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Author: Subject: Hardening steel
mark chandler

posted on 2/2/19 at 06:35 PM Reply With Quote
A bit more experimentation today, heat to 840 degrees for an hour, water quench and temper @ 340 degrees for an hours soak, now my stud strips the threads out of a hardened nut cleanly @ 7 tons with no deformation on my machined threads so now awaiting a set of ARP nuts to arrive so I can see where the fail point is with these.

The threads were a good fit before hardening, after the nut felt a like they had a little play so tomorrow I will try cutting the threads in hardened metal in an attempt to retain closer tolerances.

The thread depth by my DRO was 0.77mm, from the various tables I should be 0.77978 I assume as I am using the same bit of round for my experiments it may have reduced slightly with the constant heat cycles.

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daviep

posted on 2/2/19 at 07:36 PM Reply With Quote
Excellent thread and I completely agree with your ethos on trying to do it yourself.

One question, what are the HSS nuts and bolts are you referring to? Presumably they are not High Speed Steel!

Cheers
Davie





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mark chandler

posted on 2/2/19 at 08:35 PM Reply With Quote
This is the description

"high tensile, UNF full, hex nuts" they seem pretty good quality, 1/10th the price of ARP, I have 20 of these on route delayed due to snow so will be able to see how far above 7 tons I get.

When you look at the thread engagement it's amazing that they can sustain 7 tons of hydraulic pressure pushing the stud through the nut!

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daviep

posted on 2/2/19 at 11:35 PM Reply With Quote
It maybe that you are using normal grade 5 nuts which are the imperial equivalents of metric class 8

It would be interesting to compare the results with a known grade 8 nut (equivalent of metric class 10).

7/16" Grade 5 nut should be good for at least 6400kgs
7/16" Grade 8 nut should be good for at least 8100kgs

Cheers
Davie





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mark chandler

posted on 3/2/19 at 12:09 AM Reply With Quote
As someone noted earlier on, also the depth of engagement, bang at 7 imperial tons makes them grade 5 I guess, I was able to spin the thread off the stud as a spiral.

The ARP nuts should be tough, not sure how PSI compares to ton as it's rated sq/inch

Brand:ARP
Manufacturer's Part Number:301-8354
Part Type:Nuts
Product Line:ARP 12-Point Nuts
Summit Racing Part Number:ARP-301-8354

UPC:672036040864
Thread Size: 7/16-20 in.
Nut Style: 12-point
Nylon Insert: No
Self-Locking: No
Wrench Diameter: 5/8 in.
Nut Material: Steel
Nut Finish: Black oxide
Washers Included: No
Fastener Yield Strength (psi): 180,000 psi
Quantity:

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daviep

posted on 3/2/19 at 08:51 AM Reply With Quote
For comparison

Grade 5 - 120,000psi
Grade 8 - 150,000psi
ARP. - 180,000psi

7/16" unf has a stress area of 0.1187 sq in

so for ARP nuts

180,000 * 0.1187 = 21,366lbs or 9712kgs

Regards
Davie





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Oddified

posted on 3/2/19 at 09:04 AM Reply With Quote
quote:
Originally posted by daviep
For comparison

Grade 5 - 120,000psi
Grade 8 - 150,000psi
ARP. - 180,000psi

7/16" unf has a stress area of 0.1187 sq in

so for ARP nuts

180,000 * 0.1187 = 21,366lbs or 9712kgs

Regards
Davie


Nearly 10 tons..i think you'd have to be running some serious boost to need that per stud.

Ian

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mark chandler

posted on 3/2/19 at 12:17 PM Reply With Quote
It also has 14 of these pulling down the head, 12psi today, I am hoping this will drop when the ported head goes on as the Eaton is just stirring air, pressure is just what's being backed up in front of the valves.
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Oddified

posted on 3/2/19 at 01:40 PM Reply With Quote
From what i've seen/experienced most Eatons are best kept below 10psi, exponential diminishing returns above that with heat and power loss.

Ian

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mark chandler

posted on 3/2/19 at 06:22 PM Reply With Quote
The inlet heat is pretty much out of control, I have a decent sized intercooler which I had recored a few months ago, it's better but after a 15 seconds at WOT the inlet temperature jumps 40 degrees - much better than before... It recovers quickly although I need a new front charge cooler radiator.

I,m hoping with a much better flowing head to see a drop in inlet temperatures as its will not be having to work so hard, I have ported it as far as I dare go which made a decent improvement.

With the size of pulleys it's running at its limits, I did think about modifying a m112 to fit however research shows that these are very inefficient at moving air fast, okay better at lower RPMs

[Edited on 3/2/19 by mark chandler]

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mark chandler

posted on 23/2/19 at 04:53 PM Reply With Quote
Slow progress on this as I have been awaiting ARP nuts to test my thread strength, 12 arrived on Thursday with more on there way - ARP nuts are lovely compared to the other ones I have.

Today I heated 2 short lengths of EN24t to 840 degrees C and let it soak for an hour then quenched in the correct oil, both came out nice and hard.

Next I machined one in the hardened state with a really good fit, the other out to one side then tempered both at 400 degrees C, which gives W grade hardness - researching TWR had their own studs for racing XJS's, they used W hardness 9/16 studs.

I now threaded the heated and tempered sample and moved to destruction testing, it did not pan out that way as both can withstand over 10 tons of pressure, I will make 14 studs tomorrow , threading then annealing to stress relieve.

Head is not due for a couple of weeks so I will clean the injectors and flow test using an old pump and regulator to see if they are good for another year.

I asked ARP to quote for rolled threaded studs, they showed zero interest in making anything, either contacting directly or via an agent so Hobson's choice, "We make some for XK engineering, call them" unsurprisingly XK engineering do Jaguar XK engines not AJ16 so a complete waste of time.

[Edited on 24/2/19 by mark chandler]

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britishtrident

posted on 23/2/19 at 08:29 PM Reply With Quote
Everybody misunderstands stretch bolts, once a stretch bolt had been used once the elastic limit of the bolt actually increases, use it again and increases further the bolt isn't weakened. The value of E of the steel and the ultimate tensile strength is not altered. Undo and re-use too many times and the strain (nb not stress) failure limit is eventually reached and the bolt will start to neck and weaken.

Stretching beyond the elastic limit is how piano wire is manufactured so it retains its tension in use and to make it its properties more predictable.





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mark chandler

posted on 23/2/19 at 08:46 PM Reply With Quote
That may be so, Aston Martin rate the ones I have pulled out the engine as good for 10 uses provided they meet measurement specifications.

Problem is the use of UNC threads in the block, correct for studs so a hang over from the past but too aggressive for stretch bolts as you are exerting so much force twisting them they are not really pulling the head down - hence my move to studs as I am getting 30% more power out the engine 3.2 putting out +400hp

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phelpsa

posted on 24/2/19 at 08:39 AM Reply With Quote
T&K Precision will do you a set in S99G (12.9 equivalent) for 12ish a stud. S99G has been pretty much the motorsport industry standard for studs and fasteners for some time is it's easy stuff to get hold of if you want to make them yourself.
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mark chandler

posted on 24/2/19 at 05:54 PM Reply With Quote
Thanks, I will bear that in mind, for now my single point cut EN24W studs will be going in my car the money has been spent, all 34 &#128077;
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phelpsa

posted on 24/2/19 at 06:44 PM Reply With Quote
quote:
Originally posted by mark chandler
Thanks, I will bear that in mind, for now my single point cut EN24W studs will be going in my car the money has been spent, all 34 &#128077;


Good stuff

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