Guest Anonymous Posted November 13, 2002 Share Posted November 13, 2002 I just bought a maxima n47 head and would like to know your opinions on how I should set it up. I am building a 2.8 .50 over flat tops and plan on running my su carbs. I have lightened and balanced the bottom end an now its time for the fun stuff!!! Quote Link to comment Share on other sites More sharing options...
Guest Anonymous Posted November 14, 2002 Share Posted November 14, 2002 Don't have any direct info for you yet but I'm basically frankensteining my F54 block to the N47 maxima head with my L24 Crank/Rods. DAW seems to be the resident authority on the N47 Maxima head around here. Yeah I know some people will get on me about the small loss of displacement from destroking the L28, but I'm just working with what I have already in parts, and I like the rev happy character of the L24 even if it's not a huge difference. 2.6 Liters or so with dirt cheap 10.5:1 compression on a nice oversquare engine or spend the money on custom pistons with domes or significant milling of the head to build it up on a 2.8 for a minimal increase in net power from .2 liters. (yeah, yeah, no replacement for displacement I know) Also if I do this now with forged flattop pistons as the only significant change to the bottom end, when I do my turbo buildup, it works out to not having to mess with the bottom end and simply slapping on my P90 and the associated equipment for the turbo as a head up turbo conversion on a pre built and strong bottom end. Of course I might just be cheap for now and used cast pistons but at 55-60 bucks per vs 70-80 per it's not a big jump to go to forged and will save me some money long term. In my situation it's a compromise for long term plans. I'll get about 8.3:1 compression just by switching the head and which may not be perfet but it's pretty workable on a turbo engine since the suggestions are for between 8.1 and 8.5:1 for the compression for a good turbo buildup. Just for comparison, my wife's VW Passat has a 1.8 Turbo with a static compression of 9.5:1 and with the turbo it's good for 170 from the factory and it's got a nearly flat torque curve of 166 lb feet from about 1800-5000 rpm. Don't necessarily need displacement to have good power output in other words. Quote Link to comment Share on other sites More sharing options...
Guest Anonymous Posted November 14, 2002 Share Posted November 14, 2002 I know about being cheap! The pistons that I am going to run are cast and I bought them on Ebay. I paid 100.00 for them. They were new with moly rings and were alredy balanced. I polished and lightened the rod beams myself,so no real $$ spent except to have them balanced. I dont mind spending money on the head. I want to do it right.I thought that it might be fun to see how some of you guys would spend my money and see what kind of power I end up with. It could be a way to see what kind of power this head motor combo can make vs a n42 or e88. The local speedshop wants to design my camshaft for me. They have a list of people that they have worked with that is unbeleavable including Jeg Coughlin and other people like GM and Ford. It will be interesting to see what they come up with and how expensive the are. Since they will probably put me in the poor house, I wanted you guys's cheap advise on valve size and how much to mill off, if any at all.I was also hoping someone might have some aftermarket valves and springs to use in it Quote Link to comment Share on other sites More sharing options...
DAW Posted November 15, 2002 Share Posted November 15, 2002 Don't mill anything off the head, especially since you're increasing displacement a bit. As it is now you may have to go back and replace the headgasket with a thicker one if you have detonation problems with your c.r. which will be something like 10.6:1 (I didn't crunch the numbers but that's close). You might need to run octane booster. Valves: you're on a budget so I wouldn't look to aftermarket valves. Your exhaust valves/springs are fine as is, you need to install L28 (N42/N47) intake valves/seats/springs. You don't want the Maxima cam in there so either use a performance cam or an L28 (from N47 or P79 Z/ZX head). Unless you've got a lot of time on your hands leave the exhaust port liners alone. You'll need to richen up the SUs and install lighter damper springs. A couple of steps colder on the plugs. Conservative on the timing until you've gotten all the lean spots out then try to bump it up a little at a time. DAW Quote Link to comment Share on other sites More sharing options...
Guest Anonymous Posted November 25, 2002 Share Posted November 25, 2002 I wouldn't worry about lighter dampening springs, just use thinner oil like air tool oil or 3in1 oil. Yes, you will have to replennish it more often, but it works exellent.I have done it for years, with supurb results.Enrichment is a must, and I would use skinner needles. Quote Link to comment Share on other sites More sharing options...
Guest Anonymous Posted November 25, 2002 Share Posted November 25, 2002 Something I've used for a long time is the shock absorber oil for RC cars. I'ts available at hobby stores in alot of viscocities from 5wt on up. I've been using the silicone based oil as it's less sensitive to temperature thinning the viscocity and it works fine but you can also use the mineral oil as well. It's also pretty inexpensive and comes in a nice squirt bottle that makes filling the reservoirs pretty easy and you don't spill much if any usually. Quote Link to comment Share on other sites More sharing options...
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