what head gasket are you guys using

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22 November 2004
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Atlanta
It appears I may have blown my head gasket.

I know that when my MB rebuilt my engine as a low comp engine he used the oem gasket again.

I have heard a couple guys recommend the cometic gaskets, but I have also heard that others have had issues with cometic gaskets warping.

Just curious what is the best gasket to go with.
 
Not sure what warping means when it comes to Cometic gaskets? When does this presumably happen?

I use Cometic on my builds, but do not have many accrued miles to date on the NSX, so didn't want to post stating that these are the end all for head gaskets. But for all other FI builds I have performed, the Cometic gaskets have served me well, assuming the mating surfaces are up to par.
 
The warping i am speaking of stems from the layers being sandwiched together.

As I understand it the bottom layer gets much hotter than the other layers. This in turn causes the middle layers to warp and separate from the bottom layer.

I had heard that this was a big issue in the integra circles and as a result many people went back to the oem gasket.

Again this is secondhand information and it could be dated and a non issue anymore. But just thought i would check to see if anyone knew anything about it.
 
I have heard of no issues with the thin Cometic head gaskets. The thick ones some folks use to reduce compression may be a different story...

All the stock ones will fail with enough boost...I guess any motor will fail with enough boost...:rolleyes:
 
I have tried:
OE organic
OE sheet metal layered
Copper
Cometic layered
Thick and Thin
Cometic w/receiver grooves

Open deck blocks
T-Sleeved Blocks
O-ringed blocks
Copper and Stainless o-ring

Copper spray sealant
Hylamar spray sealant

OE bolts
ARP studs
Right torque and wrong torque

Before I ever started building I was told that the OE 3.0 gasket was prone to blowing. RTR
I also started with ARP head studs because that’s what I used on other engines. Unfortunately the torque I was told to use was too low. The torque was higher then the OE bolt but less then the minimum needed to stretch this material. I spent years blowing gaskets and trying everything to solve the problem. I even built a still to super heat water and I pumped this water through the engine for hours so that I could re-torque the head studs before the engine went back into the car. Nothing solved my problem until I made it full circle back to the head studs.
I called ARP to talk engineering and maybe even design another stud with an undercut shank. What I found was that the 65 foot pound torque was below the minimum of 70 needed to stretch the material. Stretch is needed to act as a spring to compensate for the heated expansion of the block and heads. Without this stretch, the first time the engine cools it is susceptible to being left with little or no pressure keeping the gaskets from blowing. In this case it would be better to use the OE bolts with the correct torque.
I had the right Engineer on the line so we talked further to discuss their experience with the most difficult applications. 4 bolts per cyl are not enough for boosted applications so we need to overcompensate to accommodate this deficiency. Aluminum blocks are also difficult because they can’t hold as much torque as iron and you benefit little by increasing the size of the stud. Studs are better then bolts because; unlike bolts the threads don’t have to rotate while pulling to get the stretch, studs can be hand turned into the aluminum block so that all the threads are engaged before the bolt eventually starts to pull and stretch the stud.
According to this Engineer; HP diesel engines are the hardest gaskets to keep intact. He stated that the minimum torque and the advertised torque are for typical applications, and that more torque can be used before their studs are past their threshold. Of course they have limits but in those diesel applications they have seen better result when taking studs that had an advertised torque of 85 lbs and torque them to 120. I took that info and experimented with a trashed block. I came up with a torque of 85 foot lbs as a reliable number that never pulls threads and is well past the minimum stretch.

Ever since I have never blown a gasket in any of my engines. My engine is making lots of boost and lots of power and I beat it at the track like it was a rental. This engine has an evolution of overkill but I credit the gasket durability to the ARP studs torque to 85 foot-pounds.

For street applications the OE gaskets are fine.
For combo street/track cars OE gaskets and ARP studs are fine.
For dedicated track cars you have more options but I’m not sure if all of them are needed. T-sleeved
Copper o-rings
Cometic layered gaskets with a receiver grove the o-rings in my block
The gaskets are sprayed on both sides with a full film of Hylamar coating
ARP Studs
Minimal block and head surfacing with a very smooth finish.

