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2mm redblock headgasket

VB242 said:
My V16T cam is interference, when I was setting up the timing belt, I had to turn the crank backwards after a piston was stopped by a valve. It's had the head cut a couple times and the block decked. That was with a stock head gasket.
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Yep, but the timing belt wasn't on.

The op asked about valve clearance, I was partially assuming the op was concerned about engine operating clearance.
 
Steerfromdarear said:
The mesure were from the machine shop I remeasure today

Cylinder head measurements from rocker cover mount to head gasket surfaces
Is 145.11mm

Piston stick out is .60 mm

I have a 1.8mm when tightened head gasket
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Its okey to use the 1.8mm headgasket.

However what no one has mentioned is that there can be different compression ratio between cylinders now.

The 8v cylinder heads do not have the same deck thickness, so the deck can become weak if to much material is removed.

Be sure that the timing belt tentioner does not bottom out, most likely its fine.

Regarding squish, its possible to get into detonation problems in some motors if the squish distance is not small enough or not big enough.
I have noticed that there is a big misunderstanding about squish area and distance in turbo motors here at turbobricks unfortunately, its like a mind virus hehe.
 
volvo240e+t said:
Its okey to use the 1.8mm headgasket.

However what no one has mentioned is that there can be different compression ratio between cylinders now.

The 8v cylinder heads do not have the same deck thickness, so the deck can become weak if to much material is removed.

Be sure that the timing belt tentioner does not bottom out, most likely its fine.

Regarding squish, its possible to get into detonation problems in some motors if the squish distance is not small enough or not big enough.
I have noticed that there is a big misunderstanding about squish area and distance in turbo motors here at turbobricks unfortunately, its like a mind virus hehe.
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Please elaborate on that last comment. Long ago there were some pretty big discussion about the quench distance. But that is about a generation ago. A fresh mention of what to look for is always good.
 
dl242gt said:
Please elaborate on that last comment. Long ago there were some pretty big discussion about the quench distance. But that is about a generation ago. A fresh mention of what to look for is always good.
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I understand squish/quench this way;

NA engine: Generally best to have the squich tight but take max rpm into account, and use all the area that the chamber has to offer.

Turbo engine: The stock turbo engine squish for example is engineered for a certain cylinder filling and swirl from the intake port, this design makes it possible to control at what angle peak combustion pressure happens and how much the peak pressure is.

If there is more cylinder filling, then there is more energy in a chamber of the same size, thus the combustion is faster.
In this scenerio it becomes harder and harder to control the peak combustion pressure as there is more and more cylinder filling.

However if one wants less squish effect it is not wise to have the distance 1.5mm or 2mm, the distance has to be at least 2.5-3mm, especially with a flat piston because then there will be a fuel mixture between piston and head that in some circumstances cannot be reached by the flame front and cannot be cooled by the surface of head and piston, because of that the fuel mixture can auto ignite.

Another method is to taper the squish area so the distance gets larger and larger to the center of the bore.

Then there is a another discussion to be had about lean pockets that can form in the fuel mixture that can also cause knock.
The intake port, valve throat area and chamber design after the fuel injector are responsible for the job of keeping the fuel droplets suspended in the air.
If the air takes a turn around a corner to fast the fuel can actually go in another direction and create a lean pocket in the air fuel mixture.
Another way is if the walls of the intake port are to smooth, then the fuel droplets can get to close to the wall and fall out of the air.

I hope this is not to boring to read, I just love the science behind all of this.
Im still trying to get a holistic understanding in all of this so please tell me your understanding.
 
Thank you for elaborating on your understanding. Personally, I had only known about the n/a reference you make above. I didn't know about the turbo engine design you mention and find that very interesting. As an example of what you describe for a turbo engine. One of our member has used a head from Erland Cox and the chamber design is like you describe. Check out the differences in the chamber in this thread. https://www.turbobricks.com/index.p...-barn-car-revival.290558/page-40#post-6378685
 
dl242gt said:
Thank you for elaborating on your understanding. Personally, I had only known about the n/a reference you make above. I didn't know about the turbo engine design you mention and find that very interesting. As an example of what you describe for a turbo engine. One of our member has used a head from Erland Cox and the chamber design is like you describe. Check out the differences in the chamber in this thread. https://www.turbobricks.com/index.p...-barn-car-revival.290558/page-40#post-6378685
Click to expand...
Thank you for showing me this thread, very valuable information for me 👍
 
Regarding squish, I think that the general understanding of it here is pretty good. I'm not sure how conducive to effective squish the relationship between stock piston crowns and stock cylinder head chamber design is. If you look at each, they don't match up well at all. There are sections of the piston crown that gets near the head deck, which is better than nothing, but it's not awesome. Probably better for a turbo application.
 
My basic understanding of tight squish is that it provides additional turbulence, which mixes the A/F mixture more uniformly. A more uniform mixture burns more consistently, which allows more timing advance without knock (especially at part throttle).

Flat-top pistons have the opportunity for more squish area, while dished pistons have less area. The 16valve pent-roof combustion chamber provides both a smaller combustion volume and better A/F mixing.

Here are some old squish/quench/chamber design threads (in no particular order):
- https://turbobricks.com/index.php?threads/squish-engines.48895/page-7#post-568835
- https://turbobricks.com/index.php?t...ne-shop-squish-stuff-etc.124696/#post-1598430
- https://turbobricks.com/index.php?t...-cometic-youve-run.274989/page-3#post-4578699
 
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