2003z Posted September 27, 2006 Share Posted September 27, 2006 I know its a stupid question, but the PO of the car said it he replaced the original with a turbo engine in anticipation of a future upgrade. When I took the headers off today, I see its an N42 and not an F54. It was rebuilt by a commercial engine rebuilder and has a p90 head, so I just want some confirmation. Maybe they used whatever block they had. Also, looking at the cylinder walls and all the honing marks, is any other prep needed other than a good cleaning. I plan on replacing the pistons with nissan motorsports pistons and upgrading to an MSA cam, but I don't know which one yet. I am staying NA with SUs. Quote Link to comment Share on other sites More sharing options...
2003z Posted September 27, 2006 Author Share Posted September 27, 2006 one last question, for now. Is the carbon on top of the block indicative that the pistons dont come all the way to the top of the block on compression? Quote Link to comment Share on other sites More sharing options...
nismopick Posted September 27, 2006 Share Posted September 27, 2006 need... to... learn... how... to... use... a... camera.... Quote Link to comment Share on other sites More sharing options...
2003z Posted September 27, 2006 Author Share Posted September 27, 2006 need... to... learn... how... to... use... a... camera.... my picture is fine, apparently though, you have nothing useful to say. Quote Link to comment Share on other sites More sharing options...
zeiss150 Posted September 27, 2006 Share Posted September 27, 2006 If he built it for a turbo application he might have just used the n42 block... they are suposedly better than the F54. It could have an N42 block with "turbo pistons" and would make the bottom end the same as a stock turbo as far as the internals go. The P90 head is definatly for a turbo. If you wanna replace the pistons then replace them with flat top pistons that will give you 8.5:1 CR pretty good for a N/A engine. If you use a 1mm head gasket you'll get a little higher CR 8.7:1 these CR #'s are only good if there was no bore when the engine was rebuilt. That top ring of carbon is normal engine ware. Its there because the top compression ring doesn't go to the top of the block. the piston reaches the top of the block and there is a space between the cylinder wall and the piston so carbon builds up there. you have to be careful when you take the pistons out if you go through the top because that carbon ring can get really hard and it can damage the piston on the way out. but Im sure that yours can be taken off with a scotch brite scratch pad. Just my opinion but I would go turbo if I was you... the N/A set up might get you 180 HP to the wheels ... but a well set up turbo will give you 300... just a thought. Good luck .... Matt- Quote Link to comment Share on other sites More sharing options...
veritech-z Posted September 27, 2006 Share Posted September 27, 2006 N42 blocks had dished pistons as well, from what I understand the N/A F54s had the flat tops.. I'm sure that when the commercial engine rebuilder got their cores back, they just used whatever they had around to get the same results. I've got that same block with a p79 head, and it's a bit sluggish off the line, but has a lot of pull from a roll. I was planning on going turbo, but now I'm pretty sure I'm doing an SBC down the road. *edit* so as an answer to your question, those are dish pistons. A flat top would be exactly that: just a level plane across the top of the piston, while these have a dish in the center. *edit edit* If you are staying NA, you are going to need a bump in compression to get the performance you want. I always see Jmortensen telling people that the MSA cams are pretty small, so maybe you should ask him about what cam choice he would recommend? I understand the stock fuel injection and the height of the valve seals are the limiting factor on the cam lift, but there are ways around that. I know I've skimmed threads about good cam choices for NA, so a quick search should turn up some good results. Quote Link to comment Share on other sites More sharing options...
2003z Posted September 27, 2006 Author Share Posted September 27, 2006 thanks! I'm definitely staying NA. Quote Link to comment Share on other sites More sharing options...
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