Stock piston specifications

Dr.Jeff

True Classic
Do we have the detailed dimensions for the stock 1500 SOHC X1/9 pistons listed anywhere? Basically I'm talking about all of the critical design specifications dimensionally. Thanks
 
Some dimensions are listed in the Ultimate SOHC thread. To get all the dimensions, you will most likely have to have one on hand, and mic it.
 
Do we have the detailed dimensions for the stock 1500 SOHC X1/9 pistons listed anywhere? Basically I'm talking about all of the critical design specifications dimensionally. Thanks

General piston specs are listed in that book known as a "Factory Shop Manual". Also found in another odd place called a "Haynes Owners Workshop Manual" (pages 31-33 for basic [1300] piston design photos, pages 158-159 for 1500 piston specs).
 
General piston specs are listed in that book known as a "Factory Shop Manual". Also found in another odd place called a "Haynes Owners Workshop Manual" (pages 31-33 for basic [1300] piston design photos, pages 158-159 for 1500 piston specs).
Not the data I asked about. Those sources only offer very basic service data for diameters, ring size, etc. As I stated, I'm looking for detailed dimensions for the critical design specifications. Much more involved than general service specs. But thanks for the input anyway.
 
Sounds like you need a set of engineering drawings. I wonder if Fiat or the OEM have them available if you find the right person?
 
Is this what your looking for?
From Midwest-Bayless site...
12277_3_.jpg
 
Is this what your looking for?
Thanks Andy. I just searched through their site and found where this came from. This is the type of information I'm looking for, however it is for a high performance one with increased compression. Ideally I'd like to get the same information for a stock piston. But it is more than I had before. ;)
 
What level of detail are you looking for? Like a tooling drawing with radii and chamfers etc or something thats in between the pic you have and a full on drawing?
 
What level of detail are you looking for?
Enough detail to approach piston manufacturers about some special made items. Frankly I'm not positive how much info they need to be able to decide if they are interested and how much it will cost. But I figure it will be about what's in the pic (added to what we already know from the manual), but for a stock piston (that pic's for a high compression one). Thanks.
 
Enough detail to approach piston manufacturers about some special made items. Frankly I'm not positive how much info they need to be able to decide if they are interested and how much it will cost. But I figure it will be about what's in the pic (added to what we already know from the manual), but for a stock piston (that pic's for a high compression one). Thanks.

Jeff, when I bought high compression pistons for the Ecotec, Wiseco had 13.8 :1 "standard" pistons. I had them machine the valve pockets slightly deeper and had the pistons coated. Other than that everything was normal Ecotec dimensions. This was about 6 years ago and the cost was $625 for the set.
Not sure what you are designing but if you are changing basic dimensions (moving the pin, changing the ring dimensions, redesigning the crown or skirts, then you will probably be starting with a rough unmachined blank. If you are wanting to do a special crown shape then you could start with a high compression piston and have it machined to your spec. All you need then is enough material to work with. AND, machine shop work to get where you want to go.
It could be rather expensive.
Wiseco might be a place to start, don't know if they have 1500 pistons of not.
 
Enough detail to approach piston manufacturers about some special made items. Frankly I'm not positive how much info they need to be able to decide if they are interested and how much it will cost. But I figure it will be about what's in the pic (added to what we already know from the manual), but for a stock piston (that pic's for a high compression one). Thanks.
I think the drawing above has the rings specs wrong. The thicker ring is most likely the bottom ring, not the first.
I don't have enough experience to design a custom piston myself so I rely on someone else to advise me. If you reach out to the piston manufacturer that you want to work with you might find that they have the information on hand that they need to make your custom pistons . You'll need to provide them with some basic info like bore size, and valve head diameters though.
They can also probably give you some good application specific suggestions about things like which rings to use and where to place them on the piston. (Hint, use a piston diameter that's common, that allows you to choose from a good selection of off the shelf rings. For example 87 mm. Folks like Total Seal will make custom rings for you, but if you're designing the piston you would want a pretty good reason to want to use something different than everyone else.)
If you have a custom dome shape that you want to replicate some piston manufactures can scan an example to replicate them.
A good piston manufacturer can also recommend a wrist pin, and a method to retain it.
You might also consider buying a spare set while you're having the custom set made.
 
