest concern as Paul said is you will change the friction coefficient with the lube. Moly lube or motor oil won't have the same properties.

As a result, with the same torque applied to the bolt, you won't get the same tension on the bolt, thus same behavior of the head/engine that could lead to HG failure.

 

A bolt to be efficient has to be pulled until you reach a tension zone close to yielding point (10-15% before to be safe since nothing is perfect and you'll have variations everywhere: dimension but also material properties).

 

You'll be amazed to see that when you torque a bolt to this point, 70% of the torque applied is to counteract friction to turn it. Only 30% (if it is not even less)will be "used" for bolt tension. Change the friction coefficient by 2 (from unlube to lube with moly is probably realistic), you'll have drastic change happening in the bolt.

 

 

Same goes for everything. Suspension bolts are also very important. If you don't torque them properly, they might get loose overtime but they will also allow slippage of components in between each other (you will ultimately shear the bolt leading to failure).

 

IMO, it is dumb to try to torque bolt to torque spec if you don't have the right conditions. Try to torque a rusted bolt to torque spec is useless, bolt should be changed, thread should be cleaned!

The same way, to put some lube where is it not specified will result in a bolt with too much tension, you'll get past the yield strenght and you'll get less tension than expected leading to the same condition! (as soon as the bolt will yield, its section will reduce somewhere)

 

Since I'm in it, by going close to yielding with bolt, you'll change the microstructure of the metal, it might change the strenght of the bolt, torque will then not be similar to obtain same performance (if reachable again!)

So critical bolts torqued to spec (ie close to yielding) should be scraped each time they are untighted/torqued again.

 

In the inductry, we could usually autorized 1 reused of the bolt depending on the criticity of the usage.

 

Critical usually means "deadly" (suspension, steering, braking)

Engine failure is critical for our wallet only

 

Example:

- Bolt used on suspension, no reuse (who wants to see his wheel popiping out of his vehicle???)

 

One more comment on bolts, there're grades to know there properties. So depending on the grade, you'll change how you should torque them (standard head bolt vs. APR is a good example). So to buy hardware store bolt to replace stock bolt is not a good idea.

 

Paul is very right: don't second guess, do what manufacturer is telling you BUT be smart and check correct conditions are met.

 

Hope that helps

 

==> Most of my comments are off-topic, sorry for the OP

[Zmanco]

Thanks Guys, as you guys do this for a living, those of us weekend mechanics without formal training learn a lot from these sidebar discussions.

 

We now return to the originally scheduled programming

[jc052685]

This is what the car was running on. I have done some smoothing and pulled timming for the newest headgasket.

 

[TrumpetRhapsody]

Just off the top of my head.... that's still waaayyy too much timing between 100-185kpa. Needs to drop at least 5* across the board lol

[jc052685]

Just off the top of my head.... that's still waaayyy too much timing between 100-185kpa. Needs to drop at least 5* across the board lol

 

I did. That is what it was running. The new timmimgn map has not been run yet on the street. Fixing a few other things first.

[FlatBlack]

 

This is a conservative table on a flat top motor, but just to show you how different ours are, I've got on 100 kpa:

 

20 22 25 30 34 34 34 34 34 34 34 34

[Zmanco]

Here's my advance table. I've only driven it through about 180% which won't exactly correlate to you as it's referenced to Load instead of MAP and at my altitude, 100% load is around 81 kPa. I'd suggest pulling a lot out (at least 10-15 degrees) above 100 kPa and 3000 rpm and then slowly add it back. Much easier to approach it from below than above - as you are well aware by now

[jc052685]

 

This is a conservative table on a flat top motor, but just to show you how different ours are, I've got on 100 kpa:

 

20 22 25 30 34 34 34 34 34 34 34 34

 

conservative on what fuel?

[FlatBlack]

91 Octane in Arkansas [Map made by Mike in New York for their 91], I get 93 when I can.

 

I'd start out with a map like mine and add timing back when you get a knock sensor, that's what I'm planning on doing. I was actually looking up the KnockSenseMS kit today.

 

 

I'm running a 1mm Fel-pro which should put me around 8.7:1 SCR with a P79 head. Haven't blown anything yet and I've driven the crap out of the car. [Those fuel tables are really old BTW]

[jc052685]

Yeah i am on Texas 93 (which I am told is pretty good)

[BRAAP]

 

That is VERY safe/conservative, and in my not so humble opinion, an EXCELLENT beginning timing curve for an initial tune to start tuning a boosted L6 from!

The only thing I would change is to add more timing in the 2500+ RPM columns below the 80KPa rows, maxxing out at approx 45-48 degrees in the 40 KPa row, (will help tremendously in MPG and tip in throttle response, that's about it).

 

From this point, you should be able to add timing in small increments till power plateaus and/or audible/knock sensor recorded detonation shows on the dyno, (Audible meaning, standing literally right next to the vehicle in a safe location), then back off a couple/few degrees, compensate for varying conditions such as ambient and inlet air temps as necessary etc.

[FlatBlack]

Thank you very much for the advice, BRAAP! I take absolutely no credit for this though - Mike [mikeatrpi] modified this off of Dave's [cygnusx1] L28ET map, after Mike blew a head gasket on the Flat Top F54.

 

I will play with the tables tonight according to your recommendations!! I've just been tuning Fuel until now and I'm just waiting to get some $$$ to get the knocksenseMS for the Knock Retard so I can start adding timing where it counts.

[TrumpetRhapsody]

Here is what i've been running. I combined, averaged, and smoothed a bunch of people's maps, and tweaked it a bit based on drivablity. It's fairly conservative IMO, and will be improved once I get knocksense going.

 

I've only had this up to about 180kpa so far, and it's on my full Turbo motor (F54/P90).