zclubhouse Posted January 26, 2008 Share Posted January 26, 2008 Hello everyone. I am a new member (been reading the forums for some time) but now I humbly ask for some info I havent been able to find on my own. I plan on introducing my project properly with documentation of the build in the near future, but for now, here is a quick bit of background info on the cobbled together project: 73 240z with a R200 with some 3.91s, 1978 N/A L28 with a 5 speed tranny, dual SU carbs, long tube header, mild cam (do not have exact specs,) stock internals and rebuilt to stock specs 2000 miles ago with the exception of the cam and a mild port and polish of the heads. I plan to autocross the car in the summer but I want to install a nitrous kit for a bit more fun while not competing. I had great success running a small 50 shot on my VW 2.1L 16V, but that was with a fully built motor and DIGI 1 fuel. So what I am wondering is if the crank in the L28 can take a 50, 75 or 100 shot and any experience people have had with this. I understand that common wisdom involves triple carbs, forced induction or a V8 as the next logical step, but I have this love of the spray. Is this sort of set up rare due to the above wisdom, or is it rare because it doesnt work well? I will be running a 140gph fuel pump but I wasnt going to run a seperate/aux fuel system for the nitrous. I have never ran or installed nitrous on a carb set up and any help or suggestion of maintaining or even reaching the extra few psi of fuel pressure without a controller would also be appreciated. The system is very basic and I am planning on running it on a WOT switch for the occasional 1/4 track day. Thanks in advance for the help. Quote Link to comment Share on other sites More sharing options...
510six Posted January 26, 2008 Share Posted January 26, 2008 You could run a "wet" shot, but at least 5 psi of fuel pressure would be needed.The L28 has a forged crank and rods, the pistons are the weak spot when running "squeeze". PM me for more info. Quote Link to comment Share on other sites More sharing options...
cockerstar Posted January 26, 2008 Share Posted January 26, 2008 Oh, please dont withhold any information about nitrous systems! I read and Holley(NOS) said that their systems are good for +50% of the stock horsepower rating on a fully stock engine assuming that the fuel pump is putting out exactly what it is rated for. I'm that an L28e would be fine for a 75 shot with a stock fuel pump, but with something after market a 100 shot would be feasible. The pistons *should* be the limiting factor in the engine. (within reason of course ) Anyone know what they are good for? Quote Link to comment Share on other sites More sharing options...
510six Posted January 26, 2008 Share Posted January 26, 2008 With VG30 100,000 mile core motor pistons a 120hp shot to the wheels worked fine, with the exception of the top of the piston compressing down and seizing the compression ring(after 80 10lb bottles of nitrous). Running nitrous isn`t that much different than setting up a motor to run boost, combustion pressues will increase and ignition retard is needed as HP goes up. Setting up a system that is consistant and has proper saftey provisions made is what becomes more involved and expensive. Quote Link to comment Share on other sites More sharing options...
cockerstar Posted January 27, 2008 Share Posted January 27, 2008 How an I to determine which pistons I have? I have a '79 280ZX. I know which head I have, but I dont remember a piston break down. *surfs the boards looking for the answer* Quote Link to comment Share on other sites More sharing options...
510six Posted January 27, 2008 Share Posted January 27, 2008 If you have a NA L28 your pistons are cast, the L28et has cast pistons as well however they are stronger. The NA pistons should survive a 100 whp shot provided proper safety precautions are taken. Quote Link to comment Share on other sites More sharing options...
