Forged Pistons

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FVartist42
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Joined: May 17th, 2013, 11:54 am

Forged Pistons

Post by FVartist42 »

Since there is a problem acquiring pistons with the proper ring groove width, what is the problem with a forged piston designed to our specifications? Has anyone looked into the feasibility and cost? Would'nt a forged piston be superior to those we now use, that needs to be cut down?

Can anyone tell us the cost of the pistons current being sought by Dietmar?

Bruce Fuchiwaki
racing stuff
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Re: Forged Pistons

Post by racing stuff »

Forged pistons did a lot for extending the service life of F/Ford 1600 engines and the F/C (Pinto), regardless of the internet dribble that you may have read that led to new engines being introduced into those classes.
Better strength, longer useful life, less "junk" shedding that gets into the oil.
It may be something to look into for F/Vee !
Keith
Averill Racing Stuff, Inc.
248-585-9139
http://www.racing-stuff.com
brian
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Re: Forged Pistons

Post by brian »

Forged pistons are the norm in the aftermarket supply chain. Finding cast pistons is much more of a challenge. I do not have heartburn regarding us using forged pistons. There are several companies that can deliver what we want for under $400. Maintain the existing weight, dimensions and ring locations and we're good to go.
The above post is for reference only and your results may vary. This post is not intended to reflect the views or opinions of SCCA and should not be considered an analysis or opinion of the rules written in the GCR.
FV80
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Re: Forged Pistons

Post by FV80 »

As long as there is a decent supply of cast pistons at reasonable cost, the Committee maintains that the cost of forged pistons as well as the potential for having "something more than idential" forged, means that forged is not the best way to go for the class. K/S pistons are currently being ordered (without cylinders .. as would be forged pistons) (
Contact Dietmar for information http://www.QuixoteRacing.com) for something around $35 per piston .. as opposed to ~$100 per piston for forged. Also, the AA Products P&C sets (available through most aftermarket suppliers) meet the current rules and have been shown to be good material and reliable and sell for something less than $200 per P&C set.

We endeavor to keep FV costs AS LOW AS POSSIBLE as long as it doesn't compromise safety - within the constraints of availability.

Steve
The Racer's Wedge and now a Vortech, FV80
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brian
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Re: Forged Pistons

Post by brian »

Great news Steve. I agree that costs are probably the most important thing but suggest we consider the life expectancy in the cost calculation. A modern forged piston will outlast a cast version hands down.
The above post is for reference only and your results may vary. This post is not intended to reflect the views or opinions of SCCA and should not be considered an analysis or opinion of the rules written in the GCR.
FV80
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Re: Forged Pistons

Post by FV80 »

agreed, Brian. however, included in my calculation is the fact that the cylinders also degrade and we will ultimately need a source of those as well - even if we allow forged. So where would be the gain for the class?
The Racer's Wedge and now a Vortech, FV80
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Re: Forged Pistons

Post by brian »

More stable ring lands will reduce wear and we could consider boring the cylinders slightly oversize and source pistons to fit.
The above post is for reference only and your results may vary. This post is not intended to reflect the views or opinions of SCCA and should not be considered an analysis or opinion of the rules written in the GCR.
FV80
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Re: Forged Pistons

Post by FV80 »

brian wrote:More stable ring lands will reduce wear and we could consider boring the cylinders slightly oversize and source pistons to fit.
We did consider boring cylinders but none of us (Committee) was ever able to find anyone that would give us a quote on doing ONE set. Do you have any ideas?
The Racer's Wedge and now a Vortech, FV80
To sign up in the FV Registry for updates about SCCA Formula Vee, please send me an email or PM with your name, location (city/state), make/model of car, phone # and any other appropriate info.
brian
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Re: Forged Pistons

Post by brian »

My shop will size hone a set for about $80. Resizing will be slightly more but I'm confident that it would be cheaper than buying a new set. At .010 there would be virtually no performance advantage, but would double the life of the cylinders. Aftermarket piston makers could easily size pistons to fit the larger bores but I doubt KS or other OEM could do it.

Back in the day, I installed "big bore" kits, 83mm. (6mm overbore) on all 40 hp rebuilds to improve performance. They were a bit thinner and less resistant to heat, but lived as long as stock. Removing .010 to .030 will not effect reliability.
The above post is for reference only and your results may vary. This post is not intended to reflect the views or opinions of SCCA and should not be considered an analysis or opinion of the rules written in the GCR.
FV80
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Re: Forged Pistons

Post by FV80 »

Brian,
I'm dumb so bear with me please :) WHAT does "size hone" mean ?? Would guess it means "hone to true at whatever size it ends up at" .. but ... ??
... also interesting that we (the Committee) never thought of asking YOU about honing. It does show that there is probably a LOT of info out there that we don't yet have in our Vee books...

