BRAAP

Using Vacuum advance only with the mechanical advance locked. Hmmm… As I understand the general ignition requirements of petrol engines and how mechanical and vacuum advance function, that is an odd approach, one that I am struggling grasp how it would successfully deliver a street engines ideal ignition advance curve. I guess it could be done, just seems like the harder way to get the job done. Dizzy ignition tuning. First off, I strongly recommend the Jacobs Ignition book. It is a wonderful resource, explains in great detail the ignition process/event, how the engine uses it and how to find your engines ideal ignition advance curve, the procedures I used for tuning my L28, hope this bit of info is helpful. http://www.amazon.ca/Performance-Ignition-Systems-Christopher-Jacobs/dp/1557883068 This is my personal layman’s interpretation of the mechanical and vacuum advance systems. What the engine really wants for ignition advance; First off, the combustion event is a burn, NOT an explosion. It is very fast, burn, but again, not an explosion. For your aluminum pistons and head gasket sake, just remember explosions bad. All this fuss over ignition timing has to do with one thing. Getting the cylinder pressures to maximum just after the piston passes over Top Dead Center, (TDC). Some of you may be thinking, “why are igniting the fuel mixture BTDC, (Before Top Dead Center)?” This is because of the time it takes for the spark to ignite the fuel surrounding the plug electrode and for that small kernal of flame to propagate and consume al the fuel and air in the cylinder, refereed to as flame front, which takes time. Remember the fuel burns, not explodes. As such, we lead the ignition timing so that those pressures take place at the proper time to get the most out of the fuel in the cylinders, i.e. more torque. Because the flame front travels at fairly consistent speed, (factors such as mixture, charge temperature, quality of fuel, cylinder pressure at the time of combustion, etc all have small effect on how fast that flame front travels), the faster the engine spins, the more we have to lead the ignition timing. Now for the wrench. This advancing for added RPM only takes place up to about 2500-3500 RPM or so, beyond that point we do not continue to add more ignition timing. I read whey that is many years ago, forgot that bit so my apologies for not including that, I’m sure one of the more knowledgeable ignition gurus will chime in. At any rate, if ignition takes place too late in the cycle we end up with cylinder pressure not reaching the pressure it is could pushing on the piston to turn the crank that converts our tires into a dense fog, i.e. energy wasted as heat instead of work. If ignition takes place prematurely we end up with the cylinder pressure peaking before TDC, which we often hear as pinging, again, wasted energy. As you can see, it is delicate balancing act to get the ignition to take place at the correct time over varying RPMs and load conditions. Ideal ignition advance for most all petrol engines follows this basic trend. For a given engine load, (can be read as a steady manifold vacuum), the ideal ignition advance curve rises with RPM up to a point, then plateaus. That plateau can be anywhere between 1500-5000 RPM in extreme cases, most 2 vale engines that operate to 7000 RPM will typically plateau between 2500-3500 RPM. The mechanical ignition advance meets this requirement very well. As engine load decreases, say from WOT down to approx 1/3 throttle for cruising down the highway, the amount of ideal ignition advance for optimum combustion will be more, but still follow that same curve as described above, (for those more advanced ignition tuners, yes the ideal curve/slope will vary slightly as load changes but for this discussion we are calling it the same, just trying to convey the trend that is present), the vacuum advance meets this requirement quite well. Mechanical advance; As we just covered, the mechanical flyweight ignition advance system does a good job of meeting the engines advance requirements over a broad RPM range for a given load. Starting low at low RPM, rising over a specific RPM range and then plateau across the rest of the rev range. See graph below for a generic WOT (Wide Open Throttle) mechanical advance curve, not to be used for the L6, (curve hits plateau too soon for most, typical