Pro-x vs Wiseco??

[1promodfan]

Just wondering which one is "supposed" to be better?? And why? Just trying to get a few opinions on these. I'm in the process of a re-build.

[leager-n-ky]

I have always had good luck with Wiseco, The last R I bought had a Pro-X in it and the guy swore by it, So when I rebuilt it I went back to the pro-x, and it split from the top of the wrist pin on one side up and over the top, and down to the wrist pin on the other side. They told me I must have broke the motor in wrong, and there was nothing they could do. I'm sticking with Wiseco now.

[Master LTR450]

you cant go wrong with either really.

[86 Quad R]

i 2nd that.

for the regular rider/performance i say pro-X but for a racer/higher performance, High compression. i say wiseco. i've had extremely good luck with either and i punish the hell out of an engine.

i will say this tho....... a wiseco is much more forgiving when piston to wall clearances get excessive. :cool:

[86' trx rider]

I have run both of them also. I never had a problem with ether one but, i feel that my top end last longer with the wiseco. The guy I used to buy my parts from swore by wiseco. The difference between the prox and wiseco is the prox are cast and the wiseco are forged. Witch is suposed to make the piston solid with no air gaps in the aluminum, but the prox may have unseen air pockets from the casting process.

[All250R]

Originally posted by 86 Quad R
i 2nd that.

for the regular rider/performance i say pro-X but for a racer/higher performance, High compression. i say wiseco. i've had extremely good luck with either and i punish the hell out of an engine.

i will say this tho....... a wiseco is much more forgiving when piston to wall clearances get excessive. :cool:
For my 2cents I think this sounds right. People though like to ask questions like what is "best". This question is really most valid when comparing like products, like two cast piston manufacturers. Most of the stuff we buy though is like asking what is better, an apple of an orange? The answer is specific to your application. When you design something you design it for an intended use and you weigh and decide on the trade-offs. When you want something you usually have to give something else. In the physical world there's rarely a case you get something for nothing.

The question is what are the pros and cons of a cast piston vs a forged piston. In the old days Wiseco's pistons were prone to manufacturing irregularities that caused their products to have more variance. It was more important to hone specifically to that particular piston. For reasons I'd have to refresh myself on what specifically about these older pistons caused them to stick as often as they did, but they carried more probability of being stuck than they do today. One thing I've noticed about them is they seem to tend to collapse more than the cast pistons. I find a lot with Wiseco's that the cyl:bore clearance is always at the max or more. But forged pistons are stronger and can take abuse longer than cast pistons. My unconfirmed suspicion is that a wiseco can run longer than a cast but will beat up your bore more if you take advantage of a longer repalcement interval. They also tend to expand faster under the same amount of heat than cast pistons. In bores that have an iron liner that means breakin and clearance setup are more critical. If you're the kind of guy that can't warm up your engine, you need a cast piston setup nice and loose. Wisecos aren't for you. Forged aluminum is also heavier than cast. However, because the material is stronger, wiseco will machine a lot more mass from the piston than cast manufacturers can. Within sizes I've noticed if I remember correctly that sometimes the cast part will be heavier and sometimes the forged part will be heavier. It depends on the version of the piston the manufacturer is making at the time. I don't think however for most people that this variance in weight matters too much.

Cast pistons are what manufacturers like Honda use from the factory. They're easy to setup at a tighter tolerance than forged with less chance the customer is going to stick their new engine. Honda will tell you to change your piston pretty frequently though especially if the engine is used under racing conditions.

Like 86 Quad said, I like cast pistons for more run of the mill builds. I feel they're easier on the bore if they stay tighter longer and with regular maintenance will provide good, reliable service. If I'm building a high compression motor or running a lot of RPM I'll be inclined to use a forged piston.

[machwon]

Wiseco is the best choice for the best performance. Otherwise they both provide a reliable everyday build.

[rustyATV]

I have a friend who helped me set up a motor and was harping on how I should stay away from Wiseco until I told him I'd been running them for years without issue.

I've run both pistons and now use the lighter Wiseco's, but I miss getting that new small end bearing that came with the Pro-X. When I switched I was, like "Wait. They forgot the bearing!"

[wilkin250r]

This issue always seems to pop up every few months. If you search, you'll find lots of threads on the topic (with many of my own replies in them).

Here's the difference, and YOU can decide for yourself which is best.

Pistons aren't really one solid mass, they're made of of many small particles pressed together (envision a sand castle). It's the different grain structure that makes them different.

When aluminum is forged, pressure is applied as it cools, and it is pounded into shape. This spreads out the individual grains in the direction across the dome, creating many flat layers almost like fiber reinforcing for fiberglass. It makes for a very strong piston, which is good. However, it also increases thermal expansion outwards against the cylinder walls, which is a bad thing.

With cast aluminum, all the little particles are round, so they expand the same in all directions.

Ok, so now we know the difference, what does it mean?

Forged pistons expand faster due to heat. This means that seizures are more likely, and require a larger piston/bore clearance to allow for extra expansion. But the piston itself is stronger, and lasts longer.

Cast pistons aren't quite as strong, but they can be set up with tighter tolerances, and less expansion means less risk of seizures.

[C-LEIGH RACING]

Reguardless of which brand of piston you decide to use, neither one is no better than the other & is totaly dependant on the person running the boring bar, the honing machine & that bore gauge with new piston in hand.

Trusting a borer to do a quality job & not checking behind them when finished, can be one of the biggest mistakes you'll make when building an engine reguardless of the borer.

My bore man only bores 2 stroke cylinders, loves what hes doing & 80% of his bore jobs are 2 stroke air craft engines with no room for error.
Neil

[machwon]

I disagree, Wiseco's totally rule when it comes to performance. Here's a tip, they don't call them "pro-lites" for nothing. Put them on a scale you'll notice a huge difference. 7.5% on a stoker blaster build I did last week. Some pistons are 10% heavier depending on the model. Too many R people i've done cylinders for tried pro-x and threw them away after one ride, they could tell the difference that much. Even more so if you're running a Pro-x cylinder and using other than a Wiseco piston, your asking for trouble. Lately that new brand has been failing in a matter of hours almost minutes.

Bore tolerances are important but they don't matter with a junk piston. For performance you need to watch your piston quality and weight as well.

[C-LEIGH RACING]

What new brand you refering to Bob.

Lite, does make a difference, no dought.

Oh, you Blaster builds pulling 16 tooth front sprockets, 200cc legal.
Neil

[machwon]

Neil, I sent you a pm on the piston brand.

[woodsracer144]

i have a pro x top end for sale if you want mor info let me know its on ebay right now...