rjracin240 Posted August 31, 2011 Share Posted August 31, 2011 (edited) Here is the dilema, motor let loose last HPDE I went to. Motor was one of those Z car motors built from a bunch of stuff laying around and had quite a few miles, in its defense though lasted about 10 years of racing! Motor is a stock 240 block with 280 bottom end Z pistons, prior history unknown. E88 head that I had from my original motor basically stock. Engine had been running hot with some mild detonation for a while, but on the last day it ran, went way hot, loud detonation, then the cloud of oily smoke out of the crankcase vent. 0 PSI in #4 cylinder and the rest of the cylinders between 110 and 130. Car has trip 40 Mikuni's, 21/2" exhaust, tilton flywheel. Question is if block is usable should I put oversize pistons and a E31 head on it and let it roll or F54block and a P90 head. Have the following heads Virgin E31 head, E31 head that someone has shaved and done a valve job too (contemplating welding it back up and resurfacing so has close to stock compression, would rather use this head than get into the virgin head and save it for some later build) P90 head is also wrecking yard head that someone has shaved to just below the P90 on the side of head, this might be a good thing and might put compression closer to where it needs to be. Second P90 is unshaved but was a 93 with Hydraulic Lifters that I would swap out if used. Do work at a facility where they have a weld engineer and different methods of welding from MIG to TIG so any restoration of head should not be a problem. In order for weld engineer to work up a procedure, does anyone know the characteristics of the base material for the cylinder head?? Of course all info that is generated during this build will be shared for all on here. Any help and feedback would be appreciated. Edited August 31, 2011 by rjracin240 Quote Link to comment Share on other sites More sharing options...
johnc Posted August 31, 2011 Share Posted August 31, 2011 Budget? Quote Link to comment Share on other sites More sharing options...
Gollum Posted August 31, 2011 Share Posted August 31, 2011 I'd use the virgin P90. Excess shaving of the head will usually not help when it comes to valve shrouding, but maybe it's had some major chamber work. Pictures please? Also, the hydraulic lifters in the P90 you have are fine. I have yet to actually see a lifter failure on them personally, and have owned those heads in the past with no issues. The lifters will rev a heck of a lot higher than the stock springs will go, and we've seen people on this site reving those lifters past 8k without issues. The only reason I can see replacing them would be for cost, as finding the OEM nissan part can get expensive. Solid lifters are readily available and affordable. That's the reason to swap them, if at all. But as John said..... budget? Quote Link to comment Share on other sites More sharing options...
rjracin240 Posted September 1, 2011 Author Share Posted September 1, 2011 Budget.....hoping to keep cost's down by using stock parts bin use and then just doing the neccesary machining of these parts, so take that as the obligatory balancing, cylinder head freshening (3 angle grind etc)rebore if needed with the use of good OEM style piston replacements if needed. Would like to do it right so will be going to a reputable machine shop, if boring is necessary would like to use a boring plate (any specs or pictures of one would be appreciated as there is a lot of thick plate laying around work that I could gt burnt up for a boring plate) Bottom line building a parts bin motor so I can keep my daughter in college, EX Wife, etc....not to say that if there is a key item that needs to be procured or machined that I would not attempt to save to accomplish this! Hope to accomplish 200 crank HP if possible. Will get some pictures together over the weekend, not sure if I still have the hydraulic lifters; there is a lot of new info out there since I last was actively on here. Old school said dump those lifters and replace with solid, dont use the P79 use square port! Need to re-inventory parts this weekend, thanks for suggestions so far keep em rolling. Quote Link to comment Share on other sites More sharing options...
Mack Posted September 2, 2011 Share Posted September 2, 2011 Whoever told you not to use the P79 because of the round exhaust ports is just parroting old BAD information. The linered heads will flow just as well, if not better than the square port heads if you just clean up the bowl area with a dremel. It takes about 5 minutes to do. I've said this a few times in recent threads, as I feel this cylinder head gets overlooked a lot..... I would suggest a maxima N47 (referred to on this site as an MN47 quite often). They came on 81 to 84 maximas, have a smaller intake valve (helps low end torque), but a 39CC chamber. sitting on top of an F54 flat top block, this will produce 11.7:1 compression with a felpro head gasket, and it has a TON of quench. You can unshroud valves and open up the combustion chamber a bit if you don't want the compression THAT high. It is a linered head, but as I said, it really doesn't make that much difference unless you are going hog wild on the porting. I think it's a much better alternative to shaving and shimming a P79 or P90 Quote Link to comment Share on other sites More sharing options...
Noddle Posted September 2, 2011 Share Posted September 2, 2011 I would suggest a maxima N47 (referred to on this site as an MN47 quite often). They came on 81 to 84 maximas, have a smaller intake valve (helps low end torque), but a 39CC chamber Also the R30 Skyline ( '81 to '85), with the L24e engine has the 'N47' head. Quote Link to comment Share on other sites More sharing options...
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