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[Fot] GT6 crankshaft prep for mild race use

Subject: [Fot] GT6 crankshaft prep for mild race use
From: sjanzen at me.com (Scott Janzen)
Date: Tue, 04 Sep 2018 08:22:07 -0400
References: <CAMmo4o8_-HPZ3zfZ=qn9HyAFPSmWiwSvYDO1_a5FkB3avQLCTA@mail.gmail.com>
My GT6 has the full external oiling system- fed off the main (vertical) galley, 
to the remote filter, then the cooler, then a manifold from which four lines 
run - one to each main.
I have never gone the extra step of drilling the crank.  I have a 30 psi 
pressure switch on the number one bearing oil feed line wired to a big red 
light on my dash, which has never come on. Hot oil pressure is 70+ at full rpm, 
40+ at idle.
I use a stock TR6 pump with the wire basket on suction end. Main bearings .002+ 
clearance, rods .0018-. Mains rarely show much wear, rods need replacement 
after 2- 3 seasons of 5-6 weekends.  Maybe the rods would last longer if the 
crank was drilled.
The engine is typically at 4500-7200 rpm throughout a track session.  I hit 
7000 on virtually every shift.
No bearing failures yet!  This has worked through several different engines and 
numerous rebuilds over 12 years.


Sent from my iPhone

> On Sep 3, 2018, at 5:25 PM, Jason Sukey via Fot <fot at autox.team.net> wrote:
> 
> I'm finally looking into my GT6 engine after parking it Friday of Kastner Cup 
> weekend.
> 
> Back story:
> Car ran great and allowed me to complete the competition school Thursday (4 
> full sessions), but during my first practice session Friday, I pulled in 
> early with low oil pressure and an audible rod knock.
> The #1 rod bearing was the source of the problem (extruded out the side gap). 
> That's the only bearing that shows failure.
> 
> Best I can tell it's a classic case of not enough oil to the front of the 
> engine on the 6 cyl block.
> I was not running any auxiliary oil feeds- I plan on adding that, along with 
> modifying the oil galleries in the block "per The book".
> 
> My question is this:  For the GT6 crank on a very mild engine (shifting at 
> 6200 or below), is there any need for the additional oil drilling in the 
> crank throws as suggested for the 1500 engines?  What are you other GT6 guys 
> using?
> 
> At this point, if the crank passes mag check, I'm planning to have it 
> ground/balanced/nitrided and using it for the rebuild.
> 
> Thanks for the advice,
> Jason
> 
> 
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