JE Piston 13.5 to one in 450f


58 replies to this topic
  • 642MX

Posted December 30, 2008 - 06:58 AM

#21

Gray- You recommend a CP over a Wiseco?... Not questioning CP's piston quality, but did I miss something on the Wisecos?

  • BASSic

Posted December 30, 2008 - 07:06 AM

#22

If a higher compression piston is an easy way to get more low end power, then why don't the manufacturers use higher compression pistons? If something is better and doesn't have any negative effects, why wouldn't the manufacturer use it in the first place?

  • grayracer513

Posted December 30, 2008 - 08:29 AM

#23

Gray- You recommend a CP over a Wiseco?... Not questioning CP's piston quality, but did I miss something on the Wisecos?

Wiseco's tend to be noisy, which indicates a less than correct fit. I can't remember the the details precisely, but there has been some trouble with the Wiseco wrist pins, as well.

As I recall, Ron Hamp also favors CP.

If a higher compression piston is an easy way to get more low end power, then why don't the manufacturers use higher compression pistons? If something is better and doesn't have any negative effects, why wouldn't the manufacturer use it in the first place?

Who said it has no down side? In the first place, anything that increases power increases the stress on the engine while that power is being produced. Secondly, 13.5:1 is beyond the point where the engine can be reliably run on pump premium. In most cases, pump gas works, but in some situations it doesn't, and the factory doesn't want to be on the hook for that.

Like everyone else, Yamaha has to produce a product that they can stand behind as being reasonably reliable, in spite of the fact that there is nothing reasonable about any expectation of reliability with the way most of these get used. In fact, the YZ450 itself would have been considered impossible as little as 15 years ago. High compression pistons are a fairly safe, fairly inexpensive way to add about 1-2 hp and a boost in low-mid range power, but if you want the most possible reliability, stay with Yamaha OEM.

  • CBDaddy

Posted December 30, 2008 - 01:34 PM

#24

Wiseco's tend to be noisy, which indicates a less than correct fit.

As I recall, Ron Hamp also favors CP.


What is this based on? Wiseco sure sells a LOT of pistons (more than all the other powersports aftermarket manufacturers combined) to be making pistons that have "less than the correct fit". Come on man. Let's speak in fact and not spread "less than accurate" information. I'm not saying you're not entitled to your opinion, but comments about tendencies can be misconstrued by people. Wiseco pistons are amoung the best in quality and performance. There are other engine builders out there besides Hamp.

  • 642MX

Posted December 30, 2008 - 04:16 PM

#25

I'll admit Wiseco's are noisey, but I thought all forged pistons where a little loose compared to the stock cast units.

Who's Ron Hamp?....

  • CBDaddy

Posted December 30, 2008 - 04:44 PM

#26

All pistons are designed to run at the same (minimal clearance) at running temperature. Different alloys have different CTE's, so they expand different amounts. This means pistons made in different alloys (and mostly split across cast/forged lines) have different clearances at the installed (68F) temperature. But they are all designed to run at an optimized minimal clearance once up to temperature. Shapes have a lot to do with noise, wear, and skirt contact, which is another reason I feel Wiseco is among the best in quality and performance. Wiseco has the ability to program shapes on their pistons that other piston companies cannot. Cam and barrel are critical to the shape, and being able to program the lathes to machine complex skirt shapes is not something every piston company is capable of.

  • 642MX

Posted December 30, 2008 - 04:49 PM

#27

All pistons are designed to run at the same (minimal clearance) at running temperature. Different alloys have different CTE's, so they expand different amounts. This means pistons made in different alloys (and mostly split across cast/forged lines) have different clearances at the installed (68F) temperature. But they are all designed to run at an optimized minimal clearance once up to temperature. Shapes have a lot to do with noise, wear, and skirt contact, which is another reason I feel Wiseco is among the best in quality and performance. Wiseco has the ability to program shapes on their pistons that other piston companies cannot. Cam and barrel are critical to the shape, and being able to program the lathes to machine complex skirt shapes is not something every piston company is capable of.


