Are head and cylinder gaskets compression gaskets? Options

[Mark Henry]

Yep if want to use a gasket on a stock engine go for it.

But, if you are using 96mm I'd think hard on the subject. You will be leaving 1mm hanging out in the chamber, not hard to imagine it will deform slightly when torqued, lifting off the head. You are now introducing a sharp edge (hot spot) inside your chamber.

I have a hard time with the "the bulletin was meant only for VW busses" argument, VW was having issues with the lower CR bus engine, but that doesn't apply to a higher CR 914 engine? (IMG:style_emoticons/default/confused24.gif)

As far as engineers go VW/ Porsche is excellent, but not infallible. I guess pulled and broken head studs, head cracks, oil leaks, IMS, D-chunk, etc. are just figments of our imagination.
Food for thought, VW engineers told Porsche engineers that they couldn't stroke out a T4 to 2.0, 4 years later VW started putting 2.0 into busses.

I have nothing but respect for the Crusty one, on this this subject we had a agree to disagree arrangement. We talked many times by PM, he spent a fair bit of time explaining a step-by-step timing belt/water pump repair when I did it on my passat.
We just never discussed head gaskets. (IMG:style_emoticons/default/biggrin.gif)

[N_Jay]

I have to agree with you on one point, you DEFINELT don't want the gasket protruding into the combustion chamber.

Now I am scratching my head (no pun intended) as to what I did with my 2.4 when I built it.

I guess I will get a reminder when I pull the heads (due to a broken exhaust valve spring)

[stevegm]

Yep if want to use a gasket on a stock engine go for it.

But, if you are using 96mm I'd think hard on the subject. You will be leaving 1mm hanging out in the chamber, not hard to imagine it will deform slightly when torqued, lifting off the head. You are now introducing a sharp edge (hot spot) inside your chamber.

I have a hard time with the "the bulletin was meant only for VW busses" argument, VW was having issues with the lower CR bus engine, but that doesn't apply to a higher CR 914 engine? (IMG:style_emoticons/default/confused24.gif)

As far as engineers go VW/ Porsche is excellent, but not infallible. I guess pulled and broken head studs, head cracks, oil leaks, IMS, D-chunk, etc. are just figments of our imagination.
Food for thought, VW engineers told Porsche engineers that they couldn't stroke out a T4 to 2.0, 4 years later VW started putting 2.0 into busses.

I have nothing but respect for the Crusty one, on this this subject we had a agree to disagree arrangement. We talked many times by PM, he spent a fair bit of time explaining a step-by-step timing belt/water pump repair when I did it on my passat.
We just never discussed head gaskets. (IMG:style_emoticons/default/biggrin.gif)

Interesting. Yes, I am using 96mm P&C. The more I learn, the less I know. I assume nobody makes a head gasket that is designed to use on the 2.0 liter head with 96mm P&C?

[DBCooper]

I asked him why most people put silicone in there and he replied:

"...because most people don't know what the phuck they are doing and it makes them feel better".

Ha ha, that's hilarious. I never met him but can see him saying that, clear as a bell. Good guy. And krusty.

[N_Jay]

Hey! Hay!

I know all about the famous o-ring failure. (What type of seal would you have suggested?

That aside, I was thinking more along the lines of a annealed aluminum or copper ring, not a silicon rubber one.

All in all, just engineers daydreams.

Still wonder, why the head bolt torque is not adjusted up or down based on the surface area of the cylinder to head seal? Hmmmm?
Seems the clamping force in PSI is what you want to control?

[KeithVonLaws]

I bet more failures occur due to Pre-ignition or detonation from poor tuning or other build mistakes like Mark's reference to the 96mm gasket overhang/hotspot.
Its plainly obvious clamping issues and surface finishes make a difference.
Besides clamp load - bore distortion and surface finishes and all the usual
hurdles we have to look at for a racing engine.....If your building a mild street application I would lean to focusing on proper build techniques attention to small details..... Lap the head to the cylinders... measure and equalize everything
and use proper tuning .


In my case Personally, I would like to see for myself if I can build a
reliable 250 hp Type IV engine for track day events and some limited road driving for under $6000.00 - Thats my goal...pretty lofty I know. I am slowly getting my components together.