will be between 2500-3000 for the plateau). The amount of advance the dizzy allows to take place is dictated by the amount of throw the flyweights have. The start of that slope and the pitch of that slope is determined by the spring tension on the flyweights and/or mass of the flyweights themselves. (Some of you are already thinking ahead and visualizing modifying the spring tension and/or flyweight mass as well limiting the already long flyweight throw). Different engines and configurations will have slightly different starting points for the rise, the slop pitch and ending points for its ideal advance curve, but in general all petrol engines have some form of this shape. For example, multi valve engines with spark plugs dead center in the chamber will have similar shape but the overall values will be much lower. Vacuum Advance: As we discussed earlier, as load decreases say from WOT down to approx 1/3 throttle for cruising down the highway, the amount of ideal ignition advance for optimum combustion will increase, the vacuum advance meets this requirement quite well. This Vacuum advance is added to the mechanical advance. For example, cruising the freeway at 3000 RPM, ideal 1/3 throttle ignition advance may be 50 degrees. Using the chart above that means the vacuum advance is adding 15 degrees to the already 35 degrees of mechanical advance. Now lets make a few extreme examples to show the importance of both mechanical and vacuum advance. If you locked the mechanical advance in your L6 then set the ignition timing so it was ideal when above 3000 RPM, (35 degrees in this case using the above chart), that means that starting and idle ignition advance will also be 35 degrees. This engine will not start! As the starter tries to crank the engine, each combustion event that ignites will try to push the piston back down before it reached TDC, kick back. Ever try to kick start a motorcycle that kicked back or pull start a lawnmower that ripped the starter handle out of your hand? To much ignition advance or the RPM you were trying to start it from. That’s why if you kick the motorcycle faster you were getting the cranking RPM just high enough to outpace the ignition event same for the lawnmower. For the L6, I don’t, you would have to find a way to get the motor to spin up past 2000 RPM or so, then flick on the ignition system to get the engine lit up. Removing the vacuum advance. Common among racers and that is fine. As we covered, the vacuum advance only adds ignition advance during part and light throttle operation. That advance helps fuel mileage considerably, (if your vacuum advance is working correctly and your Z is getting 25+ MPG on the freeway. i.e. in a good tune, disconnect your vacuum advance and check your mileage on the freeway. It will drop considerably, up to 5 or more MPG). Racers don’t care about part throttle mileage and they rarely are using part throttle during a race so that is whey they delete the vacuum advance. One more benefit with vacuum advance is throttle response. Throttle response will be much cleaner and crisper with vacuum advance vs without out it. My starting recipe for L6 ignition advance for stock to mild builds is this, then fined tuned for the specific car; (you need a “Dial Back To Zero” timing light for this. If you don’t have one, then you’ll have to accurately mark the degrees on your damper) Quality gasoline! If you are running that cheapo no name crap gasoline, don’t even bother as you are wasting your money anyhow, none of this will be of any benefit. I’ll save that rant for another thread. Mechanical advance curve, (measured/set with vacuum advance unplugged) Idle ignition timing between 15-20 degrees. Advance starts immediately off idle, maxes at 2250-2500 RPM. Max mechanical timing of 36-40 degrees. Every engine and combination will response differently, quality fuels, elevation, build up on the back of the valve, injector, spark plugs etc. Using the guidelines in the Jacobs book and if your engine is stock or mild, you should end up somewhere near what I described. Softer springs on the flyweights. Leave the vacuum advance connected to the ported vacuum port. That is the port that at idle has NO vacuum on it, but does once the throttle is cracked, (little sliver or port hole just ahead of the butterfly in the TB. Carbs also usually have a ported vacuum port). Hope that helps, Paul

