Forged Pistons...

Is there concensus as to which brand is good/better/best?

I've heard that most forged pistons need you to run a bigger clearance to the cylinder walls, as they expand more than a OEM/cast piston. This large clearance then causes a noisy motor when cold, and also wears out the cylinder bores quicker.

I also head that CP pistons expand less, and therefore give the strenth of forged, with the desired qualities of OEM/cast pistons.

So what's your opinions? In particular I'm looking at Wiseco, JE and CP pistons at this point. Anything else worthwhile?

Heard good things about CP and Wiseco.

What motor are they for??

Gary57 wrote:

What motor are they for??

That is the question Gary. I'm 65:35 now for the CA.

Read on the EXA forums that a lot of guys are doing 200wkw+ on stock (fresh) pistons though, some with, some without coating.

So are forgies worth it? What do they do better than stock besides being lighter? If you tune properly you shouldn't fry your stock pistons...

I agree. I am running around the 200 mark now with no hassles, BUT and this is a BIG BUT, I do think that if I raced my car often and drove it like a plonker it would die. The stock HG is the weakest link and will die first.

There are many guys in AUS that run 200RwKw on stock internals that do race all the time, there are a few that go up to 250RwKw. Personally if you want HUGE power and big boost run forged pistons, they not that much more than new stock pistons and give you good peace of mind.

Doc run a CA18, be different, I think they are WAY underestimated. Strive to have the strongest CA18 powered SX in the country...

Thanks for the input Gary. How much does a set of stock pistons cost? And do you just buy some midas brand or oem?

If I go stock I will definitely have them coated for peace of mind. Again, must weigh up the costs of new stock + coating vs forged.

Just need to verify that forged won't cause me to rebuild the motor after 10k kms.

Gary57 wrote:

Doc run a CA18, be different, I think they are WAY underestimated.

Yeah got nuthing but luv for the CA18 either man.

Gary57 wrote:

Strive to have the strongest CA18 powered SX in the country...

I've passed the point of having a car that beats the next guy. Always turns into pi$$ing contests and takes the joy out of modifying cars. Don't get me wrong, some heatlhy competion is good inspiration, but someone can slap a T66 on a CA18 and do one dyno run to 10,000rpm on 2.5 bar, make 500wkw and blow up the motor the next day, but they'll still hold the record for the strongest CA18. 🙂

I just want to build the car for me.

I would only go OEM, but check your pistons they may be fine... I think OEM pistons cost R800ea or something 😮 .

I just want to build the car for me.

Great statement that...

Gary57 wrote:

I just want to build the car for me.

Great statement that...

for you??? then you better go with the sr20 then. but no worries, lets see if a little test run changes your mind. we go the whole ring road around the city, late in the evening. about 80-90km's, takes about an hour! you in?

veecee wrote:

Gary57 wrote:

I just want to build the car for me.

Great statement that...

for you??? then you better go with the sr20 then. but no worries, lets see if a little test run changes your mind. we go the whole ring road around the city, late in the evening. about 80-90km's, takes about an hour! you in?

errrr I'm a bit big to be sitting in the backseat of a s13 for an hour man - lol.

pick me up when she's fully run in so I can really feel how she goes. What turbo is that again on the motor?

who said anything about the back seat???

you get the front passenger seat.

i do a hard run in. it involves a lot of revving up and engine braking. its almost run-in and going very well, so you'll be able to feel the full brunt of the motor even if its just in short bursts.

turbo is a t3/t4, has a custom branch manifold too, uprated intercooler, 266 cams, dictator management, light aluminium pulleys, cosworth headgasket, etc.

the turbo spools a little late for my liking, but when it does come in, its quite strong i think. my butt dyno says this motor a good one! its also really quiet running and smooth - so its extremely tempting to keep the car, and under different circumstances i would. the responsiveness (and torque) of this motor are the key points that i really enjoy.

So it seems the pecking order is as follows:

CP > Wiseco > JE > Arias

For a T28BB/GT2860R/GT28RS build it doesn't look like forgies are even required. Unless you're gonna redline everyday - all day.

