Deck Height with Euro Flat Top Pistons, Was: Engine Assembly Questions |
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Deck Height with Euro Flat Top Pistons, Was: Engine Assembly Questions |
ThinAir |
Mar 30 2005, 11:09 PM
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#1
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Best friends Group: Members Posts: 2,553 Joined: 4-February 03 From: Flagstaff, AZ Member No.: 231 Region Association: Southwest Region |
This started out as this topic: http://www.914world.com/bbs2/index.php?act=...=ST&f=2&t=28067
It seemed like a good idea to start a new thread with different subject. The 2.0L engine I'm building is using stock crank & rods with stock size (94mm) Euro flat top pistons. My understanding from other topics is that when you build such an engine you get slightly higher compression than stock because of the flat top piston, but you basically don't need to change anything else. When I put the first piston & cylinder in place I used the .007" barrel gasket that was included with the overhaul gasket set. I measured the distance from the top of the piston at TDC to the top of the cylinder at .022" I don't have the actualy head cc measurement, but the paperwork for getting my heads done says they were cut .005". I don't know for sure if that is just this time or if the final cut is .005 including any cuts done during previous rebuilds. Using the math formulas and various calculators mentioned in the previous topic, I figure that if I assemble the engine this way I'll end up with a compression ratio of about 1:8.2 or 1:8.4 This engine will use the stock D-jet FI. So my question is: is it ok to assemble the engine with what I have or is this compression too high? If it's too high, what should I be shooting for with Euro flat top pistons? If I need different barrel spacers to reduce the compression, it's fine with me, but I don't want to just pick some number out of a hat or build it this way without knowing that it's ok. |
Dave_Darling |
Mar 31 2005, 11:31 AM
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#2
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914 Idiot Group: Members Posts: 15,048 Joined: 9-January 03 From: Silicon Valley / Kailua-Kona Member No.: 121 Region Association: Northern California |
Get a new machine shop!! Any competent one will be able to CC the heads for you. The compression ratio that you want will vary depending on a whole raft of things. For a stock engine, with a stock cam, running stock fuel injection, I would say that somwhere between 8.0:1 and 8.5:1 should work just fine. You'll probably want to run mid-grade fuel if your CR is 8:1, and premium-grade (CA's 91 is fine) for 8.5:1. You definitely want the CR to be even across all four cylinders, so make sure you CC all four combustion chambers!! --DD |
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