In our last article, we looked at the development of the NORAD Toyota 3RZ cylinder head. As expected from Rado and Norwood, the head is a radical piece of equipment designed for maximum horsepower. In this installment, we'll examine the block, rotating assembly and oiling system that's designed to withstand the incredible stress of more than 1400 hp at 10,000 rpm.
As an option in Toyota's Tacoma trucks, the 3RZ is an economical workhorse of an engine. Generating around 150 hp, the 2.7-liter four-cylinder is extremely reliable and trouble-free. But can it be reworked to live in the high-horsepower world of sport compact drag racing?
Bob Norwood believes it can. "The stock 3RZ is an extremely tough little engine. The stock block is cast iron and strong, and the crank is a forged steel piece that needs minimal attention to handle what we're going to throw at it. Everything else gets thrown into the dumpster so what we have is a great starting point for a bulletproof engine," he says.
Chris Rado's 2003 combination featured a Toyota 3RZ that could generate at least 1100 hp. The 2004 version needs to develop at least more than 250 hp, so Norwood is looking at every facet of the engine with an eye on upping the ante.
With the expert crew at LC Engineering assisting, expectations are high. LC Engineering builds all of Chris' engines and knows how to make Toyota engines perform well. "Working with them makes my job much easier. The hands-on experience of the LC crew is a huge asset to our R&D program with the new motor. Our main considerations are strength, weight of the reciprocating assembly and reducing drag," Norwood explains. The engine will be revved much higher than it was designed to do, so the first thing the team looked at was making the block as rigid as possible.
Stiffer Is BetterThe primary benefit of having a solid block assembly is that the intended clearances of the rotating assembly are maintained no matter what stresses are loaded on them. Even a miniscule amount of shifting of the precise alignments of the rotating assembly will result in a catalog of horrors such as crank breakage, bearing failures and cylinder warpage.
The NORAD 3RZ is designed to maintain its structural integrity despite the insane loads that it's forced to bear-the team is looking to generate reliable horsepower. So they first eliminated the water passages in the block. Only coolant will run through the head for added stiffness and the team will create a better sealing area for the head gasket by filling the block. There are many options for block-filler on the market ranging from concrete to purpose-made synthetic fillers, but they add a substantial amount of weight to what's already a substantial casting.
To reduce the overall weight Norwood used structural foam, which is an amazing product. He's used it in blocks in the past with great results. It's light, very rigid and easy to inject into the block casting. "I'd only use it in alcohol motors because it has limited thermal characteristics. A gas engine gets far hotter than an alcohol engine and I'm sure you'd run into problems with shrinkage due to heat. Thankfully, we don't have to worry about that with our engine," he says.
Next, Norwood turned his attention to beefing up the main bearing assembly. The 3RZ uses a two-bolt main bearing cap and the design doesn't allow for conversion to a four-bolt. So Norwood designed an extremely rigid billet-aluminum oil pan incorporating a massive girdle that locates the main bearing caps and prevents any distortion of the bearings under load.
Norwood's ace machinist Tommy Todd carved the pan/girdle from a solid billet of T6 aluminum using a CNC mill. Todd was also instrumental in designing the oil pan drain system that provides a dedicated oil drain for each cylinder. The NORAD oil pan locates by way of extended ARP 190,000-psi studs that pass through the pan and bearing caps to complete an extremely rigid assembly.
The final machine work for the block was carried out by LC Engineering and consists of careful align-boring of the main bearing journals, final finishing of the deck surface and boring/honing of the cylinders. At this stage, the rotating assembly is ready for installation.
Rods, Pistons And Other Things
The key components in the NORAD 3RZ engine are an object lesson in no-compromise engineering. The pistons, rods and crankshaft are essential components that must perform at 100 percent to allow the engine to realize its full potential. With this in mind, Norwood selected his components very carefully.
