RB Rebuild

[cheftrd]

Article can also be viewed here:

 

http://www.skylife4ever.com/2011/04/rb26-engine-assembly-how-to-build.html

 

 

OK. It's been a while, but I've been busy preparing my bike and myself for the upcoming race season, working on other peoples, stuff, etc.

First things first; we'll start with the HKS oil pump. Here are two shots of the housing and rotor cover, all cleaned up and ready to install. In addition to having much larger gears than the stock pump, the HKS pump also has ducts to bring oil to the rear of the rotors, as well. This greatly improves oil flow into the pump, reducing cavitation. You can see the inlet duct for the rear of the rotors on the left. I guess it could be called a bridge port. There's some scuffing from the rotors, but nothing you can feel with a fingernail. Even then, this pump has so much volume over a stock one, you could beat it with a chisel and it'd still outflow the stocker.






Here's the rotors installed. The stock pump is a true Gerotor, where the HKS and most aftermarket pumps are more of a Duocentric rotor design.




Cover bolts with thread locker. Don't miss this step.




Tightening the bolts.




Look for the thread locker ring around the bolt. This tells you it's under the bolt head, as well and will aid in keeping them in place.




Installing the pressure relief piston.




Dual springs.




These shims go under the spring, inside the cap. The cap's aluminum and the shims keep it from galling, as well as setting the pump pressure.




Install and tighten the cap with crush washer.




Install the oil seal, and it's ready for action.






Here's the block, fresh from cleaning and honing, with the new main bearings installed. I'm using the Nissan N1 bearings for this motor.




Some of the pictures are sideways. Deal with it...
As you can see, the bearing with the groove is in the engine block and the non-grooved bearing is on the bottom. Never, ever use a grooved bearing on the bottom. It's Engine Building 101. The bottom bearing is where the engine's load goes. First, ain't no oil coming out of any hole or groove in the bottom shell to lube it. 100psi of oil pressure vs. 5,000psi of crank pressure? Second, it gives oil another place to run to when the squeeze is on. Third, the more surface area you have for this bearing, the more the load is distributed; the bearing surface material has less chance of breaking down, and the oil film has a better chance of keeping the crank away from the bearing. I've seen HKS race bearings that are grooved 360. This is a big no-no.




Oil squirters installed and torqued to 25lb/ft.




Cap torqued in place with bearings. Then check the size of the hole with a dial bore gauge. This is the most accurate way of checking clearance. The dial bore gauge doesn't really tell you the size. It's a comparator: You check the size of the bore using the gauge, and then use a micrometer on the gauge to see what the bore size is. Use the same micrometer to measure the size of the crank pin. The difference between the two is the oil clearance. This engine will have 0.05mm main bearing clearance. Nissan calls for 0.028-0.047, with a maximum of 0.090mm. If you're going to put the power to it, or spin the hell out of it, you want it loose. Loose means lots of oil flow between the bearings and pins. With big torque and big rpm comes big deflection; you need to give it room to move. The only problem with loose is a lack of oil pressure in the upper rpm. That's where the aftermarket oil pumps come in. They keep going long after the stock pump starts to lose steam. If you aren't spinning the RB26 way past the stock redline, or you're using tight clearances, an aftermarket pump won't do anything for you as far as oil pressure or volume goes. Most of the aftermarket pumps have the same pressure settings as stock, they just have more volume. That extra volume is stagnant until you reach the point where the engine needs it. Up until that point the pump simply returns it to the pan.




Here we check the crank runout. There is no such thing as a straight crank. This crank is bent0.02mm. That's about the best you're going to get with a straight six. Most stock cranks I've seen are around 0.04-0.06mm out.




