2618 Piston Street Use Longevity

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4vpc
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Re: 2618 Piston Street Use Longevity

Postby 4vpc » Sun Aug 06, 2017 4:26 am

digger wrote:
4vpc wrote:
BigBro74 wrote:
Or maybe they just have different design criteria/constraints :idea:

like some shmuck putting 30 psi boost or bunch of nitrous.....................you pick, but usually not warranty at 100,000mi or emissions....

:roll: Sheesh.


They're just nowhere near as intelligent and/or haven't put the required R&D in, not all obviously, but some surprisingly big names.
You can put a lot of boost and make a lot of power through a stock F20C piston.


i agree on the R&D when you are going to sell thousands and thousands of sets the cost of R&D can be readily absorbed. when you order a one of set off custom pistons they wouldn't do any testing specific to your application, its all best guess, generic, err on side of caution otherwise its too expensive.


Yes, I was pointing out why it was, not apportioning blame because I can see why. Ultimately what you need to do is get someone to design the best piston for your application and do your own R & D.

What i'm trying to point out here is that there are pistons out there which are readily available for you to study, like anyone else I started out thinking a piston is just a piston right? Slowly it dawns they ain't, then holding one of those was like they'd reinvented the wheel . Knowing what they have done is easy, why they did it something else. Getting someone to replicate it? This is where I realised some manufacturers are just plain dumb. When you show them what you want they didn't even know it existed, they look at you like you just stepped off a spaceship. 'Oval around the crown? Are you kidding? You mean like the Honda bike with two conrods?' And those that do recognise it don't have the machinery to do it - or say they don't and this is 25+ yr old technology we're talking about here.
Did you check out the bore clearance in that manual? Honda are saying it's worn beyond service limits with a much smaller clearance than you're boring to in the first place!

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Re: 2618 Piston Street Use Longevity

Postby 4vpc » Sun Aug 06, 2017 4:36 am

Mark O'Neal wrote:
4vpc wrote:If you can get your hands on a forged OE Honda F20C piston then I would recommend it, you'll learn lots with a straight edge and simple measuring tools and that's a design that is now 17yrs out of date. Top ringland is barrel shaped and looking on top of the crown you'll notice it's oval too. Bore clearance is less than leading manufacturers were using with cast pistons many years ago, and not by a little bit either, spec on P182 here: http://www.wedophones.com/Manuals/Honda ... (2000-2003)%20Service%20Manual.pdf

The top ringland is not only oval in circumference and barrel shaped from the side, but it's also been treated in some way as it's dark grey, I'm assuming anodised, to stop it wearing, but unsure why they only did that part.
A lot of aftermarket piston manufacturers are still pretty dumb and so are your pistons, that's why they still say use .040 clearance on a 3.385 piston, they haven't done any R&D, so as long as it slops up and down ok without nipping it does the job - to a fashion. I wouldn't be at all surprised if aftermarket slugs for that engine are nowhere near as cleverly designed as the Honda ones were.
The problems are finding an intelligent piston manufacturer who has the equipment to do the job and also someone who can design one, but if you take some pointers yourself from something like the F20C you'll get a lot closer than most to designing a good piston, then you've got to do your own R&D and find out how close you can get it before it hits the bore, because your block and bore is unlikely to be made in the same way as that one was......



How do you get the rings to seal at .040 clearance?


Sorry i'm from the future so 100% metric, have to dumb down and then the wheels fall off as imperial means nothing to me.
.1mm = .004 right? I got told off on here for being over precise, but I think that is .00393701

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Re: 2618 Piston Street Use Longevity

Postby kimosabi » Sun Aug 06, 2017 7:31 am

4vpc wrote:Environmental rules aren't stupid, people who think they are, well...
To create a standard production engine that puts out 120bhp per litre, revs to 8800+, covers huge amounts of mileage without needing rebuilding or breaking and meets all emission rules didn't come from someone low on intelligence.


Emissions rules can be achieved without a superduper built engine. Look at BMW's N63 or S63 V8's. Fancy stuff, exhaust in the middle and intakes on the outsides. They burn oil like there's no tomorrow, manufacturer actually decreased service intervals on them to not have a bunch of customers complain about the oil level warnings through warranty.

But they clear emissions.

