soullessjdog Posted June 12, 2009 Share Posted June 12, 2009 Im in the process of researching for my 3.1L build im going to do but im getting different rod lengths to use. One source says use 138mm rods and the other says use 240z rods i will be using a ld28 crank as soon as i can find one. Quote Link to comment Share on other sites More sharing options...
JMortensen Posted June 12, 2009 Share Posted June 12, 2009 I'd go with Wicked of the West rods. Some people say Glenda the Good, but I think that is BS. Quote Link to comment Share on other sites More sharing options...
blue72 Posted June 12, 2009 Share Posted June 12, 2009 Ah yes, the infamous witch rods, secret of all high power engine builders. Here's a little something to get you started: http://www2.zhome.com:81/rnt/L28conversion/3031FAQ.html http://geocities.com/inlinestroker/index.htm Not that the search feature here on this site doesn't work equally as well. Quote Link to comment Share on other sites More sharing options...
soullessjdog Posted June 12, 2009 Author Share Posted June 12, 2009 I have used the search but some used 138mm rods and others 240z rods witch are 133mm so witch are the best to go with manufacture dosent matter right now i will resarch that latter its witch length is the right one and best for a high hp n/a 3.1L. Quote Link to comment Share on other sites More sharing options...
blue72 Posted June 12, 2009 Share Posted June 12, 2009 Who is using 138mm rods, from what vehicle or aftermarket manufacturer did they get them, and in combination with what piston and crankshaft are they being used? I haven't heard of this one yet. Quote Link to comment Share on other sites More sharing options...
josh817 Posted June 12, 2009 Share Posted June 12, 2009 What you need is an engine calculator to get a scheme of things. This has general presets: http://www.atlanticz.ca/zclub/techtips/calcs/engine%20builder/index.html This is king pin with lots of inputs and presets, you can change them to whatever measurement you like as usual: http://www.ozdat.com/ozdatonline/enginedesign/ Play with it, figure out what works, order your parts, measure them so you know they're the right size, build, burnout. Quote Link to comment Share on other sites More sharing options...
johnc Posted June 12, 2009 Share Posted June 12, 2009 Depends on your budget. Carillo, Pauter, and others make custom rods in various materials that work very well. For a more budget build folks typically use the rods out of a 1973 240Z with the 9mm rod bolts. Quote Link to comment Share on other sites More sharing options...
josh817 Posted June 12, 2009 Share Posted June 12, 2009 Stock 240 rods and with a bench grinder and a die grinder you can polish them and lighten if you really want to. I didn't do any lightening on mine, just balanced everything because these rods don't have "balancing pads" so when you go to lighten and balance, you're taking away from structural integrity. At least, thats the general idea. Removing the casting flash and all the ridges should be fine. Make sure you keep the oil hole open on the side! I can't remember but I think it was used for flinging oil up onto the cylinder walls but sometimes it flings too much and causes a problem. I ground mine off but left the hole open from debris. I would change a few things on my set to say the least. If you are thinking of having someone else polish and balance your rods, consider buying after market setups because it takes a lot of labor... Stock: Ground off flash and casting: Polished: Shot peened (finished): As you can see I am on a budget also. No forged pistons for me. Treat the motor well and it will do fine. Unless you turbocharge it, then I'm clueless about how the pistons would up. Probably melt. Oh and there was a V07 crank on ebay last week I think for $400-something. Don't know if it sold but you might as well grab the first one you see if its in the 3-400's. People recognize that they have value, and not for a diesel motors. Quote Link to comment Share on other sites More sharing options...
Tennesseejed Posted June 12, 2009 Share Posted June 12, 2009 Josh817, thanks for posting those pics. Pretty work. Not to hijack, but do you know how much your finished rods weigh? I have searched wide but not been able to find the stock weights for 240 and 280 rods. I have been looking at the Toyota 3sgte rods as a workable replacement for a 280 build. The BE width is same and 138mm length. The only issue I see is the BE diameter is 51mm instead of 53mm. I think this can be solved by turning the main jounals down 1mm or boring the BE 1mm. Eagle says the Toyota rods are 520 grams. I think this is a lot less than stock Z rods, but I don't know how much. Jed Quote Link to comment Share on other sites More sharing options...
blue72 Posted June 12, 2009 Share Posted June 12, 2009 Stock 240Z 9mm bolt style rods weigh 710-711 grams. I'd need to clear off the press and visit the storage unit to get a measurement of L28 rod weight. I know there has been speculation on using 140mm long LD28 rods, but I can't remember if that would have encroached into the ring area too much. Musing at random to no one in particular: Let's see, with the top of the piston even with a standard L28 deck, a 140mm rod stroker crank setup would leave 26.35mm as the pin height. Same scenario using L24 rods leaves 33.35mm as the piston pin height. Quote Link to comment Share on other sites More sharing options...
soullessjdog Posted June 12, 2009 Author Share Posted June 12, 2009 if u look up kameari stats 83mm stroke 138mm rods 89mm pistons= 3.1L but then other places say 83mm stroke 133mm rods 89mm pistons= 3.1L Kameari is the most trusted engine builders of classic japanese cars so thats y i asked and the say 139.5 mm rods are 3.0L. Quote Link to comment Share on other sites More sharing options...
