Re: Compression questions

[trnsfrma@ix.netcom.com (Shawn C. Meze)]

At 08:43 PM 5/28/97 EDT, you wrote:
>Not to nit-picking but....  NO!

Well, but since you did anyways, here we go!

>"exhaust work, cam, intake, knock sensor and P/P the head" will not
>change the compression ratio.  


pic-pic-pic! Well, I simply forgot to mention 10-1 pistons. Easy as that. 
With the previously aforementioned items and machine work done, the 
compression will be well over 11-1. The knock box will be a neccessity, 
unless you like running retarded timming. 


>They will help (with the exception of the
>knock sensor) the engine breath better. 


Right! Absolutely, the easier you make for the engine to flow air, the more 
power it can make, given the limits of CR.


> There are only two ways to
>change the compression ratio.  You can increase the swept volume of the
>cylinder by increasing the bore or the stroke.  Or, decrease the volume
>of the combustion chamber by raising crown height (not in stock H2O VW),
>milling the head, or installing the motorsports headgasket.


(My turn) Wrong. Changing from the 8-1 or 8.5 -1 CR pistons to the 10-1 CR 
pistons. (As I mentioned before.) Yes stock H2O VW parts even..


>The knock sensor is generally used on an engine running 9:1 or higher
>compression on pump gas.  The knock sensor allows the ignition to have a
>very agressive advance curve without damaging the engine.  The KS is not
>a requirement, but in a properly tuned system will allow the engine to
>make more power than a non KS equipped car. 


In anything over 11-1 CR, its foolish not to use it. 


>Knock sensor conversions on early cars have fantastic results.  I ran the
>ignition from an '87 GLI on  my '83 Jetta 1.7l @ 8.5:1 for a few weeks,
>to test the wiring installation before doing a complete engine swap.  The
>ignition works much like running a re-curved distributor, with lots more
>mid-range torque.  Not enough to keep from completing the swap, though.


Kinda. It senses the engine knocking and retards the ignition until it 
"hears" no further knock. Its constantly adjusting. The performance 
advantage it gives greatly outweigh simply not using it. 


>I like to keep my VW motors stock on the internal mechanicals.  Engine
>swaps, sure.  Bolt-ons, no problem.  But nearly every bored, stroked,
>monster motor that I have run across was short lived.  My Mk1 lives
>happily with a G60 transplant, and nearly every bolt-on modifcation I
>could build, fit, or buy.  It is approaching 180K miles, with the G60 in
>place for about 90K.  


Who said anything about boring and stroking?? The motor build up I discussed 
is all stock VW parts. Id be willing to bet hard cold cash that the motor I 
talked about would easily outlive a G60 motor. (or just the charger for the 
matter...) 


>No internal problems whatsoever.

How do you know unless you've taken it apart and measured and inspected 
everything? Or are you just speaking in general terms?? Oh, am I picking 
too?? heh, silly me.......


Shawn 

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