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RE: 2.5/2.6l (was k24/26 hybrid aka RS2) - Crank, Rods & clearances??
The angle change the rods go through with each revolution is greater with
longer throw of the crank and a shorter rod. This means that a lot of energy
goes into side loads of the crank and rod. The longer the rods are the
better leverage they have on the crank, less angle change, longer life
expectance and more torque.
According to my calculations (which are suspect this late in the work day) a
2.5L Eurovan crank (95.5mm stroke) in a 2.3L Audi engine (82.5mm bore) would
net 2671cc engine. The wrist pin would have to be moved up approx. 5.5mm in
the pistons to retain the original rods from the 2.3L engine. I have no idea
if the 2.5L crank will fit in a 2.3L block or if the rods could handle the
increased stroke of the crank. JE Pistons will make almost any piston
configuration you could want though. Stock (well factory parts from
different engines) rod, cranks and block and custom pistons, might work.
And if you bore the block to Audi's max spec (83.01mm) you end up with
Anyone for a 2.7L Audi I5 engine?
As for my math... like mileage your results may vary.
Just some random thoughts escaping...
From: Ken Keith [mailto:firstname.lastname@example.org]
Sent: Friday, September 17, 1999 4:19 PM
Subject: Re: 2.5/2.6l (was k24/26 hybrid aka RS2) -
Crank, Rods & clearances??
> > Can't this be done by just changing out the crank &
rods? i.e. go from the
> > 86.4mm stroke crank to the 92.8mm?
> This obviously depends upon which pistons you're starting
with but I
> seriously doubt it. If the deck height of the block stays
the same, then the
> additional stroke has to be accomodated by either raising
the pin height of
> the piston (which is the best approach) or running shorter
rods (which is a
> highly questionable approach).
What are the negatives to using shorter rods?
> Here in the US, Eurospec put together a crank-and-pistons
kit for the 20v
> non-turbo motors that ran about $2k (I don't know if they
ever got around to
> doing one for the 10v motors or not)
Also, they will refer you to a dealer, like