L98 Questions for you engine guys....
11-29-2005, 08:10 PM
#1
Drifting
Thread Starter
L98 Questions for you engine guys....
Just curious because I'm looking at an L98 out of a 90 corvette to build. Is the corvette block a 2-bolt or 4-bolt? Are the pistons cast or hypereutectic?
Thanks in adavance!
Thanks in adavance!
11-29-2005, 09:33 PM
#3
Team Owner
Member Since: Sep 2003
Location: Freedom is never more than one generation away from extinction.
Posts: 20,161
Received 640 Likes
on
444 Posts
St. Jude '03-'04-'05-'06-'07-'08-'09-'10-'11-'12-'13-'14-'15-'16-'17-'18-‘19-'20-'21-'22-'23-'24
Hypereutectic !!! Why can't the mfgrs just say cast. 
What stupid name do they have for forged? Supercalafraglistic!
What stupid name do they have for forged? Supercalafraglistic!
11-29-2005, 09:54 PM
#4
Team Owner
Member Since: Sep 2001
Location: Athens AL
Posts: 59,642
Received 1,400 Likes
on
1,016 Posts
C7 of the Year - Unmodified Finalist 2021
C4 of Year Finalist (performance mods) 2019
Cast pistons, 2-bolt for corvettes
11-29-2005, 10:05 PM
#5
Melting Slicks
The term "Hypereutectic" means the piston is an aluminum alloy poston. Although hypereutectic pistons are cast, the casting process is not what the name is referring to. Hypereu pistons have a high silicone content to achieve the low expansion rate and closer cylinder wall tolerance of a common cast piston, with strength closer to a forged piston than a conventional cast piston. They are a better piston for a normally aspirated engine because you can run a tighter piston to wall clearance without the skirt slap issues of a forged piston. Ring life and seal is also improved with these tighter clearances. Hypereu's are also lighter and dissapate heat quicker than conventional forged pistons.
Unless you are considering boosting your engine the hypereu's are your best choice.
Brian
VTvette
Unless you are considering boosting your engine the hypereu's are your best choice.
Brian
VTvette
11-29-2005, 10:51 PM
#7
Race Director
Originally Posted by CentralCoaster
The 84-85 were forged.
11-29-2005, 11:30 PM
#8
Le Mans Master
Originally Posted by Togo
wow - that's news to me - forged bottom end on a motor with cast heads? (not being scarcastic - just hadn't ever heard this!)
11-29-2005, 11:47 PM
#9
Melting Slicks
Member Since: Oct 2000
Location: Heidelberg PA
Posts: 3,426
Likes: 0
Received 4 Likes
on
4 Posts
Cruise-In V Veteran
Originally Posted by VtVette
The term "Hypereutectic" means the piston is an aluminum alloy poston. Although hypereutectic pistons are cast, the casting process is not what the name is referring to. Hypereu pistons have a high silicone content to achieve the low expansion rate and closer cylinder wall tolerance of a common cast piston, with strength closer to a forged piston than a conventional cast piston. They are a better piston for a normally aspirated engine because you can run a tighter piston to wall clearance without the skirt slap issues of a forged piston. Ring life and seal is also improved with these tighter clearances. Hypereu's are also lighter and dissapate heat quicker than conventional forged pistons.
Unless you are considering boosting your engine the hypereu's are your best choice.
Brian
VTvette
Unless you are considering boosting your engine the hypereu's are your best choice.
Brian
VTvette
Last edited by 85vet; 11-29-2005 at 11:52 PM.
11-30-2005, 12:00 AM
#10
Safety Car
The pistons were TRW's ,I wish they would have continued that in all vetts.
The Syclica in the hyper pistons I think is eather 4 or 6 more that forged I forget now.
Strong but don't bet your life on it,even the strongest break.
The Syclica in the hyper pistons I think is eather 4 or 6 more that forged I forget now.
Strong but don't bet your life on it,even the strongest break.
11-30-2005, 01:34 AM
#11
Melting Slicks
I have a set of '85 forged pistons you can have if you want them just pay shipping. PM me if you're interested. I swapped them out a while ago. The problem you're going to have is finding a used 350 block with any kind of mileage that is true enough not to need an overbore.