[Mueller]

Hey! Hay!

I know all about the famous o-ring failure. (What type of seal would you have suggested?

That aside, I was thinking more along the lines of a annealed aluminum or copper ring, not a silicon rubber one.

All in all, just engineers daydreams.

Still wonder, why the head bolt torque is not adjusted up or down based on the surface area of the cylinder to head seal? Hmmmm?
Seems the clamping force in PSI is what you want to control?

Not enough room for a ring on the top of the cylinder to be reliable.It can and has been done, just not as reliable as the 2 proven methods in this thread. I'm going the method Jake and Len recommend, if I change my mind and decide factory method only, I might as well throw away my 205/50-15 tires for the 4 lug Mahles I want since Porsche never installed that size tire!

Heck, I should toss those SSI heat exchangers since surely Porsche wanted carbon steel only (IMG:style_emoticons/default/smile.gif)

[Mark Henry]

In my case Personally, I would like to see for myself if I can build a
reliable 250 hp Type IV engine for track day events and some limited road driving for under $6000.00 - Thats my goal...pretty lofty I know. I am slowly getting my components together.

Well that's a topic for another thread, but I'd say no to the 250hp. You're expecting too much from a pushrod engine based on a 90 year old design.
I have well over $8K in parts into my long block alone, count my EFI and exhaust close to $12K for 180hp.
That's just in parts.

If 250hp is your goal I'd forget about the T4 and /6 and go straight to a V8. Even then your budget might be a tad light.

[DBCooper]

In my case Personally, I would like to see for myself if I can build a
reliable 250 hp Type IV engine for track day events and some limited road driving for under $6000.00 - Thats my goal...pretty lofty I know. I am slowly getting my components together.

Well that's a topic for another thread, but I'd say no to the 250hp. You're expecting too much from a pushrod engine based on a 90 year old design.
I have well over $8K in parts into my long block alone, count my EFI and exhaust close to $12K for 180hp.
That's just in parts.

If 250hp is your goal I'd forget about the T4 and /6 and go straight to a V8. Even then your budget might be a tad light.

You could do that, or go turbo Subaru, a half-ton lighter and still a flat four.

[Mark Henry]

You could do that, or go turbo Subaru, a half-ton lighter and still a flat four.

I did think of posting that but Keith did say he had experience with american iron.

[DBCooper]

And I almost didn't post it for fear of being too much of a Subaru fanboy. But hey, if it works....

[ClayPerrine]

[Keyser Sose]

I don't understand. If you don't like this thread then why do you keep coming back? Why not just skip it?

[injunmort]

because we all like train wrecks, and i am a special kind of stupid
duh

[stugray]

Ok, I stayed out of this conversation towards the end because I had just finished my last race of the year.
During that race I was hearing a loud "Brrrrrrrrrppppppp!!!" whenever I exceeded 6200 RPM.
I thought it was an exhaust leak, found one leak, fixed it, and the noise did not go away.
I was worried it was a head leak.
SO I decided to pull the motor at the end of the season and have a look.

First compression test just before pulling the motor was bad - 60-70 PSI cold, 75-80 PSI warm - Not good results.

So I pulled the engine Saturday and got the heads off yesterday.
This engine is a 9.5:1 CR and I routinely rev it above 6200 RPM during hard racing (20 minutes at a time).

During disassembly I DID find at least one exhaust leak between the stubs and the headers, so that was probably my "Brrrrp!!" noise.

I assembled this engine with no head gaskets jugs were brand new and heads had just been machined down to decrease comb chamber volume.

I did NOT hone these heads or do anything other than bolt them up.
When I took the engine apart I checked the torque on all the bolts and some were a little low (~20 ft-lbs).

I can detect ZERO leakage or blowby on the sealing surfaces.
My valves are a different story.

