Whats wrong with Wiseco pistons?

[wired247]

Wiseco's dont seem to be as loved in the outboard world as they are in the motorcycle and automotive world. Whats the problem with them?

[wanagofass]

Imo wiseco is simply the most common name in forged pistons, and the biggest problem with forged pistons is machinists not clearancing the cylinders enough for them. With that being said, I have heard that wisecos apply more ring tention to the cylinder under load or high rpm (not sure which) and cause more heat than competitors, I think Jay Smith was one of the people to tell me that, but he is a wizard dealer.

[Capt.Insane-o]

And the pins fall out of them. Pretty much literally. They are fine if you clearance your motor for them, have them top pinned and run your motor warm. Not so good for an inline that has operating temperature extremes. I've used them in inlines to success but would rather have the tighter piston to cylinder tolerances with a good cast piston.

[sinista]

I only ever had one failure with my 3cyl Johnson race engine, and it was the pin coming out of a Wiseco piston making a hell of a mess of the bore.. Ran genuine pistons for 3 seasons with no problems at all.

[rev.ronnie]

Wiseco builds the clearance neccissary for correct operation into their pistons. They are set up so that boring cylinders to standard oversizes will yield the correct clearance. Their standard size pistons however, in some cases, are slightly larger than OE to allow for cylinder honing to size. I have found this in some Harley applications, never on a plated bore though. If additional clearance is added to "give it some room for expansion" or whatever..it will actually be counterproductive. A loose piston runs hot, has poor ring seal and can beat itself up too. The skirt grooves on Wisecos help transfer heat from the piston to the liner. Adding .001" is 33% more clearance than they intended on a .003" clearance application...what do you think will happen?

On the last Mercury inline engine I installed them in, the running clearance was .002". This was built into the piston and I bored and honed it to a standard oversize. There was a good amount of "cam grind" built into the piston, so I guess that's how they get away with running them so tight. That motor was quiet as a mouse and runs beautiful.
I machined an HPDI block for Wisecos a couple weeks ago and they had .005" clearance built in. Again, I went to the exact oversize and again, it runs quiet and strong.

In any case, using Wisecos, I have noted the rings to have a thinner face and radial thickness. They have all seemed to me to have less tension and drag than a stock ring. This helps aid bore conformability, under load, when the cylinder may be distorted.

My opinion in consumer engines, is that most failures are attributed to people not warming the engines up properly before hammering down. A forged piston just does not have the tolerance to that like a cast piston.

I have been using Wiseco pistons for well over 30 years in everything from motorcycles, boat engines, 1500+ hp drag race and 9000+ rpm circle track engines, and snowmobiles and have not had any problems that can be attributed to the pistons design or materials. Sure, we have burned them down, torched them, scuffed them and everything else that we have done, along with every other kind of piston we have used, so I wouldn't throw them under a voodoo cloud because of it.

That said...I don't have any first hand experience using them in hi-po Mercury racing engines at this time. I may put a set in mine this winter....just for fun.

[rev.ronnie]

I only ever had one failure with my 3cyl Johnson race engine, and it was the pin coming out of a Wiseco piston making a hell of a mess of the bore.. Ran genuine pistons for 3 seasons with no problems at all.

I recently built a OMC V4 and it had TRW forged pistons from the factory..it suffered the same fate, it had lost a pin and more were loose. It had a million rounds on it though. I put cast pistons back in it. Have you seen factory forged pistons in the triples?

[sinista]

Nope, have only seen cast pistons. Have also run Sierra pistons in the twin cyl race motors, finger ported, lightened, carved up the windows etc and had no problems with them turning 9000rpm on small tunnels.

In defence of Wiseco's, a few motors I look after for a team here running an S3000 modified F1 motor, we had Wiseco pistons custom made, top pinned etc from the Wiseco factory, these have run really well making very good HP, after a strip down they look good. They do wear really fast tho, .007 after a few races. Making the piston go from .007 oval to 0.014.

[rev.ronnie]

I use the Sierra pistons too. I've had great results with them.

Are the Wisecos you are using actually wearing the skirts or are they collapsing and losing their barrel shape?

[sinista]

They don't show apparent signs of wear, the squirts still look good and the teflon coating is not worn off. They are losing the shape.

Out of the box they were exactly .007" oval, then after a few runs 0.014"

We didn't have any more pistons so assembled motor with them. The clearance was still .007"
We just got a season out of the motor with no issues from the Wiseco's and managed to win the F1 nationals. So they did their job and produced good H.P

We used to run Mahle's, but the pins kept on moving...

[sharpeye Mike]

The performance dealer in my end of the woods will no longer sale wiseco because of the pin issues.
He lost several motors to it.

[Eagle One]

I've seen this type of post several times and it usually always comes down to Wiseco's have problems but Mercury race pistons and Wizard pistons are the best. SIMPLY STATED PEOPLE, YOU NEED TO KNOW THAT BOTH MERCURY RACE PISTONS SINCE 1995 AND WIZARD PISTONS ARE ALL BUILT BY THE SAME MANUFACTUER..... WISECO.... When I buy a full box of 12 Mercury race motor pistons at one time they even come in a Wiseco box!!The stock engine Wisecos are side pinned as some of the early Mercury pistons were from Wiseco and just about every time a side pin piston fails and the pin comes out it is HEAT related and I've seen just about every brand there is and they'll all fall out due to heat. The top pinned models can't, They're bent over at the bottom to keep them from it. In 1998 and early 1999 THERE WAS A PROBLEM with Wisecos but it has long been corrected when Wiseco was purchased by a new owner in 1999. Simply read and follow the directions and usually you won't have a problem. Now I'm sure this will draw a lot of flack but this is just a fact. Not trying to start a controversy, just stating it like it is

[terry taylor]

:iagree: Flack isn.t fact,, and fact isn,t flack:leaving:. [ i,m a poet and didn,t know it]:cheers:

[JWTjr.]

