Shoota_77 Posted June 11, 2014 Share Posted June 11, 2014 Yep same as last few posts. Last step before pulling the engine back out again is mineral oil and provided everything is feeling half ok I'd give it heaps. Heaps of boost and heaps of load. You need to try and undo all the glazing of the bores that idling will have done. Hopefully there is enough cross hatch (you did hone the bores I'm hoping???) to bed the rings in a bit better. As per above you need to force the rings hard out against the bores hence why you want plenty of boost or load to achueve that. Good luck, it's a bitch to have to pull the engine out again if it's no good! Link to comment https://www.sau.com.au/forums/topic/444268-rb26-compression-with-poncams-type-b/page/2/#findComment-7309528 Share on other sites More sharing options...
XKLABA Posted June 11, 2014 Share Posted June 11, 2014 This /\ /\ When I built my engine I comp tested at +/- 150psi before starting it, started it and let it run for 5mins, dumped oil refilled with mineral diesel oil, took it out to the M4 did some controlled loading till I got to the mountains then vaired from 3500rpm to 4500rpm as it climbed the hill came back down turned around and did a couple of 2nd gear hill starts at 4000-5500rpm, went home dumped oil and refilled then comp tested at +/- 170psi, a year later it comp tested at the same +/-170psi Link to comment https://www.sau.com.au/forums/topic/444268-rb26-compression-with-poncams-type-b/page/2/#findComment-7309534 Share on other sites More sharing options...
AngryRB Posted June 11, 2014 Share Posted June 11, 2014 (edited) Which will increase overlap and drop compression. Why are you worried? I don't understand why the cams were adjusted, says on the RHDjapan website that they are a drop in cam which don't need adjustment and if adjusted 1degree will dramatically impact idle and low end torque. If it affects idle then that means compression test will be crap. Maybe set the cams to normal position and retest? Edited June 11, 2014 by AngryRB Link to comment https://www.sau.com.au/forums/topic/444268-rb26-compression-with-poncams-type-b/page/2/#findComment-7309585 Share on other sites More sharing options...
GTSBoy Posted June 12, 2014 Share Posted June 12, 2014 Desperate measures for bedding in rings on an engine that had been accidentally glazed up after a rebuild used to be to tip a tablespoonful of Bon Ami down the carby. I shit you not. Slightly harsh treatment to be sure, but given that it is either that or take it apart and re-hone with new rings...... You could rig the AFM up to a hose onto the TB to bypass the turbo if you were needing to do it to an RBDET. Link to comment https://www.sau.com.au/forums/topic/444268-rb26-compression-with-poncams-type-b/page/2/#findComment-7309591 Share on other sites More sharing options...
Piggaz Posted June 12, 2014 Share Posted June 12, 2014 I don't understand why the cams were adjusted, says on the RHDjapan website that they are a drop in cam which don't need adjustment and if adjusted 1degree will dramatically impact idle and low end torque. If it affects idle then that means compression test will be crap. drop in means they fit without head mod (shimming doesn't count here). How does Tomei know what the user wants out of his setup? Link to comment https://www.sau.com.au/forums/topic/444268-rb26-compression-with-poncams-type-b/page/2/#findComment-7309592 Share on other sites More sharing options...
AngryRB Posted June 12, 2014 Share Posted June 12, 2014 (edited) My point was, the maker of the cams suggests that changing the timing of there cams will affect idle and low end torque, extra duration creates poor combustion efficiency at low rpm, so at 200rpm it would loose a lot of compression on a test if OP has increased the Overlap. http://www.rhdjapan.com/tomei-camshafts-poncam-rb26dett.html Edited June 12, 2014 by AngryRB Link to comment https://www.sau.com.au/forums/topic/444268-rb26-compression-with-poncams-type-b/page/2/#findComment-7309644 Share on other sites More sharing options...
andre_gtr Posted June 12, 2014 Author Share Posted June 12, 2014 Cool thanks guys will give it a bash Link to comment https://www.sau.com.au/forums/topic/444268-rb26-compression-with-poncams-type-b/page/2/#findComment-7309937 Share on other sites More sharing options...
Piggaz Posted June 12, 2014 Share Posted June 12, 2014 Has it had the mixtures and timing looked at after being screwed together? Link to comment https://www.sau.com.au/forums/topic/444268-rb26-compression-with-poncams-type-b/page/2/#findComment-7309941 Share on other sites More sharing options...
