Search



Go Back   Third Generation F-Body Message Boards > Tech Boards > Engine Swap
Register Forgot Password?

Engine Swap Everything about swapping an engine into your Third Gen.....be it V6, V8, LTX/LSX, crate engine, etc. Pictures, questions, answers, and work logs.

Welcome to ThirdGen.org!
Welcome to ThirdGen.org.

You are currently viewing our forum as a guest, which gives you limited access to view most discussions and access our other features. By joining our community, at no cost, you will have access to post topics, communicate privately with other members (PM), respond to polls, upload content and access many other special features. Registration is free, fast and simple, join the ThirdGen.org community today!


Reply
 
Thread Tools Search this Thread
Old 02-20-2002, 08:49 AM   #1
Senior Member
 
Join Date: Oct 1999
Location: Carrollton, TX, USA
Posts: 779
Car: 1992 Chevy Camaro RS
Engine: 305 TBI
Transmission: T-56

Classifieds Rating: (1)
Send a message via AIM to mult68
Forged vs Hypereutectic Pistons???

Keith Black Hypereutectic 383 Pistons (Part Number KB-100) - $24.65 each

SRP Forged 383 Pistons - $56.63 each

TRW Forged 383 Flat Top 2VR Pistons - $41.00 each

Going on a 383 Superram Daily Driver car.....with a max of 150HP shot of nitrous. I was orginally going to go with the SRP pistons...but read this in a book.

"one advantage of the cast piston over the forged piston is that it requires less piston to bore clearance and in a high performance street engine, for instance, this will mean quieter operation, better ring seal (less piston rock) and frequently more power beacuse of it. High-performance street engines work from idle through to 5500 rpm much more than they do from 5500rpm to 6500rpm. If an engine is not going to be constantly turning high rpm cast pistons are the better option. "

Its an old book, so maybe pistons now a days are different....which is what I wanted to find out. I thought hyper pistons would be a good middle ground.....but if what is said above is not really true, or not true anymore, or not something to worry about...I'll get the forged pistons...probably go ahead and get the SRPs instead of TRW. Any input please.
mult68 is offline vBGarage Page   Reply With Quote
Old 02-20-2002, 10:34 AM   #2
Supreme Member
 
Join Date: Oct 2001
Location: Illinois
Posts: 1,063

Classifieds Rating: (5)

Send a message via AIM to SoCo80p
hypers and nos do NOT mix, never use them unless its just a mild engine, forsure go with the SRP's there a excellent piston and will handle the spray no problem
__________________
SoCo80p is offline vBGarage Page   Reply With Quote
Old 02-20-2002, 10:58 AM   #3
Senior Member
 
Join Date: Oct 1999
Location: Carrollton, TX, USA
Posts: 779
Car: 1992 Chevy Camaro RS
Engine: 305 TBI
Transmission: T-56

Classifieds Rating: (1)
Send a message via AIM to mult68
what about the whole piston to bore clearance blah blah. Just ignore it and go with the forged? Definetly the max rpm i'll be hitting is 6500 rpm.
mult68 is offline vBGarage Page   Reply With Quote
Old 02-20-2002, 12:37 PM   #4
Supreme Member
 
Join Date: Apr 2001
Location: USA
Posts: 4,969
Car: yy wife, crazy.
Engine: 350, Vortecs, 650DP
Transmission: TH-350
Axle/Gears: 8.5", 3.42

Classifieds Rating: (0)

Hypereutectic pistons are fine for 150HP shot of the juice.

Forged pistons are only needed for a 450+HP motor, plus a 250HP shot of nitrous.

The term hypereutectic means that the casting of the piston has a higher level of silicon in it.

What we call a regular cast piston is a eutectic. The 'hyper' part just means there's more than 11% of silicon in the piston.

By using higher amounts of silicon in the casting, the piston has better thermal characteristics than that of a regular cast piston. IE, it's more resistant to melting from heat. Kinda like a forged piston.