Do you happen to have knowledge of possible SLEEVING of stock cylinders? We deemed it too expensive (more than a new set of P&C) when we tried to find someone about a year ago.
BTW .. "Virtually no performance advantage" ==> Only the top competitors would do it right away .. but it WOULD still be "AN" advantage... no matter how slight. (and would soon be perceived by some as "GOTTA HAVE IT").
Steve, FV80
The Racer's Wedge and now a Vortech, FV80
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brian
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Re: Forged Pistons

Post by brian »

Some engine builder prefer to increase the clearance on new cylinders. Cylinders are delivered with usually .025 clearance between the piston diameter and the cylinder. Generally speaking, this is increased to about .045. Attempting to bore off a couple of thousands is challenging, so a hone is used. A hone can be used to square up, remove taper, clean up minor imperfections and establish a finish for the rings to seat properly. Once this clearance exceeds a desired range, .007 and larger, the rings become unstable in the piston and wear quickly and cause blowby and smoke.

The research I have done on sleeves confirmes your conclusions. In order to have enough material to hold the sleeve properly, you have to start with a larger cylinder and bore out for a 77mm sleeve. Starting with a worn out 77mm, 40 hp cylinder will end up being to thin to be stable enough.

You know I agree with your opinion regarding perception, advantages and spending money. Unfortunately, there will always be snake oil engine builders and gullible competitors willing to spend money on perceived advantages. I've learned that if a competitor saves a buck on spec tires or whatever, they're likely to spend it somewhere else anyway. In this case, if a customer needs new cylinders, I'd prefer to have two options. Chances are if the cylinders are worn out, the piston is toast as well so the whole deal is a push.
The above post is for reference only and your results may vary. This post is not intended to reflect the views or opinions of SCCA and should not be considered an analysis or opinion of the rules written in the GCR.
hardingfv32
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Re: Forged Pistons

Post by hardingfv32 »

FV80 wrote:We did consider boring cylinders but none of us (Committee) was ever able to find anyone that would give us a quote on doing ONE set. Do you have any ideas?
There is absolutely no need to bore the cylinders. Just hone the cylinders and order the size (OD) piston you want from the forged piston manufacture. There is no extra charge to have custom sizes. They just change a value on the CNC program.

Ordering new stock pistons is a complete waste of time and money unless you plan to used new Chinese cylinders. New pistons in old cylinders are of no value in a real race engine.

So what do you do about the perception that NOS Kolbenschmidt cylinder sets are the only way to go if you are building a top of the line race engine? Could it be "AN" advantage?

Brian
cendiv37
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Re: Forged Pistons

Post by cendiv37 »

So... Pistons are to be free? How free shall they be? Details please gentlemen.

IMHO, there are builders who want/need new stock dia. pistons, even to go in used cylinders because they cut the piston tops so far that the pistons don't last very long. Why do they cut the tops so far? Perceived or real advantage... How do we control any real or perceived advantage if we allow "custom, build to your (whatever) spec." pistons?

Lets get the discussion started on what and how to control "custom" pistons in FV or let's hold the line and order the K&S pistons and count on the new Chinese cylinders which are now improved and available. The time to decide is now, but just allowing forged or custom CNC pistons is not the panacea some would have you believe. Allowing them is a great benefit to engine builders, but how will it effect the class?
Bruce
cendiv37
brian
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Re: Forged Pistons

Post by brian »

I think the existing rule is fine, just allow for forged and oversize pistons. While I don't agree with Brian's cost analysis for one off pistons an any size, it''s a great idea. It's more likely that manufacturers will make std. over bore sizes and charge less for them but I hve no heartburn regarding custom sizes as long as there is a max size.

Years ago, I asked for a rule change to allow alternative ring land sizes to eliminate the costs of spacers and was turned down by the Committee and CRB. Maybe it's time to reconsider that since we rewrote the rule to allow the Chinese pistons ring lands already.

Unless too much material is taken off the tops, I don't think it's a life expectancy issue. Pistons die from hammered ring lands in our engines.
The above post is for reference only and your results may vary. This post is not intended to reflect the views or opinions of SCCA and should not be considered an analysis or opinion of the rules written in the GCR.
Rickydel
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Re: Forged Pistons

Post by Rickydel »

Some vintage guys have been talking about the possibility of having worn cylinder walls built up and then machined back out to size.
We can use cylinders indefinitely, without sleeves.

Opinions???
brian
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Re: Forged Pistons

Post by brian »

I'm afraid that isn't likely to work. By "build up" it means adding material and short of welding, which would warp the crap out of everything, I can't think of how one could do it. There is a metal spray technique used on crankshafts but it includes the extreme heat as well.

