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rb30det just run in, low comp no3

skylite

By skylite,
in Engines & Forced Induction

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skylite Enthusiast

skylite

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just finished runnung in rb30det in r33. done the 1000 kms then wound boost to 1 bar. blowing smoke great!!! comp test ... 70 psi in number 3 and 110 in the rest of the cylinders. done leak done test and its blowing past the rings. a fews days later and a couple a hundred ks more and comp getting to 90. thought ide try a couple of hundred more. so at 1,400 kms done a comp test tonite to show only 70 again. brought those f...kin acl pistons and rings 4 rb30 non turbo. will pull it down tomorrow to see whats going on. where can i get some forged pistons and do it properly this time and how much. does anyone know what comp it should have with these pistons. oh yeah would do a search for these questions but havent got all night to sort through the chit chat.

cheers dave.

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Bl4cK32 Grand Master

Bl4cK32

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ACL rings? I hear very bad thing about these (only in RB engines so far), they just dont bed in properly. I'm betting if you pull it down you'll still be able to see the hone pattern on the cylinder wall.

-rb25

my rb30 bottom end still showed hone marks on the bore and it had done near 400,000 kms in a vl before i got it.

Sydneykid Grand Master

Sydneykid

Posted
Posted
just finished runnung in rb30det in r33. done the 1000 kms then wound boost to 1 bar. blowing smoke great!!!  comp test ... 70 psi in number 3 and 110 in the rest of the cylinders. done leak done test and its blowing past the rings. a fews days later and a couple a hundred ks more and comp getting to 90. thought ide try a couple of hundred more. so at 1,400 kms done a comp test tonite to show only 70 again. brought those f...kin acl pistons and rings 4 rb30 non turbo. will pull it down tomorrow to see whats going on. where can i get some forged pistons and do it properly this time and how much. does anyone know what comp it should have with these pistons. oh yeah would do a search for these questions but havent got all night to sort through the chit chat.  

             cheers  dave.

What oil did you run it in on? They all sound a little light on compression, but a compression test is not an exact science. A leak down test would be much better and far less likely to give random results.

I have a spare set of brand new forged 87.5 mm JE pistons with Total Seal rings, ceramic top coated, oil retention skirt coated, they are balanced and ready to go. PM me if you are interested. :cheers:

ace_nz Apprentice

ace_nz

Posted
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you cant hone a bore properly with a ball hone, they wont break the glaze, you need a decent fixed hone with some 500 grade stones, possibly followed by finishing stones to plattoe hone the pattern. I would have done a wet comp test to see if that made a big difference to your low cylinder that way you rule out valves, is your inlet cam timing correct as well cause that will bleed off compression and make them low overall.

  • 3 weeks later...
R31Nismoid Grand Master

R31Nismoid

Posted
Posted

ok, a question for all u guys saying to use total seal rings...

Total seal rings, how are they better?

just out of "interest" to extend my knowledge a bit more on the "pro" side of them...

As you mention them down here in vic and a lot of people go green in the face at the thought of using em.

skylite Enthusiast

skylite

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it appears to have been running lean. when i got the injectors cleaned b4 use they told me two werent pulsing. even though they were ok when they came out. when he went to show me that they were not working they had come good. he said maybe because they were in the bath ova nite. or i also put xf throttle body with closest t.p.s i could find, it was very close to original but n.q.r. but i dont think this would be a problem. just needed more fuel i think. there was no pinging or any signs like that. i kills me to say it but a good dyno may have saved the engine. ive gotta get some injectors b4 it goes on the road again. im thinking sard 550cc cos greenline have a special at the moment. anyone seen any cheaper? they also have 850cc for the same price but it may be ovakill. rb30det, cooler, t3/t4 hybrid. custom plenum.

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