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Has anyone done 2.0na high cr?
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ideola  



Joined: 01 Oct 2004
Posts: 15548
Location: Spring Lake MI

PostPosted: Fri Jun 26, 2020 11:42 pm    Post subject: Reply with quote

I think it was Augidog who had a high CR NA made with S2 pistons + NA head.
Digging thru some of his old posts might be interesting:
http://www.924board.org/search.php?search_author=augidog
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ideola  



Joined: 01 Oct 2004
Posts: 15548
Location: Spring Lake MI

PostPosted: Fri Jun 26, 2020 11:48 pm    Post subject: Reply with quote

safe wrote:
Note that you need "spacers" to center the rods on the crank with those bmw rods.

I'd be intereseted in how one would implement this solution.
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safe  



Joined: 18 Mar 2017
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Location: Sweden

PostPosted: Sat Jun 27, 2020 12:00 am    Post subject: Reply with quote

ideola wrote:
safe wrote:
Note that you need "spacers" to center the rods on the crank with those bmw rods.

I'd be intereseted in how one would implement this solution.

Me too, probably making spacers on the small end centering in the piston.
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gegge  



Joined: 27 Jul 2007
Posts: 1124
Location: Sweden

PostPosted: Sat Jun 27, 2020 12:09 am    Post subject: Reply with quote

I made thick 22mm washers in aluminium in order to center the rod, nothing fancy. It is mportant that they are a tight fit to the wrist pin and doesn´t move. The inside of the piston was wedge shaped, two parallell surfaces to would be better thogh. But there are no horizontal forces on the rod so I guess it worked...
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TJC  



Joined: 04 Apr 2010
Posts: 828
Location: Central-ish Arizona, USA

PostPosted: Sat Jun 27, 2020 12:21 am    Post subject: Reply with quote

ideola wrote:
safe wrote:
Note that you need "spacers" to center the rods on the crank with those bmw rods.

I'd be intereseted in how one would implement this solution.


Many moons ago I did my time at a high performance/race engine machine shop in Phoenix, Az. I don't remember the application right off the top of my head, (probably a open wheel sprint car Chevy V8 or midget 4 cylinder engine), but we took rods that were too narrow at the big end and machined spacers from chrome moly tubing and then tack welded them onto the rods. we split them at the parting line of course, resized the rods and made sure they had the proper chamfer on them to facilitate proper clearance and oiling. I think we were using Carillo rods at the time. It was over 30 years ago and actually may have been for the all aluminum Chevy V4 engines we built for midgets...a designed first conceived by my late friend Ron Trainor.
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ideola  



Joined: 01 Oct 2004
Posts: 15548
Location: Spring Lake MI

PostPosted: Sat Jun 27, 2020 12:24 am    Post subject: Reply with quote

Cool, thanks for that. Follow up questions:
1. So these washers are at the little end, placed over the pin bushing?
2. Rough estimate of the thickness of the washers?
3. Any thoughts on specific flavor of alu?
4. Why alu vs steel?
5. Any concerns about the alu deforming over time due to the harder metal of the rods and pin?
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