I would suggest that the Chinese/A&A sets would adequately serve most needs and actually cost less than refurbishing methods being discussed. But, even for some vintage folks, having maximum hp. has become the norm.

Off subject a bit here but the level of hard racing in vintage really concerns me. Many vintage cars, vees and others, just aren't strong enough to safely withstand a shunt at today's speeds. Seeing a driver doing 120 in a formula junior gives be the heebie jeebies.
The above post is for reference only and your results may vary. This post is not intended to reflect the views or opinions of SCCA and should not be considered an analysis or opinion of the rules written in the GCR.
Rickydel
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Re: Forged Pistons

Post by Rickydel »

There are some circle track fellas that have joined our vintage group, and they talk of an outfit that already does refurbish cylinders to bring them back to stock dimensions. I will do more research and get back to you all.

Ricky
Rickydel
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Re: Forged Pistons

Post by Rickydel »

These guys know of a shop that has done cylinders for Harleys for $275 ea.!
They "Think" the price would go down to about $100 ea for a bulk FV order.
FV80
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Re: Forged Pistons

Post by FV80 »

Rickydel wrote:These guys know of a shop that has done cylinders for Harleys for $275 ea.!
They "Think" the price would go down to about $100 ea for a bulk FV order.
Suspect that's out of our price range for the desired task :shock:
The Racer's Wedge and now a Vortech, FV80
To sign up in the FV Registry for updates about SCCA Formula Vee, please send me an email or PM with your name, location (city/state), make/model of car, phone # and any other appropriate info.
brian
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Re: Forged Pistons

Post by brian »

Harley cylinders have a lot more material to work with.
The above post is for reference only and your results may vary. This post is not intended to reflect the views or opinions of SCCA and should not be considered an analysis or opinion of the rules written in the GCR.
Rickydel
Posts: 199
Joined: July 5th, 2006, 11:09 am

Re: Forged Pistons

Post by Rickydel »

"Suspect that's out of our price range for the desired task :shock:"

I agree. But because I brought up the subject and said I would get more details, I didn't want to leave readers hanging.

Oh well.
sharplikestump
Posts: 183
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Re: Forged Pistons

Post by sharplikestump »

I can't believe there is still a push for forged pistons and o/s or reworked cylinders. Makes me question the motive(s). Unless the application is a much higher revving engine, or much higher compression, the forged pistons are not only unnecessary, but an actual disadvantage. I see no problem with ring grooves "beaten out", unless the lateral ring groove clearance was excessive at the time of the build. Furthermore, most of us engine builders know that there are unfair features that can be incorporated into forged pistons.
Enlarging the cylinders would require o/s rings which are very hard to obtain in a 77.25mm dia. IMO, any larger than that and you DO have a cc advantage. I feel that with the latest cylinders offered by AA, there is absolutely zero justification for doing so. I have yet to find a single cyl. that is .0002 out of round. They now have the same number of fins as the K/S or Mahle, are available with a phone call, are of far better metallurgy, and have what I consider to be a significant advantage in the form of not only a wider seat, but the correct base diameter for the cases that we use. No more crushed or wandering O-rings.
As it has been determined, there was insufficient interest in purchasing the required quantity of K/S cylinders. It was also determined that K/S has no interest in producing any pistons. For those that wish to purchase full sets, just pistons, or just cylinders, I am willing to break up sets, with pricing as follows:
(4) new AA pistons, pins, and stock rings.....$120. plus shpg.
(4) new late style AA cylinders.................$120. " "
Full late style AA set.............................$219. " "
Full early style AA set............................$179. " " [If for some reason you prefer these, (which I no longer do) I highly recommend they be reinforced with weld dabs on all (4) sides].
Or you can order either full set direct from AA.

I am not trying to get rich on these, as the time spent on the phone and preparing them to ship more than eats the profit. I just want it known that there are good components available. A visit to the AA website should convince you that these people know what they are doing. I really don't care who you deal with. Both AA and I generally have either set in stock.
Mike Palermo Jr.
303-838.9515
fveeguy@yahoo.com
sharplikestump
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Re: Forged Pistons

Post by sharplikestump »

[quote="brian"]Some engine builder prefer to increase the clearance on new cylinders. Cylinders are delivered with usually .025 clearance between the piston diameter and the cylinder. Generally speaking, this is increased to about .045.

Brian, are you sure that you don't actually mean .0025, and .0045?
brian
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Re: Forged Pistons

Post by brian »

yea, I'm dyslexic and mess up writing numbers occasionally. Two and a half thousands to four and a half thousands.
The above post is for reference only and your results may vary. This post is not intended to reflect the views or opinions of SCCA and should not be considered an analysis or opinion of the rules written in the GCR.
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