[Fot] Piston to head clearance

[Lorne Fritz]

Good point.

On Thu, Jan 11, 2024 at 6:45 PM <tr4racing at googlemail.com> wrote:

> That is one thing to consider.
>
> When is turbulence supporting and when is turbulence overdone and
> disturbing.
>
>
>
> I could imagine to force too much turbulence with a very small squish gap
> the flame front expansion is compromised, thus slows down, and lowers the
> hp output.
>
> That’s why we had the best power with 0.047” gap.
>
>
>
> Cheers
>
> Chris
>
>
>
>
>
> *From:* Fot <fot-bounces at autox.team.net> *On Behalf Of *fubog1 via Fot
> *Sent:* Thursday, January 11, 2024 8:01 PM
> *To:* Lorne Fritz <lorne.fritz at gmail.com>; Steven Belfer <
> steve at artwithcars.com>
> *Cc:* fot at autox.team.net
> *Subject:* Re: [Fot] Piston to head clearance
>
>
>
> Steve nailed it, both on the ##s, & the importance of it.
>
> It depends on what rods & crank, piston to wall clearance & what RPM, but
> for most applications that's right in the ballpark.
>
> I've run as little as oops not enough ie .025 or less, .028 minimum (you
> won't get any carbon deposit on the squish area), but to play it safe
> nowadays I use .030-.032
>
> Also on these engines it's not only a CR related issue, the squish is very
> critical, you want to minimize the clearance between piston top & head to
> maximize the squish effect, which creates turbulence, which assists in good
> combustion...
>
>
>
> Glen Efinger.
>
>
>
>
>
> On Thursday, January 11, 2024 at 01:00:50 PM EST, Steven Belfer via Fot <
> fot at autox.team.net> wrote:
>
>
>
>
>
> You want as little as necessary because this is where your high CR comes
> from.  The thickness of the head gasket is the major part of P to H
> clearance.  I ran .026 P to H clearance at Cal Speedway and the piston
> kissed the head and I spun a bearing.  My machine shop guy likes .040 for
> safety but I’ve been running .032 and it’s working out great
> ~Steve
>
>
> > On Jan 11, 2024, at 9:13 AM, Lorne Fritz via Fot <fot at autox.team.net>
> wrote:
> >
> > 
> > Hi.  In the past I have had pistons hit the head and leave a
> mark(TR3/4).  What piston to head clearance are most of you running? Thanks
> in advance,  Lorne
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