Sounds like your well educated about them. I've used Wiseco's for years and always liked them. They are priced right and easy to get. :busted:

  • CBDaddy

Posted December 30, 2008 - 05:14 PM

#28

Sounds like your well educated about them. I've used Wiseco's for years and always liked them. They are priced right and easy to get. :busted:


Thanks man. I'm not trying to start a fight or sound like a commercial. I'll be the first one to say "to each his own". I'm just trying to help pass along good information in a (hopefully) objective way. :moon:

  • gtxkid

Posted December 30, 2008 - 06:55 PM

#29

Kieth black is the one who came out with what is called sivolite piston.
It is a half cast and half forged type piston.

  • 642MX

Posted December 30, 2008 - 07:13 PM

#30

Thanks man. I'm not trying to start a fight or sound like a commercial. I'll be the first one to say "to each his own". I'm just trying to help pass along good information in a (hopefully) objective way. :busted:


You don't sound like a commercial...lol. I enjoy reading and learning like others on here. Thanks for sharing your knowledge. :moon:

  • 642MX

Posted December 30, 2008 - 07:14 PM

#31

Kieth black is the one who came out with what is called sivolite piston.
It is a half cast and half forged type piston.


Interesting, I've heard of Kieth Black before. Isn't he famous for making high powered hemi's?....

  • grayracer513

Posted December 30, 2008 - 09:41 PM

#32

Let's speak in fact and not spread "less than accurate" information.

Good idea. Let's start with this statement:

Wiseco has the ability to program shapes on their pistons that other piston companies cannot.

By "other companies", let us stipulate that you do not mean CP, or JE either, for that matter. Both these companies use extremely sophisticated CNC equipment to model and construct their products. CP also supplies racing pistons to F-1 teams, F3000, CART, and others, and counts Ferrari and Porsche among their customers.

Since you brought up the point regarding CTE (which is coefficient of thermal expansion), let's discuss that. Aluminum expands much more than iron and steel when heated. Early on, this lead to the need to build in additional clearance when cold fitting in order that operating clearance would be correct. Metallurgy addressed this by adding silicon to the alloy to reduce the CTE of the piston so as to reduce the requirement for such loose fitting. There was a snag, however, that directly related to forging aluminum pistons.

The alloy with the added silicon was too hard to forge by conventional cold strike methods, so forged pistons usually featured less of the additive than cast pistons did, and needed to be fit looser because of it. An example would be one of the first racing engines I did for money, a Chevrolet 302 built up from a 283, and using Jahns forged pistons fit at .012". By contrast, the 383" stroker that was the last performance car engine I built used a set of TRW forgings and fit up at .002".

There are two questions raised here. The first is, "what changed?" What is so different about the old Jahns and the newer TRW pistons that would allow so much less clearance. The answer is both metallurgy and production technique. Other means besides the use of silicon for creating low expansion alloys were found that left the aluminum more malleable. Also, pressure casting, hydro-forming, high temperature forging, and forge while cooling technologies were introduced. Together, these collectively allowed the forging of low expansion alloys. The processes are more expensive, and involve more complex tooling, also.

The second might be, "why is it important?" Why has so much energy gone into finding a way to produce low expansion forged pistons if all you have to do is compensate for the CTE delta between piston and barrel with extra clearance? Because, while it is possible to find the clearance needed to have the piston be the right size at operating temperature, it is not possible to get the piston to obediently stop expanding at a desired target temp. If the piston fits right at full temperature, what then can we expect to happen if it runs 10% hotter than normal? Uh-huh, seizure.

Additionally, the conditions that cause the noise generated by piston slap contribute to accelerated wear.

Since there is an alternative to forged pistons that rattle and slap at low temperatures, why would one build one any other way? Companies decide what level of technology to build into their products based on several criteria, and that's where I'm going to leave that. Using a higher CTE alloy and fitting it loose is old school (and that comes from a guy who is usually proud of being an old schooler). IMO, it doesn't fit in with the entire concept of a YZF at all. Shape and configuration of the skirt absolutely is important, you're right. But then why are CP's so much quieter?

As you say, everyone is entitled to have their own opinion. I would use a 13.5:1 CP piston. If the choice were limited to Wiseco, I would stay with stock. But that's just me.

There are other engine builders out there besides Hamp.

