What compression ratio to get Forged Pistons

[Bone]

What compression ratio to get Forged Pistons for Forced Induction/NOS:

9.6 to 1 (stock)
or
9.2 to 1
or
9.0 to 1

Suggestions please.

 

[TurboFreak]

I would go as high as possible since you are not f/i. From the three choices above I would pick 9.6:1 but my real pick would be 10.5:1 for n/a.

 

[earl lee]

I would go as high as possible since you are not f/i. From the three choices above I would pick 9.6:1 but my real pick would be 10.5:1 for n/a.

I think he wants to know what cmp to use for a blown application.

 

[Wifey]

What compression ratio to get Forged Pistons for Forced Induction/NOS:

9.6 to 1 (stock)
or
9.2 to 1
or
9.0 to 1

Suggestions please.

7.5 to 8.0, O ring heads, then turn the Boost way up :idea: And be sure to get the pistons coated:rock:

 

[Bone]

I think he wants to know what cmp to use for a blown application.

Correctomundo. Blowned and juiced.
I haven't been able to update my sig in awhile now.

 

[Bone]

7.5 to 8.0, O ring heads, then turn the Boost way up :idea: And be sure to get the pistons coated:rock:

Why not 6.9 then??:dontknow:

http://www.diamondracing.net/home.asp

Drag Racing Action Magazine
Saving TIME
A New Piston Design Is On The Market
by John DiBartolomeo

Engine development will always involve generating horsepower. Different design variants require testing in order to find the right combination of parts. One of the first parts of the process involves fitting a piston dome to a cylinder head chamber.
The correct size piston dome, one that allows for maximum compression ratio yet doesn’t completely shroud the valves and spark plug, will always make power. Accomplishing this task usually involves ordering of a set of pistons with a blank dome. The engine builder’s job, then, involves machining and hand fitting one of those pistons to the cylinder head. This one piston dome is then replicated on each piston. In the case of a small block Chevrolet this involves having to hand fit both a right and left piston due to cylinder head valve placement. Time consuming, but necessary. Until now!
Diamond Pistons has been manufacturing racing pistons since 1968. They’ve recently come across a method of rapid prototyping that enables them to produce a mock-up piston in a matter of hours rather than days. The design of this “new” piston is created entirely on a 3D computer CAD program and fed to Diamond’s prototyping equipment, which in turn produces the piston.
This technology uses a powder and a binding agent to create, layer by layer, a solid sample. Individual parts, part arrays, or a multiple of different parts can all be built at one time using this kind of equipment. Once the powder-spraying process is complete, an applied coating seals the outside of the part against hydroscopic action (water absorption). This coating is absorbed into the part .040 of an inch so it can be machined.
The Zircon mock-up piston will eliminate time and money invested in correcting costly mistakes. This is accomplished by assembling the mock-up piston in the engine, which allows the customer the ability to evaluate and ensure dome clearance/volume as well as valve pocket depths and locations. If any grinding or machining is necessary, it can very easily be done at this time. The Zircon piston is soft enough to machine, yet maintains its dimensions very well. Once all the correct dimensions are verified, the mock-up piston is returned to Diamond, at which point it’s mesurements are entered into a computer program and sent to the production department to produce a complete set of aluminum racing pistons.
While Diamond stocks hundreds of off-the-shelf pistons to fit most racing applications, both professional and sportsman engine builders know that a set of custom designed pistons will allow for more air/fuel flow over the dome, as well as fill the combustion chamber enough to build compression pressure. More pressure inside the combustion chamber simply leads to more horsepower. In the past, accomplishing this required the same procedure mentioned earlier. Now, however, that process has been greatly simplified.
This method of manufacture is also an aid in the unlikely event of an engine explosion. Ordinarily, when just one or two pistons need to be replaced, new pistons must be reordered and the whole hand-fitting process must be gone through all over again. Now, with your finished design piston already digitized and saved as a computer file, the real time spent is waiting for the production department to produce the part. Once the piston is shipped and placed in your hands, it’s all finished and ready to install.
This new piston doesn’t make any more power than a piston built the traditional way, but it will greatly simplify the engine builder’s job. Most know that time is money, so whenever time is saved, so are dollars.

SOURCE

Diamond Pistons
23003 Diamond Dr. Dept DRA
Clinton Township, MI 48035
586-792-6620
www.diamondracing.net

The new Zircon mock-up piston on the right is built to resemble every single dimension that a finished piston might have. This includes not only the dome, but also the ring lands and pin height as well. This enables an engine builder to be able to certify that each dimension is in the proper spot before a finished piston is built.

The building of the Zircon piston involves the use of a rapid prototyping machine that actually “sprays” the compound in layers of powder and a bonding agent. This particular piston is done, while you’re seeing it sit in a tray out of the machine. The extra powder all around the piston is basically “over-spray” that’s cleared away. With the powder-spraying process complete, an applied coating then seals the outside of the part against hygroscopic action (water absorption). This coating infiltrates into the part .040-of-an-inch and allows the piston to be machined as the engine builder sees fit.

This raw aluminum piston forging shows just how “raw” a piston is before it’s gone through several machine operations to complete the product. Usually, engine builders will purchase the piston with a “blank” or full dome and machine it themselves to their liking. This involves a very time consuming operation that then has to be duplicated on each piston.

