Potential NF Piston Option??? Engine Experts Help.

[passat TS]

[ Converted text/html to text/plain ]

I had great answers so far.

Just to help the discussion.

1=2E I got the 7A information from 2 very good sources (one is Ron Wood, of=
 VW
Specialties). So, it is possible. I tried to get a bottom from a 7A, but had
no success (too much $$$ for a good one).

2=2E The is a full blown race car. It will use only race gas, hence the hig=
h CR.
3=2E Mike, I'll check these places again. The key is the money. I can get c=
ustom
pistons, but that will add a big $$$ to this project.

4=2E Another lister(Alan Kramer) suggested the clay test. I just wanted to =
avoid
it, since I'll have to R/R couple of times during the process, and the ARP
head bolts I bought were in back order until the end of the month. I think =
if
I use the stretched bolts I have in the donor NF, the results can be fouled.

5=2E One of the answers came up with the 1mm deck. I have 0.75mm in the hea=
d to
reach the max stated at the Bentley. Can you point me to the site you did t=
he
calculations, and the values you put in the formula? I might be using a wro=
ng
number. or Can I go beyond the Bentley number?

Thanks again for all the answers.

Carlos.

>From: "Michael Gough"
>To: passat TS
>Subject: Re: Potential NF Piston Option??? Engine Experts Help.
>Date: Fri, 04 Oct 2002 08:10:48 -0700
>
>I'd get the whole 7A bottom end and toss the NF head on top. From the
>calculations I have it'd give you like 14:1 compression though....
>http://not2fast.gotdns.com/turbo/compression/compression.html
>Also there are a TON of VW tuners with high comp pistons floating around.
>Euro spec seems to have a huge selection
>http://www.eurospecsport.com/caspist.html
>HTH
>Mike
>
> > [ Converted text/html to text/plain ]
> > I want to raise the CR of a NF Engine as much as possible. The target is
> > 11.5:1 but
> > anything better than the 10:1 I have today will be welcome.
> >
> > The ideal situation would be custom pistons, but all the places I
contacted
> > want a
> > minimum of 2 sets ordered.
> >
> > Here are the options I found so far:
> >
> > 1. Find someone interested in split the custom run at around $500 for e=
ach
> > set.
> > Pistons anyone?
> >
> > 2. Stock 7A pistons. They will raise the CR to 11.2:1, but the ones I
founded
> > are
> > too expensive. Can anyone find a set for under $600.
> >
> > 3. I found at the Wiseco catalog a set for VW 1.8l that has several ide=
al
> > measurements. I called them yesterday and the tech person seems to agree
that
> > it
> > would work. It will raise the CR to 10:8:1. The good thing is that it w=
ill
> > cost under
> > $400/set, the bad thing is that it has flat top. It has enough material=
 to
> > machine the
> > pockets, but that would reduce the compression to 10.3:1. This is the s=
ame
as
> > deck
> > the cyl head at $40.
> > Questions:
> > 3.1 Can I use flat tops? (valve clearance, combustion problems)
> > 3.2 Can I use flat tops and deck the cyl head to achieve a higher
> > compression
> > without the above problems?
> >
> > I really appreciate any help, I'm about to finish the head work(last
polishing
> > phase)
> > and need to make this decision.
> >
> > Carlos.
> >
> >
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