Oversized Fit Pistons

[LJennings]

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[LJennings]

There's no need, Roland. I was making proportional comparisons.

Total HP increase is proportional (roughly) to total displacement increase.

Total displacement is proportional to single cylinder displacement.

Single cylinder displacement is proportional to the square of the bore.

Ergo, total HP increase is proportional (roughly) to the square of the increase in the bore, or:

(73.315/73.065)^2 * 100, or roughly 100.685% of original HP

If a Honda makes 120hp (roughly) before you overbore it, it will make 120.822hp afterwards.

But a tiny bump in compression ratio will increase that figure by a few thousands of an HP...

...and slightly worse breathing will decrease it by probably more than that increase.

Has anyone consider the effects of thermodynamics in their calculations?

[Daryl DeArman]

Has anyone consider the effects of thermodynamics in their calculations?

We really don't need 3rd or 4th order approximations. The larger factors already show that the change is likely very small, and given the repeatability of even the best dyno's, the delta could be over/understated by as much as 100%.

[alangbaker]

Physics can't be beaten, Roland.

It's a most around 0.8hp, and probably a bit less, because the restrictor (in fact, the whole intake tract) won't allow a complete scaling of the displacement change.

[Jayeff]

I don't think anyone is quibbling about the increase in HP. What is sad is that it will become the new, more expensive standard in short order. Rightly or wrongly.

[LJennings]

Since........the oversized piston proposal was approved what is the next rule creep? Repairing cylinder heads?

[stonebridge20]

Really, if the Honda gets a .010 over bore, the Ford should get up to a .015 overbore. 005, .010 and .015 over bores would be wonderful. Imagine the cost savings since Ford blocks are considerably more expensive than Honda blocks.

[Roland V. Johnson]

Physics may not be beaten, but racing engines and cars are somewhat of an inexact science. If that were not true there would never be a need to go testing, all the F-1 cars would be perfect out of the box, and the only need for dynos would be to run an engine in.
Besides this is as much about the process of the rules change as the change itself.

[alangbaker]

But you're talking vastly more complex complete systems with lots of interactions.

This is a TINY change in only one element; considerably less than 1% (0.68549292% to be precise).

On its own, that would present about that much change in power, all else being equal.

I realize all else is NOT equal, but the changes in those second and third order effects are MINUSCULE. You get a TINY bump in the compression ratio which creates a TINY^2 change in power—something on the order of 5 thousandths of one percent; 0.00005 (yes, I looked into it). The cylinder walls will each move 0.125mm further away from the valves. Sorry, but that's just not enough of a change to be material.

Taken all in all, I have to believe the difference in power is close to the error bars for most dynos.

[Daryl DeArman]

But you're talking vastly more complex complete systems with lots of interactions.

This is a TINY change in only one element; considerably less than 1% (0.68549292% to be precise).

On its own, that would present about that much change in power, all else being equal.

I realize all else is NOT equal, but the changes in those second and third order effects are MINUSCULE. You get a TINY bump in the compression ratio which creates a TINY^2 change in power—something on the order of 5 thousandths of one percent; 0.00005 (yes, I looked into it). The cylinder walls will each move 0.125mm further away from the valves. Sorry, but that's just not enough of a change to be material.

Taken all in all, I have to believe the difference in power is close to the error bars for most dynos.

^ Exactly ^

A couple double blind dyno runs would prove so.

[Daryl DeArman]

Physics may not be beaten, but racing engines and cars are somewhat of an inexact science. If that were not true there would never be a need to go testing, all the F-1 cars would be perfect out of the box, and the only need for dynos would be to run an engine in.
Besides this is as much about the process of the rules change as the change itself.

Actually, they aren't an inexact science. They don't get to play by their own rules. They are a HUGE list of compromises, all that testing and work on the dyno is to determine whether or not the designers/engineers/builders and tuners made the best compromises to reach their goal.

[reidhazelton]

Besides this is as much about the process of the rules change as the change itself.

[Roland V. Johnson]

Thanks Daryl, that would mean that they used physics to arrive at the wrong answer for the compromise.

[Keith Robinson]

Alan
As you well know the loss of one tenth of a second per corner at our track (or any track) means you are not going to win.
To suggest that 0.8 hp is not going to make a difference is simply wrong.
Anyone wishing to win is going to have to 'repair' their engine to fit the O/S pistons.

Also to suggest that the 'intake tract' is in some way already at its maximum is illogical other wise there would be no need for a restrictor in the first place.
To suggest that volumetric efficiency is already at its maximum due to the restrictor is in my opinion also incorrect.