A forged piston is just that, it's heated to a very high temp after it is cast. This causes the aluminum to become very hard. They have the highest level of heat resistance. That's due to there expanding ability.

Because of there ability to expand, you must allow more clearance so they don't seize themselves to the cylinder walls as they heat up and get bigger. And they usually require more ring gap because of how small they become when they cool. Otherwise the ends of the rings would be touching at start-up, and that would be very very bad.

The piston rock is caused at start-up from the pistons being smaller, and having more room to move. Once the pistons warm up, and swell, then the clearance is smaller, and they sit tighter in the cylinders.

I think hypereutectic pistons got a bad name for the same reason that EFI did when it first came out.

A bunch of beer drinkin' old timers were sitting around sayin' "Why can't they just leave stuff alone? All this new stuff is confusing us. If it's confusing us, then it must be bad. So let's tell everyone how bad the new stuff is."

AJ

Last edited by AJ_92RS; 02-20-2002 at 12:58 PM.
AJ_92RS is offline vBGarage Page   Reply With Quote
Old 02-20-2002, 12:55 PM   #5
Senior Member
 
Join Date: Oct 1999
Location: Carrollton, TX, USA
Posts: 779
Car: 1992 Chevy Camaro RS
Engine: 305 TBI
Transmission: T-56

Classifieds Rating: (1)
Send a message via AIM to mult68
Quote:
Originally posted by AJ_92RS
Hyperuetectic pistons are fine for 150HP shot of the juice.
Forged pistons are only needed for a 450+HP motor, plus a 250HP shot of nitrous.
383 Block, Scat 9000 Crank, Eagle H rods, AFR 190 (maybe 195) heads, LT4 hot cam, SuperRam system, T56 tranny, 12bolt rear end with 3.73 or 3.42 gears, ~10.1 comp. and the 150hp max nitrous shot. Hyper pistons or forged pistons? Daily driven, want it to last as long as possible, taken to track every now and then.
mult68 is offline vBGarage Page   Reply With Quote
Old 02-20-2002, 01:00 PM   #6
Moderator
 
five7kid's Avatar
 
Join Date: Mar 2000
Location: Littleton, CO USA
Posts: 42,124
Car: 82 Berlinetta/57 Bel Air
Engine: LS1/LQ4
Transmission: 4L60E/4L80E
Axle/Gears: 10B-3.73/9"-3.89

Classifieds Rating: (14)

Quote:
Originally posted by AJ_92RS
The term hyperuetectic means that the casting of the piston has a higher level of silicon in it.

What we call a regular cast piston is a eutectic. The 'hyper' part just means there's more than 11% of silicon in the piston.
You have that part mostly correct. "Hyper" means "above" or "over". So, a hypereutectic aluminum alloy has a silicon content that is "above" the eutectic point (the % at which the alloy will be liquid above a certain temp, or solid below that temp - no liquid & solid "slush", or two-phase mix). In metalurgy, that is illustrated in what is called a "phase diagram".

Quote:
By using higher amounts of silicon in the casting, the piston has better thermal characteristics than that of a regular cast piston. IE, it's more resistant to melting from heat. Kinda like a forged piston.
That isn't quite right. The silicon makes it stronger. Since it is stronger, it can maintain the same required minimum strength at a higher temp. (The temp at which melting occurs is irrelevant - by that time, you're dead. Liquid starts to form at the same temp for both materials, anyway.)

FWIW, what we call "cast" and "hypereutectic" are both made with a casting process; the methods have to vary slightly to keep the hypereutectic material molten so it will flow properly into the mold.

Quote:
A forged piston is just that, it's heated to a very high temp after it is cast. This causes the aluminum to become very hard.

Way off. They are made out of a different alloy entirely. The material is forced into shape without being molten, which induces grain flow, which is a big factor in making them stronger. Rough machining, stress relief, and final machining follow. Other processes may be involved, depending upon the design.

Quote:
They have the highest level of heat resistance. That's due to there expanding ability.

