Deck heights

[louisb]

So what are the deck heights some of you are running? How about minimum. I know Berg recommends as low as .040 with their parts. Anyone here studied the effects of quench and squish in a VW motor with min/max deck heights?

edit: Found this on another forum. http://www.rbracing-rsr.com/squishcalc1.html

--louis

[John Rayburn]

.060. I like tight decks, especially with a hemi cut chamber. Semi hemi tends to leave alot unburnt, and a tight deck gets things alot more efficient. More deck with semi hemi leaves you with an overly rich situation that really can't be jetted out.

[Harry/FDK]

So John, if you like it tight. Wouldn't you go for .040 then.

[airstuff]

anybody running ZERO deck??

[Jim Ratto]

deck is a balancing act once you get into a big cc motor.
if you ran too little deck, you'd need 70cc+ chambers and then you run into problems like John mentioned. Big bubble chambers that one spark plug can't take care of , esp. with AF/R dumping in at 11.5-12.5 or richer.

[Harry/FDK]

I just set up to ZERO, and then figure out what to do...Extra shim on bottom, copper head gasket on top.
Jim, i just send PM.

[louisb]

It seems from what I have read that most other engines use a smaller deck height, say .40 to .45 than what we normally run. It may be due to combustion chamber design though. Its another one of those questions of why do VWs do it one way, and everyone else does it another.

For the 2332 I am looking at 0 deck + .050 copper gasket + 58ish cc chamber. That should give 9.5 comp I think.

--louis

[Jim Ratto]

It seems from what I have read that most other engines use a smaller deck height, say .40 to .45 than what we normally run. It may be due to combustion chamber design though. Its another one of those questions of why do VWs do it one way, and everyone else does it another.

For the 2332 I am looking at 0 deck + .050 copper gasket + 58ish cc chamber. That should give 9.5 comp I think.

--louis

probably because the cranks whip due to lack of "enough" main bearings (we have a two rod throws in between mains....bad.... makes crank whip)
Type IV center mains help...

an old friend of mine "swept together" an 1835 with cw 69mm, VW rods, and ran something like .030-.040 and his pistons had a date with his heads and yeas they kissed one another.

[Harry/FDK]

And the differences in shims is just Horrible. I just don't know what to do right now in assembling the top part.

[stealth67vw]

I'm still in mock up stage, but I will be running .047" deck and 57cc chambers with .090 barrel shims and no copper gasket. I'm using a  Bugpack 78mm crank, CB 5.5 H-Beams and Mahle 94 Bs for a compression of 9.3:1 I have the luxury of a precision surface grinder at work, so I can grind my shims to the perfect height.

[stealth67vw]

probably because the cranks whip due to lack of "enough" main bearings (we have a two rod throws in between mains....bad.... makes crank whip)
Type IV center mains help...

Another reason is most water cooled engine do not have nearly as much thermal expansion.

[DKK Ted]

I ran "0" deck before, but ran a .060 copper head gasket, ran a Erson cam, 271@50 W/ .616 lift. And IDA's. Drove this car back and forth to Bergs and home, around 50 miles a day, everyday. And had some fun burnouts before I left for home. A kid a heart. . I love it!! Anyway Mark had told me that I need minium of .042 deck, or copper head gasket. The Type4 uses 0 deck with a .042 head gasket. BUT no less. The problem I'm having with the new motor, I believe from my other post is something else, I hope. But it can be done, I did it. 

[John Rayburn]

So John, if you like it tight. Wouldn't you go for .040 then.

                                               Yes! I'd go for .040 as long as piston to valve clearance allows it, I run over .600 at the valve and 8200 RPM.

[Casey]

Wow, John thats some serious RPM! Is that what you shift at? How much hp does your motor make? Do you like the bigger intake? thanks, Casey.

[louisb]

probably because the cranks whip due to lack of "enough" main bearings (we have a two rod throws in between mains....bad.... makes crank whip)
Type IV center mains help...

an old friend of mine "swept together" an 1835 with cw 69mm, VW rods, and ran something like .030-.040 and his pistons had a date with his heads
and yeas they kissed one another.

Was that with a German forged crank? Wow. So I guess the larger deck heights have more to do with design flaws than anything else. With all the aluminum cases coming out now, you would think they could come up with a case designed for street use that fixed some of these problems. (Of course most VW people would be too cheap to step up for something like that.)