CamH Posted January 27, 2008 Share Posted January 27, 2008 If you have a NA L28 your pistons are cast, the L28et has cast pistons as well however they are stronger. The NA pistons should survive a 100 whp shot provided proper safety precautions are taken. I don't believe that the turbo pistons are stronger, they are simply dished and have lower compression. Quote Link to comment Share on other sites More sharing options...
cockerstar Posted January 27, 2008 Share Posted January 27, 2008 I don't believe that the turbo pistons are stronger, they are simply dished and have lower compression. I have dished pistons, and a higher compression than the l28et (7.3 vs 8.4) N42 Pistons: Dished Compression Ratio: 8.3:1 HorsePower: 140HP @ 5200 RPM Torque: 149lb/ft @ 4000 RPM Factory Octane Requirements: 87 (US) If any ZX drivers havent checked out the sticky over there' date=' they should. Its great! Here it is What are the proper safety precautions assuming that I'm running a WOT only system? Do I need an aux fuel system or can I use the stock pump? I'm sure it would be a good idea to not run on 87 octane either Quote Link to comment Share on other sites More sharing options...
ZXT_bean Posted January 27, 2008 Share Posted January 27, 2008 I have dished pistons, and a higher compression than the l28et (7.3 vs 8.4) If any ZX drivers havent checked out the sticky over there, they should. Its great! Here it is What are the proper safety precautions assuming that I'm running a WOT only system? Do I need an aux fuel system or can I use the stock pump? I'm sure it would be a good idea to not run on 87 octane either damn that is one hell of a sticky.. ;)and as for the actual topic of the thread.. im very interested in the answer myself.. seeing as how this is exactly what i planned on doing.. but i was considering a 4barrel intake manifold.. and a plate setup.. and as for an aux fuel setup.. i dont think that would be needed.. just put in a turbo fuel pump.. and a 3 port fuel pressure regulator on, and i think that should be all you need.. please correct me if im wrong here. Quote Link to comment Share on other sites More sharing options...
510six Posted January 27, 2008 Share Posted January 27, 2008 I have dished pistons, and a higher compression than the l28et (7.3 vs 8.4) If any ZX drivers havent checked out the sticky over there, they should. Its great! Here it is What are the proper safety precautions assuming that I'm running a WOT only system? Do I need an aux fuel system or can I use the stock pump? I'm sure it would be a good idea to not run on 87 octane either It would depend on the horsepower that your trying to make with the nitrous. Running anything more than a 100 wheel horsepower shot with stock NA pistons is asking for trouble. Using the stock mechanical pump with nitrous is not a good idea , this link describes it in greater detail. http://webpages.charter.net/beckracing/page14.htm A nitrous fuel system should have an electric fuel pump and have the ability to be regulated, I ran a Holley blue fuel pump on the "wet" port nitrous and it worked without a flaw, a return style regulator was used to keep a constant and cool fuel supply when the nitrous is activated. Running a dead end regulator will work, but fuel can "boil" out of the lines and cause a lean condition when the nitrous solenoid opens. There also has to be a way to tell if your fuel mixture with nitrous is lean , going lean with nitrous is VERY bad. I would recomend a wideband 02 meter and jetting the fuel mixture rich and changing jets until the desired fuel/air ratio is gained.11.0-11.8 is a safe nitrous tune, better to run a bit rich then to use the aluminum in your pistons /cyl head as fuel. Bottle pressure with nitrous will determine the flow and amount of nitrous, being consistant with pressure make the system safer and the horsepower levels reliable. A nitrous gauge near the bottle is a must it ensures that the pressure is what you determine (900-1100 psi), using a bottle heater with a pressure controlled regulator will ensure that bottle pressure is consistant. http://www.watsonperformanceproducts.com/servlet/Detail?no=665 http://search.ebay.com/nitrous-pressure-gauge_W0QQfkrZ1QQfnuZ1QQfsooZ2QQfsopZ32 Safety switches. I will start at what should be wired in series nearest to the solenoids first. Clutch switch: This is used for two applications, first if a problem develops the clutch can be pushed in and the solenoid deactivates. Second, if using a after market ignition box with a dual stage rev limiter the clutch switch can be used as a staging rev