Don M

I got my block back from the machine shop right after I returned from Muncie. I took a copper gasket, the ARP head studs, and a cylinder head and started to check the durabilty of the ARP studs VS TQ applied with a super accurate 1400 dollar TQ wrench I got last winter.

The purpose of this was to check the total amount of TQ I could apply to the ARP studs and not permanently deform them. The idea was to come up with the highest yield I could get before I exceeded the fasteners abilty to continue to apply clamp load and not deform.

The results were very good and I will tell ya the ARP-2000 material is a very ductile and very strong!

ARP has recommended a total TQ of 96 ft lbs using their Moly based lube or 122 ft lbs using 30 wt oil. This according to ARP provided 75% of total yield. Roughly of course. I found out some interesting results while going higher.

First I measured the studs with a micrometer that is accurate to 40 millionths of inch. This was to determine the stretch of the studs after they were TQ'd and removed.

I went to 105 ft lbs and found zero stretch on any of the 26 studs. Then I went to 110 with the same results. I continued torquing, removing and measuring until I got to 151 ft lbs and found 1 stud of the 26 had moved under .001 or 1 thou.

I then proceeded to 160 ft lbs and most of them had moved about 2 thou permanantly. For grins I went to 170 and then to 188 ft lbs were most of the studs were now permanantly moved about .006! I am betting from the way the fasteners felt that I could have gone to 200 ft lbs, but I had concerns of possibly tearing the threads up in the block or deforming them and plus I was just plain tired from torquing those things so many times.

To keep things consistant I washed the studs, washers and nuts in my ultrasonic cleaner between changes to avoid any contamination of small dirt particles, etc. I applied a liberal amount of ARP lube to all the surfaces each time and the temperature was keep constant. The fasteners were allowed to cool between measurements to avoid any heating giving me a false or stretched reading that was not accurate.

I am still amazed at the ability of the ARP studs to take that kind of abuse and stretch this little. That is a super ductile fastener that will do that.

ARP still recommneds officially the 75% yield at 96 ft lbs is best, but says the fasteners should not deform up to 122ft lbs using their moly lube. I found out they can take a little more than that. I guess they have a safety factor built in.

At 125 ft lbs I measured zero permanent stretch! This was after they were TQ'd and retorqed 5 times previous. This is awesome performance. Usually you will break a stud made from 4340 steel at anywhere from 135 ft lbs and up. The ARP went to 188 and only moved .006. That is one tough stud.

To the guys that have purchased the studs from me, I can now say the ARP's are good to 125 ft lbs with ease. The clamp load difference between the ARP recommended 96 and 125 is just over 25% more not counting friction losses.

For a stud that is over 6" in length, .006 thou is not much at all

Don~

joefarmer

Hey Don!!

Do you speculate any differences in tq readings between the copper headgasket and a marine gasket? In what instances would you recommend increasing the tq? Say, if, uh, someone was adding methanol, would that be a good reason?

Thanks!
brandon.

Don M

Brandon,

Crank them down to 125 ft lbs. They are just fine at that level.

I know I am going to get reamed by some on this subject, but I have seen way too many gaskets fail with methanol systems installed. Water and a very small amount of meth might be ok, but many guys are blowing their gaskets on Diesel only. Some can be traced back to poor machine work, poor installation, and the inherent troubles with the 24 valve cylinder head VS the 12 valve design, but the methanol seems to be causing a detonation problem or a high peak pressure spike before or very near TDC.

The systems are just asking for long term reliability issues, IMO.

I would rather see you run Nitrous. Even lots of Nitrous. At least you dont get any detonation. No engine or gasketing system can take detonation for long. With a spark engine and meth/water you can get away with it. The cylinder temps are not high enough in most cases to pre-ignite the methanol. Unlike a Diesel that can have a 600 degree cylinder temp long before TDC.


Don~

Timinva

Don do you recommend backing the nuts off and retorqing them to 125? Or just tighten them down from 96 to 125? No problems with mine at all at 96 ftlbs. Tim

Don M

Back them off one at a time and go back to 60, 90, 110 and finally 125.