Here's one big reason we check the runout. Plastigauge. I'm sure there's one out there somewhere, but I don't own one: A dial bore gauge long enough to get to the center of an inline six cylinder with a crank girdle. Most other engines you just install the center cap and measure. The other caps can be removed so they don't interfere with the gauge. Anyway, If a crank has a 0.02mm runout, that means it takes up 0.01mm of oil clearance as it rotates in the bearing. Not only do we need to know how much the runout is, but we need to know where it is. Once we know where the high spot is, we can place it at 90 degrees to the cap so that it won't affect our plastigauge measurement. Lay a piece of the gauge across the entire pin.




Reinstall the cap and torque it down. The remove it carefully. Be careful not to spin the crank while the plastic is in there either. It should look like this. Nice and even across the entire area the bearing rides.




Measure the width of the plastic with the paper it comes in. Here you can see that it's thinner than 0.038mm, but wider than 0.051mm. That puts it somewhere in the middle, which is just where we want it. We also know that the runout is 0.02mm, so the smallest the clearance at the center bearing would be is 0.038ish, which is well within our design specs.




Bearings all oiled up.




Here's the 4130 chromoly Crower crank in for the final time.




and nailed down. Here, the first thing we do is just snug down the bolts, then loosen them a little. Hit the crank nose with a plastic hammer to move the cap rearward, then hit the flywheel hub with a plastic hammer. This aligns the thrust bearing in the center cap so that when you push in the clutch, the thrust surface is touching 360 degrees. Keeps thrust bearings from wearing as much for you traffic light clutch riders. We have 0.10mm of endplay, which is right in the middle of the specified 0.05-0.18mm.






Use an oil pump gasket. Silicone sealants don't do well in high pressure oil passages. Especially when the extra that's been squeezed off breaks away and clogs stuff up.



Final step for now is to bolt on the oil pump.






As soon as Arias gets off their but and sends me the piston rings, I can finish putting the bottom together.


A few notes...

Why am I building this engine on a stool? Because I have a garage full of RB26's at the moment... I have three engine stands, all of which are occupied. There's trash all over the floor. It's disgusting and depressing.

This is my engine from my car. It's a rebuild, not a new build. Some parts are ugly and show wear, like the crank pins not being perfectly polished, or scuffing in the oil pump housing. That's because the motor spun over 10K rpm and made over 1K hp. It's 11 years old. I don't do bling very well. I don't mind it if that's your thing, but anyone here can ask the people like Stony who know me personally, the term "drive it like you stole it", is very appropriate.

Yes, those are the stock crank cap bolts. Guys were making over 1,000hp with them long before ARP started making studs, including this engine, with no problems. Maybe with individual caps, but not with a girdle that shares the load and keeps caps from walking around. Are studs a good investment? You bet!, Do I need them? Nope.

I don't have a "clean room". I don't build enough engines to warrant the $50,000 it would cost me here in Japan. Occasionally some dust shows up in some pictures. Trust me that it get's cleaned out before anything is assembled... I'm obsessive with the air blower . I use lint-free paper towels on everything and then blow the hell out of it to get any lint off... There is no such thing as a "clean" engine. You just do the best you can.

This thread was brought over here from Zeroyon.com by request. I'm not showboating, I don't need the business or have any desire to be well-known, so please don't take it that way. I have a lot of RB knowledge that I learned the hard way. Unlike many other tuners, I don't feel threatened by sharing this info. My bread and butter comes from fixing stock stuff these days. The satisfaction I get from sharing is not a bigger ego (there's no more room for it...), but saving someone the $5,000 you'll spend every time you drop a valve, ventilate a block, etc.

All questions and comments, public or private are welcome and I'll answer them the best I can. There is no magic here. Anyone with the right tools and the ability to read can build this engine in their garage.

Edited February 8, 2015 by cheftrd

[stony]

Thanks Matt for taking the time to post that. like you said it may save someone some money in the future. Stay tuned folks I'm sure there is more to come.

 

 

Stony

[Z24O]

very informative thread matt

thankyou

[Evan Purple240zt]

Thanks Matt, great descriptions too.

 

Evan

[Almighty Wez]

Nice. More RB info everyday here its great I'll be more then ready when my 26 swap comes.

