Neither. What you have is a 2-ring piston designed to utilize the top and oil rings ONLY. Simply throw away your second ring and install as normal. NOTE: If you see a V-shaped groove below the top ring groove, that’s actually an Accumulator Groove and you can’t put a ring in it.
You don’t, CP-Carillo do. Attempting to alter the ring groove(s) of your CP piston could severely compromise the integrity of the part. The good news - if you have the correct rings and your piston is in good condition there should be no reason to alter the ring grooves.
Due to the wide variance of expansion rates typical of power adders (nitrous, turbos, etc.), air cooled versus water cooled, marine applications, etc., it can be difficult or impossible to give ring end gap recommendations that will be accurate across the board. Please be aware that the information provided is only a guideline and that any concerns should be addressed with your engine builder. All information is provided in inches of ring gap per inch of bore. EXAMPLE: A recommended ring gap of .0040 per inch on a motor with a 4.000 inch bore would yield a ring end gap of .016 inches as .0040 x 4.000 = .016
DOMESTIC AUTOMOTIVE: Normally Aspirated (no power adders) up to 600hp.
See figure 1. Assuming your top and second rings are of different thicknesses you can simply measure your rings and compare them to the groove dimensions. (SEE DRAWING) In instances where the top and second rings are of the same thickness the top ring will generally be of a shiny silver/copper color whereas the second ring will be of a dark grey or black coloring. Both rings will normally be marked with a dot(.), number, or letter that will aid in determining which side of the ring will face up toward the dome of the piston. If the rings don’t have a dot or letter to mark “up”, check the ID of the ring and they should be beveled. The inner beveled edge of the top ring will face up towards the cylinder head, and the inner beveled edge of the second ring will face down towards the crank. Additionally, some second rings will have a tapered hook groove on the OD. This hooked edge will face downward as its function is to scrape oil back down into the crank case. See figure below.
In the rare instance that you receive a ring with no designation, though it could mean the ring manufacturer has determined that it will work effectively either way, we recommend that you contact us for clarification. All of our oil rings for 4-stroke applications utilize a 3-piece design which consists of two thin oil rings separated by an expander (wavy) ring.
PLEASE NOTE: DO NOT ALTER YOUR EXPANDER. Oil ring gap specifications are for the top and bottom rails only! Oil ring expanders are designed to butt against each other and when installed along with the rails allow the ring to have the correct tension when seated in the cylinder.
You may also have a piston that requires the use of a rail support, that rail will have a dimple to prevent rotation.
Piston to wall reference chart for different bore types.
Your pistons should have come with a Spec Sheet that will have the recommended piston to cylinder wall clearance written on it, as well as where the piston should be measured. As always, you’ll want to consult with your engine builder to verify whether that is the correct clearance for your application. NOTE: You cannot accurately measure your piston to wall clearance by sliding a flat feeler gauge into a round hole next to an elliptical object (piston). EXAMPLE: Bore = 3.898 / Piston measurement at gauge point = 3.895 / Remaining piston to cylinder wall clearance = .0030
Yes all of CP-Carrillo parts all are forged. All CP-CARRILLO and BULLET Series pistons are forged for maximum strength and durability. We predominantly use 2618-T61 and some 4032. 4032 is a high silica (glass sand) content material that has good scuff resistance and allows tighter piston to wall clearances, however this is at the expense of strength. The greater the silica content, the more brittle the material, so 4032 does not lend itself well to high cyl. pressure applications such as those found in Super charged, Turbo charged, or Nitrous Oxide applications, with relatively light piston weights. 4032 has been used in some low boost applications in OEM and in some high boost diesel applications, but the pistons are much thicker and heavier than there 2618 counter parts, in an effort to keep them from failing. 4032 is also more expensive to machine, because it wears out tooling quicker. 2618-T61 on the other hand is a low silica content material, so it is more ductile/forgiving, so it is the material predominately used in high cylinder pressure applications. However, 2618 does require more cylinder to wall clearance because of the lack of silica and it reduces anti-scuffing qualities.
