Confirmed piston replacement solution for the 340s engine

[WinnipegStPaul9]

Hey!! Watch the "old" stuff Lindner. After all, I'm "vintage", not "old".

DA

[HoosierDeereMan]

With the limited demand for 340/s pistons we are going to have to pay alot more to get them done with any piston manufacturer. Yes, $200 + for a piston seems like a lot to pay. Especially if you have a running sled and would only buy these as a back up plan! On the flip side it boils down to how bad do want the sled to run and enjoy it vs. sitting there in pieces collecting dust and taking up space? Everyone's situation is different and with the limited amount of 340/s sleds out there it puts us in a tough position to get this done as a group to take advantage of reduced cost with more volume. This results in the endless search to find a existing piston that requires slight modification to work in our application or in Brian's case buying the only know set of nos pistons left on earth. We go through every year with RS engines used in the 295s and 340s. 1,000 piston minimum orders with Wiseco and Art are going to cut it here. It will have to be a custom piston maker who is willing to work with us as a small group and deal in small volumes. The 295/s and 340/s pistons are just different enough that we can't do a viable option for both. Then we also get into the deal of what sizes do we need? I may be wrong here but I'm not aware of any overbore sizes available for these engines as they were race engines. So I would assume everyone is dealing with std bores, With the guys looking for pistons I think an overbore size is our best option because it would cover everyone's needs with worn bores. Most of these guys can do these in .5mm increments. So in the 340/s case we could do 60.5mm or 61mm as a overbore.

Just throwing this out there but I left the deal with Wossner in limbo. I can pick this up and persue again if there is interest.

Troy

[lwb140]

i would be intersted in some i dont know how many some is but the cheaper they are the more id buy . i would replace the ones in my sled with the machined wisecos in it for sure and ...well id buy some for sure wade

[pjr2011]

Took some detailed, macro photographs of intake and exhaust port leading edges of a 340s cyclinder that some of you paranoid, glass-half-empty, don't-think-it-will-work types should appreciate... I've taken some more measurements and edited the pictures to clearly show what I've been talking about, regarding the neccessity of chamfering the intake port leading edge to allow this specific piston alternative to work properly.

As you can also clearly see, the same type of method was factory implemented AND used on the wide exhaust port leading edge to ensure ring snagging would not occur. The current intake port is only slightly wider than the exhaust port, so if this engineering trait can be used on the exhaust port with 100% success, there isn't a reason why it can't also be amended to the intake port as well- as long as it's done properly.

This also mirrors what I've seen on three different other sled engine brand manufacterers as well...

*EDIT- You'll have to click on the photo to enlarge it enough to see the modification specs text I've inserted into each.

Phil

[WinnipegStPaul9]

Took some detailed, macro photographs of intake and exhaust port leading edges of a 340s cyclinder that some of you paranoid, glass-half-empty, don't-think-it-will-work types should appreciate...
Phil

Geez PJ, there's nothing about this quote that will piss anyone off................
DA

[pjr2011]

Geeez Don, it is what it is.......isn't it?.....................................................

[lwb140]

just to clearify my interest in swapping pistons in my 340/s with the wisecos in it is because it has a wicked vibration in it, like shake the windshield screews out of it at 3800 rpm kind of shake . at minimun it needs dissassembled and inspected ,posibly weighing the pistons the motor including crank are fresh so there should be no issues otherwise wade

[WinnipegStPaul9]

Coming from a medical background I demand evidence based research before making an informed decision. Everyone that has an idea of which piston to use, put a set in, run the sled for 500 miles and I guess we'll know what works and what doesn't. Until then everyone's ideas are unfounded. The proof is in driven miles.

Finally, I am willing to "donate" an RS/2 to this project and put the miles on if needed.

DA

[HoosierDeereMan]

Here is a picture of the Wiseco 2012PS (left piston) and OEM 340/S piston (right piston) with the wrist pin installed to show the differences. Note the skirt length, timing port window height, and skirt angle at the port timing window corners. The Wiseco has .040" longer skirt, the port window is .023" shorter, and does not have the angles cut to clear the crank at the port timing window. We weighed each Wiseco and then machined the Wiseco's to match the OEM 340/S piston. The pistons were then re-weighed to ensure for balance. The Wiseco's are much lighter that the OEM 340/S piston. I haven't noticed any vibration in the engine. I have rougly 200 miles on the engine running these pistons. It survived the UP of Michigan, and the abreviated Vintage Challenge at St. Germain last year.

