BRAAP

EFI system basic run down and simple tuning/drivability diagnosing tool; These two links are invaluable to to Datsun EFI tuning and diagnosing; http://www.atlanticz.ca/zclub/techtips/efisystem/280zfuelinjectionbook.pdf http://www.atlanticz.ca/zclub/techtips/EFI&fuel.htm 1) Water Temp sensor; In altering the resistance of the water temp sensor circuit, this offers a linear AFR change across the entire RPM range under all conditions. More resistance is richer, less is leaner. The only way to get “leaner” mixtures with the OE EFI is to use the resistor/potentiometer in place of the water temp sensor itself, but then you loose the coolant temperature compensation. I’m sure a savvy electrical engineer could build an electronic doodad that reads the water temp sender and then alters that return signal to the ECU both above AND below that of the water temp sender resistance. 2) TPS; The OE TPS is like a single pole double throw switch. Throttle closed portion of the TPS is for Idle and decel injector shut off. WOT portion of the switch closes the other circuit which actually kicks in at approx ¾ throttle opening, not at WOT as one would assume, everything in between idle and ¾ throttle is “open circuit”. I tried a Bosch TPS for a Fiat years ago that closed the WOT circuit only at WOT, at above 3/4 throttle position, the engine surged and had flat spots till the WOT switch was closed, at WOT. Discovering that resulted in further investigation using a manual switch in the cockpit hooked up the TPS to see how the ECU uses that TPS switch under various conditions. i.e. the throttle no longer actuated the TPS I did with a switch. a) The idle circuit is a richer mixture and will only allow the engine to rev up to 3200 RPM, then as the RPMS drop, the EFI kicks back on at 2800 RPM. This is a VERY violent rev limiter! Many of you have found this after washing your engine bay and the TPS connector gets wet. This is incorporated for high RPM, when you drop the throttle to closed under deceleration conditions, the ECU shuts off fuel delivery to the engine completely for emissions. If you have a very free flowing exhaust, and depending on how rich your AFR’s are to begin with or BCDD removed, you will notice a slight to moderate ”POP” in the exhaust as the fuel is turned back on as the RPMS drop down through 2800 RPM, but only at closed throttle during decel. b) The WOT switch alters how much influence the AFM has on the fuel map and adds to the fuel mixture. Open circuit, mimicking part throttle cruise, the AFM has tremendous influence on the injector pulse widths. At WOT, it has substantially less influence and the pulse width is mostly based on the ECU dedicated map, though the AFM does still have an influence, remember, it is substantially less of an influence at WOT than it does at part throttle. Also, the when the WOT switch is closed, the base fuel map is fattened as well. 3) Thermo time switch AND cold start injector; The Thermo time switch function is to allow the cold start injector to dump more fuel into the intake via the cold start injector during start up only and only for a couple seconds, when it really really cold outside and the engine is really really cold. Without the cold start injector and/or Thermo time switch, if the EFI is in good tune and the out side temp is really cold, around the freezing point, and the engine is also cold, the engine may take a few more revolutions to fire off during cranking. That is the only side affect of eliminating the cold start injector and Thermo time switch. Personally, I prefer to remove that system for my cars and all my customers, Been doing so since the late ‘80’s here in Pacific Northwest temps rarely get below 20 degree F and no ill effect regarding cold starts. 4) Inlet Air Temp sensor; The IAT is in the front of the AFM, looks like little white pencil eraser of sorts. It reacts to VERY quickly to temp change. The ECU uses this to adjust for air density based on Temperature. The IAT functions just the same as the water temp sensor, and by altering its resistance has the same effect on AFR as the water temp sensor, just on a much finer scale, not as drastic as the water temp sensors affect. 5) AFM; This complex electro-mechanical device is a well engineered, durable, intricate piece of antiquated equipment, and performs its intended job VERY well! It functions is tell the ECU how much “volume” of air the engine is ingesting, hence the name Air Flow Meter, (MAF stands for Mass Air Flow sensor and MAF’s measure the MASS of the air the engine is ingesting, which is more accurate as the engine actually needs fuel added based on the mass of the air, not the volume. The terms MAF and AFM are not interchangeable physically or in terminology in technical discussions). At WOT, the AFM actually tops out, full open between 4000-4500 RPM! After that, all fuel delivered to the engine is based on RPM, water temp, and air temp. The AFM has NO affect on the injector pulse width above 4500 RPM at WOT. The air flow flap opens as the “volume” of