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Re: 2618 Piston Street Use Longevity

Postby Warp Speed » Sun Aug 06, 2017 7:34 am

4vpc wrote:
Mark O'Neal wrote:
4vpc wrote:If you can get your hands on a forged OE Honda F20C piston then I would recommend it, you'll learn lots with a straight edge and simple measuring tools and that's a design that is now 17yrs out of date. Top ringland is barrel shaped and looking on top of the crown you'll notice it's oval too. Bore clearance is less than leading manufacturers were using with cast pistons many years ago, and not by a little bit either, spec on P182 here: http://www.wedophones.com/Manuals/Honda ... (2000-2003)%20Service%20Manual.pdf

The top ringland is not only oval in circumference and barrel shaped from the side, but it's also been treated in some way as it's dark grey, I'm assuming anodised, to stop it wearing, but unsure why they only did that part.
A lot of aftermarket piston manufacturers are still pretty dumb and so are your pistons, that's why they still say use .040 clearance on a 3.385 piston, they haven't done any R&D, so as long as it slops up and down ok without nipping it does the job - to a fashion. I wouldn't be at all surprised if aftermarket slugs for that engine are nowhere near as cleverly designed as the Honda ones were.
The problems are finding an intelligent piston manufacturer who has the equipment to do the job and also someone who can design one, but if you take some pointers yourself from something like the F20C you'll get a lot closer than most to designing a good piston, then you've got to do your own R&D and find out how close you can get it before it hits the bore, because your block and bore is unlikely to be made in the same way as that one was......



How do you get the rings to seal at .040 clearance?


Sorry i'm from the future so 100% metric, have to dumb down and then the wheels fall off as imperial means nothing to me.
.1mm = .004 right? I got told off on here for being over precise, but I think that is .00393701


And there you have it! LOL

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Re: 2618 Piston Street Use Longevity

Postby digger » Sun Aug 06, 2017 7:47 pm

4vpc wrote:
Mark O'Neal wrote:
4vpc wrote:If you can get your hands on a forged OE Honda F20C piston then I would recommend it, you'll learn lots with a straight edge and simple measuring tools and that's a design that is now 17yrs out of date. Top ringland is barrel shaped and looking on top of the crown you'll notice it's oval too. Bore clearance is less than leading manufacturers were using with cast pistons many years ago, and not by a little bit either, spec on P182 here: http://www.wedophones.com/Manuals/Honda ... (2000-2003)%20Service%20Manual.pdf

The top ringland is not only oval in circumference and barrel shaped from the side, but it's also been treated in some way as it's dark grey, I'm assuming anodised, to stop it wearing, but unsure why they only did that part.
A lot of aftermarket piston manufacturers are still pretty dumb and so are your pistons, that's why they still say use .040 clearance on a 3.385 piston, they haven't done any R&D, so as long as it slops up and down ok without nipping it does the job - to a fashion. I wouldn't be at all surprised if aftermarket slugs for that engine are nowhere near as cleverly designed as the Honda ones were.
The problems are finding an intelligent piston manufacturer who has the equipment to do the job and also someone who can design one, but if you take some pointers yourself from something like the F20C you'll get a lot closer than most to designing a good piston, then you've got to do your own R&D and find out how close you can get it before it hits the bore, because your block and bore is unlikely to be made in the same way as that one was......



How do you get the rings to seal at .040 clearance?


Sorry i'm from the future so 100% metric, have to dumb down and then the wheels fall off as imperial means nothing to me.
.1mm = .004 right? I got told off on here for being over precise, but I think that is .00393701


What alloy are they ? 0.04mm is 0.0016". A piston that size would be 0.0020-0.0025" in 4032 according to JE. Pretty much all forged Pistons I've used are oval shaped in plan view and barrel shaped in elevation view.

Can you tell us how the ovality and barrel sizes compares between the oe and aftermarket forged?

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Re: 2618 Piston Street Use Longevity

Postby englertracing » Sun Aug 06, 2017 9:26 pm

4vpc wrote:Environmental rules aren't stupid, people who think they are, well...
To create a standard production engine that puts out 120bhp per litre, revs to 8800+, covers huge amounts of mileage without needing rebuilding or breaking and meets all emission rules didn't come from someone low on intelligence.



FYI, that motor isn't the holy grail
BMW is making 199hp/L from the s1000 engine and meeting emissions, no variable timing....

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Re: 2618 Piston Street Use Longevity

Postby MadBill » Sun Aug 06, 2017 11:19 pm

Power per unit of displacement doesn't scale very well. E.g., a front-running 10 cc tether car engine can produce more than 14 hp, or 1,400 hp per litre... :-k
Felix, qui potuit rerum cognscere causas.

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Re: 2618 Piston Street Use Longevity

Postby Mark O'Neal » Mon Aug 07, 2017 2:20 am

Perhaps Honda can't keep the cylinders round.......

Image

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Re: 2618 Piston Street Use Longevity

Postby 4vpc » Tue Aug 08, 2017 10:00 am

digger wrote:
4vpc wrote:
Mark O'Neal wrote:

How do you get the rings to seal at .040 clearance?


Sorry i'm from the future so 100% metric, have to dumb down and then the wheels fall off as imperial means nothing to me.
.1mm = .004 right? I got told off on here for being over precise, but I think that is .00393701


What alloy are they ? 0.04mm is 0.0016". A piston that size would be 0.0020-0.0025" in 4032 according to JE. Pretty much all forged Pistons I've used are oval shaped in plan view and barrel shaped in elevation view.

