Information on 602-603-604 engines

jeff swisher

Veteran Member
Apr 26, 2018
1,936
Yukon Oklahoma
I found this information and it looks like the 602 engine has Cast pistons.
Not Hyperuetectic high silicone.
Last page stated there was a piston change in the 602 and part number changed.

https://staffordmotorspeedway.com/wp-content/uploads/GM-602-CRATE-ENGINE-TECH-MANUAL.pdf

Now I wonder who makes the pistons and what silicone content they do have.
That is what lead me to doing a search.
I still do not know.

During the searching I found many manufactures sell aftermarket pistons in Forged for these crate engines.
Cheater pistons?
Interesting read for sure with all kinds of stuff I did not know about these crate engines.
Not that I knew much about them anyway.
 

1980RS

Veteran Member
Jun 17, 2006
6,004
MN
Years ago before all this hyper stuff came about we used to run the crap out of cast pistons. Ran nitrous on them and everything. The last set I used were some 13:1 Hyduty pistons and the only reason the cast piston failed was I spun a rod bearing and the piston hit the head and broke, sure wasn't the pistons fault. I know of may a racer using Hypers and most of the ones that failed are BBC pistons for some reason.
 

biker

Veteran Member
Gold Member
Dec 7, 2014
4,703
Canada
T
I found this information and it looks like the 602 engine has Cast pistons.
Not Hyperuetectic high silicone.
Last page stated there was a piston change in the 602 and part number changed.

https://staffordmotorspeedway.com/wp-content/uploads/GM-602-CRATE-ENGINE-TECH-MANUAL.pdf

Now I wonder who makes the pistons and what silicone content they do have.
That is what lead me to doing a search.
I still do not know.

During the searching I found many manufactures sell aftermarket pistons in Forged for these crate engines.
Cheater pistons?
Interesting read for sure with all kinds of stuff I did not know about these crate engines.
Not that I knew much about them anyway.
Thanks for posting. Very cool to see all the specs and measurements.
 

Chevyforever

Veteran Member
Jan 4, 2011
1,354
Ontario, Canada
GM, (Chevrolet) seems to offer Hypereutectic pistons in a number of its crate motor offerings according to the 2021 catalog.
Sandlapper posted a link to that 602 Crate manual a few months ago, I read it all and found it quite interesting.
 

G72Zed

Veteran Member
Sep 8, 2015
3,757
Canada
The "NEW 2020/21" made in USA "602" crates are better built and now beating GM's rating by a good margin. Last 1/2 dozen on the dyno were in the 380hp+ range and some close to 430TQ, this is compared to GM's 350hp 390TQ ratings.

Exhaust port changed, I have an inclining that the ring pack has changed as well, along with better machining.
 

sandlapper

Veteran Member
Oct 9, 2020
1,194
SE CSA
Yup, I had that crate manual somewhere some time ago but ... now I read it again more closely ... on about page 13 or 14 it speaks of pistons ... I quote:
Pistons The piston on the far left (below) is installed in 19258602 engines. This piston has a grafal coating on the skirt. The piston in the center (below) does not have a skirt coating and is installed in 88958602 engines. They both are a cast aluminum dished piston with 4 valve reliefs. The piston on the right (below) is installed in 603 & 604 engines. It’s a flat top piston with 4 valve reliefs made from high-silicon aluminum.

Soooo ... regardless if new or old 602, it seems their pistons are CAST and Not Hyper. My interpretation of that is ... 1) I was wrong in stating all 602 have Hypers ... and 2) a CAST piston is essentially an Eutectic piece which has less silicon; thus is Less brittle ... while a Hypereutectic piece has more silicon; thus is More brittle. Mr. Christian, keelhaul that laggard!
 

sandlapper

Veteran Member
Oct 9, 2020
1,194
SE CSA
FWIW,
this a built 355 restricted CT race motor. Had a top quality ROSS piston come apart at full song and it destroyed everything: crank, most rods most pistons, block, CT pan. Iron production heads survived w/ minimal damage. Ross piston was race duty and 2618 forging. I'm not bitter & don't blame Ross; I blame me and my budget. Those pistons were apparently aged/cycled out and its time was up. Too many races. It seems it snatched the wrist pin towers out of the piston; but cannot be certain where it began. No, I didn't & don't have X-ray eyes. It WAS a very good, strong, winning piece.
 

1980RS

Veteran Member
Jun 17, 2006
6,004
MN
FWIW,
this a built 355 restricted CT race motor. Had a top quality ROSS piston come apart at full song and it destroyed everything: crank, most rods most pistons, block, CT pan. Iron production heads survived w/ minimal damage. Ross piston was race duty and 2618 forging. I'm not bitter & don't blame Ross; I blame me and my budget. Those pistons were apparently aged/cycled out and its time was up. Too many races. It seems it snatched the wrist pin towers out of the piston; but cannot be certain where it began. No, I didn't & don't have X-ray eyes. It WAS a very good, strong, winning piece.

Yup, everything has a cycle life.
 

Doug Tenney

New Member
Apr 20, 2013
1
Valley Forge, PA
To be clear, folks shouldn't confuse alloy selection with the manufacturing process. "Hypereutectic" describes the aluminum alloy, not the manufacturing process, so in theory, a manufacturer could forge aluminum parts out of a hypereutectic alloy. This explains it really, really well: https://en.wikipedia.org/wiki/Eutectic_system. (Think of silicon being the Beta constituent, on the RH side of the theoretical diagram.)
 




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