Physics can't be beaten, Roland.

It's a most around 0.8hp, and probably a bit less, because the restrictor (in fact, the whole intake tract) won't allow a complete scaling of the displacement change.

[Roland V. Johnson]

The Kent engine has been around for about 40 years. In all that time it has not been allowed a .010 in piston because that would be a performance advantage. The Honda now has been allowed a .25 mm over bore (.00984 in) with as far as I can tell no member input. I have been educated now that the overbore has no performance advantage. I did not know that .00016 in made that big of a difference. I do not see the logic in allowing this when a new block is about the same price as boring the old one, and they are available.

enough said

[Steve Bamford]

Alan
As you well know the loss of one tenth of a second per corner at our track (or any track) means you are not going to win.
To suggest that 0.8 hp is not going to make a difference is simply wrong.
Anyone wishing to win is going to have to 'repair' their engine to fit the O/S pistons.

Also to suggest that the 'intake tract' is in some way already at its maximum is illogical other wise there would be no need for a restrictor in the first place.
To suggest that volumetric efficiency is already at its maximum due to the restrictor is in my opinion also incorrect.

To be clear are you suggesting 0.8 equates to one tenth of a second in a corner?

[Keith Robinson]

No, I was just trying to illustrate that any difference, no matter how small, will make it necessary for the pointy end guys to go for the +.010" and then it will become the norm as others have suggested.
It will be good for the engine builders and that's not a bad thing!

To be clear are you suggesting 0.8 equates to one tenth of a second in a corner?

[Steve Bamford]

No, I was just trying to illustrate that any difference, no matter how small, will make it necessary for the pointy end guys to go for the +.010" and then it will become the norm as others have suggested.
It will be good for the engine builders and that's not a bad thing!

Ok because the one tenth of a second per corner usually equates to a huge difference. I still stick with my thoughts this will make zero difference on the race track. Allow it, don’t allow it, I hope we just ensure a practical discussion about it.

[Purple Frog]

If one would listen to an Eric Langbein or Steve Lathrop during the debrief session they could gain 1/10th a second on every corner even if they were 3 hp down.

Geez... it must be February up North.

Sometimes these threads remind me of trying to teach pigs to sing.
The pigs get aggravated.
The teachers get frustrated.

Give Cole Morgan a fresh Fit with the stock bore, against everyone who whines about the new "overbore", and i'll put all my money on Cole.
Hell... I'd probably put my money on Cole if he was driving Dad"s clapped out 7 year old Fit.

[Keith Robinson]

If one would listen to an Eric Langbein or Steve Lathrop during the debrief session they could gain 1/10th a second on every corner even if they were 3 hp down.

Geez... it must be February up North.

Sometimes these threads remind me of trying to teach pigs to sing.
The pigs get aggravated.
The teachers get frustrated.

You don't have singing pigs in Florida?

[John Robinson II]

Ok because the one tenth of a second per corner usually equates to a huge difference. I still stick with my thoughts this will make zero difference on the race track. Allow it, don’t allow it, I hope we just ensure a practical discussion about it.

Steve,
I don’t think any performance advantage is the real issue. Rule change with no member input is.
The other question I have is how minor of a failure is only going to cause a .125mm scratch or variation in the cylinder wall? Any more than that and a new block will be required.
Besides, it is already a rule. Effective 2/1/19.

Here is something else to think about, per the “new” rule you can use standard rings with over size pistons. Before you were not allowed to alter ring tension, now you don’t have to alter them, just use the smaller ones.

I just think this is a bs rule that is not needed and will do nothing to keep cars on the track.


Froggie,
You know as well as I do that listening to Eric or Steve is not the same as applying those words of wisdom.

John Kent Robinson II (yes, that is my actual middle name. LOL)

[alangbaker]

Alan
As you well know the loss of one tenth of a second per corner at our track (or any track) means you are not going to win.
To suggest that 0.8 hp is not going to make a difference is simply wrong.
Anyone wishing to win is going to have to 'repair' their engine to fit the O/S pistons.

Also to suggest that the 'intake tract' is in some way already at its maximum is illogical other wise there would be no need for a restrictor in the first place.

To suggest that volumetric efficiency is already at its maximum due to the restrictor is in my opinion also incorrect.

I'm not suggesting that volumetric efficiency is at its maximum: I'm suggesting that it is on a part of the curve where the efficiency decreases with increasing displacement. It doesn't have to be at a maximum for that. Imagine doubling the displacement, but still breathing through the same intake: it's obvious you're not going to get double the power.