[Careless]

Great thread. indispensible info because it has pics! everything here can be seen in most SBC and SBF building books, but the pics with the RB's makes it much easier to grasp.

 

thanks!

[Zardilla]

Thanks Matt - I appreciate your contribution to this board and all your help over the years on my rebuild.

[cheftrd]

Great thread. indispensible info because it has pics! everything here can be seen in most SBC and SBF building books, but the pics with the RB's makes it much easier to grasp.

 

thanks!

 

 

Those books are indispensable in learning engine building. One of my pet-peeves is when people find out I also build USDM motors, Mitsu's, Toyota,s etc. They're always saying "How can you know how to build all those different motors??" For the most part... It's the same thing. All the same rules apply. There are nuances, though. The tricky part with "rice" is the nuances aren't readily available. Things like where the RB valve train becomes compromised, oil pump drive issues, and on and on, are mostly only available places like here on HybridZ. Other forums are too ate up with trash. I frequent three forums: HybridZ, Zeroyon.com (because that's my home base. lots of us know each other over there), and woodsracer.com, which has nothing to do with cars.

[Careless]

Those books are indispensable in learning engine building. One of my pet-peeves is when people find out I also build USDM motors, Mitsu's, Toyota,s etc. They're always saying "How can you know how to build all those different motors??" For the most part... It's the same thing. All the same rules apply. There are nuances, though. The tricky part with "rice" is the nuances aren't readily available. Things like where the RB valve train becomes compromised, oil pump drive issues, and on and on, are mostly only available places like here on HybridZ. Other forums are too ate up with trash. I frequent three forums: HybridZ, Zeroyon.com (because that's my home base. lots of us know each other over there), and woodsracer.com, which has nothing to do with cars.

 

Indeed, a friend and I were discussing the same topic just yesterday. He used his ford v8 engine as a comparison to the RB but he tried to tell me that checking for bearing clearances and all the blueprinting is what makes up the difference on an RB vs. V8 machining... RB being more expensive... which I disagree with. I personally feel it's a machinist's "import car tax" and the bullcrap they try to pass off as being "harder" or so much more work.

 

I've read and read and read, and bought all the tools, minus a set of reliable mics and and bore guages and the only thing I can find that is different when doing all this stuff is what tips to mount on the tool and where to stick'em! and ofcourse, numbers.

 

The rest of the nuances, as you say, are the tips that make everything last a whole lot longer, which I think are the more important things that a lot of us have to concentrate on.

 

Do you know of any good books?

 

I had "Engine Blueprinting" which was primarily SBC, and after giving that to someone, it was replaced with the Reher Morrison Top and Bottom end engine building book. I think it's the most comprehensive of what was available to me at the time. There is also an online technical document resource from the ACL bearing company called the ACL Techfax that I've read from beginning to end through multiple bus-rides and I'd have to say it has the most information regarding things always unmentioned like surface roughness, compression and tensile load on studs and bolts, metallurgy in some forms, and headgasket seating on various engines.

 

All good reads!

[Careless]

matt, i noticed that your mainbearing skirt webbing is smooth. do the N1's come like that or did you grind them down to remove the flashing? I did the same on scottyM1z's block and found a small casting error just near the oil pickup. Is that common to find small casting lines (not cracks) in those areas? I mean small cavities like super-man's hair (normal hair would burn. duh!) fell into the mold while it was being poured, and you get a thin line with rounded edges.

[cheftrd]

matt, i noticed that your mainbearing skirt webbing is smooth. do the N1's come like that or did you grind them down to remove the flashing? I did the same on scottyM1z's block and found a small casting error just near the oil pickup. Is that common to find small casting lines (not cracks) in those areas? I mean small cavities like super-man's hair (normal hair would burn. duh!) fell into the mold while it was being poured, and you get a thin line with rounded edges.

