Question about piston/rod pricing

  1. Saxperience Post Whore Joined: Sep 2007 Someones Bumhole Posts: 5721 Mk2 16v Desire
    #1
    Just after abit of help here, doing my dissertation at uni im wondering what you would be prepared to pay for a piston/rod setup package out the box. specified rod length piston bore etc to suit needs. included:

    Con-rod
    Con-rod bolts
    G/pin
    Piston
    Ring set

    Its not for a TU engine it is for another PSA engine but if someone turned round and said here you go that will handle 280-300Bar total pressure & its rather light would that make up for a hefty price tag or would you stick to a smaller power but take a cheaper build?


    PCU 2 by T.walker5190, on Flickr

    Thats an unfinished image of basically what it is, it would be for a race/high power application. Basically i have a completed package and my problem is materials. the cost difference between optimum strength and 'good' strength is quite alot. Theres no point in finishing it in its ultimate form if it costs to much for anybody to want it if you see what i mean.
  2. Saxperience Forum Bum Joined: Aug 2010 Midlands Posts: 2530 AX 16v Turbo
    #2
    No point in f1 rods for a home build project, you need a balance between cost and effectiveness. You do know there are only a handful of people that make rods? Budget ones made along side crower etc. They're all the same rod 9/10.
  3. Established Member Joined: Apr 2008 Dudley Posts: 1634 106 GTI
    #3
    I think what your up against with the pricing is the "it works factor" people who want reliability invest in specific setups like yours and look for the ultimate compromise in an engine. Then there are the people in the "it works factor" category who simply want to build something thats fast cheap and works even if its for a short period of time. Well how does this affect you as your pricing your goods at the other people. well the people on the fence as to weather going in for a big build is worth it or they are not decided on just doing it cheaply actually bring down the pricing of the high value goods as they are constantly looking at the cheapest way of buying the most expensive part!

    My view yes people will pay for the high end product however the marketing needs to be good and the contacts made who have bought need to be exploited with case studies and marketing further on there projects!
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  4. Frequent Poster Joined: Oct 2005 Posts: 751
    #4
    280-300bar peak cylinder pressure? fuck me thats high. typical pmax for downsized boosted engines is about half that.
  5. Regular Poster Joined: Sep 2011 Hertfordshire Posts: 250 2000 Saxo Woodland Green VTS, 2002 Mazda MX5
    #5
    out of question have you done some FEA analysis to prove your not going above the materials yield stress point? manufacturers will typically look at this so they can design their engine to achieve maximum efficiency and thus determine their compression ratio's and other engine design parameters without destroying the raw materials.

    also partly on what unreal106 said you need to really identify your market, is the product for low, mid or high end customers. Chances are if your looking to make it profitable your more likely to succeed tackling the low end spectrum of customers due to their being the wider market, to which then it begs the question who's going to want to pay for such a product? - just some thoughts but bit of past uni advice make sure you backup your theories because lecturers will rip your ideas to shreds if they find a potential loophole in your presentation and how you answer those questions will determine how good a grade you get! good luck though looks good and where you can provide as much research and evidence as you can!
  6. Saxperience Post Whore Joined: Sep 2007 Someones Bumhole Posts: 5721 Mk2 16v Desire
    #6
    Quote:
    Originally Posted by e8_pqck View Post
    No point in f1 rods for a home build project, you need a balance between cost and effectiveness. You do know there are only a handful of people that make rods? Budget ones made along side crower etc. They're all the same rod 9/10.
    They are supposed to be a high spec item for a race car not for a home build

    Quote:
    Originally Posted by unreal106 View Post
    I think what your up against with the pricing is the "it works factor" people who want reliability invest in specific setups like yours and look for the ultimate compromise in an engine. Then there are the people in the "it works factor" category who simply want to build something thats fast cheap and works even if its for a short period of time. Well how does this affect you as your pricing your goods at the other people. well the people on the fence as to weather going in for a big build is worth it or they are not decided on just doing it cheaply actually bring down the pricing of the high value goods as they are constantly looking at the cheapest way of buying the most expensive part!

    My view yes people will pay for the high end product however the marketing needs to be good and the contacts made who have bought need to be exploited with case studies and marketing further on there projects!
    Cool cheers matey, it isnt a marketing piece luckily it is purelly design but ive got to throw a BOM and a short part about potential buyers etc in there. Its not aimid at selling to a mass market, more aimed along side selling them as an item to a few or in a full engine supply, something like that.

    Quote:
    Originally Posted by yr51ocw View Post
    280-300bar peak cylinder pressure? fuck me thats high. typical pmax for downsized boosted engines is about half that.
    Yea it is high but the initial aim was to make something away from low power stuff. Although it is based around a PSA engine its not 100% fixed to them dimensions. A case study i read was 350pmax!

    Ive ran a version of them at 250max last night after i threw this up and knocked it down to a cheaper material which i think i may stick at and just mention that another material choice can mean 300 can be ok if a few changes are made etc.

