Holes in the center of a piston are from PRE- IGNITION, cracks along the
side and broken rings and damage on the edge of the piston is from
detonation. Detonation will generally be the most evident at the exhaust
valve side of the piston.
Pre-ignition can be caused by too lean mixture, to hot of spark plugs or
sharp edges in the combustion chamber. (head gasket intruding into the
combustion chamber) and other stuff like an air leak at the inlet manifold.
Detonation is generally caused by too much spark advance, lean mixture, poor
quality gasoline.
--------------------------------------------------
From: "MadMarx" <tr4racing@googlemail.com>
Sent: Tuesday, July 08, 2008 3:27 PM
To: <colordog.1@earthlink.net>; "'Bill Babcock'" <billbab@gmail.com>;
<fot-bounces@autox.team.net>; <westerneagleracing@att.net>
Cc: <fot@autox.team.net>
Subject: Re: [Fot] Pistons
> One thing about Wiseco pistons.
> If they suggest a piston to wall clearance of 0.003" - don't believe them.
> This is only for stock street engines.
> For racing engines they suggest on their web page 0.005 - 0.006"
> clearance.
> So be careful.
>
> A word to melted pistons.
> Pistons with a hole in the middle often die from lean mixture.
> Pistons with a hole through the ring zone often die from not enough valve
> clearance.
> Detonation often does harm the rings and break them.
>
> Cheers
> Chris
>
>
>
>
> -----Urspr|ngliche Nachricht-----
> Von: fot-bounces@autox.team.net [mailto:fot-bounces@autox.team.net] Im
> Auftrag von colordog.1@earthlink.net
> Gesendet: Dienstag, 8. Juli 2008 20:06
> An: Bill Babcock; fot-bounces@autox.team.net; westerneagleracing@att.net
> Cc: fot@autox.team.net
> Betreff: Re: [Fot] Pistons
>
> I just bought a set of Wisecos from Ken G. They are beautifully made.
>
> Steve B
> ------Original Message------
> From: Bill Babcock
> Sender: fot-bounces@autox.team.net
> To: westerneagleracing@att.net
> Cc: fot@autox.team.net
> Sent: Jul 8, 2008 10:56 AM
> Subject: Re: [Fot] Pistons
>
> Did you figure out what burned the holes? That would usually be an air
> leak, but it could be detonation. You tell by looking at the pistons.
> Look online for pictures of pistons with detonation vs. air leak--easy
> to tell.
>
> I like the pistons that Ken Gillanders sells, whatever they are. I
> think they're wisecos, but I'm not sure. You need to do a through
> cleaning of the engine after a piston holing. Lots of junk gets into
> the bottom end.
> On Jul 8, 2008, at 9:45 AM, westerneagleracing@att.net wrote:
>
>> FoT,
>> At the Wine Country Classic I burned holes in two of the pistons on
>> my TR-4A. I am interest in what you racers would suggest as
>> replacement pistons. The engine was built about a year and half ago
>> and dynoed at 165 hp. It has Carrillo rods that were not damaged.
>> Thanks.
>> Ron Jacobs
>> Western Eagle Racing
>> _______________________________________________
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>
> Bill Babcock
> Babcock & Jenkins
> Billb@bnj.com
> 503.936.7660
> www.bnj.com
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>
>
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