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Topic Review (Newest First)
05-18-2011 10:57 AM
lmsport LSX engines use low tension rings, with 1.5mm(.059") compression rings. Along with fuel injection, modern designed parts eliminate cylinder wall wear and minimize ring and piston wear.
05-18-2011 09:41 AM
cobalt327 "Thin" rings in metric sizes smaller than the traditional rings were used by GM as far back (maybe further) as '90 in the SBC. Cast pistons are generally lighter than forged pistons. The weight of a piston isn't the determining factor for what the clearance is. Aftermarket pistons are using 1/16-1/16-3/16 ring packages more often than ever. Low tension rings aren't something I would recommend for a street engine.

A 12% silicone aluminum alloy is eutectic, NOT hypereutectic. May be more, but at this point who cares.
05-18-2011 08:24 AM
MouseFink
thin rings

People can get away with running the thin, low tension rings in engines that are driven daily. In fact, I had Pontiac 455 engine with factory SD pistons (TRW) and SD rods in my 1962 Pontiac Catalina. The factory 455 SD pistons had 1/16" top rings and that is one of the reasons the 1973-1974 Pontiac 455 Super Duty engine production was cancellled by GM. That engine could not meet the 1970 Federal emissions standards. The 1/16" rings in the 455 SD Pontiac engines were not used as weight savings but as an effort to reduce long stroke thrust loading and heat build up on the 455 engine's cylinder walls. The 455 SD engine was a odd-ball engine that tried to get past Federal emissions standards but failed. GM fired the two engineers that designed that engine.

Anyway, be advised of the problems associated with using light weight pistons in an engine for a daily driver. Wieight of the pistons is not the problem, but the other issues are. If you can find light weight pistons with standard tension 5/64" top and seocnd rings with pressed in pins they would be the ones to use in a street driven engine. Pressed in pins are heavy. Light weight pistons use thin wall light weight pins because they do not have to be pressed in a rod.
05-18-2011 07:57 AM
Berres
Quote:
Originally Posted by MouseFink
Avoid light weight pistons if you plan on driving the car daily and on the street. The lighter weight pistons are usually designed for low tension, thin (1/16") top and second rings which will not last in a street driven engine and sometimes require .006" - .010" cylinder wall clearances. Light weight pistons with thin low tension rings are for racing engines that are only thrashed on weekends. If that is what you have, go for it.

High performance street driven engines use forged pistons that will accept standard tension 5/64" top and second rings and a 3/16" oil ring with .002" - .0035" cylinder wall clearance. Most lightweight pistons are also designed for floating pins, then you must have your rods bushed. You should never use cast pistons of any kind in a high performance engine. Stock pistons are hypereutectic (12% silicon alloy) cast aluminum pistons and are designed for tight cylinder wall clearances to reduce pollution and are quiet running for the knock sensors that are on computer controlled vehicles.

Ok, very helpful information, thanks for that
05-18-2011 04:44 AM
MouseFink
Rings

Avoid light weight pistons if you plan on driving the car daily and on the street. The lighter weight pistons are usually designed for low tension, thin (1/16") top and second rings which will not last in a street driven engine and sometimes require .006" - .010" cylinder wall clearances. Light weight pistons with thin low tension rings are for racing engines that are only thrashed on weekends. If that is what you have, go for it.

High performance street driven engines use forged pistons that will accept standard tension 5/64" top and second rings and a 3/16" oil ring with .002" - .0035" cylinder wall clearance. Most lightweight pistons are also designed for floating pins, then you must have your rods bushed. You should never use cast pistons of any kind in a high performance engine. Stock pistons are hypereutectic (12% silicon alloy) cast aluminum pistons and are designed for tight cylinder wall clearances to reduce pollution and are quiet running for the knock sensors that are on computer controlled vehicles.
05-18-2011 03:39 AM
Berres
Quote:
Originally Posted by 81malibuman
the icon pistons are a good product but they are made on the small side! I've used them in several applications but your machinist will need them before he bores your block or otherwise it will have to much clearance. i wouldnt recommend them for a block that wasnt machined to them
That's some good information!
05-17-2011 06:17 PM
81malibuman the icon pistons are a good product but they are made on the small side! I've used them in several applications but your machinist will need them before he bores your block or otherwise it will have to much clearance. i wouldnt recommend them for a block that wasnt machined to them
05-17-2011 04:27 PM
Berres
Quote:
Originally Posted by oldbogie
Weight doesn't affect absolute top end power at a stable RPM. But when the crankshaft is being accelerated, the weight of the masses attached to it and its own weight absorb power. This, then is power lost to the task of accelerating the vehicle.