Last notes:
The Hylamar is a pore sealing coating that stays flexible that was developed for Mercedes. It’s difficult to find in the aftermarket, but I have a contact for the small chemical company in Ohio or Michigan that makes it. It’s not cheap but $15 is a small price to pay if any benefit exists.
The other advice is a smooth deck surface. I used to build high end drag engines that in many cases used Felpro Print-a-seal type gaskets that required a specific roughness of deck surface and the OE organic gasket may like this surface, but the Cometic and the OE sheet metal gaskets want a smooth surface. Not all engine shops are capable of a smooth surface. Bob Glidden (X drag racer) and many of the big NASCAR teams have one of the 10 machines developed to grind this surface, but most use cutters that may or may not be in the condition to get a smooth surface.

Time to go to bed.
 
Listen to RacerX or call Shane at Autowave, he'll tell you the honest facts.
He knows by actually doing it and building motors.....It takes more than pretty pictures and talk.
I wouldn't trust anyone else and I've quickly learned by experience who not to trust.
 
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I have tried:
OE organic
OE sheet metal layered
Copper
Cometic layered
Thick and Thin
Cometic w/receiver grooves

Open deck blocks
T-Sleeved Blocks
O-ringed blocks
Copper and Stainless o-ring

Copper spray sealant
Hylamar spray sealant

OE bolts
ARP studs
Right torque and wrong torque


Time to go to bed.

Rob,
You are the man!
Thanks.
 
My engine was rebuilt with low compression prior to me owning the car. How can i tell if the deck surface is what you would consider "smooth"?

Also you state that for street/track the oe+arp is fine. Does this apply to a boosted car? I have the bbsc making 9.5#.
 
My engine was rebuilt with low compression prior to me owning the car. How can i tell if the deck surface is what you would consider "smooth"?

Also you state that for street/track the oe+arp is fine. Does this apply to a boosted car? I have the bbsc making 9.5#.

You should have the head's and block's deck surfaces inspected by a machine shop to determine the trueness of the surfaces. If warped, they should be machined. When they are machined, it is imperative that the minimum amount of material is removed as possible such that the NSX V motor's timing belt geometry is not grossly affected. A quality machine shop will use a high quality fly cutting bit under slow pass to achieve a good sealing surface. At the same time, the sealing of the valves should be inspected along with valves, valve guides, and valve guide seals.

Cheers,
-- Chris
 
James this goes back to what i was telling you-

I think for your application (unless you decide to go crazy boost once the bug bites) is to stick to an OE gasket (preferably from honda, not aftermarket for fitment purposes) and ARP studs
I have tried:

For street applications the OE gaskets are fine.
For combo street/track cars OE gaskets and ARP studs are fine.
For dedicated track cars you have more options but I’m not sure if all of them are needed. T-sleeved

once you get the motor out its not expensive at all to have the heads inspected and maybe machined at a head shop and I HAVE A GREAT ONE for you here in Atlanta. this goes to Chris above^^


although i disagree with your problem here- i dont think you have a head gasket problem, i think your problem is piston rings

keep in mind that with an aftermarket build rings are typically good for 30-40K on good quality stuff, not 200K like oem, and most cases will depend on how well the rings were seated after the build- this has to do with proper break in.
 
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James this goes back to what i was telling you-

I think for your application (unless you decide to go crazy boost once the bug bites) is to stick to an OE gasket (preferably from honda, not aftermarket for fitment purposes) and ARP studs


once you get the motor out its not expensive at all to have the heads inspected and maybe machined at a head shop and I HAVE A GREAT ONE for you here in Atlanta. this goes to Chris above^^


although i disagree with your problem here- i dont think you have a head gasket problem, i think your problem is piston rings

keep in mind that with an aftermarket build rings are typically good for 30-40K on good quality stuff, not 200K like oem, and most cases will depend on how well the rings were seated after the build- this has to do with proper break in.



