Z-Gad Posted April 6, 2003 Share Posted April 6, 2003 Doug, I used Ross pistons as well in my 3.1 turbo. They were a 5mm dish, 89mm bore, small valve reliefs, though I do not remember the pin height... The pistons and pins were a little over $600 if I remember correctly. I ended up getting a set of chrome total seal rings for another $225 directly from total seal. Anyway, regarding the floating of the pins... they are full floating in the piston. In order to make them 'float' in the rod, the rod end will be bored, a brass bushing will be pressed in place (the bushings had to be custom made for the pin size I received since it was an odd size) and an oiling hole will be drilled in the end of the rod through the bushing to allow lubrication between the pin and the bushing. My machine shop had been extremely patient with me, explaining things in layman's terms so I could get it through my little pea brain how everything worked Quote Link to comment Share on other sites More sharing options...
DAW Posted April 7, 2003 Share Posted April 7, 2003 McAdam, if you really want to keep your long-rod L6 project on a budget you can leave the LD28 short block basically intact and use an N42 head for n/a or a P90 for turbo. You'll end up with 83mm stroke, 84.5mm bore, 140mm rods with large floating pins, sturdy pistons with c.ht. = 46.5mm. That's a bit tall on the comp. ht., but with a turbo you won't need high rpm to get power. With the n/a setup I'm using an N42 which should be around 10:1 and I've never heard a ping. Compression cranking pressure is 210-220 already but I'm considering switching to a Maxima N47 head to boost compression higher, or to turbocharge it with the N42 using low-pressure turbo. If you want to go for more hp and higher rod/stroke, you can do the overbore and swap in shorter pistons with longer rods as you are considerring. Use 184.5mm as your working length for rod + comp. ht. That's what zero deck ht. stock is (140mm + 46.5mm = 186.50mm). The Z20 rods aren't very meaty looking. One budget possibility would be Z22E (not S) rods (148.6mm), and L28ET pistons (38.1) for a distance of 186.7mm and a good r/s and a good c.r. with a P90 head (a bit higher than the stock L28ET due to the displacement increase over 2.8L from the overbore). Even if you go n/a and use a Maxima N47 head, the turbo pistons will be sturdier than the non-turbo stock Nissan pistons you're considerring. Finally, don't let anyone talk you out of what you're ponderring as it not only can be done; it's not that difficult to do. DAW Quote Link to comment Share on other sites More sharing options...
Dragonfly Posted April 7, 2003 Share Posted April 7, 2003 Here are some lessons from the "been there done that / learned the hard way" section of my engine build-up. This is concerning the use of free floating pistons. Also the following comments are for engines that are going to be street driven and not torn apart for inspection and rebuild every 1000 miles or so. No matter where you read that you do not need to use a bushing for free floating pins ignore the urge to cut that corner (I ended up with 4 siezed pins in the rods). If you have a chioce of retainers for the pins use "wireloks" as they will not under any circumstance allow the pin to exit the piston. If you use a "spirolok" to retain your pins be aware that they are made in specific sizes none of which are the correct size for our rods which means the piston manufactuer has to compromise on the retaining grove for the spirolok (that one cost me a complete teardown and resleaving the #4 cylinder). Aviod using teflon plugs if you can as they will wear a grove into your cylinder wall over time, and if you let them go long enough they can come out and break the skirt off your piston. Make sure when you have the work done that the shop doing the work documents there measurements of center to center length of each rod after they have been fitted with their bushing, this is very useful if you are doing a true blue printing of your engine and it can allow you to optimize piston and rod configuration (this is also important for your bearing shell selection on the rod big ends). What all this stuff I am telling you now adds up to is trying to make each cylinder cary as close to an equal load as each of the others as possible. The last of my rambling... be careful of what corners you cut to save a buck, I saved $12 going with "spiroloks" over the "wireloks" and I also saved $72 by not using bushings in my fully prepped and balanced rods, I then spent $1200 to repair all the damage done after about 5000 miles of driving. Dragonfly Quote Link to comment Share on other sites More sharing options...
DAW Posted April 8, 2003 Share Posted April 8, 2003 Did you drill oiling holes into the small ends of the rods to provide lubrication to the now-mobile piston pins? DAW Quote Link to comment Share on other sites More sharing options...
