[TECH] 1.6L pistons into 1.7L Engine

[jdbubb at ix.netcom.com (Dan Bubb)]

comments within:
----- Original Message -----
From: "Patrick Bureau" <ats@longcoeur.com>
To: "'Dan Bubb'" <jdbubb@ix.netcom.com>; <Scirocco-l@scirocco.org>
Sent: Sunday, February 29, 2004 4:16 PM
Subject: RE: [TECH] 1.6L pistons into 1.7L Engine


> Yes that is what I am worried about, yet I cannot find any data to tell me
> how long a 1.6L rod is versus the 1.7L rod.

ETKA lists no difference between the 1.6 and 1.7 rods. Greg Raven's Volkswagen Performance Handbook
says all 1.5, 1.6, 1.7 rods are 136 mm center to center.

> The second question I have is can I use a 1.6L crank (80mm) versus using the
> 1.7L crank (86.4mm) in a 1.7L.

Of course! The blocks are the same height and the bearing sizes are the same so the crank will fit,
but what's the point? Using the 80mm stoke crank will get you a 1.6 L engine and not a 1.7!

> If this is possible, this would make the piston head come to 3.2mm lower.
> The question is how much compression this would create? Higher than a
> regular 1.7L or lower ?

The compression will be whatever the piston is supposed to provide. All VW heads are the same as far
as combustion chamber size (generally speaking) so the CR is determined by the piston.

> Does anyone know how close to top of head a normal 1.7L piston comes to the
> top of the block ?

Probably about 1 mm. Just enough clearance so the piston doesn't hit the head at 7000 RPM.
I guess I'll say this one more time. (making it about 10 times in the last 2 years) Nobody designs
engines where the piston is down the bore so you can increase the stroke without changing either the
rods or the pistons. It's just a really crappy combustion chamber design to do that. Increase the
stroke and use the same rod and piston and the piston WILL protrude from the top of the block!

Use the high CR 1.6 pistons with an 80mm crank and everything will be fine except you'll have
1588cc!
Use the high CR 1.6 pistons with an 86.4mm crank and the engine will turn less the 180 degrees once
you install the head!
Capish (sp)
Dan

>
>
> ---
> ATS - Patrick Bureau -  Web site :
> http://ats.longcoeur.com]http://ats.longcoeur.com
> AIM: texasscirocco - Yahoo: atsgtx - ICQ: 32918816 - MSN: atsgtx@hotmail.com
> See what I am selling today on ebay: http://tinyurl.com/22e5b
> -----Original Message-----
> From: Dan Bubb [mailto:jdbubb@ix.netcom.com]
> Sent: Sunday, February 29, 2004 9:31 AM
> To: Patrick Bureau; Scirocco-l@scirocco.org
> Subject: Re: [TECH] Need Spec on 1.7L Engine
>
> I'm pretty sure the 1.7 and 1.6 rods are the same.
> If that is true then using the 1.6 pistons with the 1.7 crank will result in
> the pistons sticking out the top of the block 3.2mm.
> The longer stroke of the 1.7 is accomodated by moving the piston pin higher
> in the piston, so the
> 1.6 pistons won't work.
> Dan
>
> ----- Original Message -----
> From: "Patrick Bureau" <ats@longcoeur.com>
> To: <Scirocco-l@scirocco.org>
> Cc: <TST@yahoogroups.com>
> Sent: Sunday, February 29, 2004 9:31 AM
> Subject: [TECH] Need Spec on 1.7L Engine
>
>
> >
> > I am considering doing something crazy (i.e. putting high compression
> > 1.6L pistons into a 1.7L engine , the kit does compose an 800 stroke
> > crank and 1.6L rods) but I was wondering, since the pistons are 79.5mm
> > and that fits like a glove in my 1.7L, can I simply slap them pistons on
> my 1.7L rods ?
> > thanks
> >
> > ---
> > ATS - Patrick Bureau -  Web site :
> > http://ats.longcoeur.com]http://ats.longcoeur.com
> > AIM: texasscirocco - Yahoo: atsgtx - ICQ: 32918816 - MSN:
> > atsgtx@hotmail.com See what I am selling today on ebay:
> > http://tinyurl.com/22e5b
> >
> >
> >
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