Jdm cam vs usdm cams.

[cranfilldaniel]

Hey guys. I got a 92 lsl with jdm engine swap and usdm harness and ecu...anyway. I need to replace my passenger Exaust cam and called Subaru dealership and they said the jdm cams were different that usdm. Any truth to this or will a usdm cam work as a replacement.

[SURTEESS]

I would think that the cams may be different, as you don't have 96 - 98 octane available in most of USA.

or if the cams are the same then the pistons may be different - to give compression variation?.

anyway that is my thought....

If you use JDM ones you might need to add fuel additive to stop pinking..

[LetItSnow]

We have what you call 96-98 octane, but not named as such.

Stolen from a thread I came across in a reddit post:

US and Europe calculate it in different ways which makes US fuel look like it has a lower rating but in reality they've got the same rating. US shows the average of the Research Octane Number (RON) and Motor Octane Number (MON) rating, which is the Anti-Knock Index (AKI) while Europe just shows the RON rating which gives a higher number than the MON rating.
More info from wiki: The most common type of octane rating worldwide is the Research Octane Number (RON). RON is determined by running the fuel in a test engine with a variable compression ratio under controlled conditions, and comparing the results with those for mixtures of iso-octane and n-heptane (a fuel standard).
Motor Octane Number (MON), which is a better measure of how the fuel behaves when under load, as it is determined at 900 rpm engine speed, instead of the 600 rpm for RON.[1] MON testing uses a similar test engine to that used in RON testing, but with a preheated fuel mixture, higher engine speed, and variable ignition timing to further stress the fuel's knock resistance. Depending on the composition of the fuel, the MON of a modern gasoline will be about 8 to 10 points lower than the RON, however there is no direct link between RON and MON. Normally, fuel specifications require both a minimum RON and a minimum MON.
Basically MON uses a higher stress test and because of that it gives a lower Octane number as the fuel is under greater stress than when it is being tested through RON method.
tl;dr:UK and rest of Europe show the RON rating. US/Canada show the AKI rating which is the average of RON and MON rating.

[scoobymal]

Japans petrol is highly refined, much better than any UK fuel, I was in Tokyo about 4 years ago, and remember seeing 103-105 on the pumps. I also owned a Subaru Impreza WRX STI V5 several years ago, it was a JDM (grey import) It would pink on UK 98 petrol, it was essential to add octane booster, or risk engine failure. Many owners of Jap import cars learned the hard way, octane booster and remap is the way to go.

[trueblue]

I do not see why you all are talking about octane level of the fuel. I follow what you are saying but do not understand why. What does that have to do with the cam? If the octane value is different in another country, I would think a remap of the ecu should be sufficient in managing the engine timing and the amount of gas injected. Why change the cam for such a small amount of difference? I am sure you will have a good answer for me that I am not aware of.