A 0.685% bump in power is down in the "noise". If it costs you $1000 to get it, you're far better off spending that grand on a test day.

I'm certainly not going to worry about it, not even if all the stars align, and I'm headed to the Runoffs.

[R. Pare]

https://www.youtube.com/watch?v=h6_Uh1IkaCA

[LenFC11]

I find it kind of funny that even those who argue the difference is very small still agree there is an advantage.. yet are ok with allowing any difference and keep saying it's ok because it's not much.

That is how the creep and expenses start. Well it's not much.. so it's ok..

And to be clear I'm in favor of the Honda. But see this as a bad decision. No real benefit to the community

I remember when racing zetec and was time for me to rebuild or get new engine..

If you recall zetec started the same way. No blueprinting... Stock.. yadda yadda yadda..

So talking to my engine builder he basically said if you want to be on even footing have to let them blueprint engine. Stock won't be even ground. So guess what I did..

Zetec in the begging was bullet proof.. then we started seeing a bunch of them hand granade..

Dejavue ??

[Daryl DeArman]

Thanks Daryl, that would mean that they used physics to arrive at the wrong answer for the compromise.

The answer was right, it was the unknown variables they didn't account for or incorrectly estimated.

[Daryl DeArman]

That is how the creep and expenses start. Well it's not much.. so it's ok..

Point is that if enough folks realized how little of a difference it is, they wouldn't spend the time or money. This difference will have less effect than 6#, but how many people cross the scales with that much cushion or more, yet consider themselves leaving nothing on the table?

* No Roland, I didn't do all the fancy math I just know that those oversize pistons aren't helping when it comes to cornering or braking, only acceleration. The 6# is helping in all acceleration vectors.

[Peter Olivola]

Rules debates like this, which become bogged down in differing interpretations of the actual impact and cost vs. rules creep miss an important aspect of the rules process and one whose importance needs to be acknowledged: Rules are an entirely arbitrary line in the sand and as much a function of politics as any technical or cost consideration.

Racing is about trying to find an advantage, not just on the track, but in understanding and ultimately influencing the rules. It is in the nature of our competitive spirit.

What arguments about technical issues and cost vs. rules creep miss is that political component. It is decried, at best, as taking away from the sport, and has been largely ignored in this discussion.

Just because someone makes a request doesn’t mean it has to be adopted. There has been an ebb and flow in the use of the word "no" at every level of the club, but it has been particularly important to the outcome of rules making.

Is “no” the right answer in this case? Ultimately, that will be a political decision.

[Will Velkoff]

I find it kind of funny that even those who argue the difference is very small still agree there is an advantage.. yet are ok with allowing any difference and keep saying it's ok because it's not much.

That is how the creep and expenses start. Well it's not much.. so it's ok..

And to be clear I'm in favor of the Honda. But see this as a bad decision. No real benefit to the community

I remember when racing zetec and was time for me to rebuild or get new engine..

If you recall zetec started the same way. No blueprinting... Stock.. yadda yadda yadda..

So talking to my engine builder he basically said if you want to be on even footing have to let them blueprint engine. Stock won't be even ground. So guess what I did..

Zetec in the begging was bullet proof.. then we started seeing a bunch of them hand granade..

Dejavue ??

This is exactly what we need to avoid. The perception of the .010 overbore will certainly trigger the individuals or teams looking to maximize every last bit of their program to send engines in to builders. Then, obviously blueprinting and other tricks start to begin, which may start to result in grenaded engines, resulting in more business for the engine builders. You won't be able to convince me any of the current FF engine builders massaging the internals will improve durability and longevity of the motor. It was quite apparent with the Zetecs that were opened and altered.

With that said, I believe this rules is being proposed to drum up business for the engine builder(s), and actually hurts us, the racers. Still, I have not heard of any member of the FF community who is asking for this. So why?

[reidhazelton]

If one would listen to an Eric Langbein or Steve Lathrop during the debrief session they could gain 1/10th a second on every corner even if they were 3 hp down.

Give Cole Morgan a fresh Fit with the stock bore, against everyone who whines about the new "overbore", and i'll put all my money on Cole.
Hell... I'd probably put my money on Cole if he was driving Dad"s clapped out 7 year old Fit.

And if they were 3hp up, they would pick up two-tenths every corner. So? Do you mean to tell me Eric and Steve don't care about 1 or 2 hp? "Were going to optimize set up and go to extremes to get the most out of it, but leave 3hp on the table."

