550 Engine Removal

A cold reboot might help.

 

Pete (Moorfan),
The final verdict is....wait for it....commercial break....jury has come back in the room...
hrrrrmmph (sound of clearing of throat)

"one time reuse is feasible but very much at your own risk "

I have polled 6 expert opinions and the jury is split 50:50.
The ones in favor of replace are usually from the racing community with large budgets. The ones in favor of reuse (preferably just once) are the realists running on their own budgets and they have not experienced a problem.

Reasons NOT to reuse would be :
1. You are unsure if the bolts had been torqued to the correct angle (i.e. there is a chance someone over-torqued them). In my case I have a clean engine from the factory with just 18,000 miles.
2. The engine has been rebuilt before and the old bolts were reused
3. You are a garage and you could be liable for the consequences
4. You have an endurance race next weekend
5. The threads, heads or flanges are damaged or the stretch region in the middle is elongated . My Engine Builders Book talks about using a stretch gauge (also mentioned in the ARP tech info ).
6. There has been some other damage in the cylinder that has put stress on the con rod
7. You are of a nervous disposition and cant sleep well
8. Money is no object

Always ready to be the guinea pig, for the sake of the forum, I will make the ultimate sacrifice and reuse them. The bolts are in great shape, they torqued up cleanly as per WSM angle spec, and anyhow the max. torque is less than 50 foot lbs.

Disclaimer: this is not to be taken as advise, it is just my personal decision for my engine.

Regards,
Ron

 

Taz,

"Trashed in Albuquerque" sounds like a good title for a song or movie,

Ron

 

Taz and Brian,

Taz said
"Brian- You may have hit on the important difference in why one says replace and one does not. Titanium connecting rods vs steel connecting rods. Steel is a whole lot stiffer. "

It was John (Cribbj) who said on another forum that the racing guys had reliability problems with the titanium rods in the 550s. But I am not sure I see an obvious connection with bolt resuability.

Regards,
Ron

 

Three times in 3 days I have heard the name, synchronicity. I need to check if Ferrari allow the name to be stamped on the con rods or they keep them anonymous. Must check at the weekend before I put the sump back on.

Regards,
Ron

 

Fibonacci coding in the last 2 pages says:

"We have landed on a section of Groom Lake, Nevada, United States of the Americas. We are preparing to assimilate mankind. We like Ferraris, but do not know how to repair. Continue to work on your cars and you will be spared. You are useful."

Seriously, congrats Ron on your decision. There's an old engineering axiom that if you don't break a bolt on tightening, it will never fail in application. Something to do with Mohr's circle, relaxation and offsetting compression, tensile and torsional stresses.

FBB's silly putty analogy is well taken, but if the con-rod bolts were properly installed, hopefully they never saw 95% of yield strength. They should be good as new.

Of course, I'm not betting $20K on it

 

Mcypert,
Thanks for your moral support, based on parts prices it will be easily $20K to rebuild if a bolt decides to go past the ultimate yield point.
Glad you are in to Fibonacci, as a mathematician by training, I can relate to that. I have seen Fibonacci series in patterns in nature and the stock market but actually I think Rifledriver's mouse was taken over by the Lambo hackers and it did a self right click and selected "view page source".
Regards,
Ron

 

Ron,

You have lots of info we don't have. You got before after bolt length, diameter, oem torque value, grip (smooth part) diameter, distance between clamping surfaces. Being a math guy you can calculate making some assumptions as to steel type 10.9 vs. 12.9 whether at 50ft-lbs you are even in the elastic or plastic range of that bolt. If you find that you are in a sub yield point you could use the bolt as many times as you wanted. Doing the math could help you sleep at night and we would be the beneficiaries of your math. Or pm fchat's mitch alsup and he can probably do the calc's in his head.

 

The titanium rods were a problem for the 355s. If anyone actually raced a 550 with the stock rods they got what they deserved or any other Ferrari rod for that matter. It is hard to believe someone in the racing business actually did that. The rods have been the weak link in Ferrari motors since the 166 and the Pankl rods were no exception. But of all those failures it was not the bolts in properly assembled motors. The Pankl rods break between the bolt boss and the beam.

My 328 has Crower rods. That is how much I like Ferrari rods in general But if you have titanium rods you are stuck with them unless major re-engineering of the crankshaft is undertaken.

Only the titanium rods are supplied by Pankl and the opinion of most is they were never very good. Fine for a street car but to go racing with them is another matter. My own experience and that of others I have talked to as well is that most machine shops don't even want to rebuild them.

I suspect if you really wanted to they could be contacted directly.

PANKL Racing - Online Store - Buy High Performance Bolts & Studs online!

 

FBB,
Not sure I have all the data I would need, but yes I did measure the current values a couple of days ago. But I need 2 more data data points to complete the calcs, what where the bolt dimensions when new and what is the max. yield point , then I know how much it has stretched and how far it can stretch.

Hopefully Dan or Russ can pop over to their parts bins and do the same measuremnts on a new bolt for us.

