boosted91t

iTrader: (65)

Bogus I agree completely..

I have run a correct bore stock mitsu mls head gasket n a 4g64 at 42psi on a 62mm Precision, on L19's. I have yet to see a need for O rings. When and if I run into an issue, then I will go from there.

5LEEPERISAH23I

iTrader: (23)

yea, i plan on running 750-800whp 38-40 PSI on a 4g64.. If i was on a 4g63 no need to o-ring at all.

I have no clue i was going to ship my head bare to Buschur. I have no clue what they use. You have a recommendation of what one? and why?

yea for sure

BogusSVO

iTrader: (1)

5LEEPERISAH23I, Yes, I do, IMHO, It is not needed.

The one I told you that cracked 1000 hp, is a 2.3 alum rod engine, that is street driven.

Have the head milled on a good surfacer, and deck the block.

I have a Buschur head on my shop floor with O rings, that I now have to pull out weld the grooves and mill the head.

https://www.evolutionm.net/forums/ev...nder-head.html

https://www.evolutionm.net/forums/ev...l#post11022107

http://www.dsmtuners.com/forums/cyli...ck-decked.html

Most often O rings are used as a "patch" for distorted surface finishes.

Now, copper O rings with a MLS HG, just mash out and do little if anything for improving sealing

Copper O rings with a composite HG, cut the top layer of a composite and apply the extra load to the perforated core of the gasket and will weaken it, the displaced top layer of the composite gets shoved to the sides of the O ring and holds the head up. This will increase the clamp load around the fire ring, but at the same time lessen the clamp load everywhere else on the gasket.

Stainless O rings on a MLS, is even worse about holding the head up, Add to that it can feather the edges of a MLS. on the fire ring, if it is not a sealed MLS. Basically, you are trying to force two parts to take the same space one should. This is the reason for the receiver grooves.

The receiver grooves allow the gasket a place to go.

tscompusa

iTrader: (31)

I have done a lot of 4g64's. some over 800whp. Heres one with no oring with a cometic HG with no issues; https://www.evolutionm.net/forums/ev...psi-800hp.html

and heres another with a power enterprise HG with a Buschur Oringed head with no issues pushing a fp black to the absolute maximum:

https://www.evolutionm.net/forums/ev...kill-mode.html

This car has shown over 730whp in vd recently we just never shared new results in colder temps and 40psi+ holding to redline

This car also was the highest HP stock appearing turbo car on the buschur dyno at the shootout making 600+

I'm personally using o'rings on my head. I ran a Stock Mitsu MLS gasket for 4 years with an o'ringed Buschur head with absolutely no issues after i torqued the studs down where they were best happy at (roughly 120) on H11 tool steel ARP L19 studs. I've ran up to 48-50psi on the fp black, and the car seen the most brutal 20,000 miles you can possibly see with its setup, killing 3 turbos in that time period from overboost. 90% WOT 10% driving normal. However this was on a 4g63. The cyl walls are much thicker.

I am now running a head i sent to buschur, had it o'ringed, milled, port/polish, and i assembled it myself. I believe O'Rings help a lot. I see others don't agree here.

From my experience, in order to get the o'rings to bite and seal the HG it requires a little more tq then what the stud manufacturer calls for (quite possibly a lube issue also and the tq is not giving proper stretch) - no way to measure stretch on studs when clamping force is applied, unlike rod bolts, so we heavily rely on "tq values" only.

If i have issues with O'Rings in my 2.4 i will gladly post back with results.

I am using a Cosworth FLS HG (I wanted the modified AMS) with copper spray on both outer layers on each side with ARP 625+ headstuds. The 625+ may cost more $, but it will be the last set of headstuds you ever buy in your life for that particular application. Is it overkill? yes, can you get away with standard ARP studs? probably. How often does H11 tool steel (ARP L19) become contaminated on a head stud? rarely ever, but i like the 625+ for extra peace of mind.

batty200

iTrader: (3)

I wouldn't o-ring. Bogus is right. Only do it if using a copper gasket with receiver groove in the block.

Clintosaraus

I don't see the point in o ringing anything unless it's a diesel engine where your doing 70+ psi and detonation is how your engine fires. on a small bore spark ignition motor at 40psi there is no point to it.

Ted B

iTrader: (6)

When it comes to O-ringing, no O-ring makes a more effective seal than an improperly designed/fitted O-ring setup.

What size turbo or how much boost is used doesn't matter. All that matters is pressure - either the mechanical pressure of torque, or detonation. If there is a high heat situation in the top of the block, that can create surface distortion that results in sealing issues, but where the 4G63 is concerned, this tends to be more of an issue with road race and 500+whp/L setups.

To effect a proper seal, the MLS gasket requires the appropriate straightness and fine finish on deck and head surfaces, and even loading across the fasteners. As sure as death and taxes, there are many instances where surfaces were improperly prepared for a MLS gasket (e.g. >RA 30), and there are many more where the studs and nuts were improperly installed and/or torqued.

Competent o-ringing involves a stainless wire where a receiver groove is machined into the mating surface, or a more malleable copper wire where no receiver groove is used. The diameter of that wire and depth of its groove must take compressed gasket thickness into consideration and be sized accordingly, or it will simply be ineffective.

And finally, when it comes to the installation/torquing of the studs and nuts, 'more' doesn't equal 'better'. APR's preload is designed to attain 75% of yield pressure, and overtightening simply reduces the ability of the stud to resist stretching. If one installs the studs finger snug, uses the latest ARP lube, and doesn't overtighten the nuts, they need no retorquing, and are very reliable in a 4G63.

tscompusa

iTrader: (31)

Ted, you're probably not aware of this because you never played with a ARP stretch gauge on their fasteners, but when you typically are tq'ing an arp fastener down by arp's recommended tq value with arp lube, you are setting that particular fastener to around 60% yield if that.

