Yes indeed. You lose low-RPM power with a very large cam. Even if you up the compression, this type of camshaft produces little power at low RPM. By increasing compression you regain some of the loss.

On the other hand, it is proven that even low-compression (meaning 8.5:1) engines can use a large cam and still make a lot of power at high RPM. This was doubted in the 1970s and 1980s, because of the experience with 10:1 and 11:1 "common" engines during the 1960s. But by 1990 it was proven that you didn't need to increase the compression. Of course, as already stated, higher compression is even better.

You need to raise comp ratio for bigger cams due to the valve overlap. often people put big cams in std type comp engine and dont understand why is doesnt perform like they expected,in some case go worse, thats why u can go as high as 12.5;1 static comp with large cams, its the dymanic comp that u really need to work on.using good fuel plays a big part as well. also exhaust/carby/injection/springs/head flow etc all have to play the game as well. ITS ALL ABOUT GETTING THE RIGHT COMBO.

So true. Premium fuel doesn't get you more Ks per liter (or miles/gallon). But higher compression will. If you also tune the carburetor and timing appropriately.

iv been told that the premium fuel does get you more k's but i dont know how true it is

Quote:Higher compression ratio is best for ANY A14, whether big carb or small carb, big cam or small cam. Higher compression results in more horsepower and better fuel economy.

The downside is the need for higher octane fuel. Stock A14 is around 9:1 compression. 10:1 is good for about 3% more power if tuned correctly, and you can still use common gasoline, though you may need mid-grade or premium grade fuel.

The increased cost of Premium fuel may be offset by better fuel economy. Or maybe not.

The other downside is cost. You pay a lot for new pistons and only gain small percentage gains.

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cheers mate.
im in new zealand. how much would they cost? do they come with rings. do u have many other hot a14 parts?

I can supply a smaller dish piston for a A14 which will raise comp approx 1 full comp ratio. where are u located, Im in sydney. cheers

hey could anyone tell me what flat top pistons are best to go into an a14 which is running flows, lumpy cam and just a bigger carby? thanks