Bangbug Posted August 28, 2015 Share Posted August 28, 2015 Today's topic is brought to you by dirtpoordaddy.com and Dirty Freegan Mods Ltd. Hello, Not wanting to buy forged pistons as the arse has just dropped out of work I figure I would try and make do with what I have. I have some domed 10:1 pistons and I'm going to use them in a turbo build. FE-DOHC. Some measurements have left me with 5.18mm in the piston crown if I flat top these buggers (about 1.8mm off) Having an engine builder owe me money is handy so I went to see him with my silly idea. He reckons have at it. "I've got oil squirters to help with cooling the piston" I offer. "Block them off, they're just creating drag" and as I sit here I ask google Oil squirter which it starts to suggest:deleteblock off plug So I guess it's popular. But this ain't no race car scraping out 1/2 hp advantages so methinks I'll leave em alone, cooler piston sounds better than any other trade off. And then..... "Mill off these here piston skirts" he reckons. "Won't that make it rattly at start up like a forged piston?" I respond. "Yeah and what?" was his squinty eyed statement. I suppose pistons pull a couple thousand g's.... but that seems excessive, I think he's getting excited and I'd like to see him do the math though some basic math would be 3000G x 9.8ms/s x 0.02g = 588W.Non-linear accelleration etc etc would be some area under the curve type shit.... I digress. Who's had a go at modifying pistons and how did it turn out? Quote Link to comment Share on other sites More sharing options...
Gaz Posted August 28, 2015 Share Posted August 28, 2015 Keep oil squirters no doubt! That is all. What about heat treatments to increase piston strength? There are coatings that can be applied to reduce heat sink. Gaz 2 Quote Link to comment Share on other sites More sharing options...
flyingbrick Posted August 28, 2015 Share Posted August 28, 2015 What's the worst that could happen? (Hahaha) 2 Quote Link to comment Share on other sites More sharing options...
Grotty Posted August 28, 2015 Share Posted August 28, 2015 Flat top them and keep oil squirts. 1 Quote Link to comment Share on other sites More sharing options...
Frosty Posted August 28, 2015 Share Posted August 28, 2015 If you remove the dome it WILL reduce the thickness of the crown of the pistion making it more prone to overheating in the middle. The reduced skirt will only cause problems with a OEM pistion unless you are very carefull, even stock you see cracked skirts from time to time and they will need to be adjusted for weight once machined. I would also think under piston cooling is a great idea. It really sounds like a set of Forged pistons is what you need, mods to a OEM piston are only going to reduce thier life span further. 1 Quote Link to comment Share on other sites More sharing options...
evil_si Posted August 28, 2015 Share Posted August 28, 2015 Leave the skirt and oil squirter, machine the crown and have it ceramic coated 1 Quote Link to comment Share on other sites More sharing options...
cute wee gem Posted August 28, 2015 Share Posted August 28, 2015 Slam them in as is and run e85 7 Quote Link to comment Share on other sites More sharing options...
kpr Posted August 28, 2015 Share Posted August 28, 2015 ^ depends how much boost you are going to wind into it. around 10psi should be fine on 10:1 running on 98 pump gas. my stinky 4age done 10psi with 11.5:1 5 Quote Link to comment Share on other sites More sharing options...
Bangbug Posted August 29, 2015 Author Share Posted August 29, 2015 E85 would be perfect! I'll have a look at coatings. This stage flattop and leave the rest, longevity would be nice, I think I could scrape 12psi out of the turbo and will probably just run two maps. Regular 7psi map and fuck your flash car 12psi map. Though I found out yesterday that a ford ranger is faster than a brand new lamborghini. Made the fucker move over he was sooooooo slow, poor car Quote Link to comment Share on other sites More sharing options...
Ghostchips Posted August 29, 2015 Share Posted August 29, 2015 What about heating the part you need to flatten with a torch? It will slump inward and retain thickness. This is very risky however, for obvious reasons. 2 Quote Link to comment Share on other sites More sharing options...
Bangbug Posted August 29, 2015 Author Share Posted August 29, 2015 They're aluminium. Aluminium is solid until a billionth of a second where it's soft then it's liquid. Hahaha. Feck! Diesel pistons will be forged steel real soon just you wait 1 Quote Link to comment Share on other sites More sharing options...
Testament Posted August 30, 2015 Share Posted August 30, 2015 either A) dont mill them at all and run 10:1 as suggested and pull boost and or timing to get it to hold together or just mill a small amount rather than right to flat. milling the skirts would only be an idea worth considering if you are raising the engine redline and you are trying to lighten the rotating assembly. oil squirters, if they are there probably just leave them unless the engines are known to have shitty oil pressure. 2 Quote Link to comment Share on other sites More sharing options...
cletus Posted August 30, 2015 Share Posted August 30, 2015 leave them stock and put in a fat head gasket? 1 Quote Link to comment Share on other sites More sharing options...
kpr Posted August 30, 2015 Share Posted August 30, 2015 ^yuck if you are only running 7-12psi. stick with 10:1. even if you cant quite get that much boost out of it, a few psi less isn't going to the end of the world. will have a more responsive engine with the extra compression, and wont lose much power. ramp the timing off aggressively past your max boost, so if it over boosts no drama. plus keep good gas in it and will be sweet 5 Quote Link to comment Share on other sites More sharing options...
drftnmaz Posted September 6, 2015 Share Posted September 6, 2015 leave as is... 10:1 with 8psi will make the same sort of power as 9:1 with 12psi, but 10:1 will be much much nicer to drive!If you are really worried then run AV gas, we run 10:1 with 18psi with a huge turbo on av and it's awesome all round 2 Quote Link to comment Share on other sites More sharing options...
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