It is no where near 75% i can assure you of that, and it is conservative to protect ARP from people who have faulty tools or just in general to protect them from having issues. So they give a large window to avoid people overtq'ing their product.

To much tq once past the yield point is far worse than under torquing i agree 100%. 20tq over probably has my studs around 65% i bet.

Pretty much anyone could get by with just standard ARP studs in their engine no matter what power level as long as the car never experiences detonation events that spike cyl pressure.

tscompusa

iTrader: (31)

Also 75% is considered a sweet spot when it comes to yield points, you can go up to 90% and have no issues. the only difference is, the 90% has better clamping force than the 75%.

but once you pass the max yield that bolt/stud is trash. it will never spring back and return to its normal state. it is now permanently stretched.

For others reading this, its like a spring. you can only stretch it so much until it will not return and will be permanently damaged. in ARP's case, the recommended spring stretch is very conservative to avoid them having 100 calls a day.

Ted B

iTrader: (6)

The first time I torque ARP fasteners using a stretch gauge was in 1983. Given the margin of error when considering threads that aren't perfectly clean, that Harbor Freight torque wrench (lever styles are the most accurate), and anything less than ARP Ultra-Lube, the actual preload is far more likely to be *higher* than indicated. And while I've seen plenty of stretched head studs, I've never experienced one myself, which I attribute at least partially to meticulous assembly. Any questions I would direct straight to ARP, who are always helpful and informative.

ARP Technical


As for yield strength, 90% wouldn't present concerns if there were no combustion forces pushing to stretch that stud, but there are. The design of the 4G63 is such that excessive clamping pressure isn't required to make an efficient seal, which is why ARP 2000s have held up in 1000whp 4G63 setups. Furthermore, I've witnessed instances elsewhere where overtightened studs created pinch spots that distorted the deck surface, which ultimately led to failure.

But like I've said previously, a good head gasket with proper surface preparation and meticulous fastener installation is all that's needed for just about any street application. And where o-ringing is concerned, it's not a haphazard exercise, requiring special attention to ring metallurgy, size, and ring/receiver groove depth with respect to gasket thickness and other factors to actually function.

tscompusa

iTrader: (31)

Ive never had any stretch either after Mic'ing them once taken out. Last time I went over 20tq to give me some extra clamping force also on my personal car. Now for a customers car, i would just torque it to spec and leave it up to the customer to decide if he or she needs to go further, but for my personal car i tend to go alittle additional sometimes.

what sucks with head studs is, theres no way of measuring stretch even if you wanted to once its tq'ed down in place.

You're right on the standard arp 2000 studs. I have a lot of customers on standard studs pushing very high boost 40psi+ & 700whp+ and no issues. they typically tq those studs 10-20tq more than what they are called for on the ARP paper though also when i ask. I believe the standard studs are recommended for around 60-70tq. a lot that i talk to take them to around 80-85tq.

But what i said about the yield you hit with the lube is true. you are not torqueing to the yield you think you are (75%). Just play with a set of ARP rod bolts once and you will see this very quickly. They keep their numbers on the conservative side to avoid failures or people overtqing by accident on all their fasteners.

right now i have my studs set at 120. the paper said 100. I dont think ill have any issues. I am very meticulous also when i work on a vehicle.

I will tell you, Steve (5leeper) is getting PM's from other members here with 2.4's that are using orings and are saying how before hte orings they had issues, but after oringing no more issues.

If not using receiver grooves are so bad then how is it that buschur oring heads dont have issues? they arent using receiver grooves and if i do a quick search on my computer with 2.4's and (br stage 3 head) it comes up with a hell of alot of results!

Are you saying the HG shifts around on the orings like slides around? therefore the orings make it more prone to leak?

Ted B

iTrader: (6)

I use a stretch gauge not as a means of determining preload, but to test the integrity of the bolt. If the bolt stretches by the projected amount before the desired preload is indicated on the wrench, it goes into the trash.

As for head studs, the simplest way view it is to remember that we need only enough preload to create a seal. The stud will not budge significantly from that point unless there is enough pressure to overcome its yield figure. If we leave 20% yield strength in reserve, it will withstand about twice as much combustion pressure as it would with only 10% in reserve.

As for o-rings, there's nothing wrong with using an o-ring without a receiver groove, so forgive if I implied differently. Copper makies the best seal where no receiver groove is used, whereas stainless with a receiver groove is the best possible configuration. I presently use a copper o-ring, the diameter and installed depth deliberately calculated to be compatible with my head gasket's compressed thickness. Their are plenty of resources on the web that explain the rationale of these things, so no need to go to lengths here.

5LEEPERISAH23I

iTrader: (23)

I have had a lot of people and shop's PM me. Im porting and O-Ringing my head no question. It for sure helps. People with personal experience and currently running the 4G64 blocks.

Jsiebert

iTrader: (10)

I personally recommend against it but that is just me. The headgasket is meant to be a failure point if **** gets bad. Look around for photos of heads that have had portions of them melted de to orings... there plenty in the evo community. Even Buschur did it once.... had his motor not been oringed he would have still had a head that was usable. However it its your car. I just highly recommend to not do it, I am also building a 2.4....well a 2.1 destroker and will NOT be oringing my motor. 100 is a lot cheaper than 1000

Sharkbite2000

iTrader: (21)

I had o ring also, my evo saw way pass 55+ psi never had a problem with the engine, never had to take the head off.