Dillon Posted October 10, 2011 Share Posted October 10, 2011 First off i know im going to get hammered for this but i have a question,yes i have done my "homework" and i know some stuff, so im not a total newb. I have a 71 240z with a "83?" l28, the block is a f54 and the head is a n42. so the question is would it hold some boost? i know the head has had some head work done to it but i dont know what exactly has been done. but it does have a cam.. so would it hold any good boost? thanks P.S. i dont know if this is the right spot for this thread Quote Link to comment Share on other sites More sharing options...
NewZed Posted October 10, 2011 Share Posted October 10, 2011 Why would you get "hammered" for your question? Quote Link to comment Share on other sites More sharing options...
Dillon Posted October 10, 2011 Author Share Posted October 10, 2011 Why would you get "hammered" for your question? well because some would say its a "newb'ish" question.. Quote Link to comment Share on other sites More sharing options...
BluDestiny Posted October 10, 2011 Share Posted October 10, 2011 (edited) Is it a flattop piston engine? Edited October 10, 2011 by BluDestiny Quote Link to comment Share on other sites More sharing options...
nash542001 Posted October 10, 2011 Share Posted October 10, 2011 (edited) It should hold as long as you have some fuel management and make sure you don't go lean. I have a stock internal N42 block with N47 head and have been running up to 16lbs on 91 octane with no issues. I have even had boost control problems and seen spikes up to 22lbs with no detonation, but while running pig rich. Don't know if stock 1976 L28E has flat top or dished piston so that could make a difference? Edited October 10, 2011 by nash542001 Quote Link to comment Share on other sites More sharing options...
Dillon Posted October 10, 2011 Author Share Posted October 10, 2011 It should hold as long as you have some fuel management and make sure you don't go lean. I have a stock internal N42 block with N47 head and have been running up to 16lbs on 91 octane with no issues. I have even had boost control problems and seen spikes up to 22lbs with no detonation, but while running pig rich. Don't know if stock 1976 L28E has flat top or dished piston so that could make a difference? thats good to know do you have a build thread up on here i could check out? i dont know what year my l28 came out of, but i think its a 83 280zx.. so i dont know if it has dished or flat top pistons, but i might check today and see. Whats better? Quote Link to comment Share on other sites More sharing options...
bradyzq Posted October 10, 2011 Share Posted October 10, 2011 thats good to know do you have a build thread up on here i could check out? i dont know what year my l28 came out of, but i think its a 83 280zx.. so i dont know if it has dished or flat top pistons, but i might check today and see. Whats better? An F54 block with an N42 head is not a stock combination. So, basically someone put together that engine. Who know what pistons are in there, or crank or rods? Quote Link to comment Share on other sites More sharing options...
neotech84 Posted October 10, 2011 Share Posted October 10, 2011 Take out a spark plug at TDC and check it out. You can get an idea of what you have without taking off the head. Quote Link to comment Share on other sites More sharing options...
Dillon Posted October 10, 2011 Author Share Posted October 10, 2011 that's what i thought from the resource i have done the n42 head never came on a f54 block.. well today or tomorrow I'll take a spark plug out and see whats in there, and do a pressure test, and ill reply back with what i find thanks again! Quote Link to comment Share on other sites More sharing options...
nash542001 Posted October 11, 2011 Share Posted October 11, 2011 (edited) thats good to know do you have a build thread up on here i could check out? i dont know what year my l28 came out of, but i think its a 83 280zx.. so i dont know if it has dished or flat top pistons, but i might check today and see. Whats better? Don't know which is better, because that all depends on you. F54 block supposed to be better since it is the last design for the engine model. As far as flat tops or dished, dished would be better for higher boost levels and you would have a compression ratio of 8.3 with that head if everything else was stock. With flat tops it would be around 9.8 which would not be good for turbo application. Some people like the higher compression NA engine. Edited October 11, 2011 by nash542001 Quote Link to comment Share on other sites More sharing options...
