Rb26 Compression With Poncams Type-B

[andre_gtr]

Hi Guys

testing compression on my rebuilt motor returns about 100psi across all 6, so my question is is this normal with these cams and have others experienced the same numbers

I have checked some guys having the same results but didnt find too many

[Piggaz]

Depends on how they have been dialed in.

[andre_gtr]

mine is currently +2 intake -4 exhaust

[AngryRB]

I know my r33 gtst dropped by 20psi with poncams, that's on standard marks.

[Adrian P]

just did compression test 3 days ago on 26 with Tomei type b.

165-170psi accross all. Fresh build.

[Ben C34]

mine is currently +2 intake -4 exhaust

Which will increase overlap and drop compression.

Why are you worried?

[andre_gtr]

fuel smell in fresh oil after 150km drive

[Ben C34]

fuel smell in fresh oil after 150km drive

Oh.

What's the history of the engine?

[andre_gtr]

its 430km old now

[Sinista32]

did you drop the oil and see excess of fuel in oil ? (fuel running down the side of the cylinders)

A loose build i.e. large clearances. or even rings. Who did the build and how was it fired up / run in

100psi is far to low for a fresh rebuild.

Edit:

Not to cause concern, more to make you even more wary and check it out thoroughly.

I run Type B's not that that has much to do with it.

After my first build it was around 85 because the builder had made a mistake which caused a catastrophic failure.

one of the symptoms before the failure was fuel in the oil.

2nd build by CRD and is around 170 across the lot.

Have you tried 2 different gauges when measuring

Edited June 11, 2014 by Sinista32

[andre_gtr]

I did the rebuild evrything was in spec initial startup was with normal mineral oil idling for about 30 min

I then drained the oil and started driving but the conditions was a bit rich and battled with tuning then after another 200km i drained the oil that was also smelling of fuel

some new oil now and smelling of fuel again after 150k

its still stock bore with stock pistons and new rings bores was honed before assembly for bedding

[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

[Piggaz]

Has the engine seen any load at all? Idling for 30 minutes is suicide.

[andre_gtr]

i'm almost at a feeling that the motor is fooked now and another rebuild is in the pipework

[andre_gtr]

yes i have pushed a bit into boost and afrs seem good on boost 12 afr and idle is around 14.3-14.9 cruising is also around those numbers

I'm not seeing any smoking etc

[Sinista32]

I wouldn't call fooked just yet. The boys on here are pretty good.

It maybe a case of pulling it out if your in doubt of any of the work.

You rebuilt with all stock internals.

Were the rings put on factory spec / positioning and double checked ?

[andre_gtr]

yip chekc ring gaps and they were spot on according to the manual

took alot of time seating the rings correctly for a proper seal

maybe I should drive it a bit more and hope it gets better?

[Piggaz]

Sitting there idling doesn't do anything for ring seal. Got to get the gases in behind the rings to push them against the bore otherwise they're just "going for the ride".

http://www.mototuneusa.com/break_in_secrets.htm

Give that a read.

[Ben C34]

What a shame about the idling.

If it was me I would give it a hard thrashing to try and bed the rings in. Back onto mineral oil also.

[KiwiRS4T]

^^^ What he said. It may be too late but give it a shot anyway. Drop the synthetic oil if that's what you've got and put mineral oil in. Do not labour the engine but give it plenty of welly - up to 6000 and button off and repeat. Watch for overheating and leaks and if ok continue for half an hour - then retest.