KiD-ViD Posted October 24, 2002 Share Posted October 24, 2002 thanks guys I am trying to lean as much as I can before I start my swap. I am interested in dynamic comp ratio right now. Grumpy can you post some of thoes great links you always do...I have learned so much from thoes about cams and engine building in general. also while I am here asking stuff...I feel stupid asking it but when talking about fuel systems people talk about -8an and -6an fittings. I assume this has to do with the size. I would figure 8 would be bigger but then again it could be like the gauge system when the smaller the number the bigger. thanks again! Quote Link to comment Share on other sites More sharing options...
KiD-ViD Posted October 24, 2002 Author Share Posted October 24, 2002 wow this stuff is HARD! heh. I got the calc and am using the one in desktop dyno as well for comparison. I am having a hard time finding the piston to deck clearance and the valve relief volume. I found some similar size pistons on ebay that said they had a 4cc valve relief so I used that and guessed and checked till I found a piston to deck clearance that would give me a DCR of 8.5 and that magic number ended up being 0.158. well I guess I will just have to wait till I actually start getting parts to see... I plan this to be a 383. 6 inch rods, 11.1:1 SCR, 304 duration, .600 seat to seat lift, 112 LSA. I am hoping it will work out good. the 11.1:1 pistons are the ross forged pistons that come with the stroker kit I want. they are 11.1:1 with 64cc heads. I want to run pump gas and all that but I am worried that it is too much comp ratio so I will just have to wait till I get closer to figure this all out. thanks again grumpy! Quote Link to comment Share on other sites More sharing options...
Guest Anonymous Posted October 24, 2002 Share Posted October 24, 2002 what year is your datsun kid-vid? and what kind of swap are you planning on doing? Quote Link to comment Share on other sites More sharing options...
Mudge Posted October 24, 2002 Share Posted October 24, 2002 I ran 11.4:1 on an LT1, stock bottom, stock pistons. It is reverse cooled which helps (and hurts at the same time), but you are probably fine if your timing work is right regardless. I am in CA also, 91 MTBE Craptane. Quote Link to comment Share on other sites More sharing options...
grumpyvette Posted October 24, 2002 Share Posted October 24, 2002 your piston to deck clearance is normally about .025 with stock or aftermarket pistons unless the block has been decked.(that does not change) tell me the cam part number and manufacturer and piston part number and manufacturer and Ill try and work it out for you (the static and dcr) the cam open and close points are what change the static to the dynamic compression ratio. remember the piston compresses NOTHING UNTILL both valves close , your dynamic compression is figured from the piston position during its rotation point at valve closeing to the tdc Quote Link to comment Share on other sites More sharing options...
KiD-ViD Posted October 24, 2002 Author Share Posted October 24, 2002 ok this is all just planning keep in mind heh. the cam is comp cams 304hr-r10 12-460-8....I know I know it has 110 and I said 112 but I wanted to see if they could custom grind it and how much more it would be. anyway, the pistons are ross pistons part #90453 I believe. they are included in an ebay package that is always up. thanks again so much. Quote Link to comment Share on other sites More sharing options...
grumpyvette Posted October 25, 2002 Share Posted October 25, 2002 dcp is about 8.2. Id drop back to the next milder cam to raise the dynamic compression slightly or go with a 112-114 lsa but that would lose you some low rpm torque Quote Link to comment Share on other sites More sharing options...
KiD-ViD Posted October 25, 2002 Author Share Posted October 25, 2002 ya I think I want 112...it sounds just about right to me. how much are they going to tack on to custom grind in 2 more LSA Quote Link to comment Share on other sites More sharing options...
silicone boy Posted October 25, 2002 Share Posted October 25, 2002 Originally posted by KiD-ViD:ya I think I want 112...it sounds just about right to me. how much are they going to tack on to custom grind in 2 more LSA Y'know, I'm building a very similar 383 and ran into clearance problems with my cam. Mine was a COMP cams Extreme Energy 270HR. As it turned out, I needed a small base circle cam and even then I needed to grind my connecting rods for clearance. Comp cams gladly made me a custom small base circle cam and didn't even charge me. They just exchanged the one I bought from Summit. That's great service. Quote Link to comment Share on other sites More sharing options...
Len Posted October 25, 2002 Share Posted October 25, 2002 Hmmmm! Grumpy thanks for the input for Kid-vid. Looks like he learned alot with or without owning a Z! I learn alot and I've got four Z's. Not as good a mechanic as alot of guys on this website. But I'm also older and wiser not to judge and call names to people I have never met (even if they don't have a Z. That's what I like about this site everyone is welcome. Hey I remember a guy named Davy; He finally bought a Z last week. I thought he had alot of knowledge along with being a nice guy. This world has enough people who judge other people for what they have or don't have! Sure hate to see it get started on this site! Len Quote Link to comment Share on other sites More sharing options...
