Gapless Piston Rings

[GeoffRain]

P194 of the GCR states:

Piston rings are unrestricted provided that:
1. One oil control and two compression rings are used
2. No modification is made to the piston for the installation of rings.

Is the top ring in a gapless set considered 2 seperate rings, or a single 2 piece ring? (the standard oil control ring is called 1 ring but it's 3 pieces)


Thanks in advance.



Geoff

[John Merriman]

It's considered ONE ring. Plenty of engine builders have used Sealed-Power gapless rings in the past. Not sure what's in vogue these days!

[Brian]

The concensus appears to be that while a two piece second ring may give better leakdown test results, it gives less power on the dyno than a well considered one piece second ring.

since we don't race leakdown testers, my engine guy has a top secret ring package that he installs...

Brian

[GeoffRain]

Thanks for the replies Brian and John.

Geoff

[Steve Demeter]

Total Seal has gapless top rings for the past few years, as well as the original gapless second rings.

Do not use gapless in the top and second ring positions. Total Seal guy told me that does NOT work.

Something about gases getting behind the rings and unseating them.

[Art Smith]

Geoff has asked a fascinating question and I'm disappointed (not surprised) with the answers to date. seeing another "surprise" forged piston change of dubious value in the 2007 GCR already had me in a cranky mood, this is as good as the next opportunity to poke at the Club's rules PROCESS (NOT about personalities!!).

does anyone else have a problem with:
a.) it's a known problem and we've chosen to ignore it
b.) the manufactor said those two rings are really only one and therefore it's OK

in the name of objectively veriable rules that anyone with a high school education can read, why isn't the right answer "THE RULE NEEDS FIXING, THANKS FOR BRINGING IT TO OUR ATTENTION"? why should we propogate the need for all the gatekeepers and secret decoder rings to avoid running afoul of "Catch23's" in the GCR??

if the objective/intent of D.2.e.1 Engine is to require a ring in each piston groove, that's not what it says in writing. the change seems fairly straight forward:

(is) D.2.e.1 One oil control and two compression rings are used.

(s/b) D.2.e.2 A minimum of one ring is required in each of the piston's ring grooves.

imagine the fun if some lad/lass with a little imagination showed up with two springs per valve and a note from their manufactor saying "the two springs were really only one" and that Tech & the Stewards of the Meet shouldn't give them a bad time given the "gapless rings" precedent!!!


Art
artesmith@earthlink.net

[Roux]

Art,

I have never been bothered by this. Any rings as long as you don't add, modify or delete any of the three ring grooves. Not a big loophole really. Our energy should always focus on areas where big HP gains come at great expense. I do not see the 0.005 overbore or the long standing ring rule as a threat. Do you?

The day that they allow special light weight rods or aluminum blocks or six speed sequential transaxles I will get excited.

Am I missing something?

I hate the thought of being a totally spec class. The chassis and a few engine areas should be left to the developers to play with (within the existing rules). Otherwise all the engines will come from one supplier and the cost might creep from lack of competition. Right now there are >6 engine builders with reputations to uphold via the few subtle areas they have to play with. that is healthy. It leaves that small element of F1 in our wingless old class. The buzz in the paddock about the trick widget on the such and such. I bet you don't find that among the SM, or SRF conversations.

[John Merriman]

Well said, Mr. Roux.
The rules are tight.
The rules are right.
The parts are smart.
The costs are lower.
The engines live longer.
The class is great.
The Kent is cool.

[Daryl DeArman]

Art,

I hate the thought of being a totally spec class. <snip>The buzz in the paddock about the trick widget on the such and such. I bet you don't find that among the SM, or SRF conversations.

I am not sure I follow the leap from "an accepted practice of doing something the rule doesn't seem to permit" being clarrified to continue to allow it, Or, enforced to disallow it makes a totally spec class. There are lots of chassis and bodies to choose from, a billion different variations of shock settings/brands of shocks/spring rates/bars to choose from, two major tire manufactures, a number of gear ratios to choose from, brake pad compounds, rotor styles and sizes doens't make FF anything close to a spec class.

And I am certain there isn't ever a buzz about trick widgets with the SM guys

Sorry, I don't really care what the rule is. I just see a HUGE difference between a Spec class and a Restricted class.

[Art Smith]

Roux-

yes, I see problems AND the very real potential for larger problems
on the horizon.