Troy

[Sprailfire340]

I am willing to "donate" an RS/2 to this project and put the miles on if needed.
DA

Is Bob on board with that?
We know what is going in mine - will provide on the snow report when I can.

[pjr2011]

Coming from a medical background I demand evidence based research before making an informed decision. Everyone that has an idea of which piston to use, put a set in, run the sled for 500 miles and I guess we'll know what works and what doesn't. Until then everyone's ideas are unfounded. The proof is in driven miles.

Finally, I am willing to "donate" an RS/2 to this project and put the miles on if needed.

DA

As do I Don and you already know me, so you should know that...hence all the actual measured data, photos and technical descriptions I've provided. Let's not suger coat anything here- My statement was entirely accurate and truthful, whether someone wants to admit it or not and my comtempt with it arises from many saying (and I've been made aware of what has been said behind my back) that "it won't work" or that "it cannot work" just because someone has never ventured out for themselves to actually try it for once, instead of just talking about it for years on end...

I can tell you this as an example- I've had many people all throughout my life tell me "I can't do something", I'm "not smart enough" to do something or that "it can't be done"... To those I've always said, well....get out of my way then, because I'm doing it and I'm going to make it work, if for no other reason to prove the naysayers wrong! Heck, you'll never know just how many folks told me back in 2000 that I couldn't own and operate a successful Corvette racing business and because of that, it drove me harder to succeed, where we grossed 1.2 million in sales in just 5 short years from starting with ZERO! I proved EVERYONE wrong after 10 years of successful business ownership!!

My point here is, I make it a point to never shoot down someone else's ideas, thoughts or plans for whatever, based on subjective conjecture or my lack of knowledge on a subject, UNLESS I have something to offer up as an alternative solution to the task at hand to keep the project moving forward and make it successful. I've worked with a number of "Negative Nancy" engineers in the field before that were like this and after seeing how they actually stalled a project by their own "failure to launch", I've learned to move on ahead or around them to get the job DONE! I'm a do'er, not a talker and that drive and/or my directness rubs some the wrong way sometimes. I can live with that...


Edison made 1,000 unsuccessful attempts at inventing the light bulb. When a reporter asked, "How did it feel to fail 1,000 times?" Edison replied, "I didn’t fail 1,000 times. The light bulb was an invention with 1,000 steps...."

Rocket scientist Robert Goddard found his ideas bitterly rejected by his peers on the grounds that rocket propulsion would not work....


I prefer to share company with those wise gentlemen above. /\ /\ /\


Phil

[pjr2011]

Finally, I am willing to "donate" an RS/2 to this project and put the miles on if needed.

DA

Do you intend on bringing the engine here to be fitted or are you or Bob doing the modification yourself? It makes no difference to me, just curious..


Phil

[pjr2011]

By the way~ For those of you that may want to do this modification, I've found that an air die grinder or a Dremel doesn't fit very well in the small cylinder or the port itself to properly chamfer the port edge at the correct angle or width- at least not for my tastes, because I found it nearly impossible to control the tool(s) cut path by just holding on to it. One slip and there goes the cylinder....

Sooo, I'm going to lock it down on a Bridgeport at the angle I want and use a small end mill to machine the chamfer, instead of the manual way. There may be better methods to perform the chamfer by hand that some may use, but I'm going this route, since you basically only have one shot to do it right.

$.02

[80spitfire]

I don't own a 340s but I would still like to thank you for doing all this research on these pistons and finding out if they'll work. It's pretty awesome to have someone with the knowledge you have volunteering to do all this research for us all here on the forum.

[JDT]

I don't own a 340s but I would still like to thank you for doing all this research on these pistons and finding out if they'll work. It's pretty awesome to have someone with the knowledge you have volunteering to do all this research for us all here on the forum.

Hear, hear.

My thoughts exactly.

Way to go PJ.