80LS1T Posted October 25, 2002 Share Posted October 25, 2002 Yeah I'm going to have to agree with you Len on this one, I dont think it should matter if he has a Z or not! I know that I have asked some stupid questions and have asked some question that have been answered a 100 times but someone always seems to push me in the right direction, and you know why cause HYBRIDZ.ORG has the nicest group of people that I know of!!! Quote Link to comment Share on other sites More sharing options...
KiD-ViD Posted October 25, 2002 Author Share Posted October 25, 2002 yeah I have posted on other boards and no where are they anywhere near as nice. I wont lie I dont have a Z as of yet...I have been trying to sell my car for awhile and as soon as its gone I should have 6k to spend on this Z. I even got a call about the car today so you cant tell me I am not trying to sell it. heh. Oh yeah and I have driven 2 hours each way for a Z meet. anyway thanks alot for the help and support guys...hope to see ya on the road by christmas! Quote Link to comment Share on other sites More sharing options...
grumpyvette Posted October 25, 2002 Share Posted October 25, 2002 sure glad to help, read this on dcr http://cochise.uia.net/pkelley2/DynamicCR.html http://www.jegs.com/cgi-bin/ncommerce3/ProductDisplay?prrfnbr=3966&prmenbr=361 this gives you a very rough idea of the wrench size necessary for each size fitting 4AN Wrench, 9/16'' & 5/8'' 6AN Wrench, 3/4'' & 11/16'' 8AN Wrench, 7/8'' & 13/16'' 10AN Wrench, 1'' & 1-1/16'' 12AN Wrench, 1-1/8 & 1-1/4 a very rough idea as to line size AN Size: -04; 1/4 Pipe AN Size: -06; 3/8 Pipe AN Size: -08; 1/2 Pipe AN Size: -12; 3/4 Pipe Quote Link to comment Share on other sites More sharing options...
cameraobsess Posted October 25, 2002 Share Posted October 25, 2002 hey kid-vid i used to be in the same spot you are in except worse. i didnt even have a car when i started posting on here. the people have been nice, helpfull, and can almost always point you in the right direction. anyways back to the topic i now have a 280zx 2+2 and will hopefully soon sell it and start working on my 240z project. if it were not for all the help i had found on this site before i had a z i would probably be driveing a fuel efficent toyota or something else with no power. i just wanted to give my two cents anyways. Quote Link to comment Share on other sites More sharing options...
Guest zfan Posted October 25, 2002 Share Posted October 25, 2002 240-extreme..Mellow out! He's working on a plan which is where a lot of us got started from, just look at Davy. Anyway you can get banned for too many comments like that. Be cool Mike Quote Link to comment Share on other sites More sharing options...
Guest Anonymous Posted October 25, 2002 Share Posted October 25, 2002 xtreme 240 (welcome to Hy Brid Z), Kid Vid is an enthusiastic HyBrid Z contributor and it seems I was looking at a lot of photos he posted of Z's and other Hy Brid members from an event this summer. Please re-read the Hybrid Introduction by Pete Paraska that we all try very hard to follow.As for not owning a Z our beloved technical wizard since last I heard did not own a Z. I put Kid Vid's name on a Zee out in the back 40 so he has one now. Quote Link to comment Share on other sites More sharing options...