I have a problem with the unwillingness to document
the rules that we all actually compete to: it undermines the rules as
written; it promotes the idea that it's OK to be in non-compliance
with the rules as written; it propogates the need for "gatekeepers";
and it introduces uncertainty into what will be found compliant and
non-compliant. if documented rules aren't the foundation of our
competition in FF, at the end of the day the biggest meanest dog on
the block or the one with the most money will always prevail..............
I prefer a fair and level playing field where the same documented rules
apply to all. accurate and completely documented FF rules is light
years from a spec class!!!

I have a problem with "surprise" rules changes with no visibility into
why the rules were changed, who requested the changes, the basis for
the change being approved, and who approved the changes. does
the club have a documented process for changing rules? was it followed?
and if not, why not? and what's the corrective action? FF has done
quite nicely without oversize pistons for years, why were they approved
for incorporation in the 2007 GCR? none of us need Mr Spock to recite
on cue "illogical" to the notion that oversize pistons don't increase
performance!! it's equally "illogical" that oversize pistons eliminate
the need for sleeving blocks; at very best they postpone for a rebuild
or two the need for sleeves for someone currently using cast pistons!!
whatever the case that was made for approving oversize pistons, at
least one insider was so impressed by the compelling nature of the
arguement they were completely surprised like the rest of us that the
change was in this year's GCR................................?

I have a problem with "secret rulings" from the "gatekeepers" for a fee
that enables one or more competitors to compete with an advantage.
it's my sense that if you're not willing to put your good name on the
line to run your latest trick widget, it shouldn't be used in competition!
if the "gatekeepers" provide a ruling on the widget, it should be made
public immediately so all have the opportunity to continue to compete
on a fair and level playing field!!

my biggest problem with the inclusion of oversize pistons in the 2007
GCR is I feel it undermines the heritage and integrity of FF. oversized
forged pistons effectively eliminates cast pistons from consideration for
anyone interested in horsepower. the forged piston's lower drag skirt and
increased displacement from the combination of larger size AND larger
required piston-to-bore clearance is just too complelling from the
perspective of performance. sole source suppliers are seldom the
lowest cost solution........................... I worry changes like the over
sized piston are gratuitous pieces of "candy" from the "bad man at the
corner" (figuratively speaking) and by 2009 or 2010 the FF community
will be "hooked"; powerless to do anything about inclusion of FF into
a homogenized formula class that is clearly part of the vision of some!!!

Art
artesmith@earthlink.net

[EACIII]

Before everyone gets all worked up, how much bigger is the new .005 piston then the old Ford Type E that is no longer around?

[Art Smith]

per Peter & Valerie Wallage's book "Rebuilding and Tuning Ford's Kent Crossflow Engine" standard size Grade E pistons measured 3.1872" to 3.1876" (p.190). piston OD is only part of the story; the other part is material. Ford's "Grade E" pistons were cast aluminum. cast pistons are run at much smaller piston-to-bore clearances than forged pistons. therefore there's two components to increased displacement: 1.) piston OD; and 2.) piston material (ie: required piston-to-bore clearance). the enclosed spreadsheet can be used to assess relative displacements using your engine builder's piston clearances.

1% displacement advantage on 115hp is 1.15hp; not chump-change in my world. the forged pistons also have a better skirt.........................

the focus of my post is PROCESS, but there's also more than a little substance


Art
artesmith@earthlink.net

[mblanc]

I think it was a completely unneeded and unnecessary change in the rules.

The obvious solution, for those that wanted 'to extend block/sleeve life' was to make this rule change, and allow the piston at -0.005"
IE 5 thou UNDERSIZE, the max piston bore has been the same in FF since they carved the GCR out of stone, it shouldn't have been changed.

Over the years we have changed piston #'s to reflect what was on the actual pistons available in the market, allowing the current piston in an undersize, would have been consistent with that practice, and would have simplified the change, and allowed the long standing max bore sizes (and all the associated compression calculations) to remain the same.

You know some are going to have to have the +.005, just because, so it does nothing to decrease costs, nor increase life, but those that chose to start at -.005 under could have concievably benefited from the increased life of two sets of pistons, to one set of sleeves.

I think there is minimal (but some) gains to be made from the bore size, it just flies in the face of the years of longstanding consistancy of rules in the class.

The change to an aftermarket crank didn't CHANGE any long standing rules, as it was just a better piece -made to the same dimensions (stroke) or should we have just added .005" (do I hear .125") stroke to that crank when it was made?

