I agree with some of your points but disagree with some of them as well. I took apart my engine last winter and brought the head to a machine shop to be shaved down 40/1000's of an inch (1.02mm). The guy there said that was a tolerable threshold for the head but it could still have been brought down more, albeit it would be more dangerous. I used an OEM gasket when I was finished and am still using the same pistons the car came with.

Also, as krazytib said about having an adjustable cam for the timing, that's false. Just by tightening the timing belt a little, whatever changes in the timing that were created by shaving the head were corrected. I know this for a fact because I've been driving my car for 4 months without a single issue. Yes, you will need to fill up with the higher octane fuel to prevent knock, but it's not that much more expensive.

Overall, I saw a huge difference in performance from just cleaning out the gunk and shaving the head down a bit. It only cost me a total of about $650 for the machine shop's labour + the OEM upper head gasket kit (which I purchased directly from Hyundai). If you're that serious about increasing the output of your engine while keeping it naturally aspirated, then I STRONGLY suggest avoiding the use of a thinner head gasket as you risk warping your head altogether and will need to spend even more money getting it re-surfaced again (if you even can). It's not expensive if you can remove and re-assemble the head yourself, which isn't difficult, just time-consuming.

Take my advice, I've been driving my car safely like this for a while now and see no signs of stopping. My father, the man who suggested shaving the head and helped me rebuild the engine, is a Master Hyundai Technician. If he doesn't know his stuff, I don't know who does.

 

Look I'm not the one who needs convincing here, but you might as well be accurate if you are going to post. 2 RDT guys (at least, that I can recall, possibly more) used Singh grooves with excellent results.

The timing isn't corrected by tightening the belt, it's pulled off . . . but like I said it's <1º and you wouldn't notice it. Red did the maths on this in a thread on RDT, and it should be around here somewhere in the archives if you are wondering about valve timing changes when the head is shaved.

 

^^^^^

Thank you for correcting me regarding the timing, Stocker. I did not word that part properly. What I meant to say was, by tightening the belt a little more, it was to ensure that the timing would not be affected by the new setup. We were worried that leaving the timing belt at the same tension after increasing the compression ratio could lead to the timing getting messed up after starting it. Increasing the tension was just a measure to help prevent that, nothing more. In any case, it worked out.

 

^ in that case you were correct. Any time you have the head off, you need to re-adjust the belt, shave or no.

 

Beta 2 head gaskets were two piece. That was one of the changes. If you had a three piece in a beta 2, it was not original.

 

I think Stocker knows this, and just wasn't clear headed when he bent to acknowledge correctness that was not so. The tensioner is on the "coast" side of the belt. Unless one believes that the belt length changes (stretches), tight/loosen tensioner does not change the length of the "drive" side of the belt. With the fixed idler on the drive side, the load from cams resistance is pulled down the one side by the crank. If the two pulleys get closer to one another, by any means, the cams will retard. Higher compression is one of the best and most effective ways to increase horsepower. One just needs to tune the engine accordingly, including the choice of fuel used.

 

Seeig as this age old topic was revived, i have 1.8 pistons in my 2.0 RD2, Its at about 260psi across all 4.

 

Not sure why this thread was revived...

I don't remember what the J2 compression tested at.



Does anyone want to guess my cars compression ratio? 1.8 pistons, 2 layer head gasket, head shaved 40 thousandths. 11.5:1?