(IMG:http://www.914world.com/bbs2/uploads_offsite/i366.photobucket.com-10819-1479145075.1.jpg)

(IMG:http://www.914world.com/bbs2/uploads_offsite/i366.photobucket.com-10819-1479145075.2.jpg)

(IMG:http://www.914world.com/bbs2/uploads_offsite/i366.photobucket.com-10819-1479145075.3.jpg)

(IMG:http://www.914world.com/bbs2/uploads_offsite/i366.photobucket.com-10819-1479145076.4.jpg)

And here is my home made spring compressor

(IMG:http://www.914world.com/bbs2/uploads_offsite/i366.photobucket.com-10819-1479145076.5.jpg)

SO long story short: No head gaskets, no special prep (other than GOOD mating surfaces), normal torques, 9.5:1 CR and engine routinely reved above 6200 RPM.

No discernible leaks after 2 race seasons.
The engine looked like new inside.

So run head gaskets if you want, I dont, and I am fairly certain that I beat on this engine more than your average DD.

[Jake Raby]

Hey! Hay!

I know all about the famous o-ring failure. (What type of seal would you have suggested?

That aside, I was thinking more along the lines of a annealed aluminum or copper ring, not a silicon rubber one.

All in all, just engineers daydreams.

Still wonder, why the head bolt torque is not adjusted up or down based on the surface area of the cylinder to head seal? Hmmmm?
Seems the clamping force in PSI is what you want to control?

Going up on head torque is the fastest way to create head leaks, with or without gaskets. Due to the non square stud pattern, and the two different lengths of head stud its pretty easy to tweak a head once its hot.

[stugray]

Hey! Hay!

I know all about the famous o-ring failure. (What type of seal would you have suggested?

That aside, I was thinking more along the lines of a annealed aluminum or copper ring, not a silicon rubber one.

All in all, just engineers daydreams.

Still wonder, why the head bolt torque is not adjusted up or down based on the surface area of the cylinder to head seal? Hmmmm?
Seems the clamping force in PSI is what you want to control?

Going up on head torque is the fastest way to create head leaks, with or without gaskets. Due to the non square stud pattern, and the two different lengths of head stud its pretty easy to tweak a head once its hot.

So what is the consensus on retorquing the head nuts on the type-IV after X miles?
IIRC for the type-I it was required.

On these engines it is much more difficult with half the nuts behind the shrouds.
Seems that at lest one of mine was below 18 ft-lbs when disassembling.
I am fairly certain that I used exactly the specified torque of 23 ft-lbs using the proper pattern during assembly.

Too bad there's no easy way to assemble the long block and put it in an oven overnight at ~280 deg F then retorque after cooling.

[stugray]

Just for future reference:

Gasket failure:
(IMG:http://www.914world.com/bbs2/uploads/post-87-1477582560_thumb.jpg)

No Gasket - No failure:
(NOTE 9.5:1 race motor run at 6200 RPM consistently):
(IMG:http://www.914world.com/bbs2/uploads_offsite/i366.photobucket.com-10819-1479145075.1.jpg)

(IMG:http://www.914world.com/bbs2/uploads_offsite/i366.photobucket.com-10819-1479145075.3.jpg)

Shit:
(IMG:http://barfblog.com/wp-content/uploads/2011/10/poop.jpg)

Shinola:
(IMG:http://www.914world.com/bbs2/uploads_offsite/uploads.neatorama.com-10819-1479408982.1.jpg)


Just thought I'd clear that up

[Mark Henry]

Shit:
(IMG:http://barfblog.com/wp-content/uploads/2011/10/poop.jpg)

Shinola:
(IMG:http://www.914world.com/bbs2/uploads_offsite/uploads.neatorama.com-10819-1479408982.1.jpg)

Can you imagine what it was like being a Shinola salesman? (IMG:style_emoticons/default/dry.gif)

[stugray]

Shit:
(IMG:http://barfblog.com/wp-content/uploads/2011/10/poop.jpg)

Shinola:
(IMG:http://www.914world.com/bbs2/uploads_offsite/uploads.neatorama.com-10819-1479408982.1.jpg)

Can you imagine what it was like being a Shinola salesman? (IMG:style_emoticons/default/dry.gif)

(IMG:http://www.914world.com/bbs2/uploads_offsite/blogs.northcountrypublicradio.org-10819-1479422279.1.jpg)