Hi Will,

I have to agree with your thoughts on the cost of those bolts for the application that the company has spotted a possible market and it being a little bit ridiculous.
I bet Volvo never even got close to requiring bolts like those or their per unit pricing!

I read on into their spiel for the “non engineer” about metallurgy with their special steels provided to NASA.
I saw let them being made with stainless steel with a grade of 10, of which, from my experience means a certificate of the metals batch origin is required on some contracts.

The key word here is the sales pitch for “Racing” and the lure for those bottomless money pockets!

No matter what you do to a production car, that is made for any number of populist customers!
This car is a street level Volvo!
It’s not going to be treated like a military jet engine or on a top end speedway for a few hundred miles, while only requiring a left hand turns!
Like I said, in my earlier post, those bolts only keep the rods from flying off the crankshaft.

The whole TTY (Torque To Yield) thing is being over emphasized as ruining bolts!
It is a method of applying a maximum strength stretch or torque with a margin of safety built in!
Ultimately you don’t want to break a bolt on installation and you have to consider its environment.
Head bolts get more heat than the rod bolts will ever see and still get used twice!

All torque methods apply stretch rated to the thread capacity related to its engagement into a material used. A rule of thumb, used in my relationship with engineers of my era, is that the maximum strength of any thread is achieved at a specification of engagement. It is the diameter is multiplied by 1.5 time to give its length needed to have the “bolt head to snap off” before the threads strip out!
Machine taps are made alone those lines too!
Bolts are made with some longer threads mostly for the application of nuts or it’s considered an adjusting screw! In the case of the 240’s alternator adjustment screws.

This company’s bolts are being used in aluminum here and the aluminum cap of the connecting rods cross section, is thinner than the bolts are of stainless steel!
When or how does the bearing cap going to get that much tensile strength forces applied?
Does Volvo use even stainless steel to begin with?
Most bolts on cars are grade five.
Farm tractors and commercial equipment use grade eight. In some cases with giant torque wrenches!
On steam turbine cases, that have 3” diameter studs, that get heated internally and nuts turned so many degrees and remeasured. Another torque method that doesn’t ruin threaded bodies!
Their used over and over for many many years!
Again, safety factors are reached by laboratory tests!

ARP has to have to have their own in house reliable certificates for NASA or government contacts!

I doubt a 850 owner wants to go that far, but the moon is 240,000 miles away!
I feel that the pocket book is more down to earth in this case! (:-)

Thanks for the sites technical reading material, even for ordinary folks that like a racing sales pitch!

Phil, a 240 man!