We've destroyed more than our share of JE forged pistons that run $400/piece. We've also had some real strong engines that were running stock cast pistons. It all depends on what you are doing. Few street cars, even with built engines are running enough power normally aspirated to warrant forged pistons. Be serious about what you are building and what you are doing with it. If you don't need the strength of a forged piston hypereu's can offer some excellent benefits mainly in terms of weight savings and thermal efficiency.
85vet is right there are some N/A engines that warrant forged pistons. I should have asked what your intended purpose is before making the statment "Unless you are considering boosting your engine the hypereu's are your best choice."
If you are going to be building an N/A engine that truly requires forged pistons few of the internals are going to be stock much less the pistons.
Brian
VTvette
We've destroyed more than our share of JE forged pistons that run $400/piece. We've also had some real strong engines that were running stock cast pistons. It all depends on what you are doing. Few street cars, even with built engines are running enough power normally aspirated to warrant forged pistons. Be serious about what you are building and what you are doing with it. If you don't need the strength of a forged piston hypereu's can offer some excellent benefits mainly in terms of weight savings and thermal efficiency.
85vet is right there are some N/A engines that warrant forged pistons. I should have asked what your intended purpose is before making the statment "Unless you are considering boosting your engine the hypereu's are your best choice."
If you are going to be building an N/A engine that truly requires forged pistons few of the internals are going to be stock much less the pistons.
Brian
VTvette
11-30-2005, 09:19 AM
#12
Melting Slicks
Originally Posted by VtVette
I have a set of '85 forged pistons you can have if you want them just pay shipping. PM me if you're interested. I swapped them out a while ago. The problem you're going to have is finding a used 350 block with any kind of mileage that is true enough not to need an overbore.
We've destroyed more than our share of JE forged pistons that run $400/piece. We've also had some real strong engines that were running stock cast pistons. It all depends on what you are doing. Few street cars, even with built engines are running enough power normally aspirated to warrant forged pistons. Be serious about what you are building and what you are doing with it. If you don't need the strength of a forged piston hypereu's can offer some excellent benefits mainly in terms of weight savings and thermal efficiency.
85vet is right there are some N/A engines that warrant forged pistons. I should have asked what your intended purpose is before making the statment "Unless you are considering boosting your engine the hypereu's are your best choice."
If you are going to be building an N/A engine that truly requires forged pistons few of the internals are going to be stock much less the pistons.
Brian
VTvette
We've destroyed more than our share of JE forged pistons that run $400/piece. We've also had some real strong engines that were running stock cast pistons. It all depends on what you are doing. Few street cars, even with built engines are running enough power normally aspirated to warrant forged pistons. Be serious about what you are building and what you are doing with it. If you don't need the strength of a forged piston hypereu's can offer some excellent benefits mainly in terms of weight savings and thermal efficiency.
85vet is right there are some N/A engines that warrant forged pistons. I should have asked what your intended purpose is before making the statment "Unless you are considering boosting your engine the hypereu's are your best choice."
If you are going to be building an N/A engine that truly requires forged pistons few of the internals are going to be stock much less the pistons.
Brian
VTvette
11-30-2005, 02:29 PM
#13
Race Director
Member Since: Sep 2000
Location: The Top of Utah
Posts: 17,298
Likes: 0
Received 23 Likes
on
22 Posts
Originally Posted by CentralCoaster
The 84-85 were forged.
Originally Posted by togo
wow - that's news to me - forged bottom end on a motor with cast heads? (not being scarcastic - just hadn't ever heard this!)
All aluminum pistons are an aluminum alloy. Eutectic is the situation where the aluminum contains and has absorbed all of the silicon that the aluminum is capable of absorbing. The alloy is 100% silicon saturated. Hypereutectic describes a state of "over-saturation". The excess silicon, that can't be absorbed, remains in suspension in the alloy. It appears as grey flecks of color in the alloy.
RACE ON!!!
11-30-2005, 02:52 PM
#14
Race Director
Member Since: Sep 2000
Location: The Top of Utah
Posts: 17,298
Likes: 0
Received 23 Likes
on
22 Posts
Originally Posted by CentralCoaster
The 84-85 were forged.
Originally Posted by togo
wow - that's news to me - forged bottom end on a motor with cast heads? (not being scarcastic - just hadn't ever heard this!)
Originally Posted by CFI-EFI
Except for 1984 and '85, the pistons are hypereutectic (cast).
RACE ON!!!