They are stronger, due to the material and forging process, in the same way hypereutectics are (explained above).

Quote:
Because of there ability to expand, you must allow more clearance so they don't seize themselves to the cylinder walls as they heat up and get bigger.

Close. Because they will withstand more heat, they must be allowed to expand more.

Enough for now...
__________________
See detail on my cars in My vBGarage

I'm a racing fool. Not necessarily in that order.

Last edited by five7kid; 02-20-2002 at 01:07 PM.
five7kid is offline vBGarage Page   Reply With Quote
Old 02-21-2002, 05:50 AM   #7
ede
TGO Supporter
 
Join Date: Aug 1999
Location: Jackson County
Posts: 14,811

Classifieds Rating: (0)
Send a message via ICQ to ede
for a power adder i'd use forged everything
__________________
MM Black Diamond 538 F&AM

Ex quocumque facere poteris te sauciabit, nihilo comprehenso.

ICON Motorsports

S10 Manual Stearing Box 75$
ede is offline vBGarage Page   Reply With Quote
Old 02-21-2002, 12:07 PM   #8
Member
 
Join Date: Dec 2001
Location: Montgomery, AL
Posts: 344

Classifieds Rating: (0)
Forged definitely. I believe SpeedPro (I think) has a new forged piston out that does not expand as much with heat so it can be fitted to the bore tighter. Look in the Summit catalog. I believe thats where I read it. I have seen KB hypers last just fine in 500hp+ motors WITHOUT nitrous or supercharging. If you are going to do either of these I would definitely go forged.
__________________
'87 IROC soon to be Cherry Red Metallic
T-Tops
383ci
Forged crank, Forged 6" H-beam rods, KB pistons 10:1 CR
AFR 190 aluminum heads
Weiand Stealth
Holley 770 Street Avenger Vacuum Secondary Carb
CompCams XE 274 cam, Pro Magnum steel roller tipped rockers
Mufflex 4" exhaust with dual tips
Hooker Super Comp headers with custom y-pipe
MSD 6AL with ProBillet Street Destributor
Hotchkis LCA's, Adj Panhard rod, Springs, Edelbrock Torque arm, Jegster SFC's, HP Motorsports 3-point Strut tower brace, Spohn LCA relocator brackets, PowerStop cross drilled brake rotors
3.70 geared 7.75" 9-Bolt Borg-Warner
TCI StreetFighter 700R4
2500 RPM TCI BreakAway Torque Converter
ASCD Fiberglass SS hood
91-92 Z28 High Rise Spoiler
17" ROH wheels with 255/45/17 Falken ZE 502's
Dragula is offline vBGarage Page   Reply With Quote
Old 02-21-2002, 02:38 PM   #9
Senior Member
 
Join Date: Oct 1999
Location: Carrollton, TX, USA
Posts: 779
Car: 1992 Chevy Camaro RS
Engine: 305 TBI
Transmission: T-56

Classifieds Rating: (1)
Send a message via AIM to mult68
Yeah I was wondering if there were any forged pistons that didnt expand as much. Not sure if they existed or not. I'll look at a few catalogs and see if i can find anything.
mult68 is offline vBGarage Page   Reply With Quote
Old 01-24-2009, 04:25 PM   #10
Junior Member
 
metalax's Avatar
 
Join Date: Aug 2008
Posts: 5

Classifieds Rating: (0)
Re: Forged vs Hypereutectic Pistons???

five7kid, excellent information! I think all the misnomers regarding Hyperuetectic vs forged pistons need to be revisited. I run KB Hyperuetectic pistons with a 100 shot of squeeze in a 400+ hp motor only and have not seen any unusual adverse affects. I'm not saying this is the very best scenario but on a buck to ET level I believe there a good choice. Some of us just don't have a John Force budget.

IMHO
Metalax
metalax is offline vBGarage Page   Reply With Quote
Old 02-01-2009, 03:32 PM   #11
Junior Member
 
Join Date: Jul 2006
Posts: 3

Classifieds Rating: (0)
Re: Forged vs Hypereutectic Pistons???

