O-Ringed Block + Gasket

[Super_Dude]

I picked up a brand new forged rb30 recently for an amazing price and I'm pretty excited about it, except the fact they O-ringed the block. They included a custom copper headgasket but I'm afraid it's going to leak and give me trouble.

I've been looking around I've found a few options

Use the copper head gasket and steel wire O-ring

Use MLS/stock paper gasket with copper wire O-ring

Use no wire and a MLS gasket

Use copper wire to fill the O-ring groove but not stick above the level of the block.

If anyone has experience with O-ringed RB's please let me know

The car is a r32 GTR that is mostly a track car and sees a bit of street driving, power is going to be in the 700-800whp range on E85.

[r33_racer]

GTRNUR has experience with this from his open deck engine.

When I last looked at doing it, the best way seems to be a standard headgasket with the copper O rings. You get the awesome sealing for water and oil from the standard gasket as it can take up the most irregularity in flatness and the O ring seals the cylinders near perfectly.

Otherwise next best would be your MLS with the copper O rings.

You could PM GTRNUR and ask for his advice.

[Super_Dude]

Thanks, pm being sent

[nick81xd]

i use steel ring with OEM nissan gasket havent had a issue up to 25psi yet

[Super_Dude]

Why did you choose to Oring your engine? How often and long have you been driving it hard?

[black bnr32]

GTRNUR has experience with this from his open deck engine.

When I last looked at doing it, the best way seems to be a standard headgasket with the copper O rings. You get the awesome sealing for water and oil from the standard gasket as it can take up the most irregularity in flatness and the O ring seals the cylinders near perfectly.

Otherwise next best would be your MLS with the copper O rings.

You could PM GTRNUR and ask for his advice.

+1

in the turbo bmw world where bore spacing is much closer than the rb and flatness causes issues with MLS gaskets, stock gaskets with copper ring sare popular as they have troubles with blowing gaskets between cylinders

[GTRNUR]

Finally back online again after the cyclone!

Have you got any data for the depth of the o-ring grove and know what diameter the wire ring is? You need to take a few measurements.

I havent used copper rings in my engine. They are stainless, and I use a standard gasket with them and a spray on coating of hylomar. The general rule is 1/6 to 1/4 of the head gasket is how far you should have the o-ring protrudeing from the top of the block. Superglue them into the block to stop them moving when the gasket is put on as well, or they can tend to move. I use a product called ZAP which is an ultra thin superglue that you get from hobby shops.

Definatly use a few coats of hylomar on the gasket if your using a steel or copper gasket. You can probably get away without it with a standard gasket but really why risk it when the head is off.

On another tangent, Ive used copper head gaskets in my VW engines (which has basically the same cylinder sealing principals as a sleeved open deck engine). The trick with the vw's is to use a propane torch to heat the gasket up to a cherry red (done with them laying flat on a piece of alloy sheet), and then let them air cool. This softens/aneals the metal, so it better takes up deformaties in the two sealing surfaces.

This tracks with what r33_racer says, with having a copper o-ring seal to the mls headgasket. I'd be very nervous about using steel on steel with this approach though as the steel will not compress, so copper only with MLS. I'd lean towards 1/6th exposed o-ring height as well. If the o-ring distorts the gasket too badly, the gasket will leak all over the place, coolant in oil etc.

Most MLS gaskets have some sort of o-ring arrangement built into the combustion area anyway. Either as part of the embossing or as an o-ring that is between the MLS layers. Have a read about what Nitto do. The idea is to have a greater sealing pressure concentrated around the combustion chambers. Both o-ring blocks and MLS gaskets do this the same way. The difference is that the standard gaskets seal much better than a MLS gasket, and will tolerate far more surface distortion before the develop a leak.

[nick81xd]

bit of extra protection againist blowing out the gasket i guess. well the old engine lasted around 60,000klm with a hard time and when it was stripped down to fix a broken oil squirter it was still sealing perfectly.

[Super_Dude]

Do you guys think a stock headgasket+steel oring would be a good setup for a track car? What is the thickness is a stock head gasket and how much stick up l do I want out of the oring? Do I need to worry about where the oring meets the factory headgasket?

The steel o ring + stock headgasket is looking like the best option right now.

[GTRNUR]

In theory metal transfers heat better from the head to the block, so copper does that better than MLS steel, and steel better than stock.

