lt1will620 Posted October 20, 2006 Share Posted October 20, 2006 Im contemplating building a motor for the SCCA GT2 class, which allows an 83.00 mm stroke, but restricts to a maximum of 86mm bore with an allowed .040" overbore. So i'm assuming im stuck with an L-28 piston. This gives me a deck height of 2mm. If i ran a 2mm head gasket, would i be okay with a piston 2mm above deck? has anyone done this before? Quote Link to comment Share on other sites More sharing options...
rags Posted October 20, 2006 Share Posted October 20, 2006 Somehow that doesn't sound like it will work as the pistons will stick up slightly more than 2mm. It would leave zero space between the head and the top of the pistons. What head are you planning to use? I'm not sure if it would work, but have you though about taking 1mm off the top of flat top pistons? That would still give you over 9 to 1 comp ratio with a P90. Joe Quote Link to comment Share on other sites More sharing options...
lt1will620 Posted October 20, 2006 Author Share Posted October 20, 2006 According to Lengine calc, it would stick up 2.030mm above deck, and after the 2mm gasket, would leave a +.030mm deck height. I could take off the top of a flat top piston, but first i want to know if i can make this work with off the shelf components. planning to use my n47 as of right now, im not dead set on anything, but i have an n47, and i like the smaller chambers as CR is unrestricted in GT2 Quote Link to comment Share on other sites More sharing options...
evildky Posted October 22, 2006 Share Posted October 22, 2006 According to Lengine calc, it would stick up 2.030mm above deck, and after the 2mm gasket, would leave a +.030mm deck height. I could take off the top of a flat top piston, but first i want to know if i can make this work with off the shelf components. planning to use my n47 as of right now, im not dead set on anything, but i have an n47, and i like the smaller chambers as CR is unrestricted in GT2 if you want a smaller combustion chamber use the E31 and fit it with the larger valves, I say custom pistons, if your going to be competing in scca road racing the $500 for sutom pistons is just a drop in the bucket Quote Link to comment Share on other sites More sharing options...
lt1will620 Posted October 22, 2006 Author Share Posted October 22, 2006 if you want a smaller combustion chamber use the E31 and fit it with the larger valves, I say custom pistons, if your going to be competing in scca road racing the $500 for sutom pistons is just a drop in the bucket very true...more or less i want to build a track car, but im making it legal for gt2 competition so i can get out there and race with some people, by no means am i planning on being a front runner in this class...im too poor for that Quote Link to comment Share on other sites More sharing options...
evildky Posted October 23, 2006 Share Posted October 23, 2006 I'm an autocrosser, not familiar with the road racing class rules, is fitting the larger valves in the E31 not allowed? the N42 also has the larger valves but without the liners found in the exhaust runners of your N47, and if your trying to keep it cheap, you can have the pistons milled a bit to get adequate clearance Quote Link to comment Share on other sites More sharing options...
Mack Posted October 23, 2006 Share Posted October 23, 2006 or you can get a maxima N47 head and have plenty of CR to go around. look into some Z series 4 cylinder pistons for a little shorter deck height and some wird bore sizes. Quote Link to comment Share on other sites More sharing options...
lt1will620 Posted October 23, 2006 Author Share Posted October 23, 2006 I'm an autocrosser, not familiar with the road racing class rules, is fitting the larger valves in the E31 not allowed? the N42 also has the larger valves but without the liners found in the exhaust runners of your N47, and if your trying to keep it cheap, you can have the pistons milled a bit to get adequate clearance In this class, any alum., non-cross flow style 2valve/cylinder head may be used, valve size and material is unrestricted Quote Link to comment Share on other sites More sharing options...
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