Where is AJ coming from? The rings don't butt together cold, that is the gap you have when you build the motor. The reason for larger ring gaps in todays schemes is that the extreme heat from nitrous will close the gap.
Forged pistons are more malible and absorb the shock of detonation that can happen easy with spray. Hyper pistons are strong and don't expand much, but they are brittle.
Short story
You want quite long lasting street car with minumum spray go hyper.
If your building a play car for a lot of strip abuse forged is the way go.
xracer27 is offline vBGarage Page   Reply With Quote
Old 02-01-2009, 03:56 PM   #12
Moderator
 
Apeiron's Avatar
 
Join Date: Jan 2000
Location: Rio Oro de Santa Ana, San Jose, Costa Rica
Posts: 20,979
Car: 1984 Z28 Hardtop / 1988 IROC T-top
Engine: 383 Carb / 305 TPI
Transmission: 4L60 / T-5
Axle/Gears: 3.54 Dana 44 / 3.08 10 bolt

Classifieds Rating: (0)

Re: Forged vs Hypereutectic Pistons???

Quote:
Originally Posted by five7kid View Post
FWIW, what we call "cast" and "hypereutectic" are both made with a casting process
For that matter, "forged" pistons are initially cast as well, before they're forged. It's also possible to have a forged a piston with a hypereutectic alloy, but it's not common.
Apeiron is offline vBGarage Page   Reply With Quote
Old 02-01-2009, 04:15 PM   #13
Member
 
lowflyr's Avatar
 
Join Date: May 2003
Location: Nova Scotia, Canada
Posts: 107
Car: 87IROC/88GTA/02Sierra/04GrandPrix
Engine: 406 / 305 / 4.8 / 3.8
Transmission: T56 / T5 / 4L60e / ??
Axle/Gears: 3.70 / 3.45 / 3.42 / ??

Classifieds Rating: (0)
Re: Forged vs Hypereutectic Pistons???

Holy crap old post! 2002! LOL

Use forged for any application using laughing gas. I can almost guarantee you'll lift the top ring land off the hypereutechtics after a number of decent length nitrous runs. The top ring will butt together and you'll have a piston that looks like the picture on the KB silvolite website under 'special clearance requirements'. If you push the limit on compression ratio I'd recommend the forged units, even without giggle juice.
lowflyr is offline vBGarage Page   Reply With Quote
Old 02-01-2009, 05:00 PM   #14
Junior Member
 
Join Date: Jul 2006
Posts: 3

Classifieds Rating: (0)
Re: Forged vs Hypereutectic Pistons???

Yes all the aluminum or steel is cast/melted it could then be poured in to a mold for a cast product or poured in to ingots/blanks that are then forged into shape.
xracer27 is offline vBGarage Page   Reply With Quote
Old 02-01-2009, 05:00 PM
ThirdGen
1992 Camaro




Paid Advertisement


Reply

Go Back   Third Generation F-Body Message Boards > Tech Boards > Engine Swap

Tags
383, aluminum, cast, comparison, forged, hp, hyper, hypereutectic, hyperutectic, kb, limit, mean, nitrous, piston, pistons
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off

 


1982 Camaro '82 || 1983 Camaro '83 || 1984 Camaro '84 || 1985 Camaro '85 || 1986 Camaro '86 || 1987 Camaro '87 || 1988 Camaro '88 || 1989 Camaro '89 || 1990 Camaro '90 || 1991 Camaro '91 || 1992 Camaro '92


All times are GMT -5. The time now is 12:39 PM.


Powered by vBulletin® Version 3.7.5
Copyright ©2000 - 2014, Jelsoft Enterprises Ltd.
All content copyright 1997 - 2014 ThirdGen.org. All rights reserved. No part of this website may be reproduced without the expressed, documented, and written consent of ThirdGen.org's Administrators.

Emails & Contact Details