RB Rebuild Guide

Borrowed from Hybrid Z – located here:

http://forums.hybridz.org/index.php/topic/72928-rb-rebuild/

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 “bent” 0.02mm. 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’ve never seen it… 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.