Lvcien Posted January 4, 2006 Share Posted January 4, 2006 I've been thinking about what to do with my new Z I've come to the conclusion that I'll be doing a 3.1L low-compression stroker leaving plenty of room for high boost... I've actually got a pretty radical plan, but I'm not going to spill a drop of it until I actually see the stroker come together... I've noticed that the size of the KA24E pistons is between 89.5mm - 90mm, the stock bore for the L28 is 86mm, I've also read that anything more than 3mm is dangerous and not recommended. Standard 89.5mm piston: http://www.courtesyparts.com/Merchant2/merchant.mvc?Screen=PROD&Product_Code=12010-00001&Category_Code= Standard 90mm piston: http://www.courtesyparts.com/Merchant2/merchant.mvc?Screen=PROD&Product_Code=12010-00002&Category_Code= Race 90mm Piston: http://www.courtesyparts.com/Merchant2/merchant.mvc?Screen=PROD&Product_Code=12010-00003&Category_Code= *The Race 90mm Pistons require Carrillo steel connecting rods I don't see the 89mm pistons, these seem to be larger... * It looks like the 89mm pistons were only on the 1989 - 1990 240SX. Any Advice on what would be best for this sort of build? Wish me luck, and this is the plan so far: Block: F54 Head: P90 Bore: ??? Crankshaft: LD28 Rods: L24 (Carrillo?) Piston: KA24E Flat-top (or J&E?) Cam: That's a secret! Compression Goal is 8:1 Please let me know is anything I'm overlooking or perhaps something else I should take into consideration ... or anything related at all to this. I'll be using a modified version of Megasquirt running with three profiles for fuel consumption & performance Econo (1 - 6 psi boost (93 Octane)) Street (7 - 13 psi boost (93 Octane)) Race (14 - 20+ psi boost (Race Fuel)) Those boost levels arn't set in stone yet, so they'll vary but you get the idea. If you've got suggestions on what I should use that's different from what's listed above please list them. Price & Time isn't that big of a deal -- I'll have roughly 600$ a month. Thanks, Chad Quote Link to comment Share on other sites More sharing options...
1 fast z Posted January 4, 2006 Share Posted January 4, 2006 180 a piston, WOW. Go get custom forged for a Third the cost of that, AND with ALL your custom dimensions, MUCH better way to go. BTW, ALL State side 240sx pistons are 89mm bore stock. A 3098cc motor is 83mm stroke and 89mm bore. USE a N42 block, as it is the TRUE siameesed block, and NOT the F54. BEST to sonic test and ACCOMIDATE for core shift, as This is the best way and the best insurence for cylinder thickness. REVERSE dome the pistons EXACTLY to that of the P90 chamber for maximum quench, and run a .020-.025" Piston to Head clearence and you can run MUCH more boost. Quote Link to comment Share on other sites More sharing options...
Lvcien Posted January 4, 2006 Author Share Posted January 4, 2006 Bryan, Thanks for the input, I feel bad because most of the time I've spoken with you I thought your name was Blake... lol. I've got an N42 block coming, so Would you advise getting custom forged pistons with the same specs as the 240sx pistons(flat top?)? how would you suggest I achieve the 020-.025" piston-to-head clearance? include the math if you can. According to a source of Tony D the stock 240z rods are good up to 600hp... You being one of the few that know the whole plan, do you think they would withstand it? I've got a P90 head and I'll prolly get ahold of you later on to port & polish it, but shipping is going to kill me. I also need to get a good condition LD28 crankshaft... I sent you a message about the cam. Anyone else? Quote Link to comment Share on other sites More sharing options...
thehelix112 Posted January 4, 2006 Share Posted January 4, 2006 You going to change your blower pulleys everytime you fill her up with race fuel? You're game. Dave Quote Link to comment Share on other sites More sharing options...
z-ya Posted January 4, 2006 Share Posted January 4, 2006 What am I missing with the N42 vs F54 block? I thought the F54 was siameesed block, not the N42. Please clarify. Quote Link to comment Share on other sites More sharing options...
SHO-Z Posted January 4, 2006 Share Posted January 4, 2006 You might want to look at the Mercedes SLK "Kompressors" They have a electric clutch like a air conditioner and use a by pass check valve when not in use. That was you can have econ no boost and flip of the switch instant passing boost. Quote Link to comment Share on other sites More sharing options...
1 fast z Posted January 4, 2006 Share Posted January 4, 2006 Yea, the Stock 240 rod, has plenty of tensile strengh to withstand. Shipping on heads isnt that bad, you could do it all for like 90 bux, thats shipping both ways. Ok, I dont know how many times I have written about the Blocks but Ill do it again. The TRUE, FULL siameesed blocks are the N42 ones, NOT the F54 blocks. F54 has water passages BETWEEN all of the cylinders, which entitles NOT siameesed. The thickness between the N42 cylinders are the full thickness of the in between bore spacing in all cylinders except for between number three and four. I own a sonic tester and I have sonic tested all L series blocks, P30's, N42's, F54's V07's. So this isnt just some far out "claims" these our FACTS. Search my old post and you will see the actuall cylinder thicknesses I have posted in the past. So to sum it up, if your going for a BIG bore motor, USE a N42 block, and get one from a first two year 280 car, for the high nickel content. Quote Link to comment Share on other sites More sharing options...
