Jump to content
SAU Community

Rb26 Compression With Poncams Type-B

andre_gtr

By andre_gtr,
in Engines & Forced Induction

 Share

Recommended Posts

Shoota_77 Veteran

Shoota_77

Posted
Posted

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!

  • Replies 59
  • Created
  • Last Reply

Top Posters In This Topic

Popular Days

Top Posters In This Topic

Popular Days

Popular Posts

SiR_RB
SiR_RB

Idling for 30mins? I was told start up check for leaks then go for a drive with varying loads Minimize idling during run in

GTSBoy
GTSBoy

It's actually funny how the old and sensible instruction to avoid idling a newly built engine coupled with the old and sensible advice to run the engine through a variety of loads and speeds (but not

XKLABA Grand Master

XKLABA

Posted
Posted

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

AngryRB Grand Master

AngryRB

Posted
Posted (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 by AngryRB
GTSBoy Grand Master

GTSBoy

Posted
Posted

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.

Piggaz Grand Master

Piggaz

Posted
Posted

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?
AngryRB Grand Master

AngryRB

Posted
Posted (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 by AngryRB
XKLABA Grand Master

XKLABA

Posted
Posted

mine is currently +2 intake -4 exhaust

100 psi is very low, what exactly did you change when doing the rebuild, are the cams timed correctly

Those setting should actually increase the compression reading, even if it is only a little bit as they aren't that big of a change

GTRPSI Mentor

GTRPSI

Posted
Posted

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.

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
 Share
Go to topic listing


  • Similar Content

  • Latest Posts

    • MBS206
      Duncan's V37.......race car?

      By MBS206 · Posted

      Even more fun, leave all the ADAS stuff plugged in, but in different locations, hopefully avoid any codes!   And honestly, all these new cars with their weird electronics. Pull all the electronics out Duncan, and just shove an aftermarket ECU and if needed a trans controller in, along with a PDM. Make it run basic but race car styled!
    • Duncan
      Duncan's V37.......race car?

      By Duncan · Posted

      To follow up a question from earlier too since I had the front bar off again (fking!) This is what is between the bumper and the drivers side wheel And this is the navigator side, only one thing but its a biggy! So basically....no putting coolers in the wheel arches without a lot of moving other stuff. Assuming I move to properly race prepping this car I'll take that job on and see how the computers respond to removing a whole bunch of ADAS modules
    • Duncan
      Duncan's V37.......race car?

      By Duncan · Posted

      So I prepped the car for another track day on Wednesday (will be interesting to see coolant temps post flushing out and the larger reservoir, with a forecast of 3-14 being 20o cooler than last time I took it out). Couple of things to mention; since I am just driving the car and not taking a support vehicle, I took the rear seats out and just loaded the back up Team Trackday style. Look at all that space! To cover off removing the rear seat....it is weird (note the hybrid is probably different because it wouldn't have folding rear seats) Basically, you remove the lower seat base, very similar to a r series but it is a clip that pulls forward to release the base rather than it being bolted down. Easy Then, you need to remove the side section of the rear seat on each side. There is a 14mm head nut at the bottom of the side piece, the it slides upwards off a hook at the top to release; you also need to unhook the seatbelt from the loop at the top. Then the centre piece is weird. You need to release/fold the seats forward with the tab in the boot on each side From there, there are 2,x12mm headed bolts holding the rear of each seat to the folding bracket, under the trim between the rear seat and the boot (4x christmas tree clips there, they suck). The seat is out but you can see where the bolts attach to the bracket
    • RP1421
      S15 Spec R

      By RP1421 · Posted

      As discussed in the previous post, the bushes in the 110 needed replacing. I took this opportunity to replace the castor bushes, the front lower control arm, lower the car and get the alignment dialled in with new tyres. I took it down to Alignment Motorsports on the GC to get this work done and also get more out of the Shockworks as I felt like I wasn't getting the full use out of them.  To cut a very long story short, it ended up being the case the passenger side castor arm wouldn't accept the brand new bush as the sleeve had worn badly enough to the point you could push the new bush in by hand and completely through. Trying a pair of TRD bushes didn't fix the issue either (I had originally gone with Hardrace bushes). We needed to urgently source another castor arm, and thankfully this was sourced and the guys at the shop worked on my car until 7pm on a Saturday to get everything done. The car rides a lot nicer now with the suspension dialled in properly. Lowered the car a little as well to suit the lower profile front tyres, and just bring the car down generally. Eternally thankful for the guys down at the shop to get the car sorted, we both pulled big favours from our contacts to get it done on the Saturday.  Also plugged in the new Stedi foglights into the S15, and even from a quick test in the garage I'm keen to see how they look out on the road. I had some concerns about the length of the LED body and whether it'd fit in the foglight housing but it's fine.  I've got a small window coming up next month where I'll likely get a little paint work done on the 110 to remove the rear wing, add a boot wing and roof wing, get the side skirt fixed up and colour match the little panel on the tail lights so that I can install some badges that I've kept in storage. I'm also tempted to put in a new pair of headlights on the 110.  Until then, here's some more pictures from Easter this year. 
    • joshuaho96
      R32 GTS (RB20DE) Injectors Replacement

      By joshuaho96 · Posted

      I would put a fuel pressure gauge between the filter and the fuel rail, see if it's maintaining good fuel pressure at idle going up to the point when it stalls. Do you see any strange behavior in commanded fuel leading up to the point when it stalls? You might have to start going through the service manual and doing a long list of sensor tests if it's not the fuel system for whatever reason.
×
×
  • Create New...