"I'm anal about what parts I put in a race engine," Norwood reveals. "I'd rather pay extra for a top-quality part than have to deal with the problems that arise when you start trying to save a few bucks. It's a matter of finding what works for your application and then sticking with it. I'm not saying that you shouldn't experiment or research your options carefully, but at the end of the day quality is the greatest consideration."
There's no question about the quality of the components in this engine. JE Pistons is an established manufacturer of racing pistons and the NORAD 3RZ features a set of 96mm custom slugs that are forged from 2618 aluminum alloy to give an 8.5:1 compression ratio.
The pistons are designed to withstand the extreme boost levels that this engine will see, but also, for weight-shaving purposes, to carry a minimum of material in non-load-bearing areas.
The wrist pins are JE 93-series high-strength tool steel items and the pins are located with JE Tru-Arc wire ring locks. LC Engineering installed its own Moly-Plasma dyke rings for best performance and then, finally, the pistons were sent to Calico coatings for treatment.
Calico coatings are the leading supplier of high-tech coatings to the performance engine industry and they offer several different coatings for different applications. The NORAD 3RZ uses Calico's CT1 Teflon-based coating on all of the bearings to assist with lubrication. Piston tops, chambers, exhaust ports and exhaust valves are coated with Calico's CT2 metallic ceramic coating to assist heat dispersion and help eliminate "hot spots".
The skirts of the JE pistons are also treated with Calico's CT3 matrix-flouropolymer high-stress lubricant coating and finally the rods and crank are coated with the CT5 flouropolymer oil-shedding coating to minimize drag.
The next component of the NORAD rotating assembly to be selected was the connecting rods. Rado's 2003 engines ran several different variations, but Norwood was specific about his choice for 2004.
"I really like Pauter Engineering's design," he says. "It's very strong. In fact, I ran Pauter rods for the entire season in Kenny Tran's Honda and we never had a single failure despite leaning on them pretty hard. (Understatement: Tran's 1.8-liter Honda is generating in excess of 1,000 hp.) Another thing I like about the design of the Pauter rods is that they have a very narrow profile and as a result we see minimal drag from them at high rpm."
Rado's 2004-spec engine's feature custom-billet 6AL4V titanium Pauter rods cut down significantly on the weight of the assembly (it's 33 percent lighter than forged steel) without affecting strength. Not inexpensive for sure, but Norwood is not interested in cutting any corners on this engine program.
The final component in the NORAD Toyota 3RZ is the crankshaft. As we found out earlier from Norwood, the stock Toyota forged-steel item is plenty strong, albeit a little on the porky side.
The answer comes in the form of LC Engineering's Pro-Lite version of the stock crank. This is a trick piece of equipment and it's a perfect example of careful development creating a part that is strong, light and reliable under extreme duress.
The stock crankshaft cores are tested and inspected for imperfections before LC begins working on them. Then the crankshaft is knife-edged to produce less crank windage and faster acceleration without sacrificing strength. Total weight reduction is around five pounds.
After the machining work is completed the crank is shot-peened and heat treated for extra strength. The journals are then micro-polished and finally the crank is dynamically balanced before it's Magnaflux inspected and treated with Calico's CT5 oil-shedding coating.
The main and big-end bearings are sourced directly from Calico and are pre-coated, and all the fasteners used in the assembly are top-of-the-line articles from ARP.
Norwood lastly comments, "The block and the rotating assembly are the heart of a race engine. If the job is done correctly, they'll take nearly anything you can throw at them. In an application such as this I prefer to hand over responsibility to a specialist like LC Engineering. We've shared ideas and I think the final result will be an absolute killer motor. LC proved last year it could build a bad-ass engine, but this year's motor will be a major step up in terms of outright horsepower."
The setup and dyno-tuning of the NORAD Toyota 3RZ will reveal lots about the potential of the combination, which we'll reveal in a future article. Next month, we'll look at the ancillary systems such as the dry-sump, charging and crankcase evacuation systems and examine the cam drive and camshaft design. Stay tuned.