Hypereutectic or Forged Pistons

[Indycars]

I don't build engines every week, so I'm looking for some opinions on whether I can use Hypereutectic pistons in my next engine. I like that they can use a much tighter clearance, stabilizing the piston and rings. This would also make it easier to keep the deck clearance low without having contact between the piston and head.

Here as some stats for the engine.

Chevy 350 - 4 Bolt Main
Scat or Eagle Rotating Assembly (355 or 383 Stroker)
Brodix IK 180 Aluminum Heads
9.5 to 10 SCR
Camshaft: 230 @ .050 / 525 Lift Solid Roller (Approximate)
Deck Clearance = .040"
No Nitrous or Blower
Max RPM: 6500
Trans: TH350 w/ High Stall Converter
Notes: Probably no drag strip runs, not without a roll bar. Although my wife keeps suggesting it.:jester:

I know that this is one of those subject that gets alot of opinions on both sides, but just the discussion will help me decide. The machine shop is pushing forged, but that's another $400-$500. If he is right, then it will be alot cheaper to pony up the money now. Changing to forged piston later will be decidedly much more expensive than doing it now.


Rick

 

[RPM]

Definitely forged. I don't know what kind of a piston they are wanting to sell you at the machine shop. 400-500 is just ridicules. Here is a set of Speed Pro forged pistons for $270.00. You might want to buy your own parts.

https://shop.enginekits.com/osb/itemdetails.cfm?ID=461

 

[Indycars]

Definitely forged. I don't know what kind of a piston they are wanting to sell you at the machine shop. 400-500 is just ridicules. Here is a set of Speed Pro forged pistons for $270.00. You might want to buy your own parts.

https://shop.enginek...ails.cfm?ID=461

Sorry, I didn't mean to imply that the machine shop prices were that much different. I was basing my numbers on Summit prices for an Eagle Balanced Rotating Assembly, the only difference was the pistons being hypereutectic or forged. When I go to the Eagle website the difference $345. In Eagle products the Hypereutectic pistons are SpeedPro and the Forged pistons are Mahle. Whatever the difference is, does my application require or maybe its on the borderline between hypereutectic and forged. What does your experiences tell you about my application???

Thanks again!

Rick

 

[one finger john]

Face it ... machine shops want to make money too. They probably have a "business plan" where each customer is going to spend X ammount of money, ensuring the machine shop makes a clear profit of 75 - 100 % on parts (sometimes more). Have a buddy that is knowledgeable help pick Jegs or Summit's parts catalogs, or do it yourself. Its' fun and you can get a real education on parts prices. Don't forget EBay. Remember that the Chevy small block is one of the most prolific engines around. When shopping for parts , have the block serial number available (decoded to ease I.D. ... you know, 1968 350 4bolt main, truck/ pass car ... etc.) Pick the parts that are suitable, call Teck hot lines to verify seclections and give the parts to the machine shop. If the machine shop refuses to use the customer (that be you) supplied parts (and the parts are correct for the application), find another machine shop. Also get a written "menu" of of the different services that the machine shop charges (bore/$120.00, hot tank/60.00, valve job/$500.00 ... etc.) Get EVERYTHING in writting before work starts. If you are not comfortable with the people that run the place or the time table the give for work completion, find another machine shop. Ask friends for recomendations.

John

Maybe Mike would chime in on this subject.

 

[GT63]

I don't build engines every week, so I'm looking for some opinions on whether I can use Hypereutectic pistons in my next engine. I like that they can use a much tighter clearance, stabilizing the piston and rings. This would also make it easier to keep the deck clearance low without having contact between the piston and head.

Here as some stats for the engine.

Chevy 350 - 4 Bolt Main
Scat or Eagle Rotating Assembly (355 or 383 Stroker)
Brodix IK 180 Aluminum Heads
9.5 to 10 SCR
Camshaft: 230 @ .050 / 525 Lift Solid Roller (Approximate)
Deck Clearance = .040"
No Nitrous or Blower
Max RPM: 6500
Trans: TH350 w/ High Stall Converter
Notes: Probably no drag strip runs, not without a roll bar. Although my wife keeps suggesting it.:jester:

I know that this is one of those subject that gets alot of opinions on both sides, but just the discussion will help me decide. The machine shop is pushing forged, but that's another $400-$500. If he is right, then it will be alot cheaper to pony up the money now. Changing to forged piston later will be decidedly much more expensive than doing it now.


Rick

I'd go with forged pistons too.

You don't really need a HIGH STALL converter, anything around 2200-2500 will let you hold the brake without surging.

http://en.wikipedia.org/wiki/Hypereutectic_piston

 

[Indycars]

I'd go with forged pistons too.

You don't really need a HIGH STALL converter, anything around 2200-2500 will let you hold the brake without surging.

http://en.wikipedia....eutectic_piston

I thought a stock converter had a stall of approximately 1300-1500 rpm, so I would consider 2200-2500 rpm a high stall converter. Not trying to start an argument, just wanting to clarify what "high stall" means in rpm.


Rick

 

[RPM]

To me high stall is anything above stock.

