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Username Post: Hypereutectic -vs- Forged pistons        (Topic#224135)
NYH1 
Contributor
Posts: 708

Loc: Central New York
Reg: 07-15-09
08-20-09 10:15 AM - Post#1757437    

At what point does it become necessary to use forged piston? Does a daily driver/mild street performance 355 or 383 with 9.4:1 compression that's only going to see a max of 5800 RPM's tops (every once in a while) with no nitrous need forged piston?

I'm getting ready to start buying parts for my rebuild. I talked to a few different people at a few different places that sell performance parts. Most of them told me that I might be better off using Hypereutectic pistons for what I'm going to do. They said they can offer a tighter fit then forged and don't expand and contract as much as forge do.

I drive about 150 miles a week. In the warmer months I'm going to drive this car probably at least half of those miles, if not more. This really is going to be a daily driver first, then mild street performance, that's why my build is so mild. If I don't need forged pistons, I'm not going to use them.

I want an honest opinion. For what I'm going to use my car for, can I use hypereutectic pistons?
'78 Camaro, mild Vortec head 385 stroker, 9.1 comp. Lunati Voodoo 262/268 hyd. ft. cam, RPM Intake, 650 AVS carb, TH350 Coan 11" 2600 stall, 8.5" 10 bolt. 3:42 posi, 1 5/8" Full length Headers, 2 1/2" Flowmaster Exhaust System.


 
motorman 
Dedicated Enthusiast
Posts: 5170

Loc: south western pa.
Reg: 01-25-00
08-20-09 10:37 AM - Post#1757446    
    In response to NYH1

the 505 HP ZO-6 corvette uses hyper pistons and they are chipped for 7000 RPM. remember all hyper pistons are not the same.
retired race engine builder,former NASCAR tech inspector. new corvettes owned 1959,1962,1963,1964,1965, 1966,1997,1999,2002,2005, 2008 plus 30+ other chevy cars and trucks along the way. 2008 corvette sold and waiting on a C-7.


Edited by motorman on 08-20-09 10:37 AM. Reason for edit: No reason given.

 
NYH1 
Contributor
Posts: 708

Loc: Central New York
Reg: 07-15-09
08-20-09 11:31 AM - Post#1757471    
    In response to motorman

I'm looking at a Scat rotating assembly. It has a cast crank, 4340 I beam rods and hypereuttectic pistons. I think they use Keith Black Pistons. I'm not sure though.
'78 Camaro, mild Vortec head 385 stroker, 9.1 comp. Lunati Voodoo 262/268 hyd. ft. cam, RPM Intake, 650 AVS carb, TH350 Coan 11" 2600 stall, 8.5" 10 bolt. 3:42 posi, 1 5/8" Full length Headers, 2 1/2" Flowmaster Exhaust System.


 
Raven18940 
Member
Posts: 265

Reg: 09-22-04
08-20-09 01:25 PM - Post#1757512    
    In response to NYH1

I'd find out exactly what the set contains, but a good quality hypereutectic piston should have no trouble coping with the demands you plan to put on the engine. It will also provide the stated tighter fit and will fit better during the warmup period (less noise and wear.)

But just to demonstrate how much abuse a hypereutectic piston can take let me tell you briefly about my SAAB. It has a 2.3L 4 cylinder that develops about 250hp @ 5500rpms and 275lb-ft of torque from 2000-4000 rpms using a max of about 15 psi of boost with a 9.3:1 compression ratio.

I know it's not a chevy, but still. So yeah, if they're good quality pistons, they'll hold for you no problem.
89 Camaro RS, small block of unverified displacement (probably a 305).
Transmission Stage Borked
Electronic Fuel Injection!


 
grumpyvette 
Senior Chevytalk Moderator -- Performance Subject Matter Expert --
Posts: 16109
grumpyvette
Age: 66
Loc: FLORIDA USA
Reg: 03-16-01
08-20-09 01:27 PM - Post#1757514    
    In response to NYH1

  • NYH1 Said:
At what point does it become necessary to use forged piston? Does a daily driver/mild street performance 355 or 383 with 9.4:1 compression that's only going to see a max of 5800 RPM's tops (every once in a while) with no nitrous need forged piston?

I'm getting ready to start buying parts for my rebuild. I talked to a few different people at a few different places that sell performance parts. Most of them told me that I might be better off using Hypereutectic pistons for what I'm going to do. They said they can offer a tighter fit then forged and don't expand and contract as much as forge do.

I drive about 150 miles a week. In the warmer months I'm going to drive this car probably at least half of those miles, if not more. This really is going to be a daily driver first, then mild street performance, that's why my build is so mild. If I don't need forged pistons, I'm not going to use them.

