forchunet Posted November 27, 2011 Share Posted November 27, 2011 (edited) Hey guys! Finally took the leap and have decided to build my own motor as opposed to buying a prebuilt one. I've started to buy some parts but before I buy too much I wanted to confirm these numbers. I keep getting different engine compression numbers from different programs. I believe the CR will be 9.17:1 (again, different programs are giving me different numbers) P90 head - 44.7cc HKS - 2mm 280zx Flat top pistos - 87mm bore, 1mm mill 280z rods - 133mm Crank LD28 - 83mm I'd like to stay under 9.6:1 compression as I want this build to be a mild pump gas street build with only the occasional autoX. HP goals = 170-180. Would late model 240Z rods and LZ22S pistons work better? I know this combo brings in about 9.6:1 with a 2mm gasket/n42 head. Edited November 27, 2011 by forchunet Quote Link to comment Share on other sites More sharing options...
BluDestiny Posted November 27, 2011 Share Posted November 27, 2011 I was making that HP with a 2.8....just saying. I had a big cam, webers and a header and 10:1 compression. I ran 91 all day. You're going to about triple the price of that motor with the machining and parts for not a lot of gain. Maybe if your future plans are to go all out on it, but if you only want to keep it as a street motor then don't bother. Quote Link to comment Share on other sites More sharing options...
Xnke Posted November 27, 2011 Share Posted November 27, 2011 Ok, let's get your numbers straight first. Many of the values you have listed are just flat wrong. P90 head - 53.6cc Nissan Factory F54 gasket - 1.25mm 280zx Flat top pistons - 86mm bore, 1mm milled crown 280z rods - 130.3mm Crank LD28 - 83mm This combination will put you at 2.9L displacement, and 9.7:1 compression ratio. Piston will be smidge under 1mm over the deck. With the most common headgasket out there in the US, the Fel-Pro MLS, you'll have about fifty thou piston-to-head clearance. I'd call it acceptable, but you MUST ABSOLUTELY MUST DO NOT SKIP check your final deck clearance once the engine is assembled using plastigage, in this case. (Yes, the common parts store Fel-Pro gasket is a metal shim gasket, with rubber "printed" onto it. The other part number that you are also able to get is still a 1mm gasket, but it's a traditional fiber gasket with steel fire rings.) Change out to either Fel-pro gasket, still 2.9L displacement but now 9.95:1 compression ratio. HK$$$$$ head gasket, will put you at 9.0:1 compression ration and slightly more detonation prone, due to the wider deck clearance. Run an appropriate cam and you'll have no problems with 10:1 compression and pump gas. Quote Link to comment Share on other sites More sharing options...
forchunet Posted November 28, 2011 Author Share Posted November 28, 2011 Sorry, correction: P90 head - 53.67cc HKS - 2mm 280zx Flat top pistos - 87mm bore, 1mm mill 280z rods - 130.2mm Crank LD28 - 83mm results in: Block Height= 207.87 mm Deck Height= 0.93 mm Chamber Volume= 53.6 cc Cylinder Volume= 493.41 cc Gasket Volume= 13.01 cc Dish Volume= 0 cc Deck Volume= -5.53 cc Uncompressed Volume= 560.02 cc Compressed Volume= 61.08 cc Compression ratio= 9.17:1 Total displacement= 2960.45 cc Changing to a 1.25mm gasket would result in 9.8:1 compression. @BluDestiny: I've always wanted a stroker ever since I caught the Z bug. Unless the torque increase is plain marginal over the 2.8L, I'm prepared to spend the extra dough. Quote Link to comment Share on other sites More sharing options...
z-ya Posted November 28, 2011 Share Posted November 28, 2011 I'm not sure using the LD crank in this configuration will gain you much. I'm also not a big fan of taking any material off OEM pistons (even though it is done for most all L31 builds using OEM 240SX pistons). So I would either just build an L28: P90 head - 53.67cc Felpro gasket - 1mm 280zx Flat top pistos - 87mm bore 280z rods - 130.2mm Crank L28 - 79mm CR: 9.9:1 Displacement: 2850 Or, since you have to bore anyway, and you will be buying new pistons, pick up a set of L24 rods and just build an L31: P90 head - 53.67cc Big bore gasket - 1mm 240SX pistons - 89mm bore, 1mm mill 240z rods - 133mm Crank LD28 - 83mm CR: 9.9:1 Displacement: 3098 Quote Link to comment Share on other sites More sharing options...
forchunet Posted November 28, 2011 Author Share Posted November 28, 2011 hmm... That L28 setup is appealing. Considering how hard it is to find an LD28 nowadays. Plus I can build it and when an LD28 does pop up I can always swap it over along with a new gasket, pistons. Or just get the HKS 2mm gasket now therefore I dont have to mill the 280zx pistons until after I get the LD28? Or thats just too much back and forth work. Quote Link to comment Share on other sites More sharing options...
z-ya Posted November 28, 2011 Share Posted November 28, 2011 I thought you already had the LD28 crank. If you don't, just build the L28 as I listed. It's not really worth the cost and effort unless you go with the 89mm bore. You can't get the HKS gasket anymore, and the Kameari one is $300. Just use a Felpro, or OEM gasket. Quote Link to comment Share on other sites More sharing options...
