danpug 1 Posted December 2, 2007 I'm reading mixed views on these, can anybody who actually knows whether they are any good not comment please? Dp engineering sell them so i can't really see them being a bodge? Share this post Link to post Share on other sites
cybernck 400 1 Cars Posted December 2, 2007 was just going to say DP Engineering have used them to great success and no problems with them . Share this post Link to post Share on other sites
danpug 1 Posted December 2, 2007 I keep reading posts on other sites about them being a bodge and causing an engine to lose its squish area? It seems like the best value way to go but i'm still unsure. Anybody know of any other companies that sell them? Share this post Link to post Share on other sites
M3Evo 0 Posted December 2, 2007 Wouldn't use a thicker gasket as a means of lower the CR of an engine myself for the reasons of squish you mention, but as you say other people have had no problems. Be interesting to see whether an engine with a set of low comp pistons would tolerate less fuel/more advance than one with a decomp plate. Share this post Link to post Share on other sites
danpug 1 Posted December 2, 2007 What problems exactly could you have? Share this post Link to post Share on other sites
projectpug 0 Posted December 2, 2007 At the end of the day there a cheap fix for lowering the compression. I wouldnt use one but thats because i like to do something properly or not at all, in other words get low compression pistons. Share this post Link to post Share on other sites
danpug 1 Posted December 2, 2007 But what exactly makes them a cheap fix? What are the results of losing some of the squish area? Share this post Link to post Share on other sites
brianthemagical 1 Posted December 2, 2007 less squish. the squish area is the periphery of the piston crown that is parallel with the head. it quenches the mixture due to high surface to volume ratios, meaning that as the cc heats up, potentially casuing det, the areas furthest fromt he s/p don't over heat. they can also add turbulence and swirl, as well as providing pressure waves around the cc to aid flame propogation for a few reasons. Share this post Link to post Share on other sites
danpug 1 Posted December 2, 2007 Would dished/machined pistons not have a similar effect? Share this post Link to post Share on other sites
Sandy 189 Posted December 3, 2007 The best value way for your plan is a 405 SRi head. Share this post Link to post Share on other sites
B1ack_Mi16 67 Posted December 3, 2007 Talking about squish, that's the reason I would never concider buying a standard T16 engine for more than just silly money. On the 405 T16 engine the top of pistons sits 5mm down the bore @ TDC.. So for example using decompressionplate and double headgaskets on an S16 engine will give you the equivalent of a T16 engine just lots cheaper. Still not my prefered way of building engines. Better get some proper pistons for the job, or as sandy mentions, a head that does the same job Share this post Link to post Share on other sites
steve@cornwall 100 Posted December 3, 2007 The best value way for your plan is a 405 SRi head. Is this the same engine as in the ZX 1.9i? If so there's one in a yard rather local to you, Dan Share this post Link to post Share on other sites
danpug 1 Posted December 3, 2007 Theres a 405 sri in drews, still complete. Share this post Link to post Share on other sites
Anthony 1,000 Posted December 3, 2007 Is this the same engine as in the ZX 1.9i? If so there's one in a yard rather local to you, Dan No it's not - the ZX 1.9 engine is basically a 1.9 GTi engine with Motronic M3.1 management (XU9JA/L engine code IIRC) 405 SRi engine is a completely different head with a larger chamber size and downdraft inlet ports that don't have the sharp bend like the GTi head, and uses a different inlet manifold that looks vaguely similar to a Mi16 one. Was used on 405 1.9 injection (SRi and GRi) and BX GTi 8v's, the earlier engines having Jetronic, the later ones Motronic M3.1. XU9J2 is the engine code IIRC. Share this post Link to post Share on other sites
gti_al 1 Posted December 3, 2007 (edited) Talking about squish, that's the reason I would never concider buying a standard T16 engine for more than just silly money.On the 405 T16 engine the top of pistons sits 5mm down the bore @ TDC.. So for example using decompressionplate and double headgaskets on an S16 engine will give you the equivalent of a T16 engine just lots cheaper. Still not my prefered way of building engines. Better get some proper pistons for the job, or as sandy mentions, a head that does the same job I think there is more to it than that. I had a brief conversation with magic about it recently, and he swears by the T16 and its tunability. He said every time he has tried or seen others do it other ways they have not worked that well. That said, i think his standards are insanely high Edited December 3, 2007 by gti_al Share this post Link to post Share on other sites
danpug 1 Posted December 3, 2007 I'm going to put an sri head on a 1.8 bottom end so no need for a plate now. Thanks for the info. Share this post Link to post Share on other sites