If Fernando Alonso shows up, does that mean we all get to run 14:1 compression since we won't likely beat him anyway?

That's not how rules work. Frog my man, I know you've been at this longer than I've been alive and you get the game here. You don't write rules depending on the driver, or because someone can do something someone else can't. Alonso is likely going to beat me even if I have carbon bodywork. Do we allow carbon bodywork?

What if Cole was racing against doppelganger Cole +.010? All things equal, who wins?

Rules are meant to eliminate grey area and create a level playing field - hopefully achieving that while keeping costs as low as possible and not allow creep. How did we get 160hp Zetecs and 320hp MZRs? Has that been better or worse for those classes?

Steve,
I don’t think any performance advantage is the real issue. Rule change with no member input is.
The other question I have is how minor of a failure is only going to cause a .125mm scratch or variation in the cylinder wall? Any more than that and a new block will be required.

Point is that if enough folks realized how little of a difference it is, they wouldn't spend the time or money.

In a logical world, perhaps. But nothing about club racing and why people do it is logical. Here is a list of some things that make little to no difference but people spend thousands on them:

Ceramic wheel bearings
REM gearboxes
Cheese grater rotors
$25/qt oil
Gold Foil
$3000 seats compared to 2 part foam
Lightened ring gears
Alum diff carriers
$5,000 Ohlins compared to $900 2-way Penskes.
48" Rigs for a FF or FC
Gun drilled bolts

Do any one of those whizbangy parts make a difference on their own? Do they collectively? Yet, do people still spend obscene amounts of money on them? Hell yeah they do.

PS. After writing the above list - that is why fields are smaller and we have $80k FFs. None of that is good. Spend $500 on an alloy diff carrier, so everyone else does and we just spent $500 to go the same minuscule amount of speed faster. It's ridiculous.

[Heel-and-toe]

With that said, I believe this rules is being proposed to drum up business for the engine builder(s), and actually hurts us, the racers.

This isn't a proposal and wasn't when this thread was started on 2/1.

[Daryl DeArman]

That's not how rules work. Frog my man, I know you've been at this longer than I've been alive and you get the game here. You don't write rules depending on the driver, or because someone can do something someone else can't.

Agreed. Taking it a step further, I don't believe you should write rules/competition adjustments because someone chooses not to build/develop/acquire something to the fullest extent allowed by the rules. What most people do, or what the average racer does shouldn't be the yard stick. This is likely the root of my pro-Fit bias. I understand why it was best to introduce the FFit at a performance level on par with a very good Kent, but shouldn't the long term goal be to have the very best FFit "equal" to the very best Kent?

Do any one of those whizbangy parts make a difference on their own? Do they collectively? Yet, do people still spend obscene amounts of money on them? Hell yeah they do.

Yes, some much more so than a +.010" overbore. ABSOLUTELY their sum net performance gain could be pretty substantial.

Spend $500 on an alloy diff carrier, so everyone else does and we just spent $500 to go the same minuscule amount of speed faster. It's ridiculous.

Yep. It's even more ridiculous when the items are highly consumable. At least the diff carrier lasts a long time.

[reidhazelton]

Agreed. Taking it a step further, I don't believe you should write rules/competition adjustments because someone chooses not to build/develop/acquire something to the fullest extent allowed by the rules. What most people do, or what the average racer does shouldn't be the yard stick. This is likely the root of my pro-Fit bias. I understand why it was best to introduce the FFit at a performance level on par with a very good Kent, but shouldn't the long term goal be to have the very best FFit "equal" to the very best Kent?

I wasn't clear. When I said 'because someone can and someone can't' it referred to talent, not the car. Just because someone is a better driver doesn't mean they get a different rule set. The yardstick should be what is affordable for the mid pack guy. If that's not, you're left with the few who can afford it and then all stand around asking where everyone went.

You write rules, in part to keep costs down.

How it was brought in and at what power level is another debate. I'm pro-fit as well - as it as brought in. I have one of the very best Kents. I'd trade it on the spot for a Honda. It's funny, I say this every time yet no one takes me up on it and I've been saying it for 5 or 6 years. If the Ford was faster, I'd keep it and just race less to afford to keep it.

The reason the Fit was brought in equal to a 'good kent' was because when you bring in a new engine unless you want to kick out all the car owners who can't or can't afford to convert, it cannot be equal to the best. Look at FC. In the beginning the Pinto guys said "uh, after a few years these Zetecs are kicking our butt'. They were told they are just Zetec haters and its cheaper in the long run, so be quiet and race. Now, everyone asks where all the Pintos went. How could this happen? Our fields are dismal! Gee, I don't know what happened, who could have ever seen that coming?

