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Re: [turbobike] Re: SOHC Honda headgasket problem

Bob Shammas (b.shammas@worldnet.att.net)
Thu, 20 May 1999 23:26:40 -0400

John,

Some good points.  Just to add a few, though, a little nitrous is great and
can complement turbocharging very well, but after a certain concentration
you end up with the same severe detonation and lack of tolerance for
ignition advance as you do with any other type of supercharging.  One way to
help out in any of these cases is to effectively remove the squish band from
your chamber.  By running the squish band on the piston 0.050-0.080" below
the deck surface you effectively remove any extra induced turbulence (since
you don't need it because flame speed is proportional to combustion
pressure) and can tolerate much more advance.  Everything is happier this
way.  Many pro-mod and funnybike people have figured this out although most
of them probably won't talk about it.  Of course all of this depends on your
combination.  For street use or low boost applications it may not be
recommended because you sacrifice some performance until you're "on the
boil".

Bob

-----Original Message-----
From: John C Williamson <john.williamson5@virgin.net>
To: Bob Shammas <b.shammas@worldnet.att.net>; Rick <gsxr1100@ptw.com>; Turbo
list <turbobike@natvideo.com>
Date: Thursday, May 20, 1999 6:44 PM
Subject: Re: [turbobike] Re: SOHC Honda headgasket problem


>After thinking about this for a bit I think that the main reason that coper
>gaskets 'go' as such (apart from the oil seep / cappiliary problem) is that
>the head may 'lift'. The PEAK cylinder pressure goes up enormously with
>ignition advance but power output may only increase marginally. So if you
>have clamping / barrel stud strength problems causing you to blow gaskets
it
>makes much sense to reduce full advance to a lower figure, and up boost
>instead, producing less peak pressure but more where it counts ie, later!
>when the crank is in a better or more advantagous position to take
advantage
>of the increased cylinder pressure to produce more torque from less
>pressure. I suspect most detonation / pre-ignition / head gasket probs are
>caused by too much advance.
>This is one of the reasons that Nitrous does not seem to cause detonation
>and head gasket probs as often, because it is inert (and can put out
fires!,
>like C02 does!) and only breaks down into Oxygen & Nitrogen (most of the
>atmosphere - and does not support combustion) LATER in the chamber as it
>takes time for this to occur. Just the same as less advance really.
>
>So basically if you want to go fast safely, go rich - less advance - and
>loadsa boost and Nitrous and you will not break the engine.. look for black
>smoke (a little!) and anything that sounds harsh or 'pings' (you cannot
hear
>it on a bike...) nedds less advance... This will still blow gearboxes /
>clutches etc,  even more so in fact but the motor should be OK without
>expensive parts.
>
>I welcome your coments (Rick?) , anybody!
>
>JOHN WILLIAMSON
>----- Original Message -----
>From: Bob Shammas <b.shammas@worldnet.att.net>
>To: Rick <gsxr1100@ptw.com>; Turbo list <turbobike@natvideo.com>
>Sent: 20 May 1999 22:16
>Subject: Re: [turbobike] Re: SOHC Honda headgasket problem
>
>
>> I like the multi-layer steel head gaskets.  They probably don't make one
>for
>> that application but I've found they seal compression very well without
>> o-ringing (I either use Yamabond-4 or Gasgacinch as a sealer) and tend to
>> leak much less oil than solid copper.  I still use solid copper for my
>KZ/Z1
>> dragbikes (and put up with the oil seepage), but go for MLS anytime it is
>> availbable for one of my newer projects.
>>
>> Bob
>> -----Original Message-----
>> From: Rick <gsxr1100@ptw.com>
>> To: Turbo list <turbobike@natvideo.com>
>> Date: Thursday, May 20, 1999 10:33 AM
>> Subject: Fw: [turbobike] Re: SOHC Honda headgasket problem
>>
>>
>> >
>> >----- Original Message -----
>> >From: Rick <gsxr1100@ptw.com>
>> >To: John C Williamson <john.williamson5@virgin.net>
>> >Sent: Thursday, May 20, 1999 6:25 AM
>> >Subject: Re: [turbobike] Re: SOHC Honda headgasket problem
>> >
>> >
>> >> I would try like john said but I use Yamabond on the head gasket.
>> >> Silicone gasket sealer made things worse than nothing at all for me.
>> >> If that doesn't work then try oringing the cylinder.
>> >>
>> >> Turbo Rick
>> >> 350HP Turbo GSXR1100 Street bike
>> >> Web Site  http://www.ptw.com/~gsxr1100/
>> >> Southern California Timing Association 1998 Fastest Bike of the year
>> >> EL Mirage Land speed Record holder 204.626 MPH
>> >> E-mail gsxr1100@ptw.com
>> >>
>> >>
>> >> > Slightly more seriously, make sure that the gasget is well annealed,
>> and
>> >> > that the surface of the head / block is FLAT and not polished. A
>> >flycutter
>> >> > usually used to machine the surfaces leaves a 'machining' pattern on
>> the
>> >> > surfaces. This 'bites' into the gasket and holds it into position.
>Make
>> >> sure
>> >> > that the surfaces are fully degreased, and then use a SMALL (I mean
>> very
>> >> > small smear!) smear of silicone gasket sealer (very thinly!) around
>all
>> >> the
>> >> > bore edges, and oilways. This stops the capilliary effect that
>actually
>> >> > makes the oil penetrate under the gasket, which allows the gasket to
>> >blow
>> >> > out of position. Try to get stronger studs as they probably lift /
>> >stretch
>> >> > under boost.
>> >> >
>> >> > John Williamson
>> >> >
>> >> > ----- Original Message -----
>> >> > From: Joe Allan <beak@seaside.net>
>> >> > To: <turbobike@natvideo.com>
>> >> > Sent: 20 May 1999 06:13
>> >> > Subject: [turbobike] Re: SOHC Honda headgasket problem
>> >> >
>> >> >
>> >> > > Hello All;
>> >> > >   Just came back from trying out my supercharged 750 Hondamatic
>dirt
>> >> > > dragger, goes good but after the 10th run down the track the
copper
>> >head
>> >> > > gasket blew :-(  Pulling it apart tomorrow....any hints??
>> >> > >   Stock studs only allow 16 pounds torque.
>> >> > >  Joe Allan
>> >> > >  Vancouver Island
>> >> > >  Canada
>> >> > >
>> >> > >
>> >> >
>> >>
>> >
>> >
>>
>