A forged 360 Mag piston that comes in around 8- 8.5:1?

[Michael Harrington]

I've done some searches here and with google but really have not found a recommended part # of a Forged piston that will be in the 8s for compression. Will be used in a 360 magnum with Iron magnum heads and a Weiand 144 street blower. When I look at piston specs and the piston states a dish that creates a "+" in the combustion chamber volume the advertised static ratio for that piston is still high for forced induction.

 

[Locomotion]

The lowest compression forged pistons that you'll find without going custom or remachining are NHRA/IHRA "Stock" class pistons. However, new, these tend to be in the "custom" price range. They do have a lower compression height similar to OEM to meet the rules. They are forged and I've seen them advertised to be ok for nitrous up to 250hp but not turbos. Not sure how a mild supercharger application would fit in. Check with the company or your engine builder.

Here is one example that you can plug the specs into your compression formula for comparison.
Consider high quality, thicker head gaskets also and milling the deck or heads an absolute minimal amount. OEM decks tend to be a bit taller than advertised..

Low compression 360 piston ad on this site.

 

[DNasty777]

Lowest off the shelf I've seen is the Carillo Bullet pistons P/N: BMR-4200-030.

 

[Michael Harrington]

Lowest off the shelf I've seen is the Carillo Bullet pistons P/N: BMR-4200-030.

Thanks. I see some places are out of stock. But I did find a site that claims to have them.

 

[RustyRatRod]

I've done some searches here and with google but really have not found a recommended part # of a Forged piston that will be in the 8s for compression. Will be used in a 360 magnum with Iron magnum heads and a Weiand 144 street blower. When I look at piston specs and the piston states a dish that creates a "+" in the combustion chamber volume the advertised static ratio for that piston is still high for forced induction.

What you need is the old TRW/Speed Pro #L2405F. That's a forged stock replacement for the 360LA engine. It would be perfect for what you are doing. The catch is, they are out of production, so you will have to find them on ebay or elsewhere. They do pop on on ebay from time to time. But you have a part number now so maybe you can find some.

 

[RustyRatRod]

Thanks. I see some places are out of stock. But I did find a site that claims to have them.

If it's a generic looking site, be careful. A lot of those are scam sites, or sites that have not updated their web site. CALL first to confirm anything is in stock.

 

[turbovan]

I’m using DSS -18cc forged pistons which put me around 9.2:1 with Speedmaster heads. My research showed that a zero deck height piston at 10:1 is less prone to detonation than an 8.5:1 piston sitting a ways below deck. I have tried the NHRA forged “stock class” pistons and do not recommend with boost. The piston crown caved in. I did also consider the trw pistons but decided against them again due to their below deck height and also weight.

 

[DNasty777]

I’m using DSS -18cc forged pistons which put me around 9.2:1 with Speedmaster heads. My research showed that a zero deck height piston at 10:1 is less prone to detonation than an 8.5:1 piston sitting a ways below deck. I have tried the NHRA forged “stock class” pistons and do not recommend with boost. The piston crown caved in. I did also consider the trw pistons but decided against them again due to their below deck height and also weight.

What head gasket are you running with the DSS pistons?

 

[Michael Harrington]

I’m using DSS -18cc forged pistons which put me around 9.2:1 with Speedmaster heads. My research showed that a zero deck height piston at 10:1 is less prone to detonation than an 8.5:1 piston sitting a ways below deck. I have tried the NHRA forged “stock class” pistons and do not recommend with boost. The piston crown caved in. I did also consider the trw pistons but decided against them again due to their below deck height and also weight.

Are you saying a piston that is zero deck but dished is better for boost than a flat top piston that comes in below the deck?

 

[turbovan]

Are you saying a piston that is zero deck but dished is better for boost than a flat top piston that comes in below the deck?

Exactly.

 

[turbovan]

What head gasket are you running with the DSS pistons?

Cometic .040

 

[PROSTOCKTOM]

Having sold several balanced rotating assemblies to customers that run blowers I can offer some insight.

If you want 8 to 1 pistons you'll need to plan on buying custom made for the application. The ones I had made were $1600 a few years ago.

Also I can not stress this enough. If you plan to run boast you need to get .250" wall wrist pins. Because they will not bend.

Using anything less than this you're asking for trouble eventually. Once the pins start giving away the engine blows up badly.

Good Luck with the project.

Tom

 

[Michael Harrington]

Having sold several balanced rotating assemblies to customers that run blowers I can offer some insight.

If you want 8 to 1 pistons you'll need to plan on buying custom made for the application. The ones I had made were $1600 a few years ago.

Also I can not stress this enough. If you plan to run boast you need to get .250" wall wrist pins. Because they will not bend.

Using anything less than this you're asking for trouble eventually. Once the pins start giving away the engine blows up badly.

Good Luck with the project.

Tom

Thank you. It's disappointing that an engine that had decades of production (360LA then 360 Magnum) does not have an off the shelf piston for boosted applications.

