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Piggaz - the 25/26 heads have the half inch npt bspt fitting between #3 & #4 from factory, (10mm hex key needed to remove it) the part number i mentioned screws straight in with a bit of thread sealent

So people dont get confused about the thread form incase they dont use the speedflow fitting. I used some generic steel fitting from the hydraulic shop down the road. 1/2"bspt/AN-10 male-male fitting.

Has any body tried different ring packages to reduce blowby/ring flutter. When we made 340rwkw on an oem piston ring package we had no oil control issues. Unfortunately bad fuel destroyed that engine and we went to cp's - ever since then we had oil control issues.

Has anybody tried total seal rings? What surface finish are people honing their cylinder to?

The problem with the CP ring package and the package that comes with most aftermarket pistons is they are too thin, made of too harder material(top usually) and oil control ring doesnt have enough tension. They state the use of better materials, but even so, the rings still cant handle the heat; not enough material or meat in them to dissipate it into the block adequately without losing tension over short periods of time.

Also the ring being too thin just doesnt offer enough sealing area to properly contain combustion pressures when the power starts climbing in these performance engines. Hence why people start having blowby issues after a rebuild. Then the builder is told to focus on getting the bore finish, cross hatch, bore size, trueness and distortion (torque plate) as close to perfect as possible just to try and give the thin rings a chance at working properly and lasting. Not that they shouldnt be doing those things anyway, but piston manufacturers will typically blame issues(poor ring sealing) on the machining processes rather then their piston/ring package just being inadequate.

We noticed this issue a few years ago and we now use the 1/16, 1/16, 3/16 ring set with a second gapless which means custom pistons for the right groove size which is no big deal, the benefit results in a near perfect 1-2% leakdown or less constantly. Ive never seen signs of 'ring flutter' and our ring guy reckons he has never seen it before either in the last 20-30 years of ring manufacturing....another supposed myth he claims lol.

Cp je wiesco and a few other pistons have a v grove between the top and 2nd ring for the purpose of having them pressurized to keep them horizontal, which will reduce flutter

Ty r33_racer slight typo on my part :P

but yeah the side drain is the first spot oil will drain down as the rest of the oil will still pool until it can get above the casting around the springs and head bolt areas

Very nice diagram ^^^

In regards to the guy that said he didn't fit restrictors because nobody had any at the time..

I used 1/4" grub screws and drilled them out, tapped the oil feeds in the block and screwed the grub screws in. Easy, cheap and easily changed if need be (not as easy as the external adjustable feed someone else came up with).

  • 2 weeks later...

ok bear with me guys, got a S1 25 on its way, doing headgasket while its out and want to fit oil resrictors at the same time, is there only 2 of these or a few along the surface of the block? what are the best to use? what size? where to get them from in aus?

ok bear with me guys, got a S1 25 on its way, doing headgasket while its out and want to fit oil resrictors at the same time, is there only 2 of these or a few along the surface of the block? what are the best to use? what size? where to get them from in aus?

Go back and read the 40 odd pages of this thread and make your desicion.

Finally managed a complete track day without exiting in a cloud of smoke. I am running an N1 pump (at about 100psi). Engine is only tuned to 15psi so will wait til its tuned to its final 21 or so psi to call it a complete success but my solution:

2 x 1mm restrictors and two 20mm holes bored as high as possible on the inlet side of the sump. I have two hoses running up to a catch can - both act mostly to relieve pressure but at sustained WOT oil is pushed out as well so one line goes to the top of the catch can and the other comes from the bottom to allow the oil to drain back. I also have two lines coming from the breathers on top of the cam covers going to another catch can. There is no oil collecting in that catch can and minimal residue. Both catch cans are currently vented to atmosphere.

If this still works at full power then I plan to run the two cam cover breathers into the same single catch can and instead of venting to atmosphere run the breather from the can through a horizontal air/oil seperator and plumb that into the turbo intake.

I don't have any drain from the back of the head as I think that really only functions as a breather.

I also haven't drilled out/relieved the oil drains although I think it is a very good idea. I didn't do it because it would have involved completely stripping the engine and sending it back to the machine shop for a proper clean. It seems a sensible thing to do at the building stage though.

I have heard good things about the Mines baffles in the 26 covers although they are probably not enough without the restrictors and maybe the breathers too.

Mark what size restrictors do u run at the moment. What pressure is the oil pump set at

0.6 for the VCT and 1 x 0.8 for the head.

TOMEI pump set on lowest setting still saw 120psi, a bleed bypass was put in and now it sees 90psi at 6k.

I'm hating this new motor for the oil issue but loving it for the power, if only it would go around Wakefield without spilling its guts.

I hope this gets sorted soon:...............

  • 1 month later...

Currently ive got a 25/30 that enjoys running with plenty of oil in the head and not enough in the sump causing surge issues under heavy braking when doing dragging and track.

currently running stock pump and 1.5mm restrictors.with no oil drain from catch can to STOCK sump

Moving to n1 pump, 1.5mm restrictors and oil drain from catch can to ASR sump

Ive attached a diagram of my catch can setup. That is exactly how it is except I do not have a drain back to sump currently.

I am going to ventilate the sump better by running a 17mm id hose from catch can to sump for oil return.

Ive had a good read through this thread, and wonder if an additional oil drain from cylinder head is required, Or just ventilate the sump a bit better will do the trick.

Ive attached a pic from a bung in the cylinder head that seems to be at the bottom of the cylinder head,passenger side, where oil sits. Potential oil drain? or not required.

post-62707-0-65403200-1337132359_thumb.jpg

post-62707-0-47281200-1337132380_thumb.jpg

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