Billet parts originate as solid blocks of aluminum and are normally used in the rare instances when forgings cannot produce the optimum design.
Based upon a few different variables, cam / barrel shape is the curvature built into the piston to insure the correct amount and rate of expansion. As the motor approaches operating temperature, the cam insures that the aluminum piston and the aluminum/ steel/ cast iron cylinder all achieve optimum operating temperature / shape at the same time.
X-Style forgings are designed to minimize friction and reduce weight without compromising strength. With the use of bracing and ribs, the forging is configured by adjusting the weight balance between high and low stress areas. This design enables the use of a shorter pin for added strength and weight savings. See figure.
While CP-Carrillo custom parts are generally made in a 4 piece minimum order, shelf parts may be purchased as singles. We also stock replacement hardware for all of our shelf parts and most customs.
It depends on the level of customization. We can make custom pistons in as short as 3 days, but the engineering part can take longer. Custom piston turnaround can vary at different times of the year. As a baseline, you can generally assume approximately 5 weeks from the time we receive all of the pertinent information to the time the parts are ready to ship. We do offer an expedite service for rush jobs but you’ll want to contact your distributor/engine builder for further information. Please keep in mind that certain operations/features must be sent out for processing and CP/Carrillo cannot be held responsible in those circumstances.
CP-CARRILLO and BULLET include double Spiral locks with most off-the-shelf pistons. Most shelf pistons that are designed to use Spiral locks utilize 2 per side (4 per piston). For instance, an 8 cylinder motor would come with 32 Spiral Locks whereas a 4 cylinder would only come with 16. Wire locks only require one per side (2 per piston).
Both CP-CARRILLO and BULLET are high quality forged pistons, made from 2618-T61 Alloy. CP-Carrillo pistons are designed for high performance racing engines and are available for many "race specific" applications. Additionally, CP-Carrillo can be custom made in as little as 3 days to your specification. BULLET Series Pistons are large production runs on centralized manufacturing cells made from dedicated “Bullet” forgings. An application specific forging, as well as manufacturing in larger quantities reduces machining time. We pass the savings on to you, offering a more economically priced part, made on the same machines as a traditional CP!
In addition, the BULLET Series features a quality 1.2mm, 1.5mm, 3.0mm ring package and includes Chromoloy wrist pins with wirelocks. The 1.2mm carbon steel nitrided top ring is extremely durable and offers reduced friction over 1.5mm and 1/16" top rings. A 1.5mm Napier (hooked face) 2nd ring is used to improve oil control over conventional taper-faced rings.
No, OEM rings will not fit; you would have to get another CP ring set.
Lateral gas ports are channels drilled at the bottom of the top ring land that assist in ring seal. These channels allow combustion gasses to enter behind the top ring and improve ring seal by forcing the ring against the cylinder wall during combustion. Gas ports are most commonly used with back cut rings, which have less friction and better performance characteristics.
CP-CARRILLO stocks a complete line of piston rings for your shelf and custom piston orders. All BULLET Series and CP-CARRILLO Sport Compact shelf piston kits include rings. Most CP-CARRILLO Powersports piston kits include rings as well.
This value depends on the engine and piston part number. CP-CARRILLO and BULLET Pistons are designed with valve pocket depths to fit most popular camshafts. We strongly recommend checking your piston to valve clearance during assembly.
Most of the CP-Carrillo forgings will have a CP logo stamped in the bottom of the piston and the Bullet Series will have a Bullet shaped logo with a CP logo.
(Answered in question: “Piston to wall reference chart for different bore types.”) Each CP-CARRILLO and BULLET Series Piston kits include a piston spec sheet with a piston to wall clearance recommendation. Always measure CP-CARRILLO and BULLET Series Pistons at the recommended gauge point, usually .500" up from the bottom of the skirt or where otherwise indicated on the spec sheet. Subtract this dimension from your finished bore size to determine your piston-to-wall clearance.