limiter for the drag strip.Typically 4k or 5k rpm. WOT: this prevents the nitrous from activating at anything less that 100% throttle. This does three things, first if a problem developes lift the throttle. Second it ensures that the carb/efi is providing maximum fuel preventing a lean condition. Third it prevents unintended activation. RPM window switch: This turns on the nitrous at a specified rpm and off at a specified rpm. This prevents low rpm activation from blowing off your intake manifold and high rpm from putting a rod through the block. http://www.centuryperformance.com/mallory/techfiles/MA1471_RPMSwitch_628.pdf Arming switch: this provides power to the nitrous solenoids, if using a nitrous only fuel pump a relay can be used to provide power to this as well.I would suggest wiring a small LED to one of the solenoids to make sure power is at the solenoid, placed where it can be visually determined at the dash. (plus it looks cool when the nitrous is on) Purge switch: this is a momentary switch that ensures that liquid nitrous is at the solenoid ensuring full power at activation. http://www.dynotunenitrous.com/store/scripts/prodlist.asp?idcategory=17 Low fuel pressure switch: This is a Hobbs switch that ensures enough fuel pressue is present to prevent a lean condition. http://cgi.ebay.com/NEW-HOBBS-PRESSURE-SWITCH-7-PSI-PROPANE-INJECTION-N-O_W0QQitemZ170189177380QQihZ007QQcategoryZ67006QQssPageNameZWDVWQQrdZ1QQcmdZViewItem Ignition, for every 50 wheel horsepower a 2* reduction in timing should be made. I would suggest running an after market CDI box as combustion pressures rise the spark tends to be "blown out" . Also today several manufactures provided ignitions with multiple features that eleminate wiring and extra complexity. Dual stage rev limiters, built in timing retards and window switches are just a couple of examples. http://www.msdignition.com/ignition_18_6520.htm http://store.summitracing.com/partdetail.asp?autofilter=1&part=MAA-685&N=700+115&autoview=sku Spark Plugs : I only use NGK V power plugs , with the gap reduced to .35-30 depending on the horsepower shot. This again is to compensate for the increased cylinder pressures. Also run one step colder plugs than stock with nitrous and replace the plugs after every bottle. http://www.ngksparkplugs.com/products/spark_plugs/index.asp?mode=nml If this sounds like a lot of work, your right it is. Remember that taking time and effort in the begining will save headaches and blown motors in the long run. Quote Link to comment Share on other sites More sharing options...
cockerstar Posted January 27, 2008 Share Posted January 27, 2008 I'm not sure if all of this is worth it... I currently have $235 into the car, counting the cost of purchase. Its part of a cheap build contest I'm in and we're running the 1/4 for a little cash ($250/person) and bragging rights. How likely am I to rip the car apart with a new fuel pump and a WOT system assuming that I'm watching my tach closely? I'm looking for the cheapest possible horsepower I can get my hands on How much do you have into your system? Quote Link to comment Share on other sites More sharing options...
510six Posted January 28, 2008 Share Posted January 28, 2008 I probably have about a grand into my current system, to do everything in a "safe" manner should cost at least that much. The problem is that a nitrous motor can rev faster than can be caught with the throttle esp. in lower gears. I would at least use an rpm switch to deactivate the nitrous at higher rpm http://store.summitracing.com/partdetail.asp?part=SUM-830449 I used two of these in my first nitrous system to act as a window switch.I would also use a clutch switch as a micro switch would be all that would be needed.Both of these items together should cost less than $75. I would also use good NGK plugs and gap them to .28 if a CDI box is not going to be used. A CDI box with a rev limter can be had for under $175. http://store.summitracing.com/partdetail.asp?autofilter=1&part=SUM%2D850600&N=700+115&autoview=sku You could buy a used bottle heater http://cgi.ebay.com/ebaymotors/NX-Nitrous-Express-Bottle-Heater-Element-Used-NR_W0QQcmdZViewItemQQcategoryZ33740QQihZ006QQitemZ160201038582QQrdZ1QQsspagenameZWDVW A pressure switch could be had used as well http://cgi.ebay.com/ebaymotors/NX-Nitrous-Express-Bottle-Pressure-Transducer-NR_W0QQitemZ160201039186QQihZ006QQcategoryZ33740QQssPageNameZWDVWQQrdZ1QQcmdZViewItem I have rarely seen good things happen when shortcuts are taken using nitrous. Quote Link to comment Share on other sites More sharing options...