air pushes it open against the return spring and then passes around it on its way into the combustion chamber. Attached to that flap at 90 degrees to it, (see pic below), is the damper flap which is cushioned by the air space above it. Engine acceleration enrichment is delivered by the “over swing” of the flap in the AFM. The flap is also counterweighted. Altering the damper flap by drilling a small hole in the upper flap and/or removing mass from the counter weight, will allow the flap to over swing further, thereby fattening the acceleration enrichment. Loosening the AFM return spring also has the same effect, but also richens the mixture within the operating range of the AFM. Of all the L-series OE EFI tuning I have ever done, I have not found a need to alter that acceleration enrichment of the OE EFI above and beyond what adjusting the return spring for good cruise AFR has delivered. Tangent; Back in the mid ‘90’s I had the wild idea of eliminating the AFM from the air stream altogether. I sacrificed an AFM and cut up the body, connected a bicycle brake cable to the damper flap with holes at various points away from the pivot for varied actuation rates. Bolted this AFM to my intake manifold plenum and connected the other end of the cable to my throttle linkage. The idea was to use the AFM electrically so the ECU thought it was in use, but actuate it with the throttle, not the air stream! Also had the TPS switch in the cockpit so I could manually trip the WOT circuit during this testing. WOW what a learning exercise that was! To drive the car without the engine stalling completely or at least drive it somewhat smoothly, the throttle pedal had to follow the RPM. With the TPS in cruise condition, open circuit, that range of pedal position to RPM was a very narrow range. With the WOT circuit closed, I had much more leeway in the throttle position to RPM range before the engine would let me know it didn’t like it, hence the WOT circuit not relying on the AFM so much for calculating fuel delivery. Also, just to drive the car I had to accelerate the same at the same rate all the time and finding that constant cruise condition to maintain a given speed that the engine would like was, oh so difficult. Tried the other holes I added along the length of the flap to alter the rate at which it was being actuated which just altered the rate I had to actuate the throttle to keep the engine running. In short, I found the AFM works as originally designed and works INCREDIBLY well, and due to the narrow range that it functions, which is only below 4500 RPM and mostly under cruise conditions, the only tuning or alterations I perform to the AFM is to adjust the spring tension, but only after the WOT tune is set by altering the water temp sensor resistance. Oh, one other point. My particular L-28, with the water temp resistance first set for max WOT performance, then the AFM adjusted for best cruise conditions, while at idle, the CO adjuster would not allow the flap to close enough to allow a lean enough mixture at idle. I used a Dremel tool and ground a small trough in the floor of the AFM just under where the flap rested at idle to allow even more air to enter the engine and not be registered by the AFM, just as the CO adjusting screw does there by allowing the AFM flap to close a little more leaning out the mixture, but only at idle. One other down side to that mod is if the fuel switch is in the AFM, (early EFI), sometimes the AFM would close just enough at idle to turn off the fuel pump. Fuel pump triggering had to be hard wired to the ignition or with the later Z oil pressure style fuel pump trigger. Here is a mixture controller I built a little while back that I gave to RTz. This was my “tuning/diagnosing” box for the OE EFI. It gets wired in series to the water temp sensor, (or for diagnosing the water temp circuit or other drivability issues, can be used in place of the water temp sender). The dial is linear variable resistor/POTentiometer and is 0-1000 ohms. I also included a single pole double throw switch that in one direction utilized just the POT alone, in the other direction added another 1000 ohms to whatever the POT was set at for quick and dirty rough/coarse testing/tuning. Middle position of the switch is open circuit, infinite ohms and will flood the engine, not useful. For seat of the pants tuning, with POT at say 250 ohms, you can then flip the switch at WOT and feel/hear/see any difference in how the car ran in real time. You would just narrow down the resistance value to what the engine likes best using that method and then once you narrowed it down, you would just add a resistor with that value in series the water temp sensor. After that WOT tuning is done, only then do you move on to fiddling with AFM spring tension for part throttle cruise. On the dyno, just turn the dial till the engine makes max power. Simple. That little box is a great tuning and diagnostic tool. It can be used in series with the existing sensor or it can be used to “bypass” the sensor.

