How to determine notches regarding head gasket type

[92EcoDiesel Jetta]

I only asked you to prove what you said man..

You said no because we are not worth your time..

Why do you post here then??

Enough. You are putting words into his mouth, he never said anyone here was not worth his time. Last warning.

Can a moderator give warning to another moderator? Is there a moderator pecking order?

[bbob203]

I only asked you to prove what you said man..

You said no because we are not worth your time..

Why do you post here then??

Enough. You are putting words into his mouth, he never said anyone here was not worth his time. Last warning.

Can a moderator give warning to another moderator? Is there a moderator pecking order?

8v was demoded a few months ago. His entire account deleted hence his new account has a "!" at the end.

[92EcoDiesel Jetta]

I only asked you to prove what you said man..

You said no because we are not worth your time..

Why do you post here then??

Enough. You are putting words into his mouth, he never said anyone here was not worth his time. Last warning.

Can a moderator give warning to another moderator? Is there a moderator pecking order?

8v was demoded a few months ago. His entire account deleted hence his new account has a "!" at the end.

Really!!! What happened?

[92EcoDiesel Jetta]

Somehow I don't buy this quenching theory by just doing fluid dynamic analysis in my head. To dissipate heat from the piston crown efficiently by quenching, it needs dwell time and contact to the head. There is no contact and the dwell time is what? milliseconds? Unless I see some proof, I am sticking to it.

[745 turbogreasel]

Remind the machinist  in you head the piston is stationary at TDC and BDC

[TylerDurden]

There is no contact and the dwell time is what? milliseconds?

1200rpm = 20r/s

1sec / 20 = .05s/rev

50ms / 360 = .138ms/degree crank

So, if you want to say dwell is ten degrees, then that's ~1.4ms.


Check that math... I've buggered it before.

[Mark(The Miser)UK]

Does 4 stroke have to be factored in? Clearly getting near to my bed time as my brain is fuzzing. 

[92EcoDiesel Jetta]

Remind the machinist  in you head the piston is stationary at TDC and BDC

Stationary for what, a milli-second? not enough time to transfer much heat. I can put my fingers on hot coals for a milli-second without much heat transfer won't get burned.

[745 turbogreasel]

Remind the machinist  in you head the piston is stationary at TDC and BDC

Stationary for what, a milli-second? not enough time to transfer much heat. I can put my fingers on hot coals for a milli-second without much heat transfer won't get burned.

Isn't the goal to not transfer heat? Unless you are running the piston  up to touch the head and sending heat from the crown to the head that way

We are protecting the  most delicate part of the piston  at the time heat is the highest. 

[Gizmoman]

Remind the machinist  in you head the piston is stationary at TDC and BDC

Stationary for what, a milli-second? not enough time to transfer much heat. I can put my fingers on hot coals for a milli-second without much heat transfer won't get burned.

Do it several gazillion times for a few hours. I'll bet you have some odd looking fingers

[Toby]

This argument is kind if metaphysical. It is no more relevant than arguing about how many fairies can dance on the head of a pin.

Has anybody here actually put in a 3 notch when a one notch was called for?

Well I have. I did that once when I did not have the correct "notch" in stock. Fresh motor that I wanted to put some miles on. I ordered the 1 notch and drove the car for over a month with the 3 notch before I swapped out the correct gasket. I was expecting more power, less smoke, better starts, and better mileage. I can not attest to cold start performance because it was not cold here then, but I noticed NO DIFFERENCE. Nothing, Nada.

It did not feel faster, did not start better, did not smoke less, and the fuel mileage did not go up.

So I ask you how important is it really?

[theman53]

I did it on my last build as to increase performance since I was running higher boost. I noticed that every time I started the engine it ran rougher and had white smoke out the tailpipe. It could be 95f out and still white smoke if you were watching.

[bbob203]

I did it on my last build as to increase performance since I was running higher boost. I noticed that every time I started the engine it ran rougher and had white smoke out the tailpipe. It could be 95f out and still white smoke if you were watching.

I bet he won't believe you.

[92EcoDiesel Jetta]

Remind the machinist  in you head the piston is stationary at TDC and BDC

Stationary for what, a milli-second? not enough time to transfer much heat. I can put my fingers on hot coals for a milli-second without much heat transfer won't get burned.

Isn't the goal to not transfer heat? Unless you are running the piston  up to touch the head and sending heat from the crown to the head that way

We are protecting the  most delicate part of the piston  at the time heat is the highest.  

I was questioning the statement from libbydiesel (copied below), the part that increasing space between piston crown and head at TDC by using a thicker head gasket will have negatively affect quench and cause the piston crowns to run hotter. I take it that Libby meant quench is needed for piston crown in a TD engine and having too thick a head gasket negatively affects quench, which is more important than the lowering of compression due to thicker head gasket.

       "The compression difference is not really of issue.  The other two factors are 'squish and quench'.  Squish establishes the correct turbulence, again probably not an issue on a pre-chamber diesel.  Of particular issue, tho, in a TD is quench where a significant amount of heat is transferred from the piston crown to the more cooled cylinder head.  Increasing the space between piston crown and head at TDC will have negatively affect quench and cause the piston crowns to run hotter."

[theman53]

Lots of good info in this old thread... http://www.vwdiesel.net/forum/index.php?topic=8369.0

If you look at page 6 of this thread you will see that sauerkraut has done this experiment. Later he went with the same engine but a 1.9 head and the correct gasket and it ran well. The 1.9 has bigger prechambers and therefore lower CR, but the starting issue was solved. Granted it is one car, one guy, one engine, one experiment, but it sounds like a good one and that our theories are not far off.