SCCA is not pro budget racing. There are a lot of people who cannot afford to convert because the upfront, lump sum cost is prohibitive. They are the ones forced out of the new engine is faster, or even equal and perceived to be faster. Right or wrong, it happens. Every time. Same in F500. Same now in FF.

[LenFC11]

Will

Exactly how I see it

Dayrl

You again agree there is an advantage. Yet still say it's ok because it's not much.. why introduce any advantage?? What is the benefit

In previous post you state 10 lbs is a lot and you would take a 10 lbs advantage.. now you say this rule change is equal to a 6 lbs advantage and is not significant.. so 60% advantage is not significant??

[stonebridge20]

The conversation is a moot point. This is a done deal with no member input.
This is the exact kind of crap that drove me out of SCCA

[Daryl DeArman]

The yardstick should be what is affordable for the mid pack guy. If that's not, you're left with the few who can afford it and then all stand around asking where everyone went.

Yes, when most everybody in the class can afford to own equipment good enough to win you get large fields (SM and SRF) come to mind.

The reason the Fit was brought in equal to a 'good kent' was because when you bring in a new engine unless you want to kick out all the car owners who can't or can't afford to convert, it cannot be equal to the best. Look at FC. In the beginning the Pinto guys said "uh, after a few years these Zetecs are kicking our butt'. They were told they are just Zetec haters and its cheaper in the long run, so be quiet and race. Now, everyone asks where all the Pintos went. How could this happen? Our fields are dismal! Gee, I don't know what happened, who could have ever seen that coming?

I agree with the "why" it makes sense, just don't think it should be the long term goal. Eventually, the Zetec, the F600, the Fit should be the standard. Heck, nobody is complaining now about the where all the Cortinas went .

[Daryl DeArman]

You again agree there is an advantage. Yet still say it's ok because it's not much.. why introduce any advantage?? What is the benefit

In previous post you state 10 lbs is a lot and you would take a 10 lbs advantage.. now you say this rule change is equal to a 6 lbs advantage and is not significant.. so 60% advantage is not significant??

Yes, I agree that there is an advantage over the standard piston.

When I was referencing the 10#, I didn't say that is was a lot. I said it was a larger performance factor than the +.010" piston will be, yet almost everybody comes across the scales at least 10# over minimum as their calculated risk / safety cushion. So, if they don't have a problem with being 10# over, why would they have a problem giving up about 1 HP?

The 6# is what would roughly end up with the same power to weight ratio (1106# at +.010" or 1100# at std bore) producing the same forward acceleration (all else equal of course). The 6# lighter does yield better deceleration and lateral acceleration.

Therefore the difference on the track won't even be as much as 6# so of course I'd take the 10# advantage.

[Heel-and-toe]

Interesting that well over 50% of the posts in this thread are by people who are not involved in the class and in several instances not even part of the SCCA. Good indication of the motivations involved.

[stonebridge20]

Interesting that well over 50% of the posts in this thread are by people who are not involved in the class and in several instances not even part of the SCCA. Good indication of the motivations involved.

Doesn't really matter if you're "involved in the class"
If you're a member of SCCA (which I still am), you should be pissed about how this rule change went down.

[Daryl DeArman]

Interesting that well over 50% of the posts in this thread are by people who are not involved in the class and in several instances not even part of the SCCA. Good indication of the motivations involved.

Motivations could be to express their frustrations with the process, or their frustrations with a class they used to be involved with. Could be just enjoying a good debate. Could be an axe to grind with the pro-Honda folks. Could be they don't have a vested interest in the outcome and therefore could be more objective. Might just be a combination of most of the above.

[reidhazelton]

Interesting that well over 50% of the posts in this thread are by people who are not involved in the class and in several instances not even part of the SCCA. Good indication of the motivations involved.

Hey Dave - It seems it's perhaps most, and those in that group were once involved. I wonder why they are not? Hum....

It should be seen as a vary large flashing red light with a screaming siren when the majority of people on a thread are people who are no longer racing or racing much less, citing issues like the very one being discussed, than those who are currently involved.

"Where did all the cars go?"

"Why did all the Kents/Pintos/494s/S2000s/FBs go away - how do we get them back?"

"How could this ever happen?"

Answer - They went home because they were ignored, or told their concerns were protectionism and they were just haters. Or, found ad hominem arguments rather than debate of the merits of the ruling. There's that too.