Any updates Pete?

Lefty loosey, righty tighty... Anything beyond that?....

Spent all last week in Madison/Verona Wisconsin. Wife was at her annual UGM conference/meeting at Epic in Verona. We arrived early enough to drive up to GreenBay and see the Packers beat on the Bills. Seeing a game at Lambeau field is an experience every football fan should experience. Great time, great people. A few highlights from the game. Not great pics, but since the game wasn't nationally televised, thought the Packer Fans may appreciate them.

Dave Rebello, (Rebello Racing), also uses the double gasket on some of their N/A Flatop piston N42/47 combos with great success.

And then there is the fully wrapped S30; http://forums.hybridz.org/index.php/topic/93465-carbon-fiber-z-rocky-auto/

Today I tried a small piece, covered the switch plate for my scratch built LSx PCM Desktop Tuning bench. Aesthetically it's far from perfect but is OK, the tuning bench functions awesome. Neat stuff, very thin, approx as thick as one or two pieces of paper. It is sticky back, a little heat forms it tightly to compound curves. FOr complex shapes, care must be exercised when applying it, also to not use too much heat. A hair dryer is adequate, heat gun on high is too hot. It cuts really easily, so easy it seems it would tear easily but seems to be fairly strong.

I ran across this thread a while back; http://forums.bimmerforums.com/forum/showthread.php?t=1479230 …which got the attention of my inner rice and I ordered a 28”x48” sheet to use sparingly in my M3, (cover the bits of the interior) and a possibly a few other gadgets around the shop such as light switch plates, etc. Starting looking over the S30 for possible uses, center dash panel, bits of the center console etc. I think the entire dash would be a bit much, though on the 260-260 dash going two tone with the lip as the split, using the black, (421) and Graphite, (420) might look pretty good if the rest of the interior is tastefully/cleanly customized to complement the faux Carbon fiber dash. This site is chocked full of cool wild ideas from Key fobs to refrigerators, Laptops and gaming consoles to cel phones, hood & roof covering to fully wrapping the exterior of a car! http://www.carbonfiberfilm.com/gallery/ Available colors; Switch plate, (not mine); E36 M3 before and after, (not mine) Tastefully done BMW E46;

Due to the fact that when the TPS is plugged in the engine wont rev past 2500 RPM, (probably like a violent rev-limiter kicking in at exactly 3200 RPM, engine comes back online at exactly 2800 RPM), and is fine unplugged, that indicates the idle switch is closed. 1) Unplug the TPS and look for water in the connecter on the TPS itself. If there is water in that connector, just blow it out, get it dry, plug your TPS back in and you should be fine. Water in the TPS connector is the most common cause for this, typically after washing the engine or some how water is able to get on the TPS. 2) If not water, using a continuity checker, verify the TPS is functioning. It is merely a double throw switch. Center pin is common. One of the outer pins makes connection to the common pin with the TPS closed, (indicating to the ECU idle which the ECU also uses to cut fuel above 3200 RPM, brings it back in at 2800 RPM as mention above), then opens as soon as the throttle is cracked open, (your Haynes manual or shop manual shows how to set that), the other pin makes connection with the middle common pin at approx 3/4 travel and maintains connection through to WOT. Hope that helps and remember when troubleshooting to look through your shop manual/Haynes manual. And please be sure to read the forum rules linked in the upper right hand corner of the page. Descriptive thread titles is one of those rules.

I'll toss in the SHO intake gaskets and a shop manual, just cover shipping, ($15 priority mail, 2-3 day service).

Very nice,also want to hear your initial impressions.

I saw "points" in the subject and was ready to join in on a discussion about the shape or RTz's head. My apologies for the thread jack...

If you car is a '74, it would be a 260Z, if it's a 280-Z then it is '75-'78. This forum has been around since early 2000, dedicated to extreme performance Z cars. Every post since 2000 is still here and rest assured the topic of diff strength has been covered and literally beat to death. There are members here running low 8 seconds in the 1/4 mile at over 150 MPH pulling, (see pic below), with the stock Datsun Diff. Instead of wasting even more bandwidth and web space on a subject that has already been covered adnauseum we ask that new members get comfortable with the search engine, (it's actually rule #2 in our rules and guidelines) as well as read the stickies at the top of the drivetrain section. Spoon feeding readily available information is something this forum frowns upon. Yes, Greg Dupree, well known VG30DETT builder/tuner and owner of Specialty Z, http://www.specialtyz.com/ probably has the most famous VG30DETT S30 conversion, it was covered in one of the Z car magazines years ago. Gregs VG30DETT Z; Here is one that started, engine in the engine bay, then scrapped; http://forums.hybridz.org/index.php/topic/52179-vg30dett-280z-conversion-picsect/ Stock Datsun rear end!

Cheap skates. They used one rear control arm for both sides!

Here's one for sale; http://forums.hybridz.org/index.php/topic/93883-fs-used-jtr-radiator/page__p__884803__fromsearch__1#entry884803

If Norm speaks performance mods, take note. Some of his ideas may be a little unorthodox, but you can't argue with his results.