Can you tell us how the ovality and barrel sizes compares between the oe and aftermarket forged?


I don't think we're on the same page here.
.1mm = .004" which is the typical piston/bore clearance you are advised to use by aftermarket forged piston manufacturers at an approx bore size of 86 - 87 mm.
Now go back and read the Honda manual and see what their recommended clearance is on a well designed forged piston, there you will find the answer to your question.
The only reason I plucked that particular engine out of the ether is because it is a reliable production car engine making high power and has forged pistons fitted as standard. Whilst it is a World leader, other engines are available which also use forged pistons, try to get one and examine it.
I have no idea why this is turning into a pissing contest about who makes the best engines, you've missed the point if you want to go there, maybe my posts are being derailed for a reason....
I have no idea what grade of alloy it is, I also don't think it is really relevant to the point I am making, but agreeably it would be interesting to find out.

The ovality I mention is around the top ringland i.e. if you were looking down onto the top of the piston crown, Elliptical is maybe a better term. Yes I know skirts are elliptical.
The barrel shape is also just the top ringland viewed from the side, not the whole piston shape which I know is also that shape.
I'm trying to lead you to the water, I can't force you to drink it. I was hoping for a debate on how we can look at a well designed piston, take some notes, discuss why they did such a thing and how it could possibly be incorporated in your own pistons.
I hope you are understanding now.

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Re: 2618 Piston Street Use Longevity

Postby ijames » Tue Aug 08, 2017 11:03 am

4vpc wrote:I don't think we're on the same page here.
.1mm = .004" which is the typical piston/bore clearance you are advised to use by aftermarket forged piston manufacturers at an approx bore size of 86 - 87 mm.


We're not on the same page because you started off by saying

4vpc wrote:A lot of aftermarket piston manufacturers are still pretty dumb and so are your pistons, that's why they still say use .040 clearance on a 3.385 piston,


and a few people thought it was funny that you were accusing other people of being dumb when you were an order of magnitude off on the typical piston clearance. Kind of called your credibility into question when you were bragging about the Honda pistons being so much tighter, especially when you never noticed the mistake, although you did finally get it correct in this most recent post. Since I don't have access to Honda service manuals, just what is the piston to wall spec on those?
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I may be a guru at something, but definitely not engine building, not even on the Internet.

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Re: 2618 Piston Street Use Longevity

Postby 4vpc » Tue Aug 08, 2017 1:33 pm

ijames wrote:
4vpc wrote:I don't think we're on the same page here.
.1mm = .004" which is the typical piston/bore clearance you are advised to use by aftermarket forged piston manufacturers at an approx bore size of 86 - 87 mm.


We're not on the same page because you started off by saying

4vpc wrote:A lot of aftermarket piston manufacturers are still pretty dumb and so are your pistons, that's why they still say use .040 clearance on a 3.385 piston,


and a few people thought it was funny that you were accusing other people of being dumb when you were an order of magnitude off on the typical piston clearance. Kind of called your credibility into question when you were bragging about the Honda pistons being so much tighter, especially when you never noticed the mistake, although you did finally get it correct in this most recent post. Since I don't have access to Honda service manuals, just what is the piston to wall spec on those?


You do, I provided the link to it and even the page number.

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Re: 2618 Piston Street Use Longevity

Postby ijames » Tue Aug 08, 2017 1:41 pm

4vpc wrote:You do, I provided the link to it and even the page number.

The link doesn't work for me, error 404 not found.
Regards,
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I may be a guru at something, but definitely not engine building, not even on the Internet.

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Re: 2618 Piston Street Use Longevity

Postby 4vpc » Tue Aug 08, 2017 2:25 pm

ijames wrote:
4vpc wrote:You do, I provided the link to it and even the page number.

The link doesn't work for me, error 404 not found.


Does this work: http://www.wedophones.com/Manuals/Honda ... (2000-2003)%20Service%20Manual.pdf
?

For some reason when I C&P it doesn't work either, If not this is the Google search I used 'Honda S2000 Workshop manual': https://www.google.co.uk/search?q=honda ... e&ie=UTF-8

It's the top one.
Thought i'd be better off letting you get the dimensions rather than me #-o

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Re: 2618 Piston Street Use Longevity

Postby ijames » Tue Aug 08, 2017 10:51 pm

That's the same link as before, and fails. The google search works, and I don't see any difference between the url that google links to, and yours, but when I copy and paste the google link I get the same fail. Oh well. My theory is that the ()'s are causing a problem since the url gets truncated at the ), but who knows.
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I may be a guru at something, but definitely not engine building, not even on the Internet.



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