--louis

[Harry/FDK]

PM to John.

[richie]

It seems from what I have read that most other engines use a smaller deck height, say .40 to .45 than what we normally run. It may be due to combustion chamber design though. Its another one of those questions of why do VWs do it one way, and everyone else does it another.

For the 2332 I am looking at 0 deck + .050 copper gasket + 58ish cc chamber. That should give 9.5 comp I think.

--louis

Louis
you need to make sure the gasket is a really good fit,usually they move around in the head a little and after you assemble,the piston will hit the copper gasket,you would be better with 0.010 deck on the cylinder and .040 copper shim,as you still have the same deck, 0.050
And your .050 deck and 58cc gives 9.7/1 compression

See here for calcs

http://www.johnmaherracing.co.uk/enginecalc.htm

cheers richie,uk

[louisb]

It seems from what I have read that most other engines use a smaller deck height, say .40 to .45 than what we normally run. It may be due to combustion chamber design though. Its another one of those questions of why do VWs do it one way, and everyone else does it another.

For the 2332 I am looking at 0 deck + .050 copper gasket + 58ish cc chamber. That should give 9.5 comp I think.

--louis

Louis
you need to make sure the gasket is a really good fit,usually they move around in the head a little and after you assemble,the piston will hit the copper gasket,you would be better with 0.010 deck on the cylinder and .040 copper shim,as you still have the same deck, 0.050
And your .050 deck and 58cc gives 9.7/1 compression

See here for calcs

http://www.johnmaherracing.co.uk/enginecalc.htm

cheers richie,uk

Thanks Richie. that is good info. Probably going to need more deck, or bigger chambers, then as I want the comp below 9.5:1.

--louis

[John Rayburn]

Wow, John thats some serious RPM! Is that what you shift at? How much hp does your motor make? Do you like the bigger intake? thanks, Casey.

                                     Yes, I do shift there, which is why I geared my trans the way I did. My car made 206 at about 6200RPM when the dyno guy shut it off... Said it caught him off guard. The run was supposed to be to 7500. There's more power happening above the 6200 aborted pull, but I don't know how much. I do like running the 46 valve, bigger valve acts like more lift.

[Rick Meredith]

Dang... next time I see you I gotta talk you into a ride!!   

[Casey]

Very interesting. Our motors are very similar. I’m running 45x36 though. Berg rockers putting me at 590 lift. It all in the heads then. I'm counting on Anthony at Heads Up. I was never figuring those rpm #'s you’re hitting....and still pulling! Great.

[Jim Ratto]

probably because the cranks whip due to lack of "enough" main bearings (we have a two rod throws in between mains....bad.... makes crank whip)
Type IV center mains help...

an old friend of mine "swept together" an 1835 with cw 69mm, VW rods, and ran something like .030-.040 and his pistons had a date with his heads
and yeas they kissed one another.

Was that with a German forged crank? Wow. So I guess the larger deck heights have more to do with design flaws than anything else. With all the aluminum cases coming out now, you would think they could come up with a case designed for street use that fixed some of these problems. (Of course most VW people would be too cheap to step up for something like that.)

--louis

yes stock CW crank. Stock rods
I saw the heads after....  ugly.

Our cranks and cases were never designed to successfully live at high rpm and close deck and/or valve to piston clearance. Look at a 911 case and crank to see "what works"

[Tony M]

Just finished my small motor - 1776 - .070 deck, .060 copper head gasket, 51cc chamber w/heag gaskets - aprx. 8.75 cr - 120 cam, 1.25 rockers. 42x35.5 valves. Used the .070 deck because it was there - .060 to .070 deck will work with most engine combos - too much and you will get a lazy motor - not enough squish.

[lawrence]

The deck height of my 1914 came out to .060 so I ran it. I believe the chamber is 55cc and the compression is 8.3:1. If this motor ever gets torn down I will probably up the CR to something in the low 9s.

[Jim Ratto]

all I want to stress is the bigger motor gets the more the CR goes up, given same deck height, same cc in heads....  don't forget that. If you build some 94 x 84 with long rods, be prepared to either stack deck spacers and copper gaskets OR have big cc chambers (or run hig CR)

[stealth67vw]

You could make soup bowls out of your heads like the Bergs like to do.