    Quote:
    Originally Posted by Wee_monkey1987 View Post
    out of question have you done some FEA analysis to prove your not going above the materials yield stress point? manufacturers will typically look at this so they can design their engine to achieve maximum efficiency and thus determine their compression ratio's and other engine design parameters without destroying the raw materials.

    also partly on what unreal106 said you need to really identify your market, is the product for low, mid or high end customers. Chances are if your looking to make it profitable your more likely to succeed tackling the low end spectrum of customers due to their being the wider market, to which then it begs the question who's going to want to pay for such a product? - just some thoughts but bit of past uni advice make sure you backup your theories because lecturers will rip your ideas to shreds if they find a potential loophole in your presentation and how you answer those questions will determine how good a grade you get! good luck though looks good and where you can provide as much research and evidence as you can!
    Yea ive done alot of FEA on it matey im sick of looking at it haha. Its definatly for a high end market i should of said when i asked more along the lines of if you were in the market to enter Le Mans or something like that for example.

    I guess the more work the better too so if i get the stuff done i need done today i may run some more tests at more like 200-220pmax and see what rough costing i can see.

    Cheers for the replies
  7. Frequent Poster Joined: Oct 2005 Posts: 751
    #7
    I have never seen an engine with peak cylinder pressures that high, most in cylinder pressure transducers dont even go that high. The highest I've seen was 180bar, and that was only because of heavy knock. Be interested to see your analysis.

    Any links to the case study showing 350bar?
  8. Saxperience Post Whore Joined: Sep 2007 Someones Bumhole Posts: 5721 Mk2 16v Desire
    #8
    180bar in what engine? No internet links only a few papers matey sorry it was a cosworth renault engine 1500cc 2020hp in an F1 that got banned.
  9. Frequent Poster Joined: Oct 2005 Posts: 751
    #9
    prototype engine I am working on.

    Ah, that makes sense, not exactly a run of the mill high performance engine! and certainly not run on any type of fuel that you can easily get hold of, hence being able to run those kind of pressures. (probably ran close to MBT ignition timing too)
  10. Saxperience Post Whore Joined: Sep 2007 Someones Bumhole Posts: 5721 Mk2 16v Desire
    #10
    Aw yea no by no means run of the mill, but as per usual motorsport fags ban anything thats good! it was around 70-72% therm eff too which makes it even more of a pisser that it got banned! the guy who build it is my engines lecturer.
  11. Frequent Poster Joined: Oct 2005 Posts: 751
    #11
    so can I ask why you are designing a piston capable of those pressures? And then "advertising" them for a PSA engine, the rest of the engine will not be able to cope, hence re-optimisation of the piston would be possible to reduce mass.

    Have you also looked into piston skirt and ring land profile? Scuffing of the bores can easily happen if this is incorrect and most companies are not willing to divulge it as it is classed as intellectual property.
  12. Saxperience Post Whore Joined: Sep 2007 Someones Bumhole Posts: 5721 Mk2 16v Desire
    #12
    Yea the PSA engine ive use ive used basically as a base for dimensions to work from if you like it dosent need to be used within a standard block.

    Profile as in dimensions of the skirt and lands for thermal expansion?
  13. Frequent Poster Joined: Oct 2005 Posts: 751
    #13
    I still think im missing the point? It sounds a really interesting piece of work and I would love to read about the process you go through, however I am not sure what the point of it is?

    You began by asking

    Quote:
    wondering what you would be prepared to pay for a piston/rod setup package out the box. specified rod length piston bore etc to suit needs
    Quote:
    ts not for a TU engine it is for another PSA engine but if someone turned round and said here you go that will handle 280-300Bar total pressure & its rather light would that make up for a hefty price tag or would you stick to a smaller power but take a cheaper build?
    But then surly people would be prepared to pay more from something that is even lighter, but itsn't capable of being used @ 350bar PMax?

    Yeah, piston skirt profile and top land profile/clearance. These are probably the most difficult thing to get correct in piston design, the crown and under body can be get very close via FEA, but the skirt and piston profile often takes a few iterations in running engines to perfect as it is difficult to simulate the true loads (mechanical and thermal) that the piston will be subject to. This ends up being an empirical data which piston manufactures end up building up over a long time.
  14. Saxperience Post Whore Joined: Sep 2007 Someones Bumhole Posts: 5721 Mk2 16v Desire
    #14
    It was intresting when i started it now its tedious ha. Its got to be handed in a week from today thankfully then its out the way!

    Yea maybe i didnt word it correctly, i didnt mention the engine it was for as if dosent really matter, more intrested in the point would people rather sacrafice a little on performance/reliability for a greater reduction in price if you were building a race car. metephorically speaking if you needed it to handle 250Bar.

    Yea the clearence is as accurate as i can get it with FEA and the relevent hand calculations. Ive taken the skirt expansion through the usual beam calculation then used some points along it to create the curve then ran it through FEA etc
  15. Frequent Poster Joined: Oct 2005 Posts: 751
    #15
    is this all a theoretical study for a uni project? Are any parts going to be made and used in a fired engine?

    Would you be willing to share your final piece of work? Always interested in research projects.
  16. Saxperience Post Whore Joined: Sep 2007 Someones Bumhole Posts: 5721 Mk2 16v Desire
    #16
    Yea just all for uni, none of it will be fit to an engine, id have to fund it if i wanted the bits made sadly. Yea it is just a theory, design & analysis piece really. I think i have to wait a set amount of time until its been marked etc before i can share any of it. The picture i uploaded isnt of the final pieces, got to be careful what you share before its marked else they can void the work if there is any doubt its not my own.