Anthony Gaulter Posted May 4, 2013 Report Share Posted May 4, 2013 So I have a ko3 turbo on my lupo 1.4s 75bhp I am wanting to lower the compression ratio on it but not sore if to put 2 gas kits in or to get a shim made and how thick dose the shim need to be? To lower the ratio it is the standard 10.5 to 1 now been told I need it at 9 to 1 any help would be nice. Quote Link to comment Share on other sites More sharing options...
Anthony Gaulter Posted May 4, 2013 Author Report Share Posted May 4, 2013 Lupo by anthony.gaulter, on Flickr Quote Link to comment Share on other sites More sharing options...
Anthony Gaulter Posted May 4, 2013 Author Report Share Posted May 4, 2013 Lupo by anthony.gaulter, on Flickr Quote Link to comment Share on other sites More sharing options...
Derv Posted May 4, 2013 Report Share Posted May 4, 2013 Obviously custom pistons would be a better solution. Otherwise you would need to increase the gasket thickness by ~1.2mm to get from 10.5:1 to 9:1, by my reckoning.How thick is a torqued down stock gasket? Quote Link to comment Share on other sites More sharing options...
Anthony Gaulter Posted May 4, 2013 Author Report Share Posted May 4, 2013 Don't know how thick they are not measured it but don't think it would be more than a 1mm, but did think of getting the pistons skimmed down. But every one says just space the head with a shim, how did you work out it being 1.2mm? Quote Link to comment Share on other sites More sharing options...
Anthony Gaulter Posted May 4, 2013 Author Report Share Posted May 4, 2013 *no more than Quote Link to comment Share on other sites More sharing options...
Anthony Gaulter Posted May 5, 2013 Author Report Share Posted May 5, 2013 Just mesued a gas kit it's 0.60mm so if I put 2 on it would be the 1.20mm Quote Link to comment Share on other sites More sharing options...
Derv Posted May 5, 2013 Report Share Posted May 5, 2013 Is it an MLS gasket? It may be that you need to separate the layers and still use a thin spacer. Quote Link to comment Share on other sites More sharing options...
Derv Posted May 5, 2013 Report Share Posted May 5, 2013 Just to make sure you understand, I worked out you needed 1.2mm on top of the stock gasket. So 1.8mm in total, if the original gasket is 0.60mm. Quote Link to comment Share on other sites More sharing options...
Anthony Gaulter Posted May 5, 2013 Author Report Share Posted May 5, 2013 Yes I can split the gasket and have the 1.2mm shim in the middle of the 2 half's of the gasket but just wanted to know how you worked out the 1.2mm in the first place, so if I ever need to lower the compretion on other cars or is there an online calculator? Quote Link to comment Share on other sites More sharing options...
Rich Posted May 5, 2013 Report Share Posted May 5, 2013 (edited) Lupo by anthony.gaulter, on Flickr Edited May 5, 2013 by Rich Quote Link to comment Share on other sites More sharing options...
Derv Posted May 5, 2013 Report Share Posted May 5, 2013 Yes I can split the gasket and have the 1.2mm shim in the middle of the 2 half's of the gasket but just wanted to know how you worked out the 1.2mm in the first place, so if I ever need to lower the compretion on other cars or is there an online calculator?I have an Excel spreadsheet I wrote a long time ago.The maths are pretty simple. If you know the bore, stroke and compression ratio, you can find the chamber volume. from that you can work out what increase you need to give a certain CR, either by increasing the cylinder head chamber, piston dish, or gasket thickness. Or you could use shorter pistons.I don't know how much abuse the stock pistons will take. I guess you may find out. Quote Link to comment Share on other sites More sharing options...
Anthony Gaulter Posted May 5, 2013 Author Report Share Posted May 5, 2013 Ha thanks well we shall find out how long they last, any chance you can email me that excel spreadsheet sounds like a handy thing to have my email : anthony.gaulter@gmail.com Quote Link to comment Share on other sites More sharing options...
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