 

[Screaming Metal]

I'm with Ron, anything above stock is high.....you can get certain converters to 'flash' stall, though I have never done such things....I'm a lowly wrench.....
Oh yea.....forged also.....500-600 is probably for top-of-the line stroker pistons where they can specify wrist pin hole locations, yada, yada, yada.... balanced with 900 trillionbagillion of a gram, special cam ground.....just go with a good quality speedpro forged that piston like everyone else uses....cheap, strong and will last......

 

[GT63]

I thought a stock converter had a stall of approximately 1300-1500 rpm, so I would consider 2200-2500 rpm a high stall converter. Not trying to start an argument, just wanting to clarify what "high stall" means in rpm.


Rick

No problem

I'm running a 3500 stall so to me that is high stall.

 

[72442conv]

I don't build engines every week, so I'm looking for some opinions on whether I can use Hypereutectic pistons in my next engine. I like that they can use a much tighter clearance, stabilizing the piston and rings. This would also make it easier to keep the deck clearance low without having contact between the piston and head.

Here as some stats for the engine.

Chevy 350 - 4 Bolt Main
Scat or Eagle Rotating Assembly (355 or 383 Stroker)
Brodix IK 180 Aluminum Heads
9.5 to 10 SCR
Camshaft: 230 @ .050 / 525 Lift Solid Roller (Approximate)
Deck Clearance = .040"
No Nitrous or Blower
Max RPM: 6500
Trans: TH350 w/ High Stall Converter
Notes: Probably no drag strip runs, not without a roll bar. Although my wife keeps suggesting it.:thinkn:

I know that this is one of those subject that gets alot of opinions on both sides, but just the discussion will help me decide. The machine shop is pushing forged, but that's another $400-$500. If he is right, then it will be alot cheaper to pony up the money now. Changing to forged piston later will be decidedly much more expensive than doing it now.


Rick

Not to go against the current, but for what you are doing Hypereutectic pistons will be fine. Now having said that I would also use the forged pistons, just because at some point or another you may decide to add nitrous or a small blower and then the Hypereutectic just won't do. If you are 100% sure that you will never decide on adding a blower, nitrous, or a big roller cam to spin the thing over 7,000 RPM's, or anything like that then the Hypereutectic pistons will be fine.
In builds just like your I have always used forged pistons because I know that I will beat the hell out of the engine and want the additional insurance that the forged pistons give. Plus nitrous is always an option
Also if you ever want to sell the car, an engine with forged pistons has more appeal to more buyers. You can do a lot more with the engine if it has forged pistons.
As RPM said Speed Pro makes inexpensive forged pistons. You can always buy Wiseco, Mahle, JE or something really expensive and trick, but the old TRW/Speed Pro pistons work very well.

 

[Indycars]

No problem

I'm running a 3500 stall so to me that is high stall.

Great! I don't mind discussions but hate the hollering online or anywhere for that matter!

Tell me, how is it different from driving a car with stock stall speed? Will my wife have any trouble driving the TBucket with a high stall converter???


Rick

 

[Indycars]

Not to go against the current, but for what you are doing Hypereutectic pistons will be fine. Now having said that I would also use the forged pistons, just because at some point or another you may decide to add nitrous or a small blower and then the Hypereutectic just won't do. If you are 100% sure that you will never decide on adding a blower, nitrous, or a big roller cam to spin the thing over 7,000 RPM's, or anything like that then the Hypereutectic pistons will be fine.
In builds just like your I have always used forged pistons because I know that I will beat the hell out of the engine and want the additional insurance that the forged pistons give. Plus nitrous is always an option
Also if you ever want to sell the car, an engine with forged pistons has more appeal to more buyers. You can do a lot more with the engine if it has forged pistons.
As RPM said Speed Pro makes inexpensive forged pistons. You can always buy Wiseco, Mahle, JE or something really expensive and trick, but the old TRW/Speed Pro pistons work very well.

Hypereutectic was the way I had it in my mind, then the machine shop really suggested forged. Made me start second guessing myself. I'm still not sure which way I will go, but I'm leaning towards forged now.

I would love to have a blower, but if I did, that would mean changing pistons anyway. I would need dished pistons to lower the compression. It seems the camshaft would also need to be changed for it to run up to its potential with the blower.

I have just one more controversy to start in my next thread, "Compression Ratio on Pump Gas".:thinkn:


Rick

 

[GT63]

Great! I don't mind discussions but hate the hollering online or anywhere for that matter!

Tell me, how is it different from driving a car with stock stall speed? Will my wife have any trouble driving the TBucket with a high stall converter???


Rick

There are a lot of variables in determining the stall speed of your torque converter rpm range. You need to consider the weight of the vehicle, transmission gear range, rear end gear, height of rear tires. torque of engine, etc. The ideal torque converter will allow you to stop at a red light or stop sign and NOT feel like it's trying to push you through it. I think most T-bucket owners are using a torque converter with a stall between 2100-2500. Some may use 1500-1800 because they don't the mind the "surge" feeling when they brake.

I'm using a TCI TH350 with a 3200-3500 stall torque converter with my blown SBC 355. I can apply little brake pedal pressure and hold a complete stop. When I hit the gas, my T will squat in the rear and take off, faster than I have the nerves for.

The bottom line, its your choice. Keep asking questions, There is a wealth of knowledge here. Collect all of the advice and opinions, and then decide for yourself which way you want to go.