CP-Carillo forged pistons - Polaris ATV Forum
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post #1 of 7 (permalink) Old 09-17-2019, 11:02 AM Thread Starter
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CP-Carillo forged pistons

Anybody used them?
Pros and cons?
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post #2 of 7 (permalink) Old 09-17-2019, 01:49 PM
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I have used them as well as Namura, Wiseco, Vertex, Pro-X, Pro Circuit, Athena, Art, Robin, Wossner, J&E, Ross, TRW, Arias, Diamond, Gibtec, Race Tec, Venolia, Mahle, Ross and BRC.

Some I have not used is Sealed Power, Keith Black, Federal Mogul, Probe, Cosworth, SRP and Omega.

Some for automotive engines and others for motorcycles and ATV's. All in all, they all do the same thing - plug a hole. The hype about which is best all comes down to max performance characteristics at extreme RPM and HEAT.

The higher the performance demand the higher the cost, but just putting in a Hi Pref piston will not make the engine faster, the piston simply compliments the engine design to extract the performance demanded of it.

Piston manufacturers sell hype to the public to profit from their design derived from extracting horse power from race engines. The piston is just one ingredient of the recipe. Of course, each manufacturer wants the public to believe just using their piston will make their engine more powerful, faster and perhaps longer lasting. Carillo was created when disgruntled J&E employees decided to compete against their former employer. However, the Dover Group owns SRP, Wiseco, J&E, Carillo rods and Crenlo (manufacturer of parts for John Deere tractor cabs and electrical enclosures).

Pros - they work
Cons - the higher the performance they are designed for, the higher the cost

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post #3 of 7 (permalink) Old 09-17-2019, 05:13 PM Thread Starter
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So you saying they're all hype then?
I'm not trying to build a hot rod or anything like that latebird. If I were, I'd start with a better platform to work with than a tired old Sportsman 800 lol.
I'm just looking to put the old Gorilla back in good, solid and dependable shape with enough balls and longevity to serve as my backup ride in case the new 1000 were to ever go down at an inconvenient time.
I've used Wiesco, Vertex, Namura and OEM's of just about every flavor but never had any dealings with Corilla.
I wasn't interested in them thinking they'd make any significant improvement in performance. I'm looking for good, quality pistons that are dimensionally true and solidly made using good materials.
I ran up on a set of Corillas for less than OEM's or Wiesco or Vertex and thought I might give them a try if they are any good. I've also seen arguments for and against forged pistons vs. cast in these engines and wondered if anyone one on here had any real-world experience with them.
Thanks

Last edited by polman500; 09-17-2019 at 06:51 PM.
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post #4 of 7 (permalink) Old 09-17-2019, 09:01 PM
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Forged pistons are stronger, denser, lighter and more uniform than cast however they also cost more than cast. Forged pistons withstand higher temperatures and higher RPM's, but serve no advantage over cast pistons in an engine not intentionally operated at the upper end of it's design limits. Cast pistons perform flawlessly for hundreds of thousands of miles in millions of cars and motorcycles, but take the family sedan to the drag strip and hold the engine at 8000 rpm waiting for the green light and it may fail before it leaves the line. Take the same engine and build it for the purpose and it may make hundreds of 1/4 mile runs using the original cast pistons, but if you want to attain 10,000 RPM and double the HP of the engine, the pistons will have to be stronger, lighter and deal with higher temperatures.

If the only change to the engine at the time of manufacture was the installation of exotic pistons and rings and the vehicle was sold to an unknowing consumer, the starting, fuel economy and sound of it and an identical standard engine would be undetectable without taking it apart to find out which one has the exotic pistons.

Just like 10 standard identical engines tuned identically will produce 1 faster and more powerful than the rest, 1 slower and doggier than the rest, 1 that fails prematurely and one that can't be broken. The rest are just 'in between' and of the 4 'most' engines 1 may possess multiple qualities making it the outstanding unit and another man possess multiple shortfall qualities. In other words, the fastest most powerful engine may be the one that fails prematurely.

In a top fuel drag racer, the pistons and rings may be replaced every 1/4 mile and in the family sedan 2 to 3 hundred thousand miles is possible with cast pistons and std rings.

My CRF has a two ring piston - one compression ring and one 3 piece oil ring - the compression ring is slightly thicker than an oil rail of a utility piston and the oil rails are about 1/2 as thick as an oil rail of a std oil ring. The recommended replacement interval is every 30 hours, but the engine runs best when kept spinning about 8 to 10 thousand RPM and red lines about 12 thousand RPM.

If you have the opportunity to get high performance pistons for less than a cast piston, it becomes an economic thing. Both will work, both will provide satisfactory performance, both will provide satisfactory economy and both will provide satisfactory engine life and if the forged piston is higher compression, you will gain some low end at the cost of high end and sacrifice longevity to gain a slight power increase.