Bogie
ok, now I better understand how weight of the pistons is affecting the car, thanks
05-17-2011 04:17 PM
oldbogie
Quote:
Originally Posted by Berres
Ok thanks for answer!

Ah, so it's how fast the engines rev that is affected. Is that affect HP and torque?
I will re-balance the engine so that isn't to consider.

But is the weight difference so noticable so it's worth 325? If it is very noticable I deal with it and order it
Weight doesn't affect absolute top end power at a stable RPM. But when the crankshaft is being accelerated, the weight of the masses attached to it and its own weight absorb power. This, then is power lost to the task of accelerating the vehicle.

Bogie
05-17-2011 04:13 PM
Berres
Quote:
Originally Posted by OLNOLAN
Glad I could help you. I have used the Speed Pro's in small and big blocks without failure.The Keith Black Icon piston appears to be a really good product but I don't have any experience with them.

good to hear, read a lot of posts also where people only have had good experience with them
05-17-2011 04:04 PM
OLNOLAN
Ok

Glad I could help you. I have used the Speed Pro's in small and big blocks without failure.The Keith Black Icon piston appears to be a really good product but I don't have any experience with them.
05-17-2011 03:54 PM
Berres
Quote:
Originally Posted by OLNOLAN
Looks like the weight is basically the same between the two pistons, Speed Pro piston book says a L2465F(std, bore) is 675 grams and a L2465F60 is 690 grams. The KB icon online catalog says the IC782(std. bore) is 673 grams but didn't give the .060 weight. Appears to me that KB versus SP weight is within 2 grams. Take your choice. Good luck


wow, thanks for that research! I searched for some weight specs my self but couldn't find any so I'm very grateful for this information!

This made my choice very easy and make me able to order today
05-17-2011 03:34 PM
OLNOLAN
Kb/sp

Looks like the weight is basically the same between the two pistons, Speed Pro piston book says a L2465F(std, bore) is 675 grams and a L2465F60 is 690 grams. The KB icon online catalog says the IC782(std. bore) is 673 grams but didn't give the .060 weight. Appears to me that KB versus SP weight is within 2 grams. Take your choice. Good luck
05-17-2011 02:33 PM
Berres Ok thanks for answer!

Ah, so it's how fast the engines rev that is affected. Is that affect HP and torque?
I will re-balance the engine so that isn't to consider.

But is the weight difference so noticable so it's worth 325? If it is very noticable I deal with it and order it
05-17-2011 01:33 PM
oldbogie
Quote:
Originally Posted by Berres
Hello!
Need some quick answers on this one.
The problem is that I need live in sweden and need pistons for my engine NOW (read "like today").

You don't want to hear the whole story but I can get KB:s forged IC782-060 with rings and the speed-pro ZL2465F60 with rings shipped today for a total cost difference about $325 (with shipping costs and taxes in my country).

Far as I know the downside of the speed-pro is the weight?
If I choose speed-pro, how much will I loose of that choice?
So wich pistons would you buy if you were me and the pistons is going to be in an 454 bored 0.060 over, 049 heads with bigger valves and ported, xe284-10 cam, holley 870 and so on... no NOS.

And ooooh, I'm on a tight budget

Thanks for quick answers!
Balance is the first problem. If you're not going to re-balance the engine the pistons and rods need to end up close to what the factory balanced the crank for. If you re going to balance the crank then lighter parts will help it to rev faster.

Given there are different piston alloys out there it wouldn't be possible to comment on which was the stronger choice without knowing more.

Bogie
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