Thousands of them, I imagine. How many of them can build a 449cc Yamaha that puts out over 60 hp? How many of them have had a bike on the Grand National podium almost every year in the last 8 or 10? There are lots of everything. Only a few are among the best there is.

  • grayracer513

Posted December 30, 2008 - 09:43 PM

#33

Interesting, I've heard of Kieth Black before. Isn't he famous for making high powered hemi's?....

Only if you think 9000 is a lot of power to get out of 600-some cubic inches. Kieth Black builds top fuel/funny car engines.

  • Yamy

Posted December 31, 2008 - 05:44 AM

#34

Only if you think 9000 is a lot of power to get out of 600-some cubic inches. Kieth Black builds top fuel/funny car engines.


Those engines are simply amazing, basically a controled explosion, If you ever get a chance to see these engines run, do it

Bring ear plugs

  • CBDaddy

Posted December 31, 2008 - 05:51 AM

#35

I will not exclude JE and CP from my comment regarding Wiseco's advantage over other piston companies to program and machine more sophisticated skirt shapes. We will have to agree to disagree. You have your sources for information, and I have mine. Our fellow TT'rs will have to form their own opinion on this one.

I acknowledge your comparison about a Jahn's piston going in at .012" to run compared to your TRW running at .002 installation clearance. I go back to the difference being the alloy and piston design. I don't think it has anything to do with the forming/casting/forging process, with all other things being equal between the two. In all my years in the aluminum forging industry, I've never seen a forging process alter the CTE of a material, and I would expect the same is true in casting and forming processes. The running clearance required for a specific application is based on many factors - bore size, running temp, fuel, coatings, forging/casting design, wall section thickness, and of course alloy (but independent of manufacturing process).

Last point - you make an illustration about if a piston can expand so much to take up cold running clearance, than it would seize if the engine temp increases 10%. Rough math on this, if a piston is running at operation temperature with a clearance of .001", and temps increase 10%, the piston would expand .0001". I would really question if decreasing the clearance by .0001" (1/5th the tolerance on a skirt diameter mind you) that it would seize. Besides, if your engine temp is swinging enough that the temperature is causing the seizure, there are bigger problems going on.

  • grayracer513

Posted December 31, 2008 - 09:36 AM

#36

I will not exclude JE and CP from my comment regarding Wiseco's advantage over other piston companies to program and machine more sophisticated skirt shapes.

Suit yourself:

http://www.cppistons.com/tech/
http://www.cppistons.com/about_us/
http://www.jepistons.com/dept/company/

Neither of these companies are behind any curve. Wiseco has no access to any equipment not available, or in fact used by JE or CP, or any of a number of other top tier piston manufacturers. To contend otherwise is just silly.

I acknowledge your comparison about a Jahn's piston going in at .012" to run compared to your TRW running at .002 installation clearance. I go back to the difference being the alloy and piston design. I don't think it has anything to do with the forming/casting/forging process, with all other things being equal between the two. In all my years in the aluminum forging industry, I've never seen a forging process alter the CTE of a material, ...

This is not at all what I said. My point was that advances in metallurgy have introduced more forgeable low CTE alloys, and that advances in the process have resulted in an improved ability to forge low CTE alloys. At no point did I suggest that any change in the forging process could change the CTE of the alloy itself. Such an assertion would be ludicrous on its face.

  • krzyaszwhiteboy

Posted December 31, 2008 - 10:42 AM

#37

Good idea. Let's start with this statement:
By "other companies", let us stipulate that you do not mean CP, or JE either, for that matter. Both these companies use extremely sophisticated CNC equipment to model and construct their products.

Yes this is true that they use CNC equipment to model their products in the construction process it is only used to machine ring grooves and oil passages for the most part. The rest of the construction (which makes the piston really) is handled by the forge shop. In the case of JE the pistons are forged by PFP in Montebello CA. The forge shop has the forging dies and drop cutters manufactured for them by RONDEE Die Inc. RONDEE uses very little CNC and almost 95% EDM to mfg. the dies. The combination of PFP and RONDEE make the forgings for JE as well as numerous high end customs like Arias, Ross, Venolia (sp), and Howard. Only two comapnies actualy do in house foirging and that is TRW and KB. I can not say where CP has there forgings made for sure but I can find out if anyone is curious. They may even also be done by PFP, but I can guarantee that they do not make there own forgings. In this country there are very few forg shops left and even fewer die shops.