Don~

HOHN

NO wonder those injectors are so expensive!!!!!

LMBO

Justin

Push Rod

Yeah, Don has all the cool toys. I plan on doing a B&E of his shop some day.



Rod

HOHN

I'll drive the getaway CTD for a small cut

Jim Fulmer

I know I am going to get reamed by some on this subject, but I have seen way too many gaskets fail with methanol systems installed. Water and a very small amount of meth might be ok, but many guys are blowing their gaskets on Diesel only. Some can be traced back to poor machine work, poor installation, and the inherent troubles with the 24 valve cylinder head VS the 12 valve design, but the methanol seems to be causing a detonation problem or a high peak pressure spike before or very near TDC.

Don, I didn't realize people were have trouble in this area, the increased Cyl pressure is a sure thing but what about detonation in a diesel.....educate me here.

As I knock on my desk I have still yet to have an issue in the past 16 months playing with this stuff.

Jim

HOHN

Jim, you obviously know that the water/meth is increasing cylinder pressure (if it didn't, it wouldn't make power).

But it also makes detonation a very real possibility. As the piston compresses the intake air, it heats it up. Normally, the hotter, the better, because nothing's going to burn until the injector fires.

But with the meth on, there's a fuel to be burned before the injector fires. That means that as the piston compressed the air charge (containing combustible meth), it MAY light off that meth as it heats up. If this happens BEFORE (by some significant amount of time) the injector fires, then your piston is compressing a burning, expanding ball of hot gasses.

Then the injector fires!! What this creates is a HUGE spike in peak cylinder pressure at a time when the engine doesn't benefit much from it (TDC). This is what takes out the HG.

As for the 12V vs 24V, I think detonation is more of an issue with the 24V because their are more "edges" in the chamber that can develop hot spots. Because the 12V has more "meat" in the chamber, is has more of a heat sink for hot spots, thus less tendency towards detonation.

I'm with Don-- I'll run the Nitrous before I run meth. Of course, that assumes that I can't get my LOX injection to work properly

Don M

Head gasket sealing on the 24 valve is not easy. Its not fun to constantly change the things out either. Every system out there has a flaw. O-rings, fire-rings, c-rings, etc.

Methanol only makes the head gaskets life and mine harder to deal with.

No headgasket can take detonation. None. No engine components can take detonation either. At least not for long.

Im not saying that detonation is a problem for sure with the methanol but it is either that or high PEAK cylinder pressures. Either one is hard on gaskets. Guys can make more HP with Nitrous and still have lower peak cylinder pressures. So something is wrong.

I never recommended methanol to anyone. I dont see why anyone would use a fuel with such a low flash point. The in-cylinder heat is high enough in a compression ignition engine to pre-ignite methanol way before TDC. The FORD guys went through this when using propane too. Another low flash point fuel that ignited before TDC. They were blowing head gaskets and detonating loud enough to hear over a WOT run. Some guys are even using Nitro/water now. LOL!

For me the choice is clear. Use diesel fuel that is injected at the correct time through the injector to avoid all detonation and peak pressure you can.

Don~

MikeR

I torqued mine down to 126 ft lbs when I did it two months ago (yes they'er DonM's).

Don M

Now if I can get ARP and myself on the same page about stud lengths we might have a product that anyone can install headache free.

Glad you like them Mike. I hear you are stepping it up in the power range. Good Luck!

Don~

Robert Venable

How does torqueing the head studs down to a higher torque help? Does the gasket seal better at a higher torque?

How about Gasket crush, does the increased amount of torque effect the crushed height?

Don M

The tighter you can TQ the nuts down the higher the clamp force you get. As long as the bolt or stud is not stretching or deforming too much. Unfortunantly its game of diminishing returns. As you TQ the the fasteners higher the friction goes up substantialy and you get less from more, so to speak.

The crushed height does not change much at all between say 90 ft lbs and 125 ft lbs using the same fastener.

Don~