Can anyone tell me how to ID a JCW cylinder head? What is the differance between a standard S head and a JCW head Thanks for your time

 

I don't think there is any significant difference between a regular S head and a JCW one. The JCW head is crudely relieved on the intake ports with some machining on the exhaust ports too, not much to look at. The only dead give away would be the valve cover attached to it. That thing has the JCW logo and JCW kit number. Just so you know, the valve gear, valves and cam are the same between the JCW and S heads.

 

Wow, my 'special' JCW head does not seem so special anymore. What a gyp!

 

It never was... they stuck it on the car to justify the outlandish price increase. The power came from the pulley, and slightly more aggressive tune.

 

Not quite true. The head is good for some power, though not what a great aftermarket head will do. Most S models with standard mods, ie, CAI, 15% pulley and exhaust achieve roughly the same WHP as a JCW car, which has all of the above except that the pulley is closer to 11%. In order to achieve a similar result in WHP, I believe that the head accounts for that.

 

Stock JCW cars dyno at around 180-185 whp. With just a pulley/CAI most people are seeing those numbers. We dynoed a car today with a Pulley, Intake, One-Ball (Not even worth counting as an exhaust in terms of reducing backpressure) and one of Jan's tunes on it, and it made 206 whp with a slipping belt.

Yes, the head flows more CFM, but the difference is negligible. Let me put it this way, if someone GAVE me a JCW head, and I had the tools and equipment to install it myself, it's not worth my time to install it. That's how pointless it is.

I guarantee you if you dynoed a factory JCW car before and after (Swapping out a stock 06 S head for an 06 Factory JCW head) they'd dyno within 5 whp of each other.

It was just justification, sadly. It's hard to sell a 7k dollar engine package if all you're doing is installing a pulley, intake, and exhaust.

 

There are actually a few more add-ons in the JCW pkg, but certainly not enough to justify the price. I get the point, definitely a gyp!

An RMW head is looking more and more attractive.