ZHoob2004 Posted August 21, 2016 Share Posted August 21, 2016 I recently (read: 9 months ago) acquired a 77 280z which I have been fixing up. Within the past few weeks, it's finally been ready to drive up and down the street and it doesn't really seem to be anywhere close to what I was expecting. So far with the car, I've swapped in a used L28 from a local acquaintance with an n42 block and mn47 head. Swapped the car from auto to 5 speed (I believe 280z) and the r180 in the back for an r200 (3.7 gears). Intake is a 280zx manifold and exhaust is an msa 6-1 header going out a straight-through muffler. Fuel system has been fully cleaned and repaired with the addition of a gauge just after the filter, using stock 280z efi. Ignition is a 280zx matchbox set to ~35 degrees total advance. As for expectations, I know I'm not making a ton of power, but am I right to expect more than the stock 130? If so, is there something missing I should have done to take advantage of these mods? This is my second car, and I was never able to drive it in stock form, so my only comparison is my B16 (160 claimed) swapped CRX with basic bolt-ons. Quote Link to comment Share on other sites More sharing options...
JMortensen Posted August 21, 2016 Share Posted August 21, 2016 Z's need a cam to make any power, and the stock FI can't deal with a cam. The MN has tiny valves, and the compression with that head is very high. I would suggest an aftermarket FI system or a switch to carbs and a healthy cam in there with some headwork. Do all of that right and you should make mid 200s hp. A 280ZX NA trans from a 80-83 will have better ratios for use with your 3.70 gears. The 280Z 5 speed has wide ratios and a big gap between 2nd and 3rd gear. Quote Link to comment Share on other sites More sharing options...
ZHoob2004 Posted August 21, 2016 Author Share Posted August 21, 2016 Alright, I can understand the gearing and the fuel being potential problems. So far I'm working with what I have and EMS and a cam are definitely in the future for this motor. Is there any reason I would be making less power than stock with this setup, and can I adjust something to compensate? Does the difference in valve size between the maxima and l28 make that big a difference? I also have a regular n47 around (needs seals), would that give me more power for the time being? Quote Link to comment Share on other sites More sharing options...
NewZed Posted August 21, 2016 Share Posted August 21, 2016 close to what I was expecting. What does it not do? Burnouts, wheel-stands, 140 mph...? Quote Link to comment Share on other sites More sharing options...
ZHoob2004 Posted August 21, 2016 Author Share Posted August 21, 2016 What does it not do? Burnouts, wheel-stands, 140 mph...? I'm hoping it can feel similar to my Honda but with more torque and less fear of speed bumps 1 Quote Link to comment Share on other sites More sharing options...
NewZed Posted August 21, 2016 Share Posted August 21, 2016 Speed bumps have nothing to do with the engine. The Honda is probably a buzzy little high RPM engine. I asked what you were expecting because there are things people do to move the torque curve up or down the RPM range. Plus, the MN47 comes from a Maxima, which is a passenger car. Already tuned for mid-range power. If somebody put your cam sprocket on the #2 position you might have the perfect truck engine. Plus what jmortensen said about small valves, which will choke flow at high RPM. But, basically, it's not a "stock" 280Z engine. So, in addition to all of the little tuning things, you don't really know what you have, if it's more power than stock or less. Pick up a used 280Z or 280ZX L28 and runit while you play with the modified engine. Sorry jm, didn't mean to overload your conversation. My stock 1978 N42/N47 engine with stock EFI system feels like it has plenty of power. Quote Link to comment Share on other sites More sharing options...
ZHoob2004 Posted August 21, 2016 Author Share Posted August 21, 2016 Ok, that all makes sense and I admit that I don't know all of what I have. I did check and replace all gaskets in the motor and have the cam timed to the #1 position. Motor was reassembled according to the rebuild book. I have a wideband in my Honda that I plan to move over to check the fueling. Anything else I should be doing to get a handle on what I have and what it's doing? I still have the stock motor as well, but it needs a bore and valve job. Would pushing towards an aftermarket ems and cam be an advisable course? Could this all be the fault of my afm? Quote Link to comment Share on other sites More sharing options...
ZHoob2004 Posted August 21, 2016 Author Share Posted August 21, 2016 Another idea I just thought of was could I switch the cam from my other head to the maxima head? The maxima is internally oiled and the old head is using a spray bar Quote Link to comment Share on other sites More sharing options...
NewZed Posted August 21, 2016 Share Posted August 21, 2016 Even the stock 280Z L28 engine is known to run out of breath between 5000 and 5500 RPM. Probably never feel like a Honda without work.. You can do a bunch of small things but each one will probably only have a small effect. Really, you should have done the research before you did the gasket refresh, you might would have made different choices. Good luck, most of the guys on here will say go big on the cam, and the head work. I was just reading one of jmortensen's old posts on big cams. Search around. Quote Link to comment Share on other sites More sharing options...
ZHoob2004 Posted August 21, 2016 Author Share Posted August 21, 2016 So then, based on the advice received in this thread so far and a bit of research on my own, my action plan is as follows: Right now - N47 cam in head (still need to figure out if this is feasible) wideband - check AFM Future - real cam standalone EMS head work close-ratio transmission? Does this seem solid? And to clarify, I don't expect this motor to rev anything like the honda, but I'm hoping to approach similar power output. The honda is high revving and makes little torque, the l28 I hope for medium revs and medium torque Quote Link to comment Share on other sites More sharing options...
madkaw Posted August 21, 2016 Share Posted August 21, 2016 Get the AFM in there very first thing to see if your not way lean or something . Plugs look okay? Quote Link to comment Share on other sites More sharing options...
