Should You Change Your SR20DET Head Gasket?

SR20DET swaps in S13/14 240SX’s are quite popular here in America. One of the questions I frequently get is, “Do you think I should change my head gasket before I swap the SR in?” I always recommend changing it because it’s fairly easy when the engine is sitting on a stand or even on the floor (don’t crush the steel pan people!). The paper gasket is fine for 205hp and probably even ok for 280hp, but in reality it’s detonation that usually destroys the stock paper head gasket. Since there are so many cheap asses that use the OEM ECUs on 91 octane in the SR20 swap world, it’s even more reason to change the head gasket. Yes, the stock ECU can handle 91 octane because it can default to more retarded ignition maps, but when people start running no cats, turning up the boost, with the little piece of shit in the corner intercooler on 91 octane, knock is bound to happen because the stock ECU isn’t calibrated for these mods. And with 91 octane, there is no headroom because the stock JDM ECU is probably already on it’s most retarded ignition map. When knock happens, the fire ring around the cylinder in the stock gasket will eventually fail.

Bart “Hijacker” Thornton from the NICO forums, also asked me if the Cosworth gasket was as good as or better than some of the double priced JDM gaskets from Apex, Power Enterprise, or Greddy. The answer is yes, it is as good as the others. I have personally tested the Apexi and HKS SR20DET head gaskets using pressurex film when I was Chief Engineer at Apexi USA in my previous life. I can tell you that the HKS, Apexi, and Cosworth gaskets all work equally as well and not one of them works better than the other. Except that the Cosworth gasket costs about half the price. I have never tested the Greddy or Power Enterprise gaskets. The Cosworth gasket rules in the Subaru and EVO world already. It’s only a matter of time before people wake up and realize they are blasting away good money on the JDM gaskets.

There is also talk that the Cosworth gasket is a cheap imitation/copy of the Greddy gasket because it is priced so low. This is the most refuckingdiculous shit I’ve ever heard. First of all, why does anybody need to copy anything Greddy? They make some cool turbo kits, but otherwise… The Cosworth SR20 gasket was engineered from scratch to fit ALL SR’s including the VEs, DE front wheel drive, DE rear wheel drive, DET front wheel drive, and DET rear wheel drive. This means it will work with all iterations of the SR engine. Cosworth designed production turbocharged 4 banger engines long before Nissan even dreamed up the SR20 and has raced turbocharged 4 bangers much longer than the Japanese. What does this mean to you? That many Japanese technologies both OEM and tuning companies, are probably copied and/or derived from Cosworth’s technology. For example, the 4AG is an econo copy of the Cosworth BDA, the SR20 is loosely derived from the BDT, the 4G63 is loosely derived from the YB, etc. Even HKS used to make parts for the Cosworth BD back in the day. Anyhow, the Cosworth stainless multi-layer gasket is Cosworth’s own design. It is not a copy of anybody else’s. What I’m trying to say is that Cosworth has been designing innovative engines and components for 50 years – longer than any JDM company.

fujisr201.jpg Click to enlarge test results

If you take a close look at the test results, you can see that the stock gasket is mediocre at best around the cylinders. The color is light red with many areas blotted in white. Then take a close look at the Cosworth gasket and you’ll see how defined and red the pressure is around each cylinder. Assuming the red imprint is solid (and not blotched or clouded with white), the brighter the red, the higher the clamping force. If the red is dark colored or blotched or clouded with white, the clamping force is lower. I think the results speak for themselves.

The long awaited 90mm SR20 gasket is now available. Here’s where you can buy the Cosworth gaskets. Save yourself some of your hard earned money people. Good luck with your project.

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