I think the drawing above has the rings specs wrong. The thicker ring is most likely the bottom ring, not the first.
I don't have enough experience to design a custom piston myself so I rely on someone else to advise me. If you reach out to the piston manufacturer that you want to work with you might find that they have the information on hand that they need to make your custom pistons . You'll need to provide them with some basic info like bore size, and valve head diameters though.
They can also probably give you some good application specific suggestions about things like which rings to use and where to place them on the piston. (Hint, use a piston diameter that's common, that allows you to choose from a good selection of off the shelf rings. For example 87 mm. Folks like Total Seal will make custom rings for you, but if you're designing the piston you would want a pretty good reason to want to use something different than everyone else.)
If you have a custom dome shape that you want to replicate some piston manufactures can scan an example to replicate them.
A good piston manufacturer can also recommend a wrist pin, and a method to retain it.
You might also consider buying a spare set while you're having the custom set made.

It is correct, the top ring groove is .041" and the bottom groove .1113" you might be looking at the space between rings.
 
One concern I have is that the piston manufacturers do not have all of the specs for a stock X1/9 piston to work from. For that matter they may not even know what a Fiat X1/9 is, or what the pistons look like. So if I had something to show them on paper and then tell them what I want to do, we can talk about it.
 
Not sure if this is what you really want but if you are looking for a set of pistons then send one "master" to Top End and they will put it in CAD and then have JE make the pistons. They can make a run of pistons from the CAD in any order qty but they are forged and expensive. I did this about 8yrs ago with my high compression pistons. I took the Kolben Schmidt piston and made a few modifications and sent it to them. They measured the piston and merged in the JE best practice details and I had a set of pistons like 6 weeks or so. Can't remember the price but I think it was $695ish. My piston is still on file there and can be purchased but it is not really a good cruising or street piston.

https://www.racetep.com/

If you are looking for a CAD model I may be able to help you with that next week. That can be used to source a Low Cost Country if you wish to be in the piston business. A lot of metallurgy is involved with pistons so that may be a bit risky as far as quality control etc. I will keep an eye on this post and see how it plays out.
 
What I'm really hoping is one of the piston makers have something existing that can be used to make what I want. For that matter they may already have exactly what I want. But as I stated I'll need something to show them in order to find out. This is for face to face meetings with all of the known piston manufacturers at the upcoming SEMA show. So having something in hand to illustrate the stock piston specs will be a big help.
 
What I'm really hoping is one of the piston makers have something existing that can be used to make what I want. For that matter they may already have exactly what I want. But as I stated I'll need something to show them in order to find out. This is for face to face meetings with all of the known piston manufacturers at the upcoming SEMA show. So having something in hand to illustrate the stock piston specs will be a big help.

Buy a new, unused stock piston and carry it with you. You need "new" so that there is no wear, heat deforming, or other dimensional problems. If they are interested in your project they can measure it. One thing to note though, is that if you have a new piston, someone has dimensions that they built it by. Contact them.
You probably need a drawing of "your" redesign of the stock piston. This may not need dimensions, just a sketch showing your requirements/idea.
All it takes after that is time and money.

PS: I'm really looking forward to your thread on casting your own engine blocks...
 
Unfortunately it is not practical to carry a sample piston with me around the show. Honestly you would have to experience it to fully appreciate why. But even if I could, the guys at the show would not be able to determine what could be done without measuring it first. So it's just easier to have the data on hand. With that they can check their database and get an idea what's available or possible. The nice thing about doing this at the show is all of their top guys will be together and you can discuss it with all of them at once. Amazing what can be accomplished in a couple minutes that way.
 
I currently have pistons made by several top piston manufactures - Cosworth, Venolia, Wiesco, BRE, and unknown others. To the best of my knowledge they all keep files of the products they manufacture. Some of our vendors also sell "performance" pistons. So you may be surprised at just how many piston manufactures "know" the Fiat SOHC engine. Fiat made LOTS of them and plenty of crazy people modified them over the years. Some still do. :)
Get on the phone and make a couple of calls. If you provide them with a little information and a credit card number you'll probably have some aluminum slugs that will fill those holes in your block in short order.
 
I don't think you need anything really to talk to the piston guys, maybe have the block bore info. They know their product in and out and will likely throw out 90% of any of the detail you give them and make their own version of the piston with their standard details. There is even an ala carte menu of features you can choose what treatments you want that they offer. If you are talking with them at SEMA likely they will defer you to give them a shout after the show with their sales guys for any sizable order.

If looking for a LCC provider you would likely talk to them about what they need to put together a quote, like a shopping list of needed info. They should be able to provide you a directional cost instantly or at least a bracketed cost.

https://performanceracing.com/news/pmi-acquired-private-equity-firm-kinderhook

JE version and original modified Kolben Schmidt version. The old one looks bigger but actually it is smaller OD. I had the crown modified just a bit, opened up the valve pockets for the big valves and had them made to a larger diameter
025.jpg



Dirty pics of an OEM original for reference

 
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