Nismo280zEd Posted October 7, 2003 Share Posted October 7, 2003 ok so i did a search bu didn't find the info i was looking for... can anybody tell me the differences between an f54 block and an N42 block? strenght, etc.? anything? Quote Link to comment Share on other sites More sharing options...
evildky Posted October 7, 2003 Share Posted October 7, 2003 the f54 came with plat top pistons and the p79 might have had otehr options for head, the n42 came with dished pistons and either the n42 head or the n47 head, I believe the f54 has some extra internal bracing making it desirable for strokers but I can't swear to it Quote Link to comment Share on other sites More sharing options...
texasz Posted October 7, 2003 Share Posted October 7, 2003 The F54 came in the '81-'83 280's and came with three setup. The first was as described above, the F54 block with flat-top pistons and a P79 head (this was the non-turbo model). The second two were almost identical and were the turbo models. They were both an F54 block with dished pistons but one had a P90 head which was mechanical and the other had a P90a head which was hydrolic (this is the undesirable one). The F54 is said to be the strongest block and thus also the most desirable one for racing or build-ups. For a daily driver I would think that either would be just fine. More info: the flat-top pistons are the ones you want if you are not going turbo as they will give you the best performance, if you are going to go with a turbo then the dished pistons are the ones you want. Quote Link to comment Share on other sites More sharing options...
Nismo280zEd Posted October 9, 2003 Author Share Posted October 9, 2003 hmm i guess thas good and bad news.. I pulled my engine out to repair the damage the fire caused in my car... and i noticed on the side of the block was F54 instead of N42, And when i took my head off to port and polish it myself I confirmed the dished pistons. So did somebody take the crank rods and pistons outta an L28E and stick them in this F54 block when they did the rebuild perhaps? kinda odd.. i noticed the oil pan is different though. Quote Link to comment Share on other sites More sharing options...
JMortensen Posted October 9, 2003 Share Posted October 9, 2003 The F54 turbo blocks came with dished pistons. That's probably what you have. If you pull a freeze plug on the side of the block you can look in and see the bracing inside the water jacket. If you are doing a NA engine you might want to get some flat tops to put in there. Then you can use the quench area. Do you have a P90 head? That would be the turbo combo from the factory. Jon Quote Link to comment Share on other sites More sharing options...
Guest ElvisTorino Posted October 9, 2003 Share Posted October 9, 2003 Why is a P90a head undesireable? Quote Link to comment Share on other sites More sharing options...
JMortensen Posted October 9, 2003 Share Posted October 9, 2003 Hydraulic lifters in the P90a can't handle really high lift cams. Jon Quote Link to comment Share on other sites More sharing options...
Guest ElvisTorino Posted October 9, 2003 Share Posted October 9, 2003 Oh...thanks Quote Link to comment Share on other sites More sharing options...
johnc Posted October 9, 2003 Share Posted October 9, 2003 There's some debate about which block (N42 or F54) is actually stronger. Here's the information I've been able to accumulate over the years. The early N42 blocks (1975, 1976 I think) had the highest nickel content of all the L6 blocks and are stronger from a metallurgical standpoint. Nissan felt that the later blocks with a lower nickel content needed some design changes to handle the additional combustion pressures in a turbo application so the added the bracing between the cylinders. The nickel content change was a cost consideration. The early N42 blocks are more dimensionally stable (the cylinders stay rounder) then the F54 blocks if your overbore is .040 or less. The F54 blocks are more dimensionally stable at larger (stroker size) overbores. A friend (Tom Smith) who worked at Electramotive in the late 1980s and early 1990s said that the F54 was developed to handle the high turbo horsepower requirements for IMSA racing in the 1980s, although they did have ring sealing problems traceable to dimensional changes in the cylinder bores at high temps (they never overbored the blocks). He also said they blow up a lot of engines before they found the right combination that would last a full race. That's all the rumors, innuendo, etc. that I've heard about the block differences. Quote Link to comment Share on other sites More sharing options...
Nismo280zEd Posted October 11, 2003 Author Share Posted October 11, 2003 so does the F54 have the additional water passages for cooling sine it's a turbo block.. or ? how can i tell with out pulling out a plug on the block Quote Link to comment Share on other sites More sharing options...
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