Then a good rule of thumb would be if it has stretched more than 50% of the max. allowable after the first installation (and 18,000 miles) I would say dont use it a second time. However the elastic yield is non-linear so the assumption that the second 50% behaves the same as the first 50% is not very accurate.

For future reference, here is what I measured:

Thread OD 9.85 mm, thread length 13.7mm
Bolt head 10mm (socket size)
OD of profiled hills either side of the middle section

Diameter of middle stretch section 8.25mm
Length of middle strength section 8.2mm
Head flange ("washer") to start of thread 27.7mm

The last three are the most critical.
Regards,
Ron

 

Ron & FBB:

FBB got me curious. Using F=T/(K*d),

where F is tensile load, T is in-lb torque, K is nut factor and d is dia in inches.

On the back of an envelope, using a WAG of 10mm for bolt size and your 50ft-lb of torque, you get:

For K=.1, stress = 128K psi.

For K=.2, it's half; 64K psi.

K is probably closer to .1, so you're okay with grade 8 bolts. Grade 5, probably not.

More info can be found at:

http://www.fastenal.com/content/feds/pdf/Article%20-%20Bolted%20Joint%20Design.pdf

Can you sleep better now? What's your number? Did you happen to check the T on removal?

Regards....Mark, also in Houston.

Oops, see you gave the d, while I has typing....

 

Mcypert,
Thanks for the article, the stress-strain graph was nice but pity the x and y axis have no dimensions to read off.

I looked at the calculation you quoted but it does not tell me how much the bolt can stretch after one use or second use. Or even whether 50 foot lbs torque takes it past the yield point or not. Plus we do not not much about the bolt material used.

The stress-strain graph shows there is room after the yield point before failure, the transition is relatively gentle from linear through yield point to quadratic for a period. However we dont know if the Ferrari 550 bolt has the same gentle behavior.

I did note that K is half if the bolt is well lubricated.

Regards,
Ron

PS congrats on your 456, I will watch out for it on Beltway 8.
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Ron:

All true. But, take a look at the next graph.

That gives some #’s. Just looking at the curve for grade 8, looks like yield point is about 140 kps. About 110 kps for grade 5.

Also, don’t know your bolt's yield strength… CribbJ and I just happen to be having some email discussions about bolts.

Take a look at this table: Metric Bolt Torque Table - CNCexpo.com

Class 12.9 bolts have a higher yield strength than grade 8 (I think?).

Also note an M10 bolt has a lubed torque spec of 47 ft-lb. Isn’t that the same as our WSM spec?

But, here’s where my model falls apart: The dim’s you gave, especially the 8.25mm necked down diameter, shoots the stress number way up there. Beyond the yield points for any bolt grade I’m familiar with.

Also, your description of your bolts makes me think your’s must be specially engineered rod bolts, like Brian’s PANKL bolts. Not just stock stuff that we can go to a chart for. How those behave is way beyond my pay-grade. Probably should keep my thoughts to myself. Just thought your’s was an interesting problem. Sorry, I couldn’t help more.

BTW, might see ya on 610, I’m mostly a inside-the-loop guy. (For those unfamiliar with H-town, you can drive 50 miles in any direction from the Courthouse and still find folks who identify themselves as “from Houston.” Cribbj, for example, lives about 50 miles from me, up there by Dallas , but we both claim Houston as home. We might be the biggest metro area in the world. And, though it seems Houstonians have overrun F-chat, I’ve yet to see one (Ferrari) on the road since I got mine.)

Regards…Mark from, where else, Houston….
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Mark (somewhere on the 610),
The yellow curve looks like the sort of elongation numbers I would expect, but you are right the Ferrari bolt is something special with its necked down 8.25mm diameter.

If only we had dimensions for a new bolt (Dave at AW Autoparts, Russ at Ferrparts? Daniel at Ricambi? ...).
Regards,
Ron

 

I am collecting all the parts, gaskets and sealants I need for the 550 engine rebuild.
Should I use a copper spray sealant for the head gasket or not?
Thanks,
Ron

PS I hear Dave Helms is the expert on head gaskets...

 

That could start some fireworks!

 

Ron, I would contact Dave & Brian offline for their recommendations, plus the head gasket manufacturer for theirs.

Having said that, if you decide to go with an MLS type gasket (ie Cometic), I would not coat it, but I would follow the gasket maker's recommendations to the "t" for the surface prep. MLS gaskets require a very flat, smooth surface with a finish no rougher than 30 to 50 Ra.

I have had very good luck with Cometic's head gaskets sealing a supercharged all aluminum V8, producing around 2.2x the OEM rated HP. But that application is quite different than our Ferrari engine. The V8 engine is much shorter, and the issues there are the very high BMEP's of the supercharged application.

The issues with the Ferrari engine are probably much the same as with any inline six, the very long head/block, and keeping such a long surface sealed well. In most respects, I would think this is a more challenging sealing application than a turbo/supercharged V8. I would keep this in mind as you're doing your research.

 

Naive question. Why would you do anything here (head gasket) other than the Ferrari recommendation?
Philip

 

For the same reason we do so many other things differently....and Ferrari wrongly...

