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RE: 2.0 to 2.5 to 2.7 liter

To: "'Maurice Dykes'" <mhdykes@thinkage.on.ca>
Subject: RE: 2.0 to 2.5 to 2.7 liter
From: gbuck@pinnaclegrp.com (Gordon Buck)
Date: Fri, 20 Nov 1998 14:22:41 -0800
Cc: "Triumphs@autox.team.net" <Triumphs@Autox.Team.Net>
Maurice,
FWIW, the Porsche 944 is a 4-cylinder engine which at 2.5 liters is just about 
max. due to the balance problem.  A 4-cyl. in-line engine always has a pretty 
strong balance problem (rocking couple or something like that) above (approx.) 
3500 RPM.  The balance shaft used on the Porsche, Mitsubishi, and others 
reduces the imbalance considerably.  A 6-cylinder in-line engine on the other 
hand is a naturally balanced design, and from what I understand has better 
all-around balance than any 4 cylinder, V6, or V8.  About the only smoother 
design is a V12 (two in-line sixes on a common crank) or probably Bugatti's new 
W18 (3 inline sixes on a common crank).  Anyway, what I'm trying to say is that 
as long as you make sure all parts are correctly balanced before assembly of a 
2.7 liter inline six, it should be a sweet and smooth running engine.  Just my 
.02. 

Gordon Buck
Sultan, WA
71 TR6
67 MGB GT

-----Original Message-----
From:   Maurice Dykes [SMTP:mhdykes@thinkage.on.ca]
Sent:   Friday, November 20, 1998 8:58 AM
To:     Scott Decker; Triumphs List
Subject:        Re: 2.0 to 2.5 to 2.7 liter


At 10:11 AM 11/20/98 , Scott Decker wrote:

>six to 2.7 liters.  Operating on the theory of 'more displacement=more
>grunt' and throwing originality out the window (sorry), is it insane
to
>think about putting a 2.7 liter in the GT6?  

>If not, then would I be better served by boring/stroking the existing
2.0 
>or just buying a TR6 block?

The TR6 and GT6 have the same bore so that is not a factor, but
different crankshafts. You will have to look at how the 2.7 is
achieved; bore or stroke changes and which crankshaft does the donor
engine require. 

I wonder if this is potentially a rough running engine? My 2.5L Porsche
944 has a counter rotating balance shaft to overcome vibration. The 2.7
certainly will not be red lining at 6800RPM :-)

-Maurice
GT6 2.5 and loving it!

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