Hey there guys I have a few questions about forged pistons okay here goes.I am looking at ordering some for my non turbo A15 but a mate of mine seems to think its a waste of money as I could easily fit Mazda pistons and shave the tops of.I am building a street motor but want only the best stuff as I want to build my motor properly.Having said that if the gains over the Mazda pistons are not enough to make a reasonable difference then I may just get the Mazda pistons and call it a day.My plans for the motor are as follows

1) Ported and gas flowed head that has been mildly skimmed with cut down L16 valves and double valve springs
2) Electronic fuel injection by way of 45mm individual throttle bodies
3) What we call a stage two cam not sure of exact specs
4) Knife edged crank & 3.5 fly wheel
5) 4-2-1 JTS headers
6) Flat top pistons
7) Electronic ignition

Now for my questions about the forged pistons

1) Is there any other benefit besides strength and the light weight over the stock items?
2) Having mentioned all the mods for my motor do I really need forged pistons?
3) Where to get decent forged pistons and what do they cost roughly?

Cheers Immy

Yes, for non turbo, not only are they a waste of money, but they are not as good as cast.

Forged pistons are only used when the extra strength is needed, because they expand too much and rattle a bit when cold.

I agree with DD,unless your talking upwards of 9000 rpm with heaps of compression running avgas,your wasting your money...last time i enquired about $1200.00 Aus. plus rings.

There were some going for about $750usd on Ebay a while back, but that was old stock being run out I think.

Thanks guys but what about the cast pistons from Bprojects would they be worth my while??

from what engie is the mazda pistons?
IOW what do I ask for walking into the spares shop?

From what I know it's the Mazda E5 pistons that you should ask for.Ask Rezlo he is a member on this site and has had great success with these Mazda pistons.When I spoke with him he told me that you have to mill the block a little to make it work properly.

After you have cracked 3-4 sets of cast Mazda pistons you will start wishing you spent the money once and went forged...

Cast pistons are rubish when it comes to 7000+rpm or any form of real power. that is unless they are actualy spec'd for that application, and I doubt youll find any good E5 "OE" or better grade pistons, they are all fairly rubbish, even KS fail super easy with the ring landings falling apart,,

Just my experience of A15's on cast pistons.

Quote:
Refering to question 1.
Forged pistons are NOT lighter than stock pistons & can be substantially heavier in many instances.

Unless you are building a race motor I would use cast flat top pistons for an A-Series. Forged pistons will weigh more. It sounds like your motor will will be 10-1 compression with a powerband of 3500-6800 range-ish. Unless a stage two cam is the NISMO option 2 cam I don't think you'll have an issue.

I'm using an 8K redline in the A12 but my motor is way undertuned, even after adding the new to me flat slide carbs I'm not expecting to be more than 100HP at the flywheel.I use standard cast flat top pistons.

Beyond 7500 RPM's , 11-1 compression and 115 horsepower I would think you'd need to start thinking about using forged pistons. I personally wouldn't use them in a street motor but I don't believe in "hot" street engines.............nothing wrong with it I just want a road car without any motor quirks.

Tom