Noah is right.

[rev.ronnie]

I didn't want to say that Wiseco was an OEM supplier, because I didn't figure anyone would believe me..

There are actually very few companies forging their own pistons. There are a lot that machine other people's parts though. I remember now that JE and Wiseco are owned by the same company or are the same company now.

[Eagle One]

Mercury Marine wasn't building all pistons of their own when I went to the plant during management school in 1976. Fact is the ORIGINAL 175 hp Black Max pistons were built by TRW. I've just seen this same post time after time about how lousy one brand is and how great another is and thought it might be the time to let some of these people know that often they are all from the same source. You'll find many of the parts from one engine brand and another are actually built by the same manufacturer. Yamaha uses ART cast pistons... So does Mercury in many applications.. Mahle once built Mercury's High Perf pistons but they also built some for both GM, Ford and Chrysler this just doesn't stop at pistons...Just because it say's Mercury on the box, doesn't mean they made it. Electrical parts, bearings and much more even though they come in a brand named box, many times are actually from the same manufacturing company. I did see such parts as rods, gears, crankshafts and other parts actually being built at the plant when I went there in late 1976 but over the years much of this has changed due to cost and ...you guessed it..OUTSOURCING.. I see people making comments about control boxes and if you look close many times most come from the same source just as water pump impellers, power trim assemblies and much more. So when you specify OEM parts you just might find many times they're exactly the same as the less expensive aftermarket brands. Hate to burst anybody's brand loyalty bubble but again facts are just facts.

[Capt.Insane-o]

That said...I don't have any first hand experience using them in hi-po Mercury racing engines at this time. I may put a set in mine this winter....just for fun.


.008 or you'll be sorry.

[sinista]

One thing I do like about wiseco pistons is they normaly make an oversize bigger than you can get in genuine. For instance my 60omc, the factory supply .030 max oversize, and Wiseco can go to 0.040. I think for old crossflow omc Wiseco go up to 0.064..

Great you the motor is already oversize and has a problem! I havent had any issues with wiseco pistons in standard motors.

[Dave Strong]

.008 or you'll be sorry.

:iagree: Have run them as tight as .006 in Nic sled motors but if you don't heat cycle them at least 6 -8 times they will stick every time. .008 is a good safe number for sure, think thats min as far as the Merc HP manuals go Mahle or Wiseco they don't care. Forged is forged, cast is cast.

Dave

[rev.ronnie]

.008 or you'll be sorry.

Good info. I want as much real world info as I can get before I install them. Don't they make a top pinned piston right from Wiseco?

[Capt.Insane-o]

Good info. I want as much real world info as I can get before I install them. Don't they make a top pinned piston right from Wiseco?

I have'nt bought a set of wiseco's in 5-6 years so I can't say for sure if they offer a top pinned. The last sets I bought for my 2.0 liters I sent to US1 for pinning, heated them up in an oven and cooled a dozen cycles and had them cryo'd, they have help up very well at 9800 rpm. I've been using the Wizards and Vertex, which for a cast piston are damn tough.

[TEXAS20225]

i have had the same results with the seizeco's as the Capt if you aint got .008 clearance you WILL be taking it apart soon real soon . ill take a set of Vertex any time over a free set of seizeco's im a small time MERCURY only rebuilder 25 or so a year i will never ever buy another set of them for any reason

[powerabout]

cast is not cast
OMC perma mold are very tough and do not expand like forged do.
Would love to get custom slugs made with the new material BRP use in the etecs

[Eagle One]

By the way. I had a ring pin failure (Only real part problem I recall every having with Wiseco after the change of ownership and the redesign of the piston) back in 2007 with an old piston made in 1998 that was new that had been on the shelf for years and Wiseco not only replaced the piston but paid parts and labor for the entire rebuild. Not pushing Wiseco's , just stating my experience.

[rock]

While Wiseco may make many different pistons for many different retailers that certainly doesn't make em the same. I am sure one manufacturer will have one set of specs and another manufacturer will have a totally different spec. This applies to all sorts of items. The company I work with manufactures fire extinguishers and they are sold under many different brand names and while they are all made in the same building there is a big difference from one to the other. I agree with the Capt. on the clearance. I have not used Wisecos in years but think I remember them requiring an extra .002 over the factory cleearance and they state that somewhere either one their web site or maybe even on the box they came in. The last time I tried to use them was during their bad pin days.
Rock

[Jay Smith]

.008" is what I set any forged piston clearance up in steel bore thats std. and I add 1/2 a thou. every step up in the over bore from std.

AND I have found the hard way forged on steel only will live on a blend oil NO 100% SYN. that was also an expensive lesson..

Jay

[JWS]

any problems using wiseco's on an OMC 3.o looper rebuild? Need pistons NOW