Re: [alfa] Re: Compresion Ratio modification

["Gwynne W. Spencer" <gwynnes1@xxxxxxxxxxx>]

In the GTV cars, the original 1570 engine was 9.0:1 and the 1750 9.5:1. It 
is a lot easier to deal with high compression on a Motronic car where the 
spark timing can be tailored along with the mixture as a function of load 
and RPM.  I know that my BMW 4.4 liter V8 is 10:1, but it has a 
sophisticated Motronic system as well as a knock sensor for every 2 
cylinders. My pld Pontiac Gran Prix with 10.5:1 eventually self destructed 
with the gasoline available in the late 80's (broken ring lands)

I ask the question not because I am dealing with the problem right now, but 
am seriously considering the purchase of a 2000 GTV that has the 10.4 
pistons and I do not want to destroy the engine (very easy to do, as heavy 
detonation is very difficult to hear, especially along with al the other 
noises that an Alfa engine produces while in full "song")

Actually a single, thicker head gasket does not scare ma anywhere near as 
much as the idea of more than 1 gasket!

How does one go about making the mixture richer in a SPICA system, but only 
at WOT ??

A Google search has come up with a $295 Spearco water injection product for 
normally aspirated engines, but says only applicable to:  Single 2 bbl, 4 
bbl and single throttle body systems only

Also one from the UK: http://www.noswizard.com/water.php and this one says 
"the required number of injectors" looks like it would be applicable to a 
multi point injected engine.

Also: http://www.kennedysdynotune.com/waterinjected.htm

Also:  http://www.syclone.freeserve.co.uk/waterinjection.htm




At 03:12 PM 6/8/2004 -0400, you wrote:

>Hi Gwynne,
>
>Date: Tue, 08 Jun 2004 14:20:39 -0400
>From: "Gwynne W. Spencer" <gwynnes1@domain.elided>
>Subject: [alfa] Compresion Ratio modification
>
>If one has a 2000 GTV engine with 10.4:1 pistons, SPICA injection and has
>problems with knock / detonation - is there a reasonable way to lower the
>CR with some form of special head gasket - I calculate that I would need to
>add about 0.8 mm or 0.032" in space between the head and the block to get
>it down to 9.5.
>
>Thicker headgasket on an all-aluminum Alfa engine?  Yikes!  The thought of it
>makes me break out in a cold sweat!  But seriously, the Digest Advertisers
>would know if one is available.  If not, there are simpler alternatives to
>addressing the knocking problem (assuming you are already running a high 
>octane).
>
>Actaully, 10:4:1 doesn't sound that outrageos on the Alfa designed
>compression chamber.  I remember the '74 Spider manual bragging about 
>being able to use
>low octane on a relatively high compression ratio.  (What was it, 10:1 
>back in
>'74?  I forget.)
>
>1)  Make sure your cooling system is up to snuff (ie radiator core is clean).
>  You want a good high flow of coolant across the head to prevent hotspots.
>Run a 50/50 mix or less.  Water is a better heat conductor than glycol.  So
>running too much antifreeze actually reduces the effectiveness of the cooling
>system.
>
>2)  Run the next cooler range on your sparkplugs.  The Lodge style
>recommended by Alfa might be better than the regular style plug as 
>supressing knocking.
>I don't know.
>
>3) Fiddle a little with the ignition timing.  Sometimes too advanced a spark
>creates an uneven flame front.  (I'm not sure if any aftermarket knock 
>sensors
>exist that would temporarily retard the spark.  In theory it's easy, I just
>haven't seen any product.  I think you would have to buy the entire 
>integrated
>ignition system with the knock sensor built in.  That could be expensive.)
>
>4)  Richen the mixture of the SPICA.  If you are on the lean side, this will
>cause pinging.
>
>5) Octane boosters help, but they are expensive.
>
>6) A water injection system is VERY effective.  But they tend to be
>expensive.  Especially if they have the feedback controls to detect RPM 
>and vacuum.
>
>Any experience with this kind of problem out there?
>
>In an old fashioned solid block engine, one might just add an extra head
>gasket, but with the Alfa wet sleeve setup, do not know if this is a
>feasible solution - would guess NO.
>
>Gwynne Spencer
>Cheers,
>Charlie
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