i think from the video given by maximo i think its enough to tell that there's a different in the top end. it slike never ending power. still screaming even at the most end of it.

just from my newbie observation of coz :D

Had the same experience with a VZ-R .21. (without modding the head)

The crank pin seem to be a weak spot. It wears much quicker than other brands.

The fact that they perform does not make up for the quick deterioration of certain parts on the motor.

the fact that one have to sacrifice something to achieve what they wanted at the first place... is normal ever since human knows what is need, what is wish and what is obsession.
as they said.. pay the price :blush:

If you have to remove shims to compensate for lost compression, Doesn't that defeat it's purpose?

Nope, the modification on the head is made to make more turbulent the mixture, lowering the Combustion head height is to regain the lost compression due to the slightly larger volume on the combustion chamber.

Look at the post I put to a magazine and see the website that someone posted on the first replies.

Sorry for reviving such old thread, but like many others buried here contains lots of good information. Maybe MXwrench and some others may look for those and put a sticky thread just for info, seems that many people are here for wrenching their own engines and look for information.

Giving life back to this post :smile:

I would like to do this mod to my engines, I remember extreme r/c magazine doing an article about the grooves and they found that 3 grooves close together had the best results on their dyno. So my questions are, where is it best to face the grooves to the exhaust port or to the main intake port? Also whats the best way to create the grooves? would i just be able to use a dremel with a cutoff wheel. From looking at Singhs work it looks like precision is not that necessary.

I plan on using this in 1/8 offroad so I am really hoping to see if i can't improve mileage more than increase power. If any one has done this mod to a model engine did you notice a runtime increase and also how much runtime did you get.

i already done mine by using triangular file. I plan to remove head shim, but how to check whether my engine is pre-ignition/pinging? is there any wierd sound?