The pistons were the same thing, dimensionally the same, the max bore was the same forever, sure don't think anybody would complain about a .005" under piston, but opening up the door in the other direction, look out.

Lets all make sure this is the LAST unneeded nor requested performance enhancement.



And another problem, now the affordable speed-pro ring will have too much end gap in the plus .005 size. so much for your savings in piston life, now you just need to buy the 'bigger set' and custom rings. Should I point out here that with the .005" under piston, we could have used the stock or the sealed power rings. How many old std size ring sets laying around could have been used?

Dumb Change.

[Roux]

Well I can't say I feel good about what I am seeing in this thread. In some ways I feel ignorant. But in the bottom of my gut I feel that my cheering for the old ring rule and the new oversize rule is not misguided. Let me try one more time.

We are probably quite polarized between a tribe of FF/CF pilots who are fully confident that 1.15HP difference is going to mean that they now have to go to 5over to win. I am a member of the more regional tribe where 1.15hp is not going to relegate the fast guys to backmarker status. (At many of our races the lap time deltas are seconds not tenths from 1st to fifth, not to mention to tenth place.) And to us, the thought of taking a tired block that has had several (not two) sets of pistons tearing way at its bores and spending less than $100 to get the bores resized 5 over is VERY appealing. That rebuild with forged pistons will last me two, three or four seasons because I am cheap and budget constrained. I imagine that at least a decent number of serious National level runners started as regional runners with tight budgets who later found the means to go all out. The need to nurture all levels of FF/CF participation is tough to dispute, and the 5over helps many guys/gals like me. I now have a plan for the block that I keep planning to sleeve, but always relagate to lower priority because of the cost.

The 5under concept is a better one. No argument in the long run. Temporarily I would have had to suck up the $500+ sleeving and that would have then paid back later.

The ring rule is still in my opinion not a real issue. Go ahead, spend a snotload of cash to develop a deciHP or two. I suspect that if there were something hiding there it would have shown up by now.

[bob darcey]

I'm just a vintage guy for whom it doesn't matter, but would like to make a few comments.

First, the CP/Ivey pistions were legalized in the SCCA a year (or more) ago, without much adverse reaction. The forged pistons have a shorter skirt and a centered pin, compared to the longer skirt and offset pin of the OEM and AE pistons. They are not dimensionally identical to the OEM and never were. It's curious that the SCCA did not try to replicate the OEM version dimensionally, but no one seemed concerned back then.

Second, a .005" bore increase amounts to about .3% displacement increase, not 1%. So, we're talking .35 HP, not 1.15 HP. On a motor that is already induction-challenged, maybe less. Without any real basis for saying this, I'd bet that the shorter skirt and better pin position provides more HP gain than that.

Third, assuming that the bowl volumes remain constant, a .005" overbore would raise the compression ratio from 9.3:1 to a whoppin' 9.32:1. Hoohah!!

[John Merriman]

There's a pretty funny cartoon in the New Yorker this week. A guy and a gal are in bed and the gal looks none too happy and then the guy says to her "Everybody's a critic." And so it is....and, in general, the more input, the better because, you know what? sooner or later, all the facts - along with truth and beauty - become clear.

As far as the gapless ring goes, they are clearly legal. When fifteen or twenty years of precedent are a fact, how is it that all of sudden in 2006, the question comes up if it's legal? It's likely that multipiece gapless rings were pulled out of a RunOffs winning motor a dozen times. After all, the rule reads "one ring...per groove..." But, hey, as far as I know, there haven't been any used by the last few winners (I'm just surmising) so it may very well be that the pro engine builders - who spend literally hundreds of hours on the dyno - have a better answer with a standard one-piece ring.

The .005 piston is a new kid on the block but it didn't just appear out of nowhere. Several times over the years competitors proposed allowing overboring to save the cost of sleeving. About eighteen years ago, I was one of those who submitted such a proposal - and I suggested the rule apply only to Regional racers. ( Mind you, this was before Regional racers would sell their mother for a half a second reduction in lap times. This was before Regional racers used half a dozen sets of tires in a season - all in order to assure they'd take home that shiny little trophy!)