Lvcien Posted January 4, 2006 Author Share Posted January 4, 2006 That works out great, I've got a 76' N42 block 1 fast Z, do you think it would be worth it to have my pistons lightened? Quote Link to comment Share on other sites More sharing options...
1 fast z Posted January 4, 2006 Share Posted January 4, 2006 Oh yes, It is WELL worth it to have pistons lightened. Every amount of mass you take out of a piston, it makes the rod and crank that much stronger. F=MA, if the M is less then the force on the rod is less. It makes a motor run so smooth and rev soooo quickly also. Makes for QUICK spool as well. Yes I will never understand why people build motors and spend thousands on it and wont get maximum lightening out of there pistons. Quote Link to comment Share on other sites More sharing options...
Lvcien Posted January 4, 2006 Author Share Posted January 4, 2006 so what would you charge to lighten the pistons I'll have made? Could you also e-mail/PM(preferred) me with the specs of the pistons I should get custom made for this application, I can send them along with the head for the work. -- What can you do to lighten stock 240z rods(is that even a good/safe idea?) Thanks again. Quote Link to comment Share on other sites More sharing options...
thehelix112 Posted January 5, 2006 Share Posted January 5, 2006 1 fast z, Do you put much stock in the comments about later turbo blocks (F54) being altered to reduce the siamese in the name of heat dissipation? I forget which book its mentioned in, How to Modify Your Nissan Datsun OHC Engine I think? Lvcien, It would be rather silly to get custom pistons made, then get them customised wouldn't it? Perhaps it'd be better to ask these knowledgable chaps how short you can make the skirts before the gudgeon pins get ripped out of the piston, and how short a pin height you can go. Good luck. Dave Quote Link to comment Share on other sites More sharing options...
Lvcien Posted January 5, 2006 Author Share Posted January 5, 2006 Thanks for the input thehelix112, so to the "knowledgable chaps" how short you can make the skirts before the gudgeon pins get ripped out of the piston, and how short a pin height you can go? all the in name of weight reduction... Quote Link to comment Share on other sites More sharing options...
hoov100 Posted January 5, 2006 Share Posted January 5, 2006 dont take out the skirts, just machine away some of the inside of the piston. Quote Link to comment Share on other sites More sharing options...
Tony D Posted January 5, 2006 Share Posted January 5, 2006 Not "Stock", the phrase was "Competition Prepped Stock Rods" the labor for that can be two hours per rod---$100 each, plus what the rod cost initially---that is close to the dollar level where you can get a decent aftermarket rod. For a race engine that was on an almost unlimited budget, in a class that required 'stock components" they used prepped stock rods to around that 600hp level. After that, they outright broke. For longevity reasons below that hp level and where the class rules allowed it (weight is also MAJOR REASON) they went with aftermarket rods.The stockers were simply inspected and replaced frequently. Aftermarket units, not so much so. There will be absolutely no reason to run the three programs in your Megasquirt. The ONLY thing you will get is resolution from the lower boost levels, making the map go from 0 to 21psia for your first example, and 0-28psia for the second one. Now the "race gas" versus "pump gas" would benefit as the advance curves would make a difference. One of the primary reasons to go with aftermarket rods is you can pick a length you want, to accomodate a custom piston with a custom pin height. if you go this far, and are going to have custom pistons made anyway, you may as well go wit hthe rods, they will be uder $1200 more than likely, and you can be sure they are lighter than stock, and probably stronger. If you are doing it, do it right and then don't worry about it. The power will be in the head. Holding it together will be in the bottom end. Quote Link to comment Share on other sites More sharing options...
Lvcien Posted January 5, 2006 Author Share Posted January 5, 2006 thanks for the input Tony, I sent you an e-mail with the plans, but don't let them slip out please, only you and 1 fast z have them so far. Quote Link to comment Share on other sites More sharing options...
Tony D Posted January 5, 2006 Share Posted January 5, 2006 no worries, if you knew what I have kept close-mouthed on in the past to this very day, you would be amazed. You forget I have signed confidentiality agreements binding me from talking about a LOT of things I saw from the years 1999-2002 when I was around some very high-end motorsports development work (peripherally, admittedly, but I knew what I was looking at! LOL) Quote Link to comment Share on other sites More sharing options...
Guest norm[T12SDSUD] Posted January 5, 2006 Share Posted January 5, 2006 Yeah Tony what about those special flat tops ?? hehehhe Quote Link to comment Share on other sites More sharing options...
1 fast z Posted January 5, 2006 Share Posted January 5, 2006 Ill have to measure what my skirts are in my stroker motor, but I belive they are three thirty seconds of an inch. It takes ALOT of time to lighten pistons CORECTLY everywhere, leaving all of the critical dimensions. Im not gonna spill all of my secrets and dimensions on a online forum, but you can "look" if ya like. (2.75 lbs lighter than a stock flat top recipicating mass) Quote Link to comment Share on other sites More sharing options...
Lvcien Posted January 5, 2006 Author Share Posted January 5, 2006 Looks good, I just spoke with Carrillo, they want $291.00 per rod... I suppose I'll speak with Crower about rods. Quote Link to comment Share on other sites More sharing options...
Lvcien Posted January 5, 2006 Author Share Posted January 5, 2006 Crower 4340 steel billet rods run $167 per rod ... I Like it, now to find the specifications... I love the prices at Crower, best I've found... but how good are they? Quote Link to comment Share on other sites More sharing options...
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