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>I have been following the thread about the 2.5 liter conversions that are
>going on out there with some interest. But as my plan is to autocross my car,
>i am going to stay with the 2 liter so the car will be homoligated.
>I have a question for those of you that know more about these engines that i
>do. Is there a difference in pistons between the 2 liter and the 2.5 liter?
>I know the bore is the same,but are the skirts different lenghts?
>Or can i just buy pistons for a 2.5 liter?
>
>Thanks for your help
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>GT6NUT (Dan Arrington)
Dan,
You are correct in that the pistons are the same diameter. And, according
to measurements of pistons I just removed from a TR6, the skirt length is
the same. I can't find any data to support this comment, but I think even
the gudgeon pins are the same size.
The stroke is longer in the TR6.
For auto-x, you probably will want higher compression pistons.
Gt6 pistons (stock) are either 7.5/1 or 8.5/1. TR6 piston are 7.75/1,
9.5/1.
You might luck out and find a set of 10.5/1.
What determines the compression rating is the distance of the top
compression ring below the top of the piston.
The closer to the top of the ppiston, the higher the compression rating.
If you buy new STOCK pistons, be ready to shell out anywhere from $360.
to $450. depending on wher you buy.
I bought a set of Hepolites from BPC for $240.
By milling the head and block and going to a hi-comp steel head gasket,
you should be able to run 9.5/1 pistons without any trouble. This kind of
head work will usually allow you to run as high as 13.1 pistons, if you
can find them.
I have a set of TR3/TR4 13:1 pistons, stock bore if you know anyone
interested. $200.
Good luck on the beefing up job.
Best Regards,
Tony
"GT6s"
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