So I'm considering just going with some cast sterling pistons with maybe some caramic and skirt coatings? Whaddaya say about that!?

i say if you stick with the ca18 you're just gonna be wasting your money like i did. from day 1 when i realised my engine was stuffed i should've bought the sr20.

come on G - you have had a few sr20's in your possession, just do it!

veecee wrote:

i say if you stick with the ca18 you're just gonna be wasting your money like i did. from day 1 when i realised my engine was stuffed i should've bought the sr20.

come on G - you have had a few sr20's in your possession, just do it!

If only the ca18 head could bolt up to a sr20 block then I'd be rolling with that by yesterday!! lol

VC stop confusing me man. Eveytime I make up my mind someone sways me the other way....

The SR20 bottom end you saw is a NA one. So no oil squirters. And will need a custom bell housing to fit RWD. Do-able, just a matter of extra dollars I guess.

I'd hate to waste a perfectly good CA though. Unless somebody buys it!

I agree Doc I wouldnt say forged pistons are nessesary unless you will be hooning it around all day.

Pssst, dont listen to VC build that CA18 😂 .

Sorry Gary I’m not going to agree. I have been watching this post for some time and I’m sure the stock CA18DET pistons can withstand a lot of punishment but why would you want to push them to that point?

DR G : Who will you be impressing telling them you still running the stock bottom end? No one going to be impressed especially you when you’re motor goes in a big puff of smoke, why would you want to take that risk questioning ever noise you heard when straying into boost?

What are you intensions with the car? I can tell you I started out just wanting 200WHP I still remember telling Sokar that I would stop modifying when I reach that number I got that number on my first dyno and still continued to modify after that run until my motor cracked a ring landing, What I am trying to say is don’t my decisions now that you going to regret in two years time

Lets take a Stock bottom CA18DET producing 200RWKW thats more then double the stock factory output of the motor that means double the BMEP from the original motor that means double the force on your stock pistons the rings the ring lands and all that, Now cutting out the big hitters like the 2JZ, 7M and RB26 that have been vastly over engineered from factory. Yes we have heard guys with SR20DET,3SGTE,2E long,4AGE,B16,B18,B20 turbos’s producing double if not three times the power , We heard about them because they are rare most people just forge there bottom ends for peace of mind but what strange is in all my years of reading about these pioneers I have never seen any of them putting constant strain on the motor at those power levels like going to track days, Drifting or dragging weekend after weekend they normally appear at a dyno day make that power then you never really see them again. I’m sure someone is going to point out a few exceptions to the rule but most if not all the cars at local drag events have forged bottom ends and I’m not aware of any of the 4 cylinder local drifter doubling there power and drifting event after event (I might stand under correction here)

Look for the amount of boost I am pushing my forged bottom end might be a little bit of an overkill but I have a few advantages and disadvantages.
My disadvantages are when cold is I have piston slap until oil temps are past 75 degrees C.
My advantages are better sealing rings then stock, thicker and stronger ring lands, lighter over all piston weight and the piston dissipates heat better this also isn’t taking into account the tighter tolerances then cast units and the improved cooling.

Pink I fully agree with you. But for me I run high boost once a month, if that, I didnt even use it once on the sports car run this weekend. So if you are going to be like me and drive the car and not race it I think the stock pistons could take a beating for a few seconds a month. But you are right I am paranoid abot every little noise the engine makes, but I think I would be even more so with the forged pistons, but that is just me.

I still say if you are going to use the power once a month or so, stock pistons will be fine BUT if you are going to be hooning it around often they wont last.

I guess its different strokes for different foks, I don’t drive my car that hard but If I wanted 10 Runs down the strip or a 10 minute blast at full boost I’m happy in my knowledge that I have built my bottom end to take the punishment but after saying that I have seen more then enough forged piston suffer the same fate with the incorrect tuning or fueling system failure

Well its up to you DR G it your CA18DET, I have nothing more to add 😂