 

 

It's ground smooth. This block is a standard block, but the N1's look exactly the same. They all have that error. It freaks you out when you first see it because it looks like a crack! The only cracking I've seen in the 26 is at the head bolt holes.

[Careless]

It's ground smooth. This block is a standard block, but the N1's look exactly the same. They all have that error. It freaks you out when you first see it because it looks like a crack! The only cracking I've seen in the 26 is at the head bolt holes.

 

LOL. well then I guess scottyM1Z got his 300 dollar RB30 for a good bargain! I sold it after grinding them down smooth and realizing that there was a casting error.

 

Someone else I sent the pic to said "doesn't look like anything out of the ordinary" but I'm not sure if he even checked the picture because the casting issue is in plain sight and I was looking for a comment on it, even if it's "ordinary". It's not something WE see everyday, so yeas.... it did freak me out at the thought of main-webbing exploding right near the oil pan pickup tube at 8000 RPM.

 

But I guess it's ok It didnt cost me any money and someone else on the boards is 0.4 litres up in displacement.

[cheftrd]

Seeing as how Arias doesn't seem to want to send me some piston rings, I'll stop on the bottom end for a while and get busy on the head. A few things have changed. When this engine started out, it was in excess of 1,000 HP. The original turbos were TD06SH-25G's, which I still have, and the head is rigged for max power drag. Seeing as that's no longer the goal, I've decided to do a little detuning. The new goal for this engine is around 600 HP with street performance/touge in mind. The original head is completely worthless for this kind of driving. 288-big lift Step Pro L cams, zero quench deck, big valves and ports, etc., aren't conducive to mid-range grunt. It would actually make less power across the curve than a properly prepped head for the intended application. Therefore, I've decided to start over and use a new head that I'll prep for exactly this type of driving, and use a pair of new Tomei 260 cams.


I'll start with the clean up in a proprietary detergent I use for cleaning engines. This is the carbon-packed chamber and oil varnished head before the soak.







After a one-hour soak and some brushing with soft-bristle brushes, it comes out looking like this.











On to the important stuff. The RB26 has three major coolant outlets along the head on the intake side. A mild port clean-up will make the coolant flow a lot better and will trap air less. Here's the small front water port that you don't need to worry about. It only runs from a bypass behind the thermostat, and is closed off by the thermostat once the engine is at operating temperature.





Here's one of the three ports. You can see how much of it is blocked by bad casting. All three ports look like this.





After scribing it to the size of the gasket.





Looks a lot better after cutting.




Next we'll go into porting. Now with video! Stay tuned.

Edited February 8, 2015 by cheftrd

[Almighty Wez]

Wow, that is some bad casting there. Makes a big difference after you port it out.

[stony]

whatcha doing with that old 1000hp head???

[cheftrd]

Going on Jon's engine.

[cheftrd]

Ahh, porting. What fun. Fortunately Nissan left us room for improvement. For engines generating power upwards of eight or nine hundred HP, there's not a whole lot that needs to be done. However, the places that need attention will give the motor more power whether it's stock or in clapped-out drag trim.

First item that needs attention is the big 'ol hump in the exhaust port. If you're using an exhaust manifold other than stock, it needs to go. In this pic you can see the offending hump. The other thing you see is that the gasket is considerably larger than the port. Same goes for the stock gasket. If you really wanted to, you could gasket match the port as long as the exhaust manifold is the same size. Resist temptation to make the port runner the size of the gasket. RB26 ports don't need to be any larger than they are for all but the most extreme applications. You'll lose power in the low and mid rpm for sure, and can hurt top-end power as well.




Here's the port with the hump removed.




When valve seats are installed, the throat is milled to remove any material overlap. While this is a good thing, it leaves the port unfinished. It leaves bad transitions and irregularities that create turbulence in the most critical part of the air stream. The goal it to make the transition through the turn and into the valve pocket as smooth as possible.

