brianjw4

iTrader: (1)

Do the LT1 motors have special pistons, or can any piston for 87-97 5.7 motors be used?

the_hunted

I belive we can use any piston. granted it fit your bore.

vseventyone

They are supposed to be lighter pistons. How much lighter I do not really know. From what I have read anyway, this is also why lt1 cranks are slightly balanced differently than other cranks with the same casting numbers from the factory. However, you may change out both the pistons and the crank. Any 350 pressed piston from 55 and up should work with the LT1 application. If I am incorrect in any of this please someone correct me. Take a look at the link below for some useful lt1 info.

http://www.automotiverebuilder.com/ar/ar99928.htm

brianjw4

iTrader: (1)

Thanks for the reponses. Sounds like I can run standard 350 forged pistons then.

The stunningman

iTrader: (47)

You need LW forged pistons. They (LT1 pistons) are definitely lighter than stock 350 due to the lack of skirting.

Red97Z

iTrader: (22)

All Gen1 SBC pistons assuming they're the right bore will work.

The stunningman

iTrader: (47)

Sure they will FIT but they CAN also destroy your bearings from being out of balance. And your telling a guy any gen 1 piston will work? WOW! There have been a lot of changes through the years resulting in lighter weight pistons, Rods and ring package weights. Thus the crank will be weighted differently according.... especially a LT1. Lighter isn't quite as problematic as putting in a heavier piston. Best bet is weigh the piston and get a suitable replacement. They do not all interchange.

As I stated ealier look into the lightweight pistons namely the LWL2256F if on a budget.

Heres a example of how pistons have changed LT1 pistons practically have no skirt (less weight)

http://www.babcox.com/editorial/ar/elements/40354b.gif

Red97Z

iTrader: (22)

My reply wasn't pertaining to piston weights, I was simply stating that 1st generation small block pistons will work in our engines as I have them in mine. I see what you're saying about technological advances in piston weights and everything, but I mean, c'mon, I'm thinkin the guy just wants a simple answer.

1997bird

iTrader: (2)

The LT-1 piston's are not that much lighter (if any) than any other aftermarket hypereutectic piston. They are lighter than the older Gen 1 cast piston's. You should always do a balance job on your rotating assembly when you go to rebuild a engine. This is probably the best spent money that you can do for your motor's longevity.

the_hunted

I started to post this but i figured he would be able to figure this out. Anytime you rebuild a motor it is optimal to balance it. A 4oz inbalance is like swinging 200lbs of dead weight.

brianjw4

iTrader: (1)

I always have my rotating assemblies balanced when doing engine builds.

Does anyone have the stock piston weight handy? I'll look for pistons as close to that weight as possible.

1997bird

iTrader: (2)

The LT1's that I have had balanced (my machinest has a digital balancer that can spin the rotating assembly 8000 rpm+) are out about 30+ grams which equates to about 223.81 lbs @ 6000 rpm. The following is an example of my last LT1 spin balance sheet:


LEFT SIDE-----------------------------------------RIGHT SIDE

Weight---RPM-------Unbalanced in lbs.--------Weight----RPM---Unbalanced

33.08g---1000--------6.21--------------------51.43g---1000------9.66
33.08g---2000-------24.86--------------------51.43g---2000-----38.66
33.08g---3000-------55.95--------------------51.43g---3000-----86.98
33.08g---4000-------99.47--------------------51.43g---4000----154.64
33.08g---5000------155.42--------------------51.43g---5000----241.63
33.08g---6000------223.81--------------------51.43g---6000----347.96
33.08g---7000------304.62--------------------51.43g---7000----473.61
33.08g---8000------397.88--------------------51.43g---8000----618.59

After the balance job the left side came in at 1.41g @6000 is 9.53 lbs. unbalanced. The right side is .82g @6000 is 5.54 lbs. unbalanced.

The STOCK piston weighed 529.7g and the wrist pin was 160.2g. A Keith Black Silvolite hypereutectic 4 valve relief .030" over piston with the same 5.7" connecting rod weighs 520g and the wrist pin weighs 145g.

aggiez28

iTrader: (19)

hell you can use a ford piston in an lt1 if you want

brianjw4

iTrader: (1)

Wow, thanks for the detailed information 1997bird. Much appreciated.