Kevin Shasteen Posted October 25, 2002 Share Posted October 25, 2002 (Boy, finally found my HybridZ Login Password-its been 4 weeks: Ug!) Kid Vid You didnt say what cylinder heads you are thinking about(?); as in their Combustion Chamber cc's. I have not looked at the DCR site Grumpy has generously offered as I already created my own prior to his offering; so I'm not familiar with the other program's format. If you are going to build a 383 (350 SBC Block w/400 SBC's crank) then you can not use a 6" Con.Rod and a Piston w/a 1.560" PCH (Piston Comp.Height); the piston will have a +.418" Deck Clearance: almost a full half inch! When working the math; first know your Block Deck Heght & subtract your Assembly Height from that. Stock SBC Block Deck Height = 9.025" Your Assembly Height: * Ross Piston Comp.Height = 1.568" * Connecting Rod .. ...... = 6.000" * Crank Offset 3.75 / 2.. = 1.875" ...................................-------- Total Assembly Height.... = 9.443" Block Deck Height 9.025" Assembly Height -9.443" ...............---------- Deck Clearance +0.418" Also; as to your DCR (Dynamic Comp.Ratio) if you want to know what cam is correct for your engine; we really need to know which pair of cyl.heads your are going with; which means we also need to know what the intended purpose of the car is going to be. If you are planning on running on the street you will need a pretty steep SCR (Static Comp.Ratio) to run a 304 Durantion Cam. Example: BTW: Your 304 cam has an IVC (Intake Valve Closing) at 78* ABDC. If you go to the Crank Angle Chart your DSC program should generate, you will find that .675 percent volume exists above the piston after the IVC has closed at 78* ABDC. 383ci / 8 cyl's = 47.875ci Cylinder Displacement 47.875ci x 16.387 = 784.53cc 784.53cc x .675 = 529.56cc Remaining After IVC From here if you want an 8.5 DCR then you will have to Divide your Remaining Volume after IVC by your desired 8.5 DCR, like so: 529.56 / 8.5 = 62.30cc Total Combustion Chamber So as you can see; if you run that cam in your 383 and you want an 8.5 DCR you will need a 62.30cc Total Combustion Chamber. The next issue would be to calculate your SCR. We do this simply by working the SCR formula: Cyl. Displacement + Ttl.Comb.Chamb / Ttl.Comb Cham 784.53cc + 62.30 / 62.30 = 13.6:1 Can someone say "DETONATION" on pump gas. If you want to run that cam with your 383 displacement and want an 11:1 SCR then you will need to work the math backwards: 784.53cc + [x] / [x] = 11:1 SCR 784.53cc / 10.1 x = 77.67cc So to run a 383 at 11:1 SCR you will need a 77.67cc Total Combustion Chamber. Now take that 77.67cc and use it to determine your DCR; remembering that your 304 Duration cam has the IVC at 78* ABDC which left .675 percent Volume of our 383's Cylinder Displacement which was 529.56cc: 529.56cc + 77.67cc / 77.67cc = 7.8:1 DCR a 7.8:1 DCR can be ran on the street but it is pushing the limit of pump gas's ability to resist detonation. You will also be giving up low rpm torque for high rpm horsepower. If this is going to be a daily driver then you would be much happier with a cam whose duration is less ( Bruise to the ole EGO I know). Seriously; if this is going to be a daily driver your 7.8:1 DCR wont allow the peak torque to come on to the cam till well after 4500rpms. You wont even reach peak hp till well after 5500rpms. If this is going to be a daily driver; you really need a cam in the 270 Duration area. Remember; when we speak about DCR or SCR, all we are doing is using a tool to identify Airflow Velocity. The tools are just that-tools to aid you and I as to when the Airflow Velocity is high or low at a particular rpm range. So, if you are going to run that cam on the street-you will need very steep gears to help the low rpm loss of torque; and your low rpm torque loss will be excessive with a 7.8:1 DCR on pump gas. Kevin, (Yea,Still an Inliner) PS: I also agree that it doesnt matter if you have a car or not to learn....learning has no prerequisites; learning is always in vogue Quote Link to comment Share on other sites More sharing options...
Kevin Shasteen Posted October 25, 2002 Share Posted October 25, 2002 Originally posted by KiD-ViD:.., I am having a hard time finding the piston to deck clearance and the valve relief volume..., Kid Vid, About the Piston to Deck Clearance that is something you will have to determine by working the Block Deck Height inches relative to the Assembly Height inches I mentioned in the previous post. As for the Piston Dish/Dome cc's you can visit KB-Piston's site. His pistons are Hypereutectic and not pure forged pistons. If you are looking for pure forged pistons you will have to go to another site; but for practicing the math on Compressions you can use KB-Pistons as a baseline model. The math process doesnt care what metal the pistons are made from. If you are interested in KB's site you can click on it here: http://www.KB-Silvolite.com/1toc.htm Scroll downward till you find the Chevy seciton/383 & enjoy. Kevin, Yea,Still an Inliner) Quote Link to comment Share on other sites More sharing options...
Mikelly Posted October 26, 2002 Share Posted October 26, 2002 240_XTREME... Take a different tone or else... There is no place here for you telling another member that he is a Liar... Check it at the door. Mike Kelly Quote Link to comment Share on other sites More sharing options...
pparaska Posted October 26, 2002 Share Posted October 26, 2002 Mike, I did you one better. I just deleted the offending post. We are playing hardball here 240_XTREME. That kind of post (you know what I mean) isn't allowed. Try it again and you're gone. Quote Link to comment Share on other sites More sharing options...
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