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| 2.2 or 2.5 pistons for long rod build https://www.slantsix.org/forum/viewtopic.php?t=50758 |
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| Author: | SlantSteve [ Wed Jan 09, 2013 12:07 pm ] |
| Post subject: | 2.2 or 2.5 pistons for long rod build |
Hi there, Im looking at either the 2.2 turbo or the 2.5 n/a pistons for a mild build I'm working on and noticed the oil return slots machined in the oil ring grooves are very small compared to a standard slant piston, it appears to be approx 3/8" slot on the 2.2 pistons, Im not sure but I think the 2.5 non turbo pistons have a much larger slot, has anyone had experience with running these pistons and any oil control issues? Also, is there a ring set number out there for a set of six rather than going 2 sets of 4? Thanks guys |
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| Author: | slantzilla [ Wed Jan 09, 2013 12:31 pm ] |
| Post subject: | |
I have always had to buy 2 full ring sets. I could not get separate sets. Be careful when using 2.5 pistons. There are 2 generations and they have a different comp height. Guess how I know........ |
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| Author: | Doc [ Wed Jan 09, 2013 3:50 pm ] |
| Post subject: | |
You need a compression height in the 1.5 to 1.6 range, to get the correct compression ratio so 2.2 pistons are a better choice. I have used the "small oil return slot" with-out any oil control issues but I alway drill 2 extra positive piston pin oiling holes, into these pistons. Doing that helps channel some additional oil out of the oil ring groove. See the post below for some ring set information, on 2.2 pistons. DD http://www.slantsix.org/forum/viewtopic.php?t=25197 |
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| Author: | SlantSteve [ Wed Jan 09, 2013 4:10 pm ] |
| Post subject: | |
Thanks very much for the replies,will read up on the rings....Doc,where did you drill the holes? In the bottom of the boss or up into the oil ring groove? I was thinking of drilling a couple of extra oil return holes in the ring groove but it sounds like that isn't necessary... I'll stick with the 2.2 pistons, sounds like the 2.5 comp height can be a bit of a prob! |
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| Author: | Doc [ Wed Jan 09, 2013 4:41 pm ] |
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You need to get a passage from the oil ring groove, into the pin area. I have angle-drilled, in one "shot" (punch and drill from the ring groove) or drilled in 1/2 way, from the ring groove and then interesect that hole with a second drilled hole, from the bottom. (See photos below) DD  
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| Author: | SlantSteve [ Thu Jan 10, 2013 4:31 am ] |
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A picture is worth a thousand words...thanks for that,makes sense now |
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| Author: | Supercharged SL6 [ Fri Jan 11, 2013 5:30 pm ] |
| Post subject: | |
I drilled my 239 KBs like the turbo 268 KBs     
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