In the following picture, you can see a small lip in the short-side radius. The short-side radius is where air is hanging on for dear life as it rounds the corner. Any disturbance here will cause the air to separate from the port floor and slam into the valve, rather than try to follow the port wall and exit around the valve. You can imagine how bad this is if you think about that air slamming into the valve and going all over the place, disturbing the rest of the air stream as it's trying to enter the port. You can round this sharp lip, but under no circumstances should you remove material from the floor of the port. Lowering the floor makes the short-side radius even shorter. Big no-no.





Here you see the where the mill gets the outside radius of the port. Not as critical is the short-side, but needs to be smoothed, just the same.





Here's what the bowl looks like when it's been smoothed out. It's hard to get a picture of the short-side radius. Just use your finger and you'll feel when the lip is gone and it's nice and smooth. This bowl could be considered finished, but I'll hit it with a 120-180 grit cartridge roll later on. You do not polish ports. Polished ports leave nothing for a boundary layer to hold on to, and will hurt power. The stock ports are smooth enough from the factory that you'll gain nothing by sanding the entire port with a cartridge roll, other than a pretty port that no one will ever see.




Another thing is to try as hard as you can to remove as little material as possible in the bowl. You do not want the port to be larger than the seat ring. The port should be expanding out as it gets to the valve seat. This makes air want to exit around the valve. If the port is larger than the seat and has to compress again to get through it, it focuses the air more towards the valve.


Other than cleaning up, this port is done.





In the following three pictures, you can see the mill cut into the intake valve bowl. The third picture shows just how bad this transition really is, with a large lip.











Here is the port after cutting.





And the port after it's been smoothed with a 120-180 cartridge roll. Can you guess how important it is to stay off of the valve seat with the carbide cutter and sand paper? Coming up against it is OK as long as you stay away from the 45 degree seat cut where the valve seats.







The reason for three and five angle valve jobs is to make the air flow smoother as it makes the turn around the seat ring, and into the cylinder. It is possible to grind the valve seat with the carbide up to the 45 degree cut and obtain another 2mm or so of port opening. While this may sound good because it makes the port opening larger, you lose the third angle in the valve seat and outflow becomes very turbulent, making the port actually flow less. Don't do it.



Here's the four ports cut, but not yet smoothed.





Once again, do not open the intake port larger than stock. Even with a 1mm larger valve, the only thing that should be opened is the bowl as it transitions outward toward the valve seat. If you open the port in the turn to the valve very much, the air will lose velocity and become sluggish right where it needs to be going fastest. Simple steady-state flow bench #'s don't mean anything here; the air flow is anything but steady state and relies on velocity to fill the cylinders. Big ports will kill sub-10,000 rpm flow.

I made this short video for cutting the intake bowl to show how quick and easy it is. The key is going slow and easy. Once you remove material, you can't put it back easily.


http://http://www.youtube.com/watch?v=DBGKP4nqcGE

Edited February 8, 2015 by cheftrd

[Almighty Wez]

Nice write up Matt I was thinking about what to do with the head porting wise, this helps out ALOT! Just like an EVO/DSM head, you don't have to do much, just a good "cleaning", good to know.

[RB26powered74zcar]

Thats exactly what I did to my head Matt. I removed the hump in the exhaust ports also. I did touch up the whole areas on both ports with a sand paper barrel though... just enough to even out the casting lines....

 

Thanks for the info!!

[Careless]

Lovin' the head porting tips. I did the same, cleaned up the radii and smoothed the transitions and casting marks, and finished it off with a very fine sprout-shaped wire wheel that was used to just whisk the lines back into the smooth surface.

 

I tried it on my Z31 heads to get used to it, and I will not be afraid to touch my RB26 head in this manner now

 

Just gotta load yourself with a beer before taking a grinder to the first port... it's kinda nerve wracking getting used to the tool. Always have a spare block of aluminum around to chip away at for a minute or so when trying a new bit. It pays to do that and get used to the skipping or the shuddering of the bit diflection BEFORE inserting it into the costly part.