Getting a 2.0 8v, Tuning help please!!

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

By and large this is a nice writeup.
But having owned and inspected both a TT ported head and a Eurospec head I
can't imagine why the exhaust port should be left alone except to polish.
Both of these heads (both currently street driven and making over 130hp at
the wheels) have much larger ports than stock.
Dan

----- Original Message -----
From: "Mark" <maardak@yahoo.ca>
To: "Adam J Garside" <adam.garside@uk.ibm.com>; <scirocco-l@scirocco.org>
Sent: Thursday, July 31, 2003 8:19 PM
Subject: Re: Getting a 2.0 8v, Tuning help please!!


> --- Adam J Garside <adam.garside@uk.ibm.com> wrote: > Hi Everyone,
> >
> > I have now secured a 2.0 8v (from an Audi) to go into my Rocco.
> > I'm planning on stripping it down on the bench then rebuilding it,
anyone
> > got any recomendations of tuning to be done during the rebuild?
> > So far I have plans to send the head off to be polished and flowed (any
> > tips for this?) I'm also going to get a new Cam and fit an Audi Throttle
> > body to a modded inlet manifold. I was also thinking of sending the
> > flywheel off to be lightened
> >
> > What are my other options to squeeze more power from it? What are my
> > options for the bottom end? lightening and balenceing?
>
> Well the old adage "Speed costs money, how fast do you want to go" is
definately true...
>
> For the head, make sure you send it to someone who knows how to get power
out of a VW
> head...  Anyone can hog out a head and call it polished.  Have the shop
flow bench the
> head and give you a printout to make sure they did a good job of balancing
the flow (you
> don't want a cylinder running lean because it flows more than the next
one)...
>
> The trick here is not so much removing alot of material, but to smooth the
passages.
> Send them your intake manifold so they can properly match the ports.  The
exhaust ports
> should be left alone (other than being smoothed and crossbuffed).  You
want the exhaust
> port on the head to be a bit smaller than the port in the manifold to
create a "reversion
> dam", so don't get them hogged out...
>
> Get a multi-angle valve job, and get them to open up the throats with a 90
deg cutter.
> The throat should no bigger than 90% of the diameter of the valve for a
proper venturi
> effect - another area where simply hogging it out as big as possible will
hurt torque...
> Make sure the shop has a modern seat cutting machine, so each throat can
be machined
> EXACTLY the same as the others, both in width and height.
>
> If you're looking for maximum flow, have the seats made .040" instead of
the usual .060".
>  You'll sacrifice a bit of longevity for performance here though...
>
> After the seats are done, and the valves butt/chamfered/polished/ground,
use a very fine
> lapping compound and lap each valve in.  When you use a very fine compound
it leaves a
> very accurate "mark" where the valves contact the seat.  Backcut the
valves within a c*nt
> hair of this "mark".  Depending on the valves you use, backcut them on as
many angles as
> necessary to make a smooth profile.  Also polish the backside of the
valves (especially
> the intake) to make it smooth.
>
> If you want to raise the compression, get them to shave about .040" off of
the head.
> That'll raise the compression of a 10:1 engine to somewhere around 10.5 -
10.75:1.
> You'll have to run premium fuel, and at the very least graft in a knock
sensor ignition.
> Also, this combo will now be an interference engine...
>
> As for the bottom end, if funds permit, get the crank knife-edged.  This
both lightens
> the crank and allows it to spin through the oil with less parasitic drag.
Use good
> quality bearings, and get everything balanced.  If you're assembling the
engine yourself
> after getting machine work done, don't assume everything is fine.
Plasti-gauge the
> bearings to see if the tolerances are correct.  Make sure all the oil
passages are clear.
>  There's alot of shitty shops out there - a bit of time checking things
out at this stage
> will save alot of headaches later...
>
> I highly recommend a lightened flywheel - just send out your pressure
plate with it to
> get balanced.  I just had mine done, and it was WAY out after
lightening...
>
> I'm sure I'm leaving some stuff out, but this is what's coming off the top
of my head...
>
> HTH,
>
> Mark.
> 80 S
> 81 S
>
>
>
>
>
>
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