I have always heard that about motors. That the rings are only good for 30-40k instead of 200k like stock rings. Why is that? Anyone know? And the break-in on most OEM cars is HORRIBLE with most people honking on the car hard right from the dealership.

J. R.
 
I have always heard that about motors. That the rings are only good for 30-40k instead of 200k like stock rings. Why is that? Anyone know? And the break-in on most OEM cars is HORRIBLE with most people honking on the car hard right from the dealership.

J. R.


I don’t have much experience with the OE rings, but I will say that I have seen plenty of blow-by related issues. Some of those instances are exaggerated from poor crank case evacuation.

What I can tell you is that the 3.2 engines will have Very, Very low-tension rings because the cylinder walls are not an Iron sleeve. The 3.2 engines bridged the motorcycle and F1 technology and are made of aluminum with a thin coating of Hondas variation of Nicasil.
 
I don’t have much experience with the OE rings, but I will say that I have seen plenty of blow-by related issues. Some of those instances are exaggerated from poor crank case evacuation.

What I can tell you is that the 3.2 engines will have Very, Very low-tension rings because the cylinder walls are not an Iron sleeve. The 3.2 engines bridged the motorcycle and F1 technology and are made of aluminum with a thin coating of Hondas variation of Nicasil.

Now is this something like FRM? Is that how you say it? I think S2000 had FRP or FRM blocks so if you run forged pistons you have to sleeve them yah? Help me out with this Racerx?

J. R.
 
Now is this something like FRM? Is that how you say it? I think S2000 had FRP or FRM blocks so if you run forged pistons you have to sleeve them yah? Help me out with this Racerx?

J. R.

J.R., Most of the aftermarket piston manufacturers offer a variety of ring choices. If you don’t ask, you will get their most common rings. Only a few of the manufacturers make their own rings, and buy from a ring manufacturer anyway.

I use Ross pistons on most of my engines, purely because the quality of material and the tolerances are equal to or better then their competition. This fact coupled with the shortest lead time in the industry, has made them my choice… as I’m always in a rush to get a build done, and have never been able to get by with an off the shelf piston.

If I had more time and more money for lets say a pro team, I would most defiantly use Mahale pistons like RTR used. I have since been to the PRI show where all the HP piston manufacturers display their products and strengths. Mahale started as a piston company that only sold to auto manufacturers but has recently opened their services to the HP public. They truly set the bar for piston technology in many ways; Ring design, material, machining, coatings, etc. You will notice how many pro teams use this more expensive brand when expense is not the limiting factor. Champion, RTR, Pratt & Miller, etc. all rely on this brand because it’s without a doubt better then the rest. A few of the other manufactures use Mahale rings on their own brand top end pistons, but the pistons weren’t made specifically for the shape of the ring.

An example of superiority is the unique material used in the design for less expansion so the piston to wall clearence can be tighter without having problems with sticking or seizing. The rings are shaped differently for less tension, and the pistons are shaped to receive this ring. The coating is patented and not used on any other brand; the pin bore is obround to be round when heated, etc. I was under the impression that Mahale makes the cast piston for the NSX and that is why RTR went to them for a forged variation… this was before they did custom work as regular business. If I remember correctly RTR was out of piston sets when I was buying parts from them, and Mahale wanted a minimum order of like 10 or 20 sets at a high price. RTR was willing to split the order with me but that was out of my budget.

To make a long story short: The aluminum cylinder design has multiple benefits; one of them is that they expand at the same rate as the aluminum pistons. This allows you to have a much tighter tolerance between the two. Many of the piston manufacturers and all the ring manufacturers have experience with motorcycle engines (Like Weisco) and they will understand your needs for a lower tension ring.

Cool stuff-
Pratt & Miller had a display at the show with a custom Mahale piston that came out of the winning engine from the 24 hr Le Mans. The piston looked nearly new.
 
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