Hmmm, why not shave the existing head 0.050"?
Sent from my iPad
On Aug 31, 2013, at 12:17 PM, Comcast-spitfirecars <spitfirecars@comcast.net>
wrote:
> Nope that is incorrect. Also, 1300 engines always had flat tops. Variation
in factory 1300 CR comes from different heads
>
> Flat top pistons alone take a 7.5:1 1500 to 8.4:1. To get 9:1 you also need
a smaller head chamber, which you get with the TKC1155 (European market) or
TKC2748 (North American market 1976 model Spitfire) heads, which are shaved
about 0.050" thinner than other 1500 heads (like the TKC 3239, 1409 and
1410).
>
> If you want more detailed actual data and measurements, then I have it--let
me know if you want some and I'll forward it You could also try taking
several engines apart and making your own measurements or talk to someone else
who also has direct experience (e.g., Ted Schumacher, Kas Kastner)
>
> Sent from my iPhone
>
> On Aug 29, 2013, at 5:56 PM, Hans <sukaspit@gmail.com> wrote:
>
>> According to Moss, their pistons raise the ratio to 9:1 for the 1500 .
8.4:1 is for the Spit 1300, I think.
>> .
>>
>> Sent from my iPad
>>
>> On Aug 28, 2013, at 4:28 AM, Comcast-spitfirecars
<spitfirecars@comcast.net> wrote:
>>
>>> Just a friendly note to say that you are not going to get anywhere near an
additional 20hp just by switching from dished to flat top pistons alone, which
only raises CR from 7.5:1 to 8.4:1.
>>>
>>> Should be fine wrt NOx
>>>
>>> Sent from my iPhone
>>>
>>> On Aug 26, 2013, at 2:00 PM, spitfires-request@autox.team.net wrote:
>>>
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>>>> Today's Topics:
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>>>> 1. High compression pistons and smog test (Hans)
>>>>
>>>>
>>>> ----------------------------------------------------------------------
>>>>
>>>> Message: 1
>>>> Date: Sun, 25 Aug 2013 17:14:21 -0700
>>>> From: Hans <sukaspit@gmail.com>
>>>> To: spitfires@autox.team.net
>>>> Subject: [Spits] High compression pistons and smog test
>>>> Message-ID: <356B6E8E-7020-4D5B-A0DF-9188CA7C22E8@gmail.com>
>>>> Content-Type: text/plain; charset=us-ascii
>>>>
>>>> I am rebuilding my California 1976 spitfire's engine and considering
using
>>>> Moss's HC flat top pistons instead of the LC (dished) ones. I have been
told
>>>> that I risk failing the NOx smog test max requirement. I understand that
this
>>>> is due to the combustion chamber's temperature potentially exceeding
2500
>>>> degrees , which generates NOx. Assuming the EGR to function perfectly and
the
>>>> fuel mixture to a bit rich, is this still potentially a high risk
problem?
>>>> There must be a few a guys out there that have been tempted to do this to
get
>>>> the nearly 20 extra hp. That is so badly needed.
>>>>
>>>>
>>>> ------------------------------
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>>>>
>>>> End of Spitfires Digest, Vol 7, Issue 48
>>>> ****************************************
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