Will Heise of Diamond Pistons showed the new piston to Jason Line of Greg Anderson Racing. Engine builders like Line and Anderson know that to make power requires a piston dome that will fill the combustion chamber fully, yet allow for enough air/fuel flow in order to fill the cylinder. Engine builders spend countless hours trying to perform this job and then have to duplicate it seven more times, in the case of an eight cylinder engine.

Once the Zircon piston is machined to the engine builder’s liking, it’s returned to Diamond who can then digitize the dome into a computer program that can be sent over to a CNC machine to duplicate the design on each aluminum piston.

The Zircon piston is replicated by the rapid prototyping equipment to be as close dimensionally to an actual piston as possible. Every dimension including strength webbing and pin diameter is kept perfect.

Diamond stocks a vast number of “stock” piston designs to fit numerous applications, but this new process will allow them to “custom design” a piston perfectly for your application.

 

[VA VIPERAM]

Bone,

You should go as low as you can without getting full dish pistons. The full dish design loses the quench area (or squish area) which decreases efficiency and causes the engine to detonate sooner.

Whatever pistons you get, have the machine shop put the fly-cutter in the exhaust relief and "drag" it over to the intake relief to cut out the material between the two. This does two things. It removes the thin material which is prone to glowing red and causing detonation, and it provides more high RPM breathing (scavaging) because it removes the barrier between the valves during overlap (TDC on the exhaust stroke).

Don't know how far into the build you're going, but if you're going to deck the block, take it all the way to zero and find a head gasket that's between 0.028" and 0.038" compressed. This will also prevent detonation and increase efficiency.

O-rings is your choice. The peak pressure in a blown engine is actually less than a 12:1 N/A engine. It's the duration of the pressure (area under the curve) that gives you more power. And you'll be able to do it on pump gas!

 

[NBT]

What compression ratio to get Forged Pistons for Forced Induction/NOS:

9.6 to 1 (stock)
or
9.2 to 1
or
9.0 to 1

Suggestions please.

Whatever you decide...let me know if you need them Cryo'd

 

[TurboFreak]

Correctomundo. Blowned and juiced.
I haven't been able to update my sig in awhile now.

OK, how many lbs of boost do you plan on running? I plan on running 15psi so I went with 8.6:1 cr. Any lower and it would kill my vacuum driving.

 

[Dave T(BADVENM)]

HMMM, makes me wonder what specs my diamond pistons are. Also makes me wonder how much more boost I can do :burnout:

I'll see if I have any info on them.

 

[Silverback]

I ran 40 pounds of boost with 7 to 1 compression. It injected methanol at boost pressures over 10psi. I got 450 hp out 2.6 liters that way.

If you are going to o-ring it, do the block if possible, not the heads. Heads occasionally need to be surfaced and then you have to rework the o-ring grooves. Not ofter that you have to deck the block. Also easier to do the block if it's out of the vehicle.

 

[includemeout]

OK, how many lbs of boost do you plan on running? I plan on running 15psi so I went with 8.6:1 cr. Any lower and it would kill my vacuum driving.

I take it you are refering to turbo,no boost at idle and low rpm's?? :dontknow:
That is what I like about the twinscrew, you can have boost all the time, don't have to wait for turbo/s to spool up :burnout:

 

[includemeout]

Why not 6.9 then??:dontknow:

No reason why not depending on type of application as Mr. Ape said

 

[TurboFreak]

I take it you are refering to turbo,no boost at idle and low rpm's?? :dontknow:
That is what I like about the twinscrew, you can have boost all the time, don't have to wait for turbo/s to spool up :burnout:

I was refering to normal around town driving. I love twin screw ie. Kenne Bell superchargers but they would also run in vacuum during part throttle around town driving. They go full boost at WOT and during part throttle they have a bypass valve so you don't run in boost all the time.

With the turbo you can make boost even in part throttle(depending on the size of the turbo) like when towing or going up a hill.

 

[JTS VENOM PERFORMANCE]

mine is around 8.5.1, no problems and can run 20lbs no problem

 

[1Fast400]

Mine was 8.7 I think.

 

[Wifey]

Personally, I wouldn't have a Diamond Piston if you gave them to me. A good friend was screwed out of his distributorship after paying Big bucks for it
This is what we use when Jerry builds an engine : http://www.venolia.com/main.html
http://www.venolia.com/catalog2005.pdf
The Choice of Champions

 

[Bone]

Good posts from everybody, THANKS.

 

[AWDisuzu]

I run 28 psi of boost with 10:1 pistons, and get 450 hp that way with 1.6 liters.


Mike

I ran 40 pounds of boost with 7 to 1 compression. It injected methanol at boost pressures over 10psi. I got 450 hp out 2.6 liters that way.

If you are going to o-ring it, do the block if possible, not the heads. Heads occasionally need to be surfaced and then you have to rework the o-ring grooves. Not ofter that you have to deck the block. Also easier to do the block if it's out of the vehicle.

 

[AWDisuzu]

your vacuum will be fine with 8.5:1 pistons. evo's and other turbo cars come with 8.8:1 from the factory, wrx's get 8.0:1, srt-4 motors are 8.1:1

all these cars can easilly run 20 psi+ with pump gas.

since the stock pistons are pretty low compression already, you might wanna go a little lower to be save if you're running high boost and pump gas.



Mike