I have built low speed long life utility engines and short lived high performance engines. Piston selection usually comes down to availability vs demand. If the engine is for a sport quad that the owner purports to ice race, I opt for forged, but if the engine is for a utility quad that the owner likes to use to go on weekend excursions into the back country, I opt for cast. Under utility conditions, the cast piston with heavy rings may outlast the 'racing' piston which may be easily damaged if subjected to high load (lugging) and low speed while the cast piston may quickly fail when subjected to long periods of high speeds.

The most interesting thing I learned about pistons is that when they break while racing it has nothing to do with how many times it has to come to a complete stop at the top and bottom of each stroke. The slowing to a stop is linear and controlled, but the acceleration from a dead stop to half way through the stroke can tear the piston apart. Forged pistons will withstand a higher acceleration rate than cast pistons.

Do you need performance or reliability? Cost vs availability. Make your choice - the engine will run with either one.

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post #5 of 7 (permalink) Old 09-19-2019, 02:22 PM Thread Starter
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latebird, how do you feel about dinosaur oil vs. synthetic for break in on a fresh rebuild?
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post #6 of 7 (permalink) Old 09-19-2019, 03:28 PM
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No such thing as dinosaur oil - it's mineral oil and synthetic oil starts with the same base stock as mineral oil - the difference is how it's made into lubricating oil.

I have broken engines in using both and either is fine, the biggest difference is the engine. If it's a cast iron or steel sleeve cylinder, it breaks in best on mineral oil and after break-in can be switched to synthetic. If you break-in a liner cylinder with synthetic oil it will take up to 5 times as long for proper break-in. Plated cylinders will break-in in about the same period of time on either mineral or synthetic oil and plated cylinders do not need honed when installing new rings. the only thing a plated cylinder needs when freshening the top end is a deglazing with a Scotch Brite pad.

I built up a 289 V8 in my 65 Mustang - bored .050 over, 12:1 TRW race pistons and double moly rings (double moly means both the first and second ring were chrome faced) - I drove the car over 5000 miles with a first generation straight weight 30w synthetic oil (I believe it was Penzoil) and the rings had not seated - I was at a Nascar race (before it was Nascar) talking to the mechanic for FireBall Roberts (Richard Petty didn't have a drivers license yet) about engines and related the story about my engine. I commented I had made a mistake putting in the double moly rings and was going to have to tear the motor down and install conventional rings. He asked me what kind of oil I was using and I told him. He knocked my socks off and said the oil I was using was too slick for the materials in the engine. He advised me to switch to a cheaper oil like Quaker State and said it wouldn't make any difference if it was multi-grade or straight weight. He told me to run it till the rings seated and then switch back to the synthetic. I put straight 30w Quaker State 'petroleum' oil in the motor and within a 1000 miles the rings seated and oil consumption was nearly zero - I could run 2500 miles between oil changes and not notice the oil level drop on the dipstick. I ran QS for 5000 miles and switched back to synthetic. The synthetic gave the engine about 10 more peak HP on the dyno.

The lesson was both oils did a sufficient job lubricating the parts and wear was decreased using the synthetic. In retrospect, the rings may have seated in the subsequent 5000 miles, but in my mind the cheaper oil enhanced the break-in. I drove that 65 Mustang 2+2 Fastback 280,000 miles total - the first 100,000 was between high school and college graduation - I finally got rid of it in 1978 when I got a new Ford Fairmont with a 302 (family car). Between the Mustang and the Fairmont I had a Ford Tempo and a 74 Mustang 2 Mach 1 - the Tempo was the only car I owned with a 4 cylinder engine and the Mustang 2 was the only car with a V6 - everything else has had a V8 except the hand-me-down 65 Ford Econoline van with a 144 cubic inch in line 6 which was never in my name - it was like a no ending loaner.

So, I break my CRF in on synthetic and it uses 200 cc of oil every 2 hour race whether it's on new piston and rings or 25 hour piston and rings - the piston and rings get replaced every 30 hours - I have a spare cylinder and whenever I rebuild the top end if I can feel a ring ridge I swap cylinders and send the old one out for re-plating. The CRF is a 2004 and still performs like new, but I am anal about maintenance on it. My 97 Ford F150 with 200,000 miles gets the cheapest 5w20 mineral oil I can put in it. I'm afraid if I put synthetic in, it will start using oil or clean some ancient crud off something and cause a bearing to go out. It's a throw away vehicle so I will drive it till it dies doing as little to it as possible. I got another newer truck that I use on Sunday.

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post #7 of 7 (permalink) Old 09-19-2019, 06:33 PM Thread Starter
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"No such thing as dinosaur oil"
LOL... Now back in the day latebird, I ain't sayin how long ago that was, they used to tell us all that oil came from liquified dinosaurs
When I started going out west pretty often a few years ago I was surprised to see that they still have a few Sinclair stations around with that big green dinosaur out there... So I'm a believer!
I still call it dino oil to this day lol.

I just wanted to get your take on it and you pretty much confirmed the conclusions I'd come to over the years.
Thanks
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