Alarms, windows, fuel pumps, belts, bearings, intervals, etc....

 

I'm not sure I buy that in this case. True, there are issues that drive us all nuts with sticky plastics and others you highlight. But, with respect, Ferrari has been building high performance motors for longer than any of us. They push the envelope and issues arise, like the 355 valve guides. But what, outside of folk lore, would lead any of to highlight a poor head gasket design or fitment? I have not read lots of stories of blown head gaskets.

Philip

 

OK guys, I confess the "copper spray" question was a lead in to promote a heated debate while I quickly reassemble the bottom half of the engine. The WSM says "do not use any sealant" and removal of the old gaskets confirms that none was applied at the factory. The old gasket condition and seal looks excellent to me. It is a long aluminum cylinder head so one could have expected more problems, maybe Ferrari have this under control after all.

Before dismantling, I did a compression test but not a leak down test and all cylinders were even around 190psi.

I will be using new Ricambi-supplied new head gaskets which I assume are the approved Ferrari replacement part.

So my real question is "would copper spray have any added benefit or provide a negative side effect"? I have read ("on the Internet but not everything is true") that a new gasket already comes with a chemical coating that bonds the surfaces as the head and block first heats up. In which case the copper spray would prevent that process from working as designed. On the other hand, any minor surface imperfections could be handled by the spray - and yes FBB, I see you mention using it in the thread below.

Related thread, well worth reading:

http://www.ferrarichat.com/forum/technical-q/322968-leaking-head-gasket-after-assembly-550-maranello.html

Ron

 

Ron:

Like said, your rod bolt issue is an interesting problem. In fact, whether to reuse the rod bolts is a $2600 question.

To recap, you’ve heard you can reuse the bolts once, but with risk.

We’ve looked at the material properties, which are unknown for the F bolts. Furthermore, the bolts look like specially-engineered bolts and may not behave like off-the-shelve stuff.

For an off-the-shelve bolt, using F=T/(K*d), (cited previously) and stress (P=F/A), we get stress = 178 kps with a K=.12, bolt torque spec of 48 ft-lb and Dmin = 8.25 mm (everything converted to inches, of course). Again, we don’t’ know the F-car bolts’ Yield Strength(YS), but class 12.9 is the highest grade regularly available in metric sizes. Class 12.9 metric, (chrome-moly, I think) have a min YS of about 160 kps.

We don’t want to exceed the YS because that will permanently deform/ stretch the bolt. If you don’t exceed the YS, you should be able to reuse the bolts. But, looks like we’ve exceeded the YS for class 12.9 bolts. If you exceed the YS, even once, the bolt won’t be as robust as new and it’s anybody’s guess whether they should/can be reused.

Your plan is to measure the length of your once-used bolts and compare to new ones. That would tell how much your bolts were stretched by one use. However, we don’t know the tolerance specs for the length of new bolts. Might be more than the elongation of a used bolt.

Here’s a thought: Take one of your bolts and measure the length. (You’re going to have to have a length accuracy of one-hundredth of an inch or better, perhaps, mark the measurement spots and average 3 or more measurements?)

Torque that bolt to spec, remove it and re-measure the length. If you get the same #, reuse the bolts. You never exceeded YS. If you get a higher #, next best case, buy one new $111 bolt (using the scenario that the bolts can be reused once) . Worst case, you need 24 new ones. It’s up to you at that point…..but I think we’d all like to hear what happens.

Of course, if you have already decided to re-use the old bolts, further thoughts on the subject are moot….

Regards…Mark in Houston

 

Mark,
Good logical plan, but I dont like the thought of torque and undo and measure.
I think it will force me over the top of the yellow curve and so necessitate a new bolt anyway. Perverse sort of Heisenberg testing, "measurement influences the experiment".

Anyway I have tightened all up now and have moved on to reassembly of sump and timing covers.
Thanks,
Ron

 

Good luck Ron..... Guess we'll know later as you're now the guinni pig (or would it be Schrodinger's cat) on the reuse-once postulate....

Regards...Mark

 

Following John (Cribbj)'s recommendations , i have been checking out the use of coolant consisting of No-Rosion and RO water (aka drinking water as created by reverse osmosis). Here is what they say about cavitation erosion:


Q. How does No-Rosion protect wet sleeve cylinder liners from cavitation erosion?

A. Most diesel engines (are?) wet sleeved engines. The area where the coolant comes into contact with metal wet sleeve cylinder liners is extremely hot. Localized boiling occurs, regardless of coolant type. As the coolant nears the boiling phase, tiny vacuoles are formed in the coolant solution. The vibration of the cylinder liners from the running of the engine causes these vacuoles to implode. The countless implosions of vacuoles cause the metal surfaces of the liners to slowly erode, causing premature engine failure. No-Rosion contains an ingredient called nitrite, which forms a highly resilient, molecular thin oxide film that protects the metal surfaces of wet sleeve cylinder liners when the vacuoles implode, thus preventing erosion.

(I think by vacuole they mean a small cavity i.e. a vapor bubble in the context of water)
Regards,
Ron