XKLABA Posted June 12, 2014 Share Posted June 12, 2014 mine is currently +2 intake -4 exhaust100 psi is very low, what exactly did you change when doing the rebuild, are the cams timed correctlyThose setting should actually increase the compression reading, even if it is only a little bit as they aren't that big of a change Link to comment https://www.sau.com.au/forums/topic/444268-rb26-compression-with-poncams-type-b/page/2/#findComment-7310038 Share on other sites More sharing options...
GTRPSI Posted June 12, 2014 Share Posted June 12, 2014 You need to lean into the motor gradually and stay away from any synthetic oil for the first few thousand Km. Load the engine, you need pressure to push the rings onto the bore to bed them, idling does nothing but take the peaks off the hone without bedding in the rings. I recon go back to a mineral oil and lay into it a bit, hopefully most of the cross hatch should still be there. Also check your mixtures, if your running rich, expect to see your oil contaminated with petrol, its not a good thing to wash the oil off with fuel on the bores, not a good start to the engines life. Link to comment https://www.sau.com.au/forums/topic/444268-rb26-compression-with-poncams-type-b/page/2/#findComment-7310234 Share on other sites More sharing options...
andre_gtr Posted June 12, 2014 Author Share Posted June 12, 2014 Timing has been set and afr are pretty close to what I want them on the map not too rich it was a total rebuild with old pistons and new rings, honed bores Link to comment https://www.sau.com.au/forums/topic/444268-rb26-compression-with-poncams-type-b/page/2/#findComment-7310240 Share on other sites More sharing options...
andre_gtr Posted June 12, 2014 Author Share Posted June 12, 2014 still running on multigrade mineral oil delo400 should i bump it down to a monograde Link to comment https://www.sau.com.au/forums/topic/444268-rb26-compression-with-poncams-type-b/page/2/#findComment-7310249 Share on other sites More sharing options...
KiwiRS4T Posted June 12, 2014 Share Posted June 12, 2014 still running on multigrade mineral oil delo400 should i bump it down to a monogradeShould be fine. Link to comment https://www.sau.com.au/forums/topic/444268-rb26-compression-with-poncams-type-b/page/2/#findComment-7310253 Share on other sites More sharing options...
XKLABA Posted June 12, 2014 Share Posted June 12, 2014 What head gasket ? Link to comment https://www.sau.com.au/forums/topic/444268-rb26-compression-with-poncams-type-b/page/2/#findComment-7310268 Share on other sites More sharing options...
Piggaz Posted June 12, 2014 Share Posted June 12, 2014 What CR was the engine built to? Have you checked with a second gauge to confirm the first gauge is accurate? Link to comment https://www.sau.com.au/forums/topic/444268-rb26-compression-with-poncams-type-b/page/2/#findComment-7310281 Share on other sites More sharing options...
andre_gtr Posted June 13, 2014 Author Share Posted June 13, 2014 not sure about these questions head gasket is tomei 1.2mm and stock pistons Link to comment https://www.sau.com.au/forums/topic/444268-rb26-compression-with-poncams-type-b/page/2/#findComment-7310659 Share on other sites More sharing options...
andre_gtr Posted June 13, 2014 Author Share Posted June 13, 2014 no havnt used a second gauge but the gauge reads about 10.5bar on my rb25det Link to comment https://www.sau.com.au/forums/topic/444268-rb26-compression-with-poncams-type-b/page/2/#findComment-7310661 Share on other sites More sharing options...
Sinista32 Posted June 13, 2014 Share Posted June 13, 2014 (edited) Never mind first post. (now deleted and edited) So your saying the same gauge reads 150psi on your RB25 ok Edited June 13, 2014 by Sinista32 Link to comment https://www.sau.com.au/forums/topic/444268-rb26-compression-with-poncams-type-b/page/2/#findComment-7310680 Share on other sites More sharing options...
andre_gtr Posted June 13, 2014 Author Share Posted June 13, 2014 Never mind first post. (now deleted and edited) So your saying the same gauge reads 150psi on your RB25 ok yes thats correct Link to comment https://www.sau.com.au/forums/topic/444268-rb26-compression-with-poncams-type-b/page/2/#findComment-7310852 Share on other sites More sharing options...
Sinista32 Posted June 13, 2014 Share Posted June 13, 2014 Time to take it for a blat as per the earlier advice given to create pressure to push the rings on to the bore and bed them in good luck Post back results Link to comment https://www.sau.com.au/forums/topic/444268-rb26-compression-with-poncams-type-b/page/2/#findComment-7310864 Share on other sites More sharing options...
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