Tony D Posted November 28, 2011 Share Posted November 28, 2011 Hard to find LD28? Hehehehe! Quote Link to comment Share on other sites More sharing options...
duragg Posted November 28, 2011 Share Posted November 28, 2011 I built the top motor that Z-Ya referenced above and it is a blast (but I used N42 head). Cheap and easy. Stroker was my intention too, but at that particular time I didn't dig up any V07 cranks, and with the headgasket cost the price delta really went beyond the Fun meter. By scrounging, DIY and some donations from friendly vendors I spent less than a grand building a strong L28. Biggest cost were the larger pistons and the cam. If a V07 crosses my path I might redo it. But I don't think I would ever do it if I were stuck with $300 head gaskets.. Quote Link to comment Share on other sites More sharing options...
forchunet Posted November 28, 2011 Author Share Posted November 28, 2011 Thanks for the insight guys. I am leaning towards keeping it an L28 for now until I can scrounge up an LD28 crank. Duragg, have you ever dynoed your car? Quote Link to comment Share on other sites More sharing options...
cockerstar Posted November 28, 2011 Share Posted November 28, 2011 ...But I don't think I would ever do it if I were stuck with $300 head gaskets. You can always use multiple felpro gaskets stacked. I don't remember all of the details on the process, but I remember something about using copper spray between them. A quick search will bring it up I'm sure. Then again, the member doing this was also using emery cloth to bring down the thickness of the piston crown. He did have a motor with a serious kick-ass reputation though. I wish I could remember his screen name! Then again, it isn't a widespread solution, so I'm sure there is some sort of implication with the method. Quote Link to comment Share on other sites More sharing options...
duragg Posted November 28, 2011 Share Posted November 28, 2011 Have not put the green car on a dyno. It feels like twice the power of the L24 which had the triples, mild cam and headers. I do plan on doing this. Heck I suppose I could run it over there this week. I'd love to see it make 200 at the wheels, but in reality probably less and if it is less I really don't want to know... I wish I had gone with a much wilder cam, for a gnarly idle is all. In this configuration the car pulls strong to 7000 and by 7200 is ready for a shift. Sometimes I push till 7500 for fun. When I finish the installation of the 4.375 R200 I will need that headroom. With the 3.345 in there now ... not so fun. You know, triples are a pain in the ass. You have to be ready to submit to them in all respects. I have mine running as well as they can. No flat spots, no bogging, no barking or spitting (usually). But setup for max power they blow through fuel like mad. If money weren't an object I'd do the http://imagineinjection.com/ Just called the dyno guys down the way, they are getting me in at 4:30 tomorrow. See the things I do for Hybridz brothers! Quote Link to comment Share on other sites More sharing options...
cygnusx1 Posted November 29, 2011 Share Posted November 29, 2011 I wish someone would find my LD28. It went missing when they stole my Deeezel Maxiwagon many moons ago. Quote Link to comment Share on other sites More sharing options...
Gollum Posted November 29, 2011 Share Posted November 29, 2011 Cygnusx1 ~ You know the cranks are rare when people are just stealing the whole car!!! Does anyone here agree that we could severely use a "My Setup" thread in this forum section? Too many people come on with these huge shopping lists wanting to spend way more money than needed to reach their goals. If we just had organized data people could see what to really expect from certain setups. Quote Link to comment Share on other sites More sharing options...
duragg Posted November 29, 2011 Share Posted November 29, 2011 Agree on setup. That is what I was trying to do with my signature line. Some company sells an offset ground stroker crank, but I don't recall who it was. Quote Link to comment Share on other sites More sharing options...
Tony D Posted November 29, 2011 Share Posted November 29, 2011 They sell whole cranks for the L-Series in Japan and the USA that have nothing to do with a Nissan Core... Quote Link to comment Share on other sites More sharing options...
Gollum Posted November 29, 2011 Share Posted November 29, 2011 They sell whole cranks for the L-Series in Japan and the USA that have nothing to do with a Nissan Core... But Tony, what people don't know just makes them smarter! Watch out now... Stir the water too much and people's myth complexes might start to crack. Quote Link to comment Share on other sites More sharing options...
duragg Posted November 29, 2011 Share Posted November 29, 2011 Spending a couple grand on one of these cranks? Quote Link to comment Share on other sites More sharing options...
forchunet Posted November 29, 2011 Author Share Posted November 29, 2011 Can't wait to see some numbers duragg! Quote Link to comment Share on other sites More sharing options...
z-ya Posted November 29, 2011 Share Posted November 29, 2011 You can always use multiple felpro gaskets stacked. I don't remember all of the details on the process, but I remember something about using copper spray between them. A quick search will bring it up I'm sure. Then again, the member doing this was also using emery cloth to bring down the thickness of the piston crown. He did have a motor with a serious kick-ass reputation though. I wish I could remember his screen name! Then again, it isn't a widespread solution, so I'm sure there is some sort of implication with the method. I'd never use stacked gaskets, especially in a high (over 9:1) compression ratio application. That is unless you like changing them Quote Link to comment Share on other sites More sharing options...
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