beren Posted January 13, 2006 Share Posted January 13, 2006 Ok, I've read the sticky about the L6 rods/chamber cc's and the linked info in that thread, but I've still got a question. When people say "I've got a 3.1 stroker", what exactly are they meaning? Do they mean, "I've bored out the cylinders, and am using different pistons" Here is where I'm in need of the schooling. The Piston sits on top of the Rod (or connecting rod), which is connected to the crank. What is deck height, and how does it affect your chamber volume and compression ratios? Can deck height be changed with a different head gasket? I'm assuming that a thinner head gasket would give you greater compression, for a slight drop in chamber volume, right? I guess this is me just asking some basic motor questions. Oh, and one more thing. What options are there if you don't want to bore the cylinders any larger? Is there a "2.8 stroker"? If so, what would that involve? Sorry for the ignorance... Beren Quote Link to comment Share on other sites More sharing options...
JMortensen Posted January 13, 2006 Share Posted January 13, 2006 Stroke is how far the pistons go up and down in the cylinder. Bore is the diameter of the cylinder. If you stroke an engine you increase the stroke. If you bore an engine you increase the diameter of the pistons. The 3.1 stroker is a 2.8 liter that has a diesel crankshaft with a longer stroke that has also been bored for larger diameter pistons. So you could also say "my bored and stroked 3.1L". You could stroke a smaller engine just as easily. I suppose you could stroke the 2.4 and use the L28 crankshaft. Don't know what the displacement would be afterwards though... Deck height is the height of the top of the block from the crank centerline, I believe. Deck height cannot be changed with a different headgasket, but can be changed by "decking the block" which means milling the top of the block down. A thinner headgasket will give you higher compression, but it won't give you less chamber volume. The chamber volume is measured straight off of the head, no gasket in there. So you're standard displacement equation has the volume of the cylinder, the volume of the chamber, and the volume of the headgasket. It has it's own separate value. As to your 2.8 stroker question, you'll find that stroking an engine is A LOT more expensive than boring an engine. So if you're going to rebuild an engine and you want more displacement, you'd do better just boring it than just stroking it. Search this site and google and you'll find many threads and many sites dedicated to the stroker 3.1. Read for a while and you'll find that it takes a different crank, different rods, and different pistons, and you need to bore the engine to make that combo happen. Then you get into rod ratio and a bunch of other crap that is just confusing as hell. I don't mean to discourage you though. Dive in, and have fun. You also might want to check out How to Modify Your Nissan/Datsun OHC Engine. It has a lot of L series specific information that you might want to know as you become more familiar. Quote Link to comment Share on other sites More sharing options...
beren Posted January 13, 2006 Author Share Posted January 13, 2006 As to your 2.8 stroker question' date=' you'll find that stroking an engine is A LOT more expensive than boring an engine. So if you're going to rebuild an engine and you want more displacement, you'd do better just boring it than just stroking it. Search this site and google and you'll find many threads and many sites dedicated to the stroker 3.1. Read for a while and you'll find that it takes a different crank, different rods, and different pistons, and you need to bore the engine to make that combo happen. Then you get into rod ratio and a bunch of other crap that is just confusing as hell. I don't mean to discourage you though. Dive in, and have fun. You also might want to check out How to Modify Your Nissan/Datsun OHC Engine. It has a lot of L series specific information that you might want to know as you become more familiar.[/quote'] Great info! One question. They way you talked about the 3.1 stroker implied that you *had* to bore as well as stroke the motor. Why is that? Can I not use the current pistons and swap rods and crank? Ok, Ok, I'm hitting the search now... Quote Link to comment Share on other sites More sharing options...
zeiss150 Posted January 13, 2006 Share Posted January 13, 2006 If you stroke a 2.4 liter with an L28 crank you get a 2.6 liter engine. Thats what the 260Z was. the 280Z was a bored 260Z. If you take the L28D crank and put it in the 2.4 block it makes a 2.7liter engine but then you get wacky CR and messed up deck heights unless you change out the pistons and if your gonna do all that work... 3.1! "there's no replacement for displacement" I think I read that on this site. The Lengine calculator is a bitch'n toy. You can, just use the Ld28 crank but the you'll only be makeing a 2.9 liter engine Once you start changing out the rods the piston deck height gets all out of wack and you have to change the pistons then you need to over bore the block so that the pistons will fit thats how you get up to 3.1 ... but you can make a 2.9 or a 3.0 engine if you want you just need the right piston crank and rod combination with out making your CR to heigh. "the more you read, the more you know" , G.I. Joe Quote Link to comment Share on other sites More sharing options...
JMortensen Posted January 13, 2006 Share Posted January 13, 2006 "the more you read, the more you know" , G.I. Joe "And knowing is half the battle. G.I. JOE!!!" Quote Link to comment Share on other sites More sharing options...
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