Torque value rod bolts titanium conrods

[Spyder22]

Who knows which torque setting to use when tightening the steel bolts on Porsche titanium con rods for a 3.0 SCRS engine?

[sww914]

I would talk to the bolt manufacturer for torque specs. I would carefully evaluate anything that you get from an internet board on a spec this important and far from stock stuff that everybody knows. That's a lot of money spinning around really fast to be taking any chances with.

[MBEngineering]

HI Leonard
the rods are defiantly TI and not polished steel as in the 954 spec' book, with std big end bolts (914 103 171 00) , std nuts (901 103 173 00) the rods are 930 103 015 01 . do you have a TI washer under the big end nut to tighten on to, TI rod usually have TI bolts, washers and steel nuts?

regards mike

[Spyder22]

Mike,
Picture attached. Don't have the part number handy here... Were on the other side when I took the photo. I weighed them and they are around 460 grams if I recall well, at least 50% lighter than the steel items. Bolts are NOT titanium. What do you think?

[MBEngineering]

HI Leonard
I have no torque settings for the 954 in the info I have, the std torque for the steel big end is 55nm and also for the 935 TI rod bolts with lube, I would double check that 55nm is correct, the part No for the rods in the 954 parts list is not a STD part so the TI rods look right, in the drivers info section it says polished steel?? and STD big end shells, but yours look like shouldered shells??

regards mike

[Flieger]

I agree that the Titanium rod bolts would be best to not constrict and overstress the Titanium rod and cap due to the different expansion rates of the metals. The bolts should be Titanium but the nuts steel to keep the nuts from working loose after the thermal expansion cycles.

[Spyder22]

Mike,
The big end shells are indeed shouldered. I don't know what you mean by the"drivers section"; have you seen similar parts offered on the internet? These are not parts offered by me, but a set I acquired a month ago together with an SC RS crankshaft. The set is a true work of art.
I'll get the part numbers for your information and I'll double check the TI vs Steel bolt story. What I'm not convinced of is that the bolts MUST be TI as well. You see many different types of rod bolts used with steel con rods and I'm sure the metallurgical composition is completely different.... I'll be back and thanks very much so far. Stay tuned!

[MBEngineering]

HI Leonard
the drivers section I refer to is from the 954 info' I have , driver's /car info' manual and parts list



as you can see the line drawings do not describe the parts to well?




the parts in the list above that have a "x" are std' parts




as you can see from the list bellow , the rods are listed as steel with std, off the shelf bearings, as the list above



if you have a part No' on the rods you have that is any where near the part No' above , the rods you have could just be 954, not having pulled a 954 engine apart, only a gearbox I could not confirm steel or TI.
have you checked the rods with the bearings fit the crank??
I have made a request to my OPC for some info on the 954 rods on the part No' above, it is not a std part as it will not come up on there parts list, will let you know the out come.

regards mike

[Spyder22]

Hi Mike,

Very nice of you to put these images on the thread! The con rods do not have a part number on them but are definitely titanium... I thought I didn't have them in the picture because they were on the other side, but no. I just checked them but no number there... The bolts turn out to be titanium after all and the nuts are steel. Used magnet.

Rods fit the crankshaft perfectly. Crankshaft is of 954 and has the 9 holes for the flywheel. You show that the 954 rods had normal bearings and not the shouldered ones. Perhaps the origin of the rods is an earlier model? 935?

[racing97]

I don't even know what I 954 is but I used to build 935 engines and that is what you appear to have. The rods and bolts are Ti we used the bolts for the initial build and one rebuild and torqued the bolts to .007 thousands stretch with out exceeding 36 flbs. If the bolts did not strech we considered them unuseable. The bolts themselves were very hard to remove and we used a similar product to the pankyl lube for torquing.
These rods were somewhat notorious for being out of round on the big end. You should torque them up off of the crank and measure the big end for roundness to whatever torque you are using.

regards

[MBEngineering]

HI racing97
have a look hear

1983 SC/RS questions

I would agree, the rods do look like 935 from what I remember, the crank could be out of a later 935 engine with 9 bolts?? as the crank in the parts list is a std part No'

regards mike

[paulweir]

55nm is correct 935 ti rods use the same torque spec as stock rods.