 

[MiradaMegaCab]

Stroke it to 408CI and use these off the shelf pistons.

Icon Pistons IC982-030 Fits SB Chrysler Dish 34cc Bore 4.030

Icon Piston IC982 (specifically designed for boost) has a 34cc dish for use with a 360 running a 4” stroke.
This will net 8.8 to 1 CR with 65cc heads.
I believe this is the lowest CR possible with an off the shelf piston.

 

[PROSTOCKTOM]

Icon Pistons IC982-030 Fits SB Chrysler Dish 34cc Bore 4.030

Icon Piston IC982 (specifically designed for boost) has a 34cc dish for use with a 360 running a 4” stroke.

I am going to disagree with you that this is a specifically made piston designed for boosted applications.

Nowhere in my ICON book does it state this, and I can tell you first hand that all the blower pistons I've dealt with will not weigh 489 grams.

While the piston you showi does have a 34cc dish this does not make it a blower piston.

Tom

 

[MiradaMegaCab]

Strange as UEM’s website and tech line states, 2618 alloy is for boost or nitrous applications.

489 grams, so this piston in not actually recommended for boost?

 

[PROSTOCKTOM]

2618 is the stronger alloy of the two used to make pistons, but this still doesn't make an IC932 a boosted application piston.

Blower pistons are far thicker than these are made and blower pistons have really thick wall wrist pins.

Sorry, but these are not blower pistons, but if you doubt me I suggest you call ICON and ask them about using this piston in a boosted application.

Tom

 

[Michael Harrington]

I must reiterate my Magnum 360 will have a cam of around 218-220 Deg duration at .050 and the 144 Weiand will make 5- 6 psi of boost.

 

[MiradaMegaCab]

Sorry, but these are not blower pistons, but if you doubt me I suggest you call ICON and ask them about using this piston in a boosted application.

Tom

I called Icon’s tech support 1-800-648-7970 and spoke to Wes ext405. He said the IC982 will handle upto 30PSI of boost.

 

[turbovan]

This is a probe 2618 low compression piston not designed for boost. Out of a turbo 360 magnum.

 

[TT5.9mag]

Having sold several balanced rotating assemblies to customers that run blowers I can offer some insight.

If you want 8 to 1 pistons you'll need to plan on buying custom made for the application. The ones I had made were $1600 a few years ago.

Also I can not stress this enough. If you plan to run boast you need to get .250" wall wrist pins. Because they will not bend.

Using anything less than this you're asking for trouble eventually. Once the pins start giving away the engine blows up badly.

Good Luck with the project.

Tom

Come on Tom, you are obviously intelligent but you cannot seriously believe some of the stuff you’re telling these guys. You don’t NEED .250 wall wrist pins for a 360 magnum on 5-7 psi making 450 hp. That’s ridiculous. It’s the cylinder pressure at peak torque or detonation that kills stuff and he isn’t going to have enough of one, and hopefully none of the other.
@Michael Harrington what fuel are you going to run? I’d have no problem running compression numbers up in to the 9.5 range on pump gas at 5-7 psi. If I were you I’d use the stock magnum pistons. Gap the rings wide and send it. I’ve made a bunch of power with stock magnums, and if you keep the tune up conservative and keep it out of detonation you’ll be fine. If it detonates it’ll kill whatever pistons are in there. Promise.

 

[TT5.9mag]

I called Icon’s tech support 1-800-648-7970 and spoke to Wes ext405. He said the IC982 will handle upto 30PSI of boost.

But not 31? How do they come up with this crap?

 

[MiradaMegaCab]

But not 31? How do they come up with this crap?

Lol, it’ll handle 31PSI at 31* Total Timing on 87 Octane Fuel with a 500 Shot of Spray. LOL

The tech was looking up the specs (material, crown thickness, etc) he went into detail as not to use Moly Rings with over 100HP of N2O and to gap the rings accordingly.
I specifically asked about 12PSI of Roots boost with a 175 shot of spray, again Wes said, “No problem!”

I’m going to run solid wrist pins and 2 electric superchargers (eBay has them) in series. This way I double my CFM at the same 31PSI. Lol

Gentlemen, carry on.

 

[TT5.9mag]

Lol, it’ll handle 31PSI at 31* Total Timing on 87 Octane Fuel with a 500 Shot of Spray. LOL

The tech was looking up the specs (material, crown thickness, etc) he went into detail as not to use Moly Rings with over 100HP of N2O and to gap the rings accordingly.
I specifically asked about 12PSI of Roots boost with a 175 shot of spray, again Wes said, “No problem!”

I’m going to run solid wrist pins and 2 electric superchargers (eBay has them) in series. This way I double my CFM at the same 31PSI. Lol

Gentlemen, carry on.

 

[TT5.9mag]

This is a probe 2618 low compression piston not designed for boost. Out of a turbo 360 magnum.

View attachment 1716440768

View attachment 1716440769

Did you happen to cut one of those apart and measure crown thickness?