No, this proposal was different. A few years back, Jay Ivey had half dozen sets of forged pistons made and he tested them exhaustively on his own nickel. They were approved. The result? A better piston, almost dead equal performance and, most significantly, a much longer-lived Kent engine. Amazingly, Ivey knew that he had to accept that the income generated by his rebuilds would actually go down! A Kent engine that is properly assembled and maintained can now run competitively for well over forty hours - and perhaps for as many as fifty from what I hear.

Obviously, the Road Racing Board has been quite receptive to ways to cut costs in FF1600. look at the long string of parts approvals and rules adjustments. So when the idea of the .005 piston came along, they looked closely at it after the Advisory Committee had done its homework first. The .005 piston was shown to provide a miniscule advantage in exhaustive tests. (Thanks for those numbers above, Bob. They reinforce the point.) The argument was made that the one major remaining maintenance item could be deferred considerably with the use of this piston - thus cutting costs considerably. The Committee and Board agreed and the approval was given. So, theoretically, a couple of hundred guys can hone the bores and install these pistons and go racing for one heck of a long time - deferring sleeving for 2-3-4 season maybe - as Steve points out above. Where's the downside in that? I don't see one. On the other hand, the idea of an underbored piston would have necessitated that the same couple of hundred guys sleeve there blocks now to gain precisely the same advantage over time.

Ya' know, not everybody's going to be happy with every decision. But the submission came with a valid premise and excellent back-up information including dyno sheets. The two rules-making groups thought it through and the pistons are now available. In my view, the system worked very well indeed; the proposal was sound and the benefit - in engine life and lower costs - goes to the individual racer and to the FF1600 class as a whole.

[Stan Clayton]

Bob and John, thank you for weighing in with your perspectives. I also want to thank mblanc for raising the question of an undersize piston. We can definitely look at that. Sooner or later folks will have to resleeve, and having the choice of starting off 5-under can mean a 10 year bore life for those on a budget. I will ask Jay Ivey to see if CP can make a 5-under piston happen before taking it to the Committee and CRB.

Our immediate concern was for those sitting on having to spend the $600 or so it takes to sleeve a good serviceable block. The +5 piston alleviates that need right off the bat. Thank you Jay and CP!

I also want to address the ring question raised above. AFAIK, the ring wording has been the same for decades...rings are free so long as there are two compression rings and one oil ring. A multi-piece compression ring assembly is no more "two rings" than a three-piece oil ring violates the "One oil control" ring mandate.

Finally, I want to address this statement from Art Smith in post #10 above:

I have a problem with "secret rulings" from the "gatekeepers" for a fee that enables one or more competitors to compete with an advantage.

For a fee...? Are you serious? Art, I'm calling you out on this. It's put up or shut up time. If you have any evidence whatsoever of any F/SRAC or CRB member accepting anything of a monetary value in exchange for a favorable ruling I want you to put it on the table for everyone to see. If not, IMO you need to apologize for overstepping the bounds of polite discourse so we can move on.

Regards, Stan

[Art Smith]

Bob-

good luck running your forged pistons at cast piston "piston-to-bore" clearances!! displacement is swept volume, not the number you get using room temperature piston OD .......... call your engine builder(s) and ask them if they're using the same clearances.


Art
artesmith@earthlink.net

[Art Smith]

Stan-

there's no direct or implied linkage of my concerns to the F/SRAC or CRB. there'a also no direct or implied linkage of my concerns to the number of rings or 0.005" oversize piston issues. the issue in question has been resolved to the benefit of all.


Art
artesmith@earthlink.net

[Stan Clayton]

Art, Bob didn't say anything about piston-to-wall clearance. He just said that the increase is nowhere near 1%. In fact, using your numbers above for forged standard versus +5 forged pistons and a typical (?) .008" clearance, the displacement change for swept volume is:

1615.1583 / 1610.1181 = 1.00313, and 1.00313 x 115 = 115.36 hp. That's less than a third of a percent increase - i.e., nowhere near 1%.

A third of a horsepower? Come on Art, get serious. With the old cast slugs guys used to lose what, a hp per hour of race time on the motor? The new pistons get 10 times that and with the oversized ones they can hold off a $600 sleeve job for twice as long. Sound pretty darned good to me.

Stan

[bob darcey]

Art:

Actually, I was using your chart (great chart, by the way).

