Jacks Transmissions Forums

I have notice some people selling a set of forged pistons.I have both the 1gen and 2gen 4g63, awd turbo.I talked to someone who works at a speed machine shop who says, all turbo motors should be forged internals.Is there anyone who knows the truth about this? I would hate to use NOS if they are not! THANKS! TED

They "should" be but they aren't.
Forged internals will take more abuse and are more forgiving than their cast counterparts.
If you're not going above stock levels or power then you should be fine; afterall, the car was designed for that and these cars don't get 250k on them by accident. A lot of people throw on a 16g and run 15 psi and have an OK car for 50,000 miles.
Anything serious should have forged internals though. At least stainless valves and a good HG.
ENGNBLDR on ebay has a helluva deal on valves, lifters and guides and you can trust his parts.


--Steve

The 4G63 is all forged except for the pistons which are cast. The crank and rods are forged from the factory and are very strong. Even the cast pistons have large ring lands and are exceptionally strong for what they are. It all has to do with the tune. People are running 9s (yes 9 second 1/4 mile times) with factory OEM untouched 4G63 engines! If your tune is good, no hiccups, no misfires, and everything is perfect, you can run ungodly amounts of power before they let go.

Having said that though, bigger forged aftermarket rods and forged pistons are stronger and are more forgiving if you do have that little hiccup in your tune. Plus they are not working anywhere near as hard when you are making good power. Not everyone can tune their car absolutely perfectly and have the car stay that way 100% of the time, so having those stronger parts works out a lot better in the long run. Plus, when you run the OEM parts on the edge of what they can handle, they will fatigue and break in time.

We really have it made with the 4G63 and what they can put up with out of the box. Look at a Subaru STI, for example. They have hypereutectic pistons which are the wrong pistion to use for boosted applications and they came that way from the factory. Those pistons break all of the time and just totally suck. Subaru along with Honda also love the open deck aluminum blocks which crack too and make you hate life.

The reason manufacturers use cast and hypereutectic pistons is due to the fact that people never let their cars warm up. The greater expansion and contraction you see in forged pistons is not ideal for the average moron that turns the key and guns it out of the parking lot. Cast and hypereutectic pistons prevent premature wear and failure which help the engine live under those types of conditions due to the fact that they will not move around so much when the temp changes as the engine warms up.

Jack

I'm not running 9's but I have a stock block w/ 200k and stock head. I'm putting down 350whp with a little rod knock and it still drives me to work everyday and I'm ruff on my car. I think the the stock block is amazing and I wonldnt be afraid to spray a little nos in to it.

I agree the stock long block is a beast. But like stated by Jack its all in the tune. You have a little hiccup and go detonation crazy you can loose the motor if making a lot of power right at the limit.

If you have a forged motor how long should you let it warm up befor driving it? I am not there yet but I do have a fully forged motor sitting on a stand for when the stock one lets go or I just decied to put it in. witch might be sooner then I think just because I want to go faster lol. I also agree the sock motor is amazing.

Another great topic of debate.
Aluminum expands faster than the cast iron and it all depends on everything. Environmental factors, PTW clearance. Etc etc.
On a typical day I let it come up to temp before driving it. And then I don't mash on it right away.
In winter I usually let the fans cycle once or twice and again I don't mash it. Last year actually, as soon as the needle came out of vacuum and hit 0, I'd lose traction so I couldn't mash it. Semi bald tires though.
I'm sure everyone has their quirks. I'm a bit over protective.


--Steve

The pistons are going to be the first thing to warm up as they are right there when combustion takes place. I always wait until I see the temp needle start to move up from its stop and just drive normally. I won't hammer on it until the temp gauge is in the middle though as cold oil can also tear in high stress areas if too cold and thick. Also note that cold oil under the piston will keep it cool even though combustion is heating the top.

You can just listen to the engine too. When cold, and you load a forged piston engine, you will hear a little piston slap. When it's warmed up you most likely won't if it's set up with tighter cleanances for street use. At that point you go from 'piston slap' to 'quiet' is when they are warmed up enough where you shouldn't do any damage if you drive on them and put them under load.

You may want to contact your piston manufacturer though, because depending on the materials used, pin offset and bore clearance, you may not need to worry about anything at all. I know the Wiseco pistons we use are an excellent street car piston due to the fact they don't expand much and can get away with tighter clearances than some other manufacturers. Many of my customers that use my engines never let them warm up and go speeding out of the parking lots with cold engines regularly. Even though that is not a good thing, the engines just keep going.

Jack

That is good info to know as to my forged engine has wisco pistons.

Hey! thanks to all for the info,i'm happy to see others that love their DSM.I don't think i'll run NOS now because this car will be a daily driver,and i want to keep it for many miles.I'm hoping to make my 1990 awd into a 12 second 1/4 mile.At this point the mods i have are,(3inch exhuast,Header, RC 550 injectors,safc,walbro 255 fuel pump, 3inch GM maf,translator, and cut the balance shaft belt)The motor is a 6 bolt 1992 4g63t talon that is rebuilt and has the 14b turbo,and does have the better head on it.I don't know if that will get me under 13's cause i'm new to these cars.So,if anyone has the ingredients for making under 13 in 1/4 and still be a driver please let me know.I joined this site because you guys seem to know what your talking about more than anywhere else.No one likes to make costly mistakes buying shit they don't need. TED