These guys make them for the L6, (though no listed in their list). Had 2 of them come through my shop from another HBZ member for his road race L28. Beautifully cut, complete with instructions for the O-ringing, etc. http://www.scegaskets.com/

Yes, but only certain locations. Greater Portland area and the Greater Medford area. All other areas are currently exempt from testing, though for how much longer no one really knows. We've been hearing rumors since the late '80' DEQ was going statewide, 20+ years later it hasn't happened.

Great info Wiki, thanks for sharing this with us. By chance does that lower hose have the anti collapse coil spring running through it like we see in some OE lower hoses?

I've got a handful of them. Take your pick... Shipped via Priority mail, 2-3 day service. http://forums.hybridz.org/index.php/topic/96164-fs-misc-z-car-eng-parts-prtr-fld-pads-diff-mounts-240-dash-harness-custom-locks-510-hubcaps-etc/page__p__904054__fromsearch__1#entry904054

Haven't driven mine yet, but did drive another friends LS1 powered 97 M3 a few months ago, pics and video, yours truly behind the wheel. http://forums.bimmerforums.com/forum/showthread.php?t=1503369&page=5 They can be set up to be very stout in the handling department, compromise is NVH, ride quality, smoothness, and road noise. There are a couple recent discussions about what it would take to have smooth, quiet, plush drivability and have modern sports car performance, mostly geared at the earlier Z but the principles would also apply to the S130 and Z31.Â

Not in your list of vehicles, but most definitely meets all the criteria you are after with very high marks in all those areas, accepts the SBC, LSx, or SBF, and in my not so humble opinion, readily exceeds all those criteria compared to the 3 vehicles listed as options and decent running examples can be had for $5000 up to really nice $10,000 (power-train can be sold for $1500-$3000 depending condition to help offset the cost of the V-8 powertrain). http://forums.hybridz.org/index.php/topic/79556-lsx-powered-bmw-m3-e36-chassis/ If the LSx is not an option, keep in mind the traditional SBC also fits a teensy bit easier than the LSx, (the SBC conversion mounting kit will be released soon as well). Drivability is world renowned and will not be sacrificed in the conversion. MPG, stock is 28-30 MPG on the freeway, 22 observed MPG combined city, fully expect to stay above 20+ combined and 28 freeway with the V8, driving politely. Tunabiltiy, SBC I assume you already know, the LSx with HP-Tuners or EFI live offers the user full 100% control and adjustability including MAF delete and 3bar boost capable for future growth. Comfort... drive one, trust me. Handling! Voted best handling car over the C5 Vette, Acura NSx, Carrera 911S, Ferrari F355, Viper GTS, something you'll be very hard pressed to meet with the cars you listed while still retaining any sort of drivability and comfort. The test is here; http://www.m3post.com/forums/showpost.php?p=989661&postcount=26 Straightline performance. Stock is a solid mid 14 second car in the 1/4 mile, 0-60 in mid to high 5's. Some of the bone stock LS1 converted versions on the road are seeing deep 13's in the 1/4 with 110+ traps, modded versions knocking on 10's. Aerodynamics, quite good actually, compared to the 3 cars listed as options, well is friggen outstanding. Braking! Again, quite good, compared the 3 cars listed as options, outstanding with plenty of room to grow if you choose. TONS of aftermarket support for the interior, body, lighting, and chassis, and the LSx or SBC will fit and you already know of about the aftermarket support for those. My $.02

You let the Today show put a shoe on you car! Never the less, very cool. http://www.youtube.com/watch?v=JRBgoIIhfJM&feature=related

Very nice Scottie.

Update with wonderful news. JTR and Sanderson Headers are getting close to releasing their E36 LSx long tube headers. Approx ETA for release of production units is 2-3 months. These pictures are of the Prototypes. Steel, long tube, 1 3/4" primaries, 3" collector, V-band connection, and they clear the stock steering shaft. These prototypes have been given the green light from which Sanderson will build fixtures/jigs around for production units. Before any headers will be offered to the public a few pre-production units must also receive the green light from JTR, (quality assurance), once the pre production units pass, production will start. Again, earliest release of approx 2 months time so long as the preproduction units fit as intended. Pics of the JTR mockup mule at Sanderson Headers. Driver side; Passenger side;

Being a group of DIYers, would there be any interest in these prebuilt tuning boxes if they were available for $40 shipped?