But oil cooling is where most high reving track engines suffer anyway, due to oil spray to the bottom of the pistons mostly doing what its designed to do. That being pulling heat out of the piston crown.

The best advice I can offer is to go an talk to someone that builds RB track engines for a living and have them put together a setup for you. Racepace for example. Trying to do it 'successfully' as a first time project is a lot to expect and will often end in tears or great expense, probably both.

Also are you serious about your 700-800whp? To build an engine like that for track you definatly want an experts advice. That level of power tends to break everything else in the driveline like a twig so be prepared to open the wallet. And you'd better be able to drive better than Mark Scaife too, because the Group A cars didnt make that much power.

If you want the engine to last more than a day you will need a good $40K+, not counting driveline. Even if you have all the tools and all the skills to do the assembly and tunng yourself, its a $30K project easily. There are a few cars for sale at the moment that are built with similar power levels but they are not track ready yet. Whole cars tend to cost a good $120K upwards that can meet your 'requirements'.

[Super_Dude]

Im serious about the power. I've got everything in the drivetrain upgraded, built head, single turbo, big fuel system, dry sump, huge brakes. I'm not going to be running that much power all the time and will probably be on low boost most of the time.

Im up in Canada and there is nobody experienced with a gtr with this much power on the track. I've talked to lots of people in the know overseas but I dont like bugging them all the time so I thought I would ask here first.

[GTRNUR]

Well here's my suggested thoights for the bottom end:

Consider a partial grout fill, to just above the welsh plugs. This is done after you acid wash and before you bore the block, and before all machining work.

Drill and slot the mains to support RB26 bearings.

ACL race series RB26 mains and RB30 race series rod bearings.

Shave the cradle 0.001" and fit and ARP main stud kit. Torque to spec and then align bore to round. Aim for a bearing clearance of at least 0.003 to 0.0035" on the mains.

Carillo or pauter rods, again aim for 0.003 to 0.0035" clearance. 22mm gudgens would be a good idea.

Have your head CC'd and do your CR calculations based on a 0 deck and get a custom piston with an RB26 dome profile to suit your target CR. Eg 9:1 needs a 5-6cc dome depending on whats done to your head. Use a good piston like a CP or wiseco, 22mm gudgens would be a good idea as well.

Have the crowns ceramic coated and the skirts moly coated.

Follow the manufacturer settings for the ring gapping when filing the rings to fit the bores.

I'd be leaning towards 12mm ARP head studs, but since that modification requires drilling and tapping the block, you may as well go for 1/2" and have thread inserts put into the block as well. If you go 1/2" you will also need custom dowels to locate the head to the block. Some will say that is over engineering but they all say that till it breaks is my theory.

Fit your head studs and torque plate, and bore to piston spec sheet clearance. 87mm max bore unless you want to entertain sleeving, which will open a bunch of other options. You must use a torque plate, especially with the ARP head studs as the bores go very out or round with the extra torque the 1/2" studs can pull on the block.

Measure deck height in cylinder 1+6 and level shave the deck of the block to achieve a 0.000" deck on all cylinders, giving you a 0.047" deck height with the 1.2mm gasket.

Drill and tap threads into the oil galleries at each end of the block, and use tapered plugs with thread sealer when assembling. This is necessary to ensure your oil plumbing is 100% clean. If you are using a standard RB30 crank, have it drilled and grub screwed as well. Use a medium loctite on the grub screws when assembling. Wide colar fitted to the crank snout isnt needed with the dry sump, so dont machine the standard one off the crank.

Since you have a decent external oil pump you will need to experiment with the oil flow/gearing requirements that will allow you to achieve about 10psi/1000 RPM you intend to use. This will require more flow than the average engine due to the increased engine clearances. I presume you have one scavenge from the back of the head and two from the sump with a 4 stage pump. This is the most common approach.

Also do a search for the oil control thread here somewhere on the forum, and determine what restrictor setup you want to run. A blocked rear and 1.5mm front is pretty standard.

As for the head gasket, I'd recommend a standard gasket, but also consider having your head o-ringed to match the block with a w-ring arrangement. One ring fits inside the other when it crushes the gasket. This with hylomar on the gasket creates the ultimate seal for your fluids and combustion. It will never blow out.