Comparing the forged 3.189" pistons (with .005" clearance) vs. the forged 3.194" (with .005" clearance):

(98.3784 - 98.0711) / 98.0711 = .00313 = .31%

Worst case??: Comparing the cast 3.187" piston (with .003" clearance) to the forged 3.194" piston (with .005" clearance):

(98.3784 - 97.8256) / 97.8256 = .00565 = .56%

Maybe .005" is still tight, I've never used the forged pistons, and don't have an engine builder to call. Our vintage club is still using the'72 GCR rules, so OEM or AE/Hepolite cast pistons. I appreciate your concerns, but I think the oversize piston is a great move.

[Art Smith]

from the post above:

per Peter & Valerie Wallage's book "Rebuilding and Tuning Ford's Kent Crossflow Engine" standard size Grade E pistons measured 3.1872" to 3.1876" (p.190). piston OD is only part of the story; the other part is material. Ford's "Grade E" pistons were cast aluminum. cast pistons are run at much smaller piston-to-bore clearances than forged pistons. therefore there's two components to increased displacement: 1.) piston OD; and 2.) piston material (ie: required piston-to-bore clearance). the enclosed spreadsheet can be used to assess relative displacements using your engine builder's piston clearances.

the focus of the post was "Grade E pistons from Ford; they're cast!! compare cast numbers to forged numbers. while not a popular observation, the numbers speak for themselves. unlike most of those with only opinions, bluster, and emotion to contribute, I actually own multiple sets of the 3.187" cast pistons and 3.189" forged pistons being discussed and have tested them in three different engines.

how many engine builders built and tested how many engines for the database that was the basis for approving the change?? the principal objective of this string of posts is and continues to be process that in my opinion needs a great deal more visbility/membership oversight or just plain fixing. good people and bad process get bad answers most of the time!!


Art
artesmith@earthlink.net

[Greg Mercurio]

Mein Gott! For years whiners have been moaning about the cost of FF, the cost of the POS Kent, the cost of re-sleeving, the decline of FF due to rebuild cost, etc, etc. etc, ad nauseum. Here's a change that defers costs and reduces the overall cost of racing in this class and it is pissed on?

Get a grip, drink decaf, or just plain stuff a sock in it.

Loved your rhyme Merriman! Thanks for the book.

[Alan Oppel]

We all rely upon other people to help us attain our goals/ pleasures. Engine builders as a group get to deal with the greatest number of competitors, and hear the most number of inputs that can be given cohesively to the governing group as far as engine related matters are concerned. I applaud the time and effort as well as investment that has been made on behalf of the people who see the end product.
The value I see is far greater than 1.15%.
Alan

[Jon Horgas]

To rely on membership to get anything accomplished, especially in our class, is simply impossible. There is way too much squable, and skirt blowing. "Oh it helps him, and it will cost me 50 bucks to change, and I don't want to", is what is heard all the time. The engine builders have their fingers on the pulse of what is going on.

If the rule says +.005 pistons are legal, they are legal for EVERYONE, and you can bet I will tell whoever is building my motor to hone out the extra material for the extra volume of air moved, no matter how little, even if is only worth .05sec a lap. That's 1.00sec in 20 laps I'll take! You cannot stop anyone who has the resources that the rest don't in their favor. Kieth Nunes did a superb job doing exactly that a few years back. He tested days on end with a mountain of tires, and motors at his disposal to "dial it in", and then used his ability to dominate everyone else!. You cannot rewrite any rule in the GCR to change a drivers will to win, or their ability. Some win, everone else goes home with less than winning. For those who go to the track, unload the car to get at the barby, canopy, mood lights, and lawn chairs because they went to have fun and enjoy being with their friends, God Bless You. You are what makes racing fun, not all the rules, provisions, adendams and restrictions.

[jivey]

message deleted

[jivey]

deleted

[RacerChuck]

P194 of the GCR states:

Piston rings are unrestricted provided that:
1. One oil control and two compression rings are used
2. No modification is made to the piston for the installation of rings.

Is the top ring in a gapless set considered 2 seperate rings, or a single 2 piece ring? (the standard oil control ring is called 1 ring but it's 3 pieces)


Thanks in advance.



Geoff

By the letter of the word, the top Ring "LAND" could have 5 pieces, it's still just one compression ring.

Although it's been 4 years since I built and raced in FF1600, the last set of "gapless" rings I recall were one ring. But instead of having two blunt faces meating at the gap, had an upper and lower "tongue" that overlapped each other. This still allowed a tight seal in the ring land for those that used porting for the top land.