CP also supplies racing pistons to F-1 teams, F3000, CART, and others, and counts Ferrari and Porsche among their customers.

Since you brought up the point regarding CTE (which is coefficient of thermal expansion), let's discuss that. Aluminum expands much more than iron and steel when heated. Early on, this lead to the need to build in additional clearance when cold fitting in order that operating clearance would be correct. Metallurgy addressed this by adding silicon to the alloy to reduce the CTE of the piston so as to reduce the requirement for such loose fitting. There was a snag, however, that directly related to forging aluminum pistons.

The alloy with the added silicon was too hard to forge by conventional cold strike methods, so forged pistons usually featured less of the additive than cast pistons did, and needed to be fit looser because of it. An example would be one of the first racing engines I did for money, a Chevrolet 302 built up from a 283, and using Jahns forged pistons fit at .012". By contrast, the 383" stroker that was the last performance car engine I built used a set of TRW forgings and fit up at .002".

There are two questions raised here. The first is, "what changed?" What is so different about the old Jahns and the newer TRW pistons that would allow so much less clearance. The answer is both metallurgy and production technique. Other means besides the use of silicon for creating low expansion alloys were found that left the aluminum more malleable. Also, pressure casting, hydro-forming, high temperature forging, and forge while cooling technologies were introduced. Together, these collectively allowed the forging of low expansion alloys. The processes are more expensive, and involve more complex tooling, also.

The second might be, "why is it important?" Why has so much energy gone into finding a way to produce low expansion forged pistons if all you have to do is compensate for the CTE delta between piston and barrel with extra clearance? Because, while it is possible to find the clearance needed to have the piston be the right size at operating temperature, it is not possible to get the piston to obediently stop expanding at a desired target temp. If the piston fits right at full temperature, what then can we expect to happen if it runs 10% hotter than normal? Uh-huh, seizure.

Additionally, the conditions that cause the noise generated by piston slap contribute to accelerated wear.

Since there is an alternative to forged pistons that rattle and slap at low temperatures, why would one build one any other way? Companies decide what level of technology to build into their products based on several criteria, and that's where I'm going to leave that. Using a higher CTE alloy and fitting it loose is old school (and that comes from a guy who is usually proud of being an old schooler). IMO, it doesn't fit in with the entire concept of a YZF at all. Shape and configuration of the skirt absolutely is important, you're right. But then why are CP's so much quieter?

As you say, everyone is entitled to have their own opinion. I would use a 13.5:1 CP piston. If the choice were limited to Wiseco, I would stay with stock. But that's just me.

I would have to agree Wiseco's forgings are done in a very unconventional way that reduces quality but increases profitability. They are good but from a forging die sinkers point of view they are no where near the best.



Sorry for interjecting here, but I always feel the need to clarify these types of things being a 3rd generation forging die sinker.

  • Yamy

Posted December 31, 2008 - 11:26 AM

#38

Neither of these companies are behind any curve. Wiseco has no access to any equipment not available, or in fact used by JE or CP, or any of a number of other top tier piston manufacturers. To contend otherwise is just silly.


I don't think CBDaddy said that the machines are different :busted:

The difference lies in how these are utilized :moon:

There is a profound difference

Everyone have a safe and happy new year! :p

  • stlavsa

Posted December 31, 2008 - 11:52 AM

#39

Gray- You recommend a CP over a Wiseco?... Not questioning CP's piston quality, but did I miss something on the Wisecos?


I am not sure about mx pistons, but I know in the car world, CP is regarded as one of the best.

For example, when we build a race motor, you normally send the pistons(be it JE, Wiseco, etc) out with the block, and each cylinder is fitted to a certain piston (size variances).

with CP pistons, its a safe bet to pick your bore size and have the cylinders bored and honed, and when you pistons come in, they will all be identical and an exact fit.


edit: In short, they have the tightest tolerances possible

  • crandy500

Posted December 31, 2008 - 12:01 PM

#40

Keith Black passed away a few years ago I believe. Maybe I am wrong(hope so). Brilliant guy..R





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