Dillon Posted October 12, 2011 Author Share Posted October 12, 2011 Ok so about 30 minuets ago i took out four spark plugs,and to my surprise one was up in the cylinder pretty far and i could see it was the "dished" style, and it was sooo shiny and the cylinder walls were shiny too! so basically i have a f54 block with dished pistons and a n42 head with mild cam.. "it lopes when at idle" Is the f54 with n42 head and dished pistons a stock combination? thanks again Quote Link to comment Share on other sites More sharing options...
bradyzq Posted October 12, 2011 Share Posted October 12, 2011 (edited) Once again, an F54 block and an N42 head are not a stock combination. However, it may end up internally duplicating an N42 head / N42 block combo. With dished pistons (if they are the usual 10.9cc dish) you have a low compression engine which is not making good use of your cam. It should be able to take some boost, though how much is really dependent on the tune. Edited October 12, 2011 by bradyzq Quote Link to comment Share on other sites More sharing options...
neotech84 Posted October 12, 2011 Share Posted October 12, 2011 Sounds like you might have a fairly fresh rebuild on your hands. Lucky you if done right, as for the cam who knows what you have you can visually check but with so many regrinds you would need to spec it out. Quote Link to comment Share on other sites More sharing options...
Dillon Posted October 12, 2011 Author Share Posted October 12, 2011 lol that's all i really wanted to know about turbo'ing it thanks but also, umm this may sound stupid, but when i first got the car, i took the valve cover "cam cover" off and everything was clean "really" clean, and on the cam there was some purple mark.. i couldn't read if it said anything because it was almost facing down.. i dont know if there is a brand that write purple stuff on their cams or if it was just a mark lol "im stupid for saying that most likely" but thanks, i still need to do a pressure test and see what kinda compression it has.. Quote Link to comment Share on other sites More sharing options...
letitsnow Posted October 12, 2011 Share Posted October 12, 2011 Guessing cam manufacturer/grinder based on paint marks is pretty shoddy at best. If you can measure the base circle and lobe height and subtract the 2 to get cam lift, you can get valve lift and estimate what cam you have. From what I understand, there are only a handful of unique L series lobes. If you have a dial indicator and a degree wheel you can figure out exactly what you've got. Quote Link to comment Share on other sites More sharing options...
Dillon Posted October 14, 2011 Author Share Posted October 14, 2011 hmm,i may do that when i get a chance oneday. This is kinda way off subject but the car has a Holley four barrel.. and the little vacuum hose from the brake booster to the carb blows air when i hit the brakes... and the brakes dont work until i go all the way to the floor, and still then they dont grab much.. anybody have an idea? or can lead me into the right direction? thanks Quote Link to comment Share on other sites More sharing options...
beermanpete Posted October 14, 2011 Share Posted October 14, 2011 (edited) hmm,i may do that when i get a chance oneday. This is kinda way off subject but the car has a Holley four barrel.. and the little vacuum hose from the brake booster to the carb blows air when i hit the brakes... and the brakes dont work until i go all the way to the floor, and still then they dont grab much.. anybody have an idea? or can lead me into the right direction? thanks If you have already ruled out bleeding, leaks, and a bad master then look for a displaced reaction disc in the brake booster. It is a rubber disc about the size of 2 or 3 quarters stacked up. It can fall out when the master is off, causing symptoms like you described. Read this for details: http://forums.hybridz.org/index.php/topic/69706-reaction-disk-pictures-and-walkthrough/ Edited October 15, 2011 by beermanpete Quote Link to comment Share on other sites More sharing options...
Dillon Posted October 15, 2011 Author Share Posted October 15, 2011 well i ruled out everything besides a bad master..but when i hit the ebrake it stops really good, so im thinking the master is bad, or the little reaction disk jumped.. like you were saying Quote Link to comment Share on other sites More sharing options...
Dillon Posted October 18, 2011 Author Share Posted October 18, 2011 (edited) well after all.. we decided to bleed the lines again, and now the brakes work, but now in the back one wheel is always locked up and cant spin it, and the other wont lock up when the brake is pushed.. at all... Edited October 18, 2011 by Dillon Quote Link to comment Share on other sites More sharing options...
Dillon Posted December 7, 2011 Author Share Posted December 7, 2011 Back from the dead guys so i resonantly did a compression test on that f54 block with n42 head l28 i have,and i got 150psi on every cylinder Quote Link to comment Share on other sites More sharing options...
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