Just throwing this out in case it helps. Another option for plugging EGR is remove the steel plugs from the bottom, (cutting/machine off the entire bottom section of the EGR plenum greatly simplifies this as the plugs are usually so corroded they don't want to come out conventionally), then tap the transfer ports that lead into the runners for pipe plugs or have them welded. Then just cut off the EGR boss for a visually cleaner looking intake. Here is a customers N47 EGR intake we did using that method above;

I recently machined an N47 intake to accept the more common 14mm O-ring injectors, (will not accept the stock Z car injectors unless you find some thick wall O-ring. O-ring injectors shown are not included, you'll have to build/source your own fuel rail). Bare intake, all threaded holes are good, all machined surfaces are good, only issue is the fitting for the stainless tube is broke off in the EGR boss, (green circle/arrow in pics). EGR is not plugged. If the current interested party backs out, it's available, $150 plus shipping. Will hopefully know for sure soon.

:lmao:

Yes, somewhat common for lowered Z cars. That is the quick and dirty way to remove unwanted negative camber after lowering a car.

Just find the 240-Z RB builds, then with the known differences between the 240 and 280, you'll be able to see it from the perspective of a 280 Z owner. This thread covering the differences of the 240-vs-280 should help; http://forums.hybridz.org/index.php/topic/57506-240z-260z-or-280z-chassisbody-differences/ Oh, and don't forget to use your keyboards shift key when posting. Staff here are known for being sticklers about members abiding by the forum rules linked in the upper right corner of the page.

If track performance is key, P-car or Z-O6. Sex appeal, NSX. Overall fun performance with quality build, NSX, P-car, Angry clown shoe. Something that allows you to tinker on it and doesn't cost and arm and a leg for new/used replacement parts, (power-train or chassis) Z-O6. If no desire to tinker on the power-train, Clown shoe has a bit of aftermarket support, P-car has tons. BLOZ UP suggestions are also very good. From your list, the best all arounder has to be the P-car.

Howdy Mario. Yes there are few different N/A grinds Nissan used through the years. The stamp on the very back of the cam indicates the grind, the "A" grind seems to be the grind of choice. TonyD mentioned in one of those "A" grind discussions, experiencing similar results using that cam in a mild Turbo application.

.... Do not use a mechanical cam in a P90a that has Hydraulic slack adjusters. The opening and closing ramps are different. If installing mechanical adjusters, then use a mechanical cam, if retaining the hydraulic adjusters, keep the hydraulic cam. There has been some discussion on here about performance hydraulic cams for the P90a, not sure if anyone ever followed through and had one ground. ...There is a factory N/A cam that that produces more power on the same boost pressure and spools the turbo sooner vs the stock Turbo cam.

No offense, but yes the L6 WILL bolt up to the trans if the trans was behind a LZ22-LZ24. ALL L-series engines and LZ engines interchange the bell housing, L13, L16, L18, L20A, L20B, LZ20, LZ22, LZ24. Also, please take the time to read the forum rules and guidelines, upper right corner of the screen. Your posts are in violation of rule#5, which if continues, posting privileges will be suspended. Here is another link that more throughly explains our position on the part of Rule #5 that your pots violate; http://forums.hybridz.org/index.php/topic/64626-lazybroken-shift-keys-rant-does-this-apply-to-you-lets-clean-it-up-please/

ALL RPM's. It isn't just a narrow band, or the upper range or the lower. The detonation threshold across the entire operable RPM range from below idle to well above redline, under all conditions drops when the compression ratio is increased.

Why would one prefer dished pistons matched with a N47 or N42 cylinder head over flat pistons matched with a P97 or P90 head? Is this the whole quench vs. non-quench debate? 2 words, detonation threshold! If I had the time this morning I'd post all the details, sadly this morning. I'm short on time. In short, the Datsun L6 is hypersensitive to detonate as mentioned in this thread already. On premium pump gas it does not like more than 9-9.5:1 compression ratio. Granted it should tolerate upwards of 10.5:1 premium on pump gas, but more often than not it doesn't and those combinations end up retarding the ignition timing so much that they lose more power from the ignition retard than they gained from bump in compression ratio. Mixing the flat top pistons with the N42/47 head generally results in engine that rattles on pump gas. There are many topic on that discussion in the L6 section.

From post #23 above... ... When at the yard, just pop hoods on all the Jags and all the 5, 6, and 7 series Bimmers.

Just curious, does this JDM bit have some special attribute that can't be had or duplicated here in North America?