ZHoob2004 Posted August 21, 2016 Author Share Posted August 21, 2016 Plugs were alright last I checked, but that was a while ago. I'll try to get the exhaust welded this week and move the wideband over on Saturday and see where I'm at there. Quote Link to comment Share on other sites More sharing options...
NewZed Posted August 21, 2016 Share Posted August 21, 2016 You haven't really said how it runs now, if it's low on power everywhere or just on the high end. Who knows, you could have a clogged air filter, a rich EFI system, or a tiny 1 1/2" exhaust pipe. There are a few lists out there of the things that give the biggest bang for buck. You might do a bit more reading and measuring to see if there's any easy-pickin's. Try the FAQ's. Quote Link to comment Share on other sites More sharing options...
ZHoob2004 Posted August 22, 2016 Author Share Posted August 22, 2016 Overall, my impression is that it's low on power everywhere, more so up high. All filters and fluids are brand new, I can't rule out the rich efi (though it's definitely better than it used to be) Quote Link to comment Share on other sites More sharing options...
beermanpete Posted August 22, 2016 Share Posted August 22, 2016 Does your car have good throttle response? If it does it is likely running as it should but does not fit your expectations. The Z engine is not peaky and the power falls off in the mid-5000 RPM range. If the Maxima head still has its original cam the power band could be lower still. Driving feel (to me) with the 280 engine (with SU carbs) is that it does not give much sensation of pulling hard because the power band is wide and flat. By contrast, my Miata is peaky and does not make much power until above 4k or so. This makes it feel faster than the Z but I doubt it actually is. Quote Link to comment Share on other sites More sharing options...
HuD 91gt Posted August 23, 2016 Share Posted August 23, 2016 A B16 in a CRX is a hot little combo. Having a little experience with Hondas 15 years ago, I'd say your car with the stock motor is probably similar to a CRX Si in stock form. First step is getting the wideband on there to see how yours is even running. With a stock cam, and the smaller valves (and high compression) you should have a torquey little motor, but it won't have the same feeling as your CRX. They pulled pretty hard past 4k. Do you have a stock manifold? I have no experience but I've heard the 6-1 header can seriously rob low end grunt. Your head probably won't flow enough in it's current form to take advantage of it's benifits. Work with what you have and try to get it all to work together. Quote Link to comment Share on other sites More sharing options...
Tony D Posted August 23, 2016 Share Posted August 23, 2016 An L28 is dead at 5300 which is why they were geared for that at top speed. If you want more power on the top end, you will need a real cam, and not something from another L-Series. Even the early heads from the L24 are not going to make that much of a measurable difference in performance gain. Quote Link to comment Share on other sites More sharing options...
ZHoob2004 Posted August 23, 2016 Author Share Posted August 23, 2016 (edited) A B16 in a CRX is a hot little combo. Having a little experience with Hondas 15 years ago, I'd say your car with the stock motor is probably similar to a CRX Si in stock form. First step is getting the wideband on there to see how yours is even running. With a stock cam, and the smaller valves (and high compression) you should have a torquey little motor, but it won't have the same feeling as your CRX. They pulled pretty hard past 4k. Do you have a stock manifold? I have no experience but I've heard the 6-1 header can seriously rob low end grunt. Your head probably won't flow enough in it's current form to take advantage of it's benifits. Work with what you have and try to get it all to work together. An L28 is dead at 5300 which is why they were geared for that at top speed. If you want more power on the top end, you will need a real cam, and not something from another L-Series. Even the early heads from the L24 are not going to make that much of a measurable difference in performance gain. Thanks both of you, this is exactly the sort of advice I was hoping to hear. Some searching told me I shouldn't have any immediate problems with switching the cams (and caps for oiling) between the heads on the car, so that and wideband are immediately happening, then it's to the drawing board for how I'm going to set up my fueling. As for the header, I do have the stock header (both z and zx), so that may be an option as well. Luckily, the used exhaust I picked up should be able to bolt on to the stock system just as well as it does the long header. Edited August 23, 2016 by ZHoob2004 Quote Link to comment Share on other sites More sharing options...
skirkland1980 Posted August 23, 2016 Share Posted August 23, 2016 A p79 head might help. The valves are bigger and with flat tops compression would be pump gas friendly. I had an 83 5 speed f54 flat top /p79 with megasquirt it was not the fastest car but very fun to drive. Quote Link to comment Share on other sites More sharing options...
BluDestiny Posted August 23, 2016 Share Posted August 23, 2016 What Tony was saying is true, on top of that the stock EFI is probably limiting you. Here is my dyno of an stock L28 (f54/p79 combo) with SU's and a 6-2-1 msa header You can see it falls off. One other thing I can think of is the weight difference. I know the CRX's weigh like 2300lbs tops fully loaded. Your Z is a little heavier than that. My engine is in a 2100 lbs 240z. Quote Link to comment Share on other sites More sharing options...
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