I want an honest opinion. For what I'm going to use my car for, can I use hypereutectic pistons?



a decent HYPEREUTECTIC PISTON SHOULD WORK VERY WELL UNDER THOSE CONDITIONS AS LONG AS YOU KEEP THE F/A MIXTURE FROM LEANING OUT AND KEEP OUT OF DETONATION WITH THE IGNITION TIMING
http://forum.grumpysperformance.com/viewtopic.php?...
" " IF YOU CAN'T SMOKE THE TIRES FROM A 60 MPH ROLLING START YOUR ENGINE NEEDS MORE WORK !"


Edited by grumpyvette on 08-21-09 06:36 AM. Reason for edit: No reason given.

 
Raven18940 
Member
Posts: 265

Reg: 09-22-04
08-20-09 01:40 PM - Post#1757518    
    In response to grumpyvette

  • grumpyvette Said:
a decent HYPEREUTECTIC PISTON SHOULD WORK VERY WELL UNDER THOSE CONDITIONS AS LONG AS YOU KEEP THE F/A MIXTURE FROM LEANING OUT AND KEEP OUT OF DETONATION WITH THE IGNITION TIMING


VERY GOOD POINT!!!

Allow me to expand on this a little for clarification. Hypereutectic pistons are very hard by their nature (because of the silicon added to them.) This hardness makes them strong, but also makes them inflexible. Inflexible is a nice way of saying they're brittle.

What it means in layman's terms is that they are strong, but intolerant of mistakes. A good knock or detonation can spell they end of the piston. A knock controlled EFI system is ideal.
89 Camaro RS, small block of unverified displacement (probably a 305).
Transmission Stage Borked
Electronic Fuel Injection!


 
chevy355s10 
Frequent Contributor
Posts: 1126
chevy355s10
Age: 24
Loc: lake city,SC
Reg: 07-05-08
08-20-09 04:39 PM - Post#1757598    
    In response to Raven18940

the pistons that come with that kit are from speedpro.

my engine see's 6500-6800 rpm's every time i have a WOT run on the free way and i am using the same bottom-end you are looking at.
David B.


Edited by chevy355s10 on 08-20-09 04:42 PM. Reason for edit: No reason given.

 
Lilracr 
Member
Posts: 69

Loc: Va.
Reg: 10-18-04
08-21-09 05:40 AM - Post#1757825    
    In response to chevy355s10

You also need to pay attention to the recommended bore to piston clearance. Different material wil expand differently.

The 6.0L truck knock when cold is a good example of bore to piston tolerance.
-Bobby- Doing more with less!


 
NYH1 
Contributor
Posts: 708

Loc: Central New York
Reg: 07-15-09
08-21-09 09:52 AM - Post#1757953    
    In response to Lilracr

Thanks for all the replies, I really appreciate it. I'm not trying to be cheap, I really do have to make every penny count. I have 3 kids (8, 12 and 16), a wife...who's great she really is, a mortgage, two car payments (they're low but we still gotta be careful). My job where I've been for 12 years is iffy at best. I just have to be careful that's all!
'78 Camaro, mild Vortec head 385 stroker, 9.1 comp. Lunati Voodoo 262/268 hyd. ft. cam, RPM Intake, 650 AVS carb, TH350 Coan 11" 2600 stall, 8.5" 10 bolt. 3:42 posi, 1 5/8" Full length Headers, 2 1/2" Flowmaster Exhaust System.


 
sedandelivery55 
"8th Year" Gold Supporting Member
Posts: 2735
sedandelivery55
Age: 54
Loc: Moore, OK
Reg: 02-20-02
08-21-09 08:19 PM - Post#1758260    
    In response to NYH1

I used Speed Pro Hypereutectic flat tops in my .040 over 400 when I built it 5 years ago. I take it to 6000 RPM at least once everytime I drive it, at least once a week. No problems, yet.
Lee

http://www.picturetrail.com

Coming soon! Big block/three pedal 70 Nova

92 GMC Sierra short/stepside
4.3 V6, 5 speed





 
stroked83 
Contributor
Posts: 240

Age: 22
Loc: central IL
Reg: 05-01-08
08-31-09 11:26 AM - Post#1763824    
    In response to NYH1

  • NYH1 Said:
I'm looking at a Scat rotating assembly. It has a cast crank, 4340 I beam rods and hypereuttectic pistons. I think they use Keith Black Pistons. I'm not sure though.



i ordered that kit with my build of a 500 horse 383 i got the kieth black pistons .06 over. the whole assembly like 1250

i would lean towards the forged that way if you ever want to throw nitrous at it you dont have to then put pistons in it. i only run 9.8 to 1 dished but i run the forged rods and pistons for plans of nitrous in the future. not much r.p.m. goin to it prolly 6600 tops

just another setup advice you can go off of.
83 silverado c-10 short bed
383ci lunati cam, dart heads, 750 demon, cal-tracs bars
8.2902 @ 83.15mph 1/8 mile 3950lbs


 
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