Dragonfly Posted April 8, 2003 Share Posted April 8, 2003 Yes I did drill the oil holes into the small end for pin oiling, I also chamfered the holes using a 100 deg. chamfer bit. What I found out the hard way is that in the book "How to Build your Datsun OHC Engine" (I believe that is the correct title) by Frank Honzowitz that when he talks about things like that he is refering to full race engines that will be taken down and inspected/rebuilt after every one or two races. My engine was holding 20psi oil pressure at idle and 70 to 80psi when driving, the pins were brand new and the rods had been lightened, polished, oil holes drilled, balanced, and shotpeened, that left me to believe that the problem was I was not tearing the engine down and inspecting these wear surfaces like they should have been. The primary reason I am saying anything about this is to save some others from falling into the same trap I did by thinking you could build an engine by following the instructions in a book for building race engines then drive it on the street and feel like you do not need to tear it down for inspection because it is not being raced. I'm not giving you a hard time for asking a legitamate question I am just realizing that I did not go into enough detail in my last post. Dragonfly Quote Link to comment Share on other sites More sharing options...
Guest Anonymous Posted April 8, 2003 Share Posted April 8, 2003 Hi, I'm pretty new to this. And the more I read, the more it's impressive on how you know all these kinds of numbers. I have a 81ZXT. Is this topic refering to the ZX (N/A)?? not the ZXT ? Quote Link to comment Share on other sites More sharing options...
Doug71zt Posted April 9, 2003 Share Posted April 9, 2003 Joe - Sorry - didn't think about the early L28 blocks. 87mm is OK with me - a loss of 40cc is no big deal. As for the dish and pin height - My thinking was to maintain the same style of combustion chamber as stock on the turbo engines. I was not sure if a flat-top piston would change the flame propagation in the chamber or not. If it results in a major cost reduction in the pistons - I'm willing to try the flat-tops. How much of a cost reduction from normal pricing can we get with 5 sets or more? I guess we should spec wirelock retainers also. Dragonfly - thanks for the reminder on the specifics of floating pins - I remembered reading your post when you first found these problems. Wirelocks are definitely more secure. That's why a like this forum - lots of good first hand information (some of it costly learned) - shared freely Cheers - Doug Quote Link to comment Share on other sites More sharing options...
rags Posted April 14, 2003 Share Posted April 14, 2003 Ian, I need your email address to add you to the list of people that were interested in the group buy. Thanks. Joe Quote Link to comment Share on other sites More sharing options...
ianz Posted April 15, 2003 Share Posted April 15, 2003 navstokes@yahoo.com Quote Link to comment Share on other sites More sharing options...
rags Posted September 3, 2003 Share Posted September 3, 2003 Well I don't know if anyone else that was in on the group buy got their motor together, but this past weekend i finished up on a NA 3 liter with an E31 on it. Only had it out a few times but so far I'm very satisfied with the results. I still have a little tuning to do on the Webers but it does pull strong. I have already started on the turbo motor which will have the same bottom end but will have a P90 on it. I'll keep everyone updated on the progress of that motor as well. I'm interested in the progress of anyone else who might have started their build with the custom pistons from the group buy. Joe Quote Link to comment Share on other sites More sharing options...
zolorin Posted September 3, 2003 Share Posted September 3, 2003 I might be interested in the group buy of one set of 6 pistons. I am planning to build 3.0TS engine since mine started to show signs of ill health due to an overheat in Florida Weather (and leak in a coolant system, which was then resolved but a bit too late) Quote Link to comment Share on other sites More sharing options...
rags Posted September 3, 2003 Share Posted September 3, 2003 Sorry, we did the group buy a few months ago. I was just asking if anyone else got their motor together using the pistons from th buy. Joe Quote Link to comment Share on other sites More sharing options...
zolorin Posted September 3, 2003 Share Posted September 3, 2003 My bad, so are you all happy with your 3.0TS/NAs -- and how are the engine wear/tear so far. I want to build one eventually but I don't want to have a motor that will last one month and will need a tear down -- don't have that kind of money. thanks Quote Link to comment Share on other sites More sharing options...
rags Posted September 3, 2003 Share Posted September 3, 2003 Gonna have to get back to you on that as we just finished the motor this past weekend. Joe Quote Link to comment Share on other sites More sharing options...
Doug71zt Posted September 4, 2003 Share Posted September 4, 2003 Sorry Joe - still collecting parts. Have the ISKY turbo cam and valve train, P90 head and 240 rods/ F54 block. Still looking for a good LD28 crank that is close by in Ontario. I am subjecting my current stock block to ever-increasing boost in hopes of finding the limit of the stock pistons. With lots of fuel and no knock - they seem to like 15 psi OK with occasional trips to 25 PSI (Wastegate problem). Pistons sure do look nice in the box though. Did you float your pins or press them in? Good luck - Doug Quote Link to comment Share on other sites More sharing options...
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