josh817 Posted June 12, 2009 Share Posted June 12, 2009 Yes but Kameari is very expensive, however you get what you payfor. Consider the following though, forged pistons are forged pistons, I'm sure Ross pistons, although "expensive" too, isn't as pricey as Kameari pistons and probably works just fine. Some things that I would go for if I looked into them would be headers, ignition, etc. Ignition I think they use like a turbo optical dizzy with an ignition box? Not sure but it reminds me of MSD which is $500 less. I think my final masses were like 703g or something. I used a three beam scale to weigh big and small ends and then an electric scale for overall mass. A good idea is to mark on the scale surface where the big end (or small end) lays, line up all the other rods on the scale in the same position when you use the scales. Sometimes if you have say like 1" of rod hanging off the edge, and the next rod you lay on the there differently so there is say 3" hanging off the edge, you will get different readings. Quote Link to comment Share on other sites More sharing options...
blue72 Posted June 13, 2009 Share Posted June 13, 2009 Ah, I see it now. The $2500 - $3000 'drag/racing' forged rod and cast piston combination Kameari sells. Looks like a good long rod combo, and the pistons only stick out .1mm above the deck. Lotsa dough though. Bore and stroke are what combine to give displacement. Installing longer rods does not increase displacement. No matter how long the rod is it is still being swung on the same crankshaft. Do you have a target rod/stroke ratio in mind? Quote Link to comment Share on other sites More sharing options...
soullessjdog Posted June 14, 2009 Author Share Posted June 14, 2009 ya but witch rods would be safer 133mm or the 138mm. I dont have a rod stoke ratio in mind im just looking to hit 350hp to the wheels and kameari dizzy is only 800 and its super accurate it has an infared laser in it and can handle 24,000 rpms. Quote Link to comment Share on other sites More sharing options...
JMortensen Posted June 14, 2009 Share Posted June 14, 2009 If you're talking turbo, you can do 350whp with stock rods, no problem. You don't need to stroke the motor. If you're talking NA, good luck. Have you searched at all? It appears that you haven't done any research whatsoever. There's a TON of guys making 350whp here and there's a lot better ways to get there than changing the rods. By the way, a witch has a cauldron and flies on a broom. "Which" is the word you were looking for. You might try a spell checker, it could help with searching for other information if your spelling is really bad. Quote Link to comment Share on other sites More sharing options...
JMortensen Posted June 14, 2009 Share Posted June 14, 2009 Also, it doesn't matter how accurate a DISTRIBUTOR is if the GEARS that drive it are not accurate. Kameari distributor for $800 is a bad deal compared to direct ignition with crankfire, where there is no gear slop to change the timing. Quote Link to comment Share on other sites More sharing options...
greenmonster80 Posted June 14, 2009 Share Posted June 14, 2009 If building on a budget use the 133mm 240sx rods. If you plan on taking full potential of the LD crank and having a real kickass L31 use the 138 rods. I got my 138mm rods from a L14 nissan engine. Old engine in a 4 cyl configuration. Rods can be purchased from either Aus or Jap. Be sure you get 2 extra to come out to a total of six. There is an early and later version. The later version has slightly heavier rods so matching up proper sets is important. I decided on the 138mm rods cause I had access to some and I have a copy of Kakimoto's engine build sheet that produced over 330ps from a L31 and copied it (I ditched the 50mm carbs and went with ITB's for easier tunning and drivability). The LD has a deeper strock so using a longer rod to take advantage of it made sense to me. I toped it of with escort (brand) pistons. Kakimoto offset bushed the pin bushing to gain 1.5mm more and used motorcycle pistons. Not my cup of tea since I found the pistons specifically built for the L14 rods. I got my LD crank, L14 rods and 89mm pistons all for around 1K. Not bad but that was years ago. I have not searched to see if L14 rods are even sold much any more. A longer rods will keep the piston straighter in the cylinder, meaning less drag on the walls during the rotation. As it was explained to me anyways. I am not a professional engine builder but I do listen to the ones I know. Quote Link to comment Share on other sites More sharing options...
soullessjdog Posted June 15, 2009 Author Share Posted June 15, 2009 thanks i think i will go with the 138mm rods im looking to make 350hp on a n/a engine but im going to go with triple carbs more original and im tired of fuel injection its more money that way and weber carbs arent bad there not hard to work on fuel injection can get complicated and costly, and the kameari dizzy has 6 servos so for the money i think its the best deal. Quote Link to comment Share on other sites More sharing options...
JMortensen Posted June 15, 2009 Share Posted June 15, 2009 thanks i think i will go with the 138mm rods im looking to make 350hp on a n/a engine but im going to go with triple carbs more original and im tired of fuel injection its more money that way and weber carbs arent bad there not hard to work on fuel injection can get complicated and costly, and the kameari dizzy has 6 servos so for the money i think its the best deal. Let me amend that last post. I think you'll spend a lot of money and you will miss your numbers by ~100 whp on a street engine. Quote Link to comment Share on other sites More sharing options...
josh817 Posted June 15, 2009 Share Posted June 15, 2009 Indeed. I have less than $200 invested in my EDIS system. However I'm using Megajolt and not Megasquirt. Quote Link to comment Share on other sites More sharing options...
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