So it appears as though I am going to be re-building the engine in my 2002 mn6 due to an issue with cyl. no. 7. Since the motor has to be re-done again, it only makes sense to step up to a forged piston at this time. I am running an A&A Procharger setup with dynatech long tubes,random tech cats and x-pipe and Corsa Indies. The car has produced over 520rwhp with this configuration before final tuning and turned 11.17 @130mph on street tires. That being said, I am not looking to increase power through displacement, lower/higher compression or more boost, I just want to fortify the bottom end to prevent this from happening again. I drive my car daily and it has over 60k on the clock, so I do need reliability. Now for the p[oint of this thread...Any advice on replacement pistons, forged w/ stock bore and compression, and any feedback from those who have similar setups would be appreciated.
Steve

 

Any forged piston will do. Look into a hyperuetectic forged piston instead of the hyeru cast piston for your hp level. For a daily driver, I'd stick with stock displacement and 9.5:1 compression for the fuel economy. I get 28.1 on the freeeway with my 346 er. To do that you need a redline under 6500 so use a near stock bumpstick. That is if it is a daily driver. As far as cylinder no. 7 is concerned, try a slightly richer A/F ratio. Or use meth injection to bring it down even further. I understand that no. 7 suffers because of the firing order and the resulting distribution of air in the intake manifold.

 

I've been doing some research on forged motors, as I plan to replace my C5 - LS1 motor with magnacharger to some type of turbo configuration.

Talked with Brian and LME motors about a forged one. They recommend Wiseco Pistons because they can dial in compression ratio based on whatever cylinder head CC you have and the Wiseco piston have a thicker ring land.

Good luck with your build.

 

You can do that with any piston. I'd rather spend the extra money and get JE or Mahle pistons. Callies or Howard rods.

Figure $3,500 - $4,000 for the short block. CR of 9.0 - 9.5:1 would suit your needs fine.

Good luck,

Mark

 

I was aware that you can specify cr, etc. and have had good luck with both JE and Mahle in the past. I am only going to be doing pistons however, no rods, it's just not in the budget at this time. What is stock CR any way, I never thought to check. I definately don't want to give up any power by lowering CR...

 

You do not want to use hypereutectic pistons. ALL are cast; there is no such beast as a forged hypereutectic piston. You want forged aluminum pistons. If you are replacing your old pistons, go with the better quality piston (forged). It is much more forgiving with a bad tune. See below. James


Hypereutectic pistons are cast internal combustion engine pistons made from aluminum with over 16% silicon content for strength and durability. The term 'hypereutectic' comes from eutectic. Special melting processes are necessary to ‘supersaturate’ the aluminum with additional silicon content. Special molds, casting and cooling techniques are required to obtain finely and uniformly dispersed silicon particles throughout the material. This produces pistons that are very hard, thus brittle. They have proven to be un-forgiving with engine knocking. For this reason they are great in naturally-aspirated engines, but should be used with caution for 'nitrous', super- or turbochargers. Generally speaking, forged pistons are a better choice for high boost.

Hypereutectic pistons are used in many original equipment engines. They are favored because of reduced scuffing, improved power, fuel economy and emissions. The reduced thermal expansion rate allows the piston to be run with reduced clearance, which reduces losses due to gases escaping past the sealing rings.

Retrieved from "http://en.wikipedia.org/wiki/Hypereutectic_piston"

 

Definately was going to use forged aluminum and great points/info. Thanks for the input. I have had forged/balanced motors in the past with other cars. I beleive I had Ross pistons in the last car which was high compression/nitrous car.

 

Ross makes an excellent piston. James

 

If possible, I'd wait until you can do both at the same time.

10.0:1 for LS1's and 10.5:1 for LS6's, I think the LS2's are closer to 11.0:1.

Mark

 

If you don't do them at the same time, you pay labor twice, and that's the biggest hit. The rods themselves aren't that much.

 

It is a no brainer to do them both at the same time and I would wait until the budget affords getting the rods at the same time as you will then have a solid bottom end, not one that is just half way done so to speak and good luck with the direction you decide on your forged setup

 

A good forged I beam rod can be had for $285. Well worth the upgrade and really not alot of $$$..Diamond, JE, Weisco, and Ross all meak great pistons...

 

Also there was a thread a while back where ECS and A&A both said they have seen stock rods bend on FI motors and neither will use stock rods anymore for boost...

Eagle 6.125" Ibeam SIR6125BBLW $215 from flatlander racing

 

I did not realize how inexpensive rods were...That price is for a set???

 

Thanks for the info...Unfortunately, waiting is not an option. If rods are as inexpensive as posted, then they really are a no-brainer. Obviously I would want to do both, but this is money I didn't plan on spending to begin with. I have already postponed a wedding...

 

Yes that price is a set. You can get Eagle H-beam LS1 specific on center rods for $409 or Callies Compstar Hbeams for $550 shipped. So even the better H beams rods are not that much more...Not that I've seen any forged I beams fail on an LS1 yet...

 

Okay, that really is a no brainer! And it is still possible to retain stock C>R., correct?

 

You can do whatever CR you want, but if you are going FI going lower is a great idea. I went 9.25 and there is plenty of power under the curve for everyday driving and then when under boost it is an animal that puts down some Sick HP for the street

 

stock C>R?? Stock crank??yes.... if thats stock compression ratio....the compression ratio will depend on the piston you pick. The piston manufacture should be able to tell you the compression ratio with a stock LS1 head. Also make sure you get the pistons for the length rod you choose and correct piston pin size. I have diamond 3.905 dished pistons that are made for the stock stroke crank and 6.125" aftermarket rods with .927" pins. Any one of the forum vendors should be able to put together a good forged rod and piston combo for under $1000.... You will need to get the whole rotating assembly balanced since your changiing rods and pistons also...

 

My intention is not too increase boost or power at this point, which is an excecise of great restraint. In the past if I were to be in this position, I would be lowering compression and dialing up boost,etc.,etc. I simply have to resist the temptation. The car made plenty of usable power before so I just want to strengthen it to prevent another re-build if possible. If I start with lower compression and more boost, than I also have to re-tune the car again which is another headache all together...