This is just my opinion, for what its worth. Im no expert and have learned what I have from others that shared their information and from breaking a few things along the way. If you cant get this machining done locally in Canada (ie torque plate honing) properly, you should just box up your head and block and send the lot to RIPS and have them do the whole build for you. If you can afford a build like this, freight to New Zealand and back is a drop in the ocean as far as money is concerned.

[Super_Dude]

How do you drill and slot the mains for rb26 bearings?

I've been changing a lot of things with this setup and now I'm onto bearings. Can I just modify the rb30 main bearings for better oiling?

Im trying to avoid machine work as I just discovered the mains have .0015 clearance and I need to open it up. I was hoping to find some bigger main bearings and avoid machining and having to re-nitride my crank

Edited July 22, 2011 by Super_Dude

[r33_racer]

He means grooving the main bearing bore so oil flows out the oil feed hole and fills the groove or slot and feeds up through the rest of the holes in the shell. This is also sometimes referred to as annular grooving.

You can get 0.001" undersize bearings. So you could eseentially get 0.0025" with those bearings without touching the crankshaft journals. The ACL bearings have an X prefix after the code to indicate they are 0.001" bigger in oil clearance over standard.

[Super_Dude]

What depth is the groove machined to? I really want to make sure this car lasts but is this a proven must have?

Also, arent rb30 mains wider than rb26 mains?

[GTRNUR]

2mm would be plenty, but check an RB26 block with a vernier depth gauge if you can get your hands on it. RB26 and RB30's use the same dimesion bearings, the only difference is that the 26 has the oil groove to provide better oil flow to the mains.

Regarding your mains being too tight, have you worked out where the clearances are too big? What are the crank dimensions? Make sure your micromoters have been certified as well, its easy for them to become 0.5 to 1 thou out if someone has dropped them.

You need to install your main stud kit, torque it to spec and have a machine shop tunnel bore/skim the main bearing saddles a little. Then the main bearings are re-installed and measured until you achieve the 3-3.5 thou bearing clearance. Remember your bearings crush a little when the cradle is torqued to spec. Align/tunnel boring the mains reduces bearing crush a little and increase oil clearances.

Don't use an N1 pump if you are going to run main clearances this big. Im thinking Tomei or external oiling only, otherwise crank movement will smash the pump.

[Super_Dude]

We used plastigauge to check the clearences so Im not sure where it is tight\loose if it is out of round. The mains were tunnel bored before i got it and the crank just had a polish and check before we plastigauged it.

The oil pump is a 4 stage weaver. With the extra flow will it makeup for the lack of 26 mains?

If a mod finds this maybe it should be moved to the rb30 forum

[r33_racer]

You should really measure it with a mic and dial bore gauge so you can check it at a couple of different spots to find out where it is tight.

The 4 stage pump will shit it in for flow. However, you may just need an upgraded pressure relief spring. I assume you are running the pump around atleast 1/2 engine speed?

I think the 26 main bearings are supposedly 1mm wider then rb30 main bearings. Not that it really matters. Also the groove depth in the block, I think from memory it is something like 4-5mm deep. When we used to get it done to our rb30 blocks it was around 5mm deep at the lowest point and it would taper up as it got closer to the parting line each side.

[GTRNUR]

You should really measure it with a mic and dial bore gauge so you can check it at a couple of different spots to find out where it is tight.

+1

Your crank could be out of round, or the cradle might not be from that block (or just be a bad match for it). Every main on the crank and block should be measured at 3 angles using a micromoter and telescopic gauge. Only then can you actually be sure your mains are round and that your bearing clearences are consistent. If you tell a good machine shop that this is what you want done, they should be able to do it for you.

Just torquing the cradle down and the associated twisting of the cradle that can happen is enough to give you an inaccurate reading.

[Super_Dude]

To be honest the engine came assembled from an engine shop with a good reputation but we just wanted to double check everything.

Im going to find another engine shop to assemble and triple check everything with the proper tools. Im worried about machining the crank though as I will need to renitride but im considering having it all wpc treated after machining.

Im thinking I might not bother with the rb26 bearings as I dont know if I trust a machine shop and Im afriad they would screw something up. Im going to talk to the machine shop and see what they have to say about it.

While ive got your attention what should we run for thrust clearances?

Edited July 25, 2011 by Super_Dude