cockerstar Posted January 28, 2008 Share Posted January 28, 2008 I'm assuming that I'd be staying off the bottle until at least third gear, but I have no idea what the feel is like because I've never driven a car with nitrous. I think between an RPM switch, a clutch switch, a new fuel pump, and a WOT only system I should be decent as far as keeping my engine safe for a few runs down the strip, right? After I get some cash from the race I can go back and do everything the right way If it does die it isnt a huge deal. It is a cheap build car after all. I still have a lot of reading to do on the subject! With the l28 intake a fogger style system should be avoided because of the uneven distribution, right? Thanx for all of your help man! Its been amazing! Quote Link to comment Share on other sites More sharing options...
1 fast z Posted January 28, 2008 Share Posted January 28, 2008 75 to 80 pistons have the same cc dish as the 81-83 turbo. Only difference between the two pistons is that the 81-83 turbo pistons have a 1.5mm top ring, compared to the earlier 2mm top ring, the second ring is 2mm on both pistons. Quote Link to comment Share on other sites More sharing options...
cockerstar Posted January 28, 2008 Share Posted January 28, 2008 What does the difference in ring widths do? Quote Link to comment Share on other sites More sharing options...
MJLamberson Posted January 28, 2008 Share Posted January 28, 2008 Id rebuild the engine, or at least make sure its all up to par before strapping on a bottle of NOS, sure they say that its safe to do 50% of stock HP but is it safe to do 50% of stock HP on a 30 year old engine? Quote Link to comment Share on other sites More sharing options...
m4xwellmurd3r Posted January 28, 2008 Share Posted January 28, 2008 I agree with that. You don't want to be putting extra stress on those old parts like that unless you want parts to fail. Quote Link to comment Share on other sites More sharing options...
510six Posted January 28, 2008 Share Posted January 28, 2008 Running (1) one single fogger in the L28 intake with an over 75 rwh shot is asking for trouble. The stock L28 throttle body, cam and intake manifold are going to limit peak horsepower even with nitrous to around 5000 rpm, the stock exhaust manifold is even worse. I don`t know if a motor will live a "few" runs under nitrous, first if you don`t have a way of checking A/F ratio you have no idea if your running lean. Even using a narrowband O2 sensor is better than nothing (the first large shots of nitrous setup for my motor were tuned with a narrowband 02 and an EGT gauge, this was before less than 1500 dollar widebands). http://store.summitracing.com/partdetail.asp?autofilter=1&part=SUM%2DG2986&N=700+115&autoview=sku Secondly, if there is a weak spot in your motor, headgasket, rings, clutch, U joints, you are going to find them in a hurry. I will never forget the feeling of the first 100rwh shot (later a 120 rwh)on my L28 stroker, the motor and nitrous setup (port wet shot done right) had about as much invested in it as a decent L28et swap into a 240z and with the bottle on ,the equal of any stock turbo L28et. Quote Link to comment Share on other sites More sharing options...
cockerstar Posted February 1, 2008 Share Posted February 1, 2008 Wait, so its perfectly fine to run a 50-75 fogger shot through the stock intake mainfold?? I was previously told that it wasnt a good idea and that wet shots were the only safe way to go with the l28 intake. I'd be content with a 50 or a 75 dry shot for now! Quote Link to comment Share on other sites More sharing options...
MJLamberson Posted February 1, 2008 Share Posted February 1, 2008 youd get addicted to it and go through a bottle a drive... I would anyways... "no officer I wasnt drinking tonight, Ive just been a little heavy on the bottle" Quote Link to comment Share on other sites More sharing options...
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