When do you really need Billet Main Caps on a 2JZ-GTE?

In our opinion, the 2JZ-GTE is one of the greatest engines ever created. It’s very easy to make over 1000whp just by selecting the right turbo, running at high enough boost, and making sure there is enough fuel supply to get there. However, MAKING the power and living through power are two different things.

If you haven’t read our “How much power can a factory 2jz block take?” article yet, you may want to give it a quick read.

Assuming you’ve replaced the pistons and rods in your engine, the next weakest link are the factory cast main caps. The factory 2jz-gte crankshaft is actually really robust, so unless you are trying to change the engine’s displacement or go to a smaller rod journal, the stock crank will take you a long way. The factory main caps however are not a robust piece.

There is no exact number that the factory main caps will fail at. We have seen them fail in 800whp cars, and we have seen them tentatively living in 1000whp cars. It is an unpredictable piece that should not be depended on. Building an engine is expensive, and losing an entire engine build to a failed main cap is devastating.

The stock main caps are cast iron, which is made by pouring melted liquid metal into a mold and letting it cool into shape. While this method is great for affordable mass production manufacturing of low power engines, it can leave opportunity for inconsistencies to form inside the metal as it cools back down. Heating metal up and cooling it back down changes the microscopic crystal grain structure of the metal. It is very hard to control the consistency of the grain structure when casting iron. These inconsistencies can eventually turn into a weakness that leads to a failure when attempting to quadruple the power level over factory numbers. This means that not even all of the factory main caps are created equal. Some may be weaker than others. So the question becomes, “how can I tell if my main caps have any inconsistencies in the properties of their metallurgical makeup?” well you really can't.

Billet main caps are made differently. They start as a large chunk of solid metal, and material is cut away until the main cap is all that is left. The chunk of metal that it starts as was created in a forging process that allows more control over the consistency of the crystal grain structure of the metal. More consistency means fewer weaknesses. And we have never seen a billet main cap break. The process of cutting the billet main cap from a chunk of metal avoids the heating and cooling of melting metal into a liquid and letting it cool back down into a solid within a mold. The billet main cap starts as a solid, and stays as a solid throughout the entire machining process.

You can think of billet main caps as an added security to your engine investment. A sort of prevention system to eliminate a weak link before it can cause a failure. Today there are several options for billet main caps for the 2JZ-GTE. Aftermarket billet main caps must be installed by a machine shop that can line bore the main journals to spec. We have our own main caps made for us that require very little machining at the machine shop in an effort to speed up the process and keep machining costs low.

It is natural for you fall into the trap of thinking “well how much power can i make before having to spend the money on billet main caps and installation?”. We can’t even count how many people have expressed their lack of enthusiasm regarding spending money on main caps. We have heard every justification in the book. “My buddy knows a guy that is making xxxx whp on stock main caps.” or “I heard the stock main caps fail at 982whp. I only want to make 981whp.” Ultimately the amount of risk you are comfortable with is your choice. Some people are more comfortable taking risks than others, and some people care less about the consequences than others. Someone with a backup engine on deck may be more willing to take risks than someone who is modding the engine that has to get them to work on monday. You can build the engine however you see fit. But it is important to understand the risks you are taking with each decision.

As a general, easy to remember, rule of thumb...we recommend billet main caps to anyone that will be using a 68mm turbocharger or larger on a 2jz-gte. A 68mm turbo is capable of making 1000whp on these cars, and we don’t recommend trying to make an engine with stock main caps try to live a life at that power level.

For maximum security, we also recommend the use of upgraded ARP CA625+ Main Studs when installing Billet Main Caps.

If you have any questions about whether or not billet main caps are right for your project, please reach out to us and let us help guide you in the right direction. We offer free build planning services and welcome your questions.

Email: sales@realstreetperformance.com

Phone: 407-695-7223

Whatsapp / Text: +1-407-724-2484

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Real Street Performance 2JZ-GE 2JZ-GTE 1JZ-GTE Billet Main Cap Set

SKU# RS02-0001

Real Street Performance 2JZ-GE 2JZ-GTE 1JZ-GTE Billet Main Cap Set

SKU# RS02-0001