RB26 Combustion Chamber Machining

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  • $1,275

RB26 Combustion Chambers have a tendency to suffer from hot spots on the quench pads. Where most combustion chambers should be coldest in this area, the RB26 has issues with detonation that show up on the intake and exhaust sides of the chamber. For a long time, it has been a common practice for top level Japanese shops and tuners to remove one or both of the quench pads to alleviate the issue in very high power builds.

After personally consulting with many experts in Japan, we decided to bring this service to North America. After a significant amount of time spent measuring, modeling, machining and cutting spare heads, we have arrived at a design for an efficient chamber without quench pads. 

This process also corrects the significant core shift that is present in many RB26 heads. We have seen instances where the cast section of the chamber is as far as 0.8mm off of the actual bore center. Our processing corrects this and matches chamber volumes cylinder to cylinder.

Original Chambers are 65cc and ours are 71cc. Make sure this is taken into account when calculating compression ratio. In order to complete this machining with the valve seats in, a significant amount of measurement must to done to make sure the finishing tools do not damage the seats.


The process includes:

-Clean the Cylinder Head

-Measure and Inspect the Provided Cylinder Head

-Machine the Combustion Chambers

-Deck the Cylinder Head

-Clean the Cylinder Head once again


If the head needs to be disassembled, additional charges will apply. Replacement parts like valve guides and stem seals are available upon request for an additional charge.