Many years ago when I first saw the C3 Vette push-in-to-open door actuation, I thought it would be rather cool to use those actuators on the S30, upper most portion of the door just under the glass. Dodge Viper uses a similar design, NISSAN GTR has flush style handle as well. C6 Vette has an interesting recessed grab… That idea faded over the years and recently resurfaces with my father customizing his ’77 Chev Short Wide pickup and was contemplating shaving the door panels and using electrics, like so many others have done. He wants some thing not stock, but also something not overly done, yet functional, and reliable. In our discussion, this idea popped back in my head, has anyone else had similar thoughts, concepts for the Z that they have done, planning or would like to do? I realize this is not really “performance” enhancement, tough feel it isn’t too ricer either, or is it? C3 Vette; Dodge Viper; Nissan GTR; C6 Vette;

Another hidden answer, StrawBerry Rhubarb. Cessna or Piper?

1 degree separation between the seat and valve face is quite common, helps with the initial sealing due to differing angles upon contact, but it is shallow enough that the material of valve will conform of the seat as it runs, sort of like lapping, but different. http://www.tpub.com/content/construction/14264/css/14264_95.htm A couple other key points to valve seats that we don’t see discussed much. Hopefully Tony will chime in to fill in the holes I left, etc. The valve to seat interface is where the valve dissipates most of the heat it acquires from the combustion process, transferring that heat back into the head via the seat, casting into the cooling system. The stem to guide interface is the other area the transfers heat from the valve back into the head, but not nearly as much as the seat interface. This is especially important for the exhaust valve as it has extremely hot gasses blowing across it that are hot enough to melt the metal which it is made from, (by the way, ALL factory L-series exhaust valves are stainless steel!), so if that valve does not get the chance to get back in full contact with the seat, it does not get the chance to cool down, which leads to a burnt valve. A burnt valve typically looks like a chunk has been broken off of the valve, (many mistakenly think and tell other that), but if you look closely, using some magnification, you'll see what looks like itty bitty torch streaks across the affected area, just like a cutting torch cut it. That is essentially what happens, the exhaust gasses "cut" that material from the valve. Valve lash being too tight not allowing the valve to seat, a piece of carbon/crud between the valve and seat, extremely late ignition timing, (combustion still taking place across the valve into the exhaust port, torching it), etc are common causes of a burnt valve. Valve seat width is also critical. A valve seat that is excessively wide has a lot more surface area when seated. For a given valve spring, the pressure exerted on the seat interface will be less per square inch with a wider seat than with a narrower seat. Where this comes into play is the wider seat will allow carbon to more easily build up or get stuck between the valve face and seat, which doesn't allow the valve to seat directly in contact with meat valve seat in order to transfer it heat into the head. Also, and excessively wide seat means a smaller I.D. of the throat which in high-performance applications is not desirable. A seat that is too narrow in width and there is not enough surface area to transfer the heat for the valve back into the head. This hotter valve also expands more so if the valve to guide clearance is not adequate, the valve could "stick" in the guide. Accepted valve seat widths as used on most 2 valve engines is .040"-.080" such as the Datsun L-series, SBC, SBF, SBM, etc, For the most part 040" is common for the intake, .060" is common for the exhaust. Depending on spring rates, materials used for the seat and valve, application it is used in, those seat widths could be different. For most stock to even moderately hot street builds with stock seats and stock valves, between .040"-.080" for either the intake or exhaust is considered safe. Tony covered the 5 angle seat. Ideally we want a radius to form the transition from port wall to the seat continuing onto the chamber walls. These added angles help to get us close to that ideal of fully radiused, close enough that going to fully radiused vs 5 angle is only worth a gain for engine built to levels we would never run on the street, such as Bonneville car or drag car to push some record run, etc.

You mean this brace under the fender that triangulates the rocker "panel-firewall-upper strut tower" in the vertical plane? As johnc mentioned, just braces for chassis stiffening/reinforcement, not really a particular name that I am aware for that particular brace.

Nigel, This thread covers it a little as well as some of the other facets in custom cylinder head building; http://forums.hybridz.org/index.php/topic/42991-custom-cylinder-head-building-what’s-involved…/ Most Valves have the faces ground on a 45 degree angle. The backcut merely helps to blend the transition from the back of the valve to the seat face. Like porting the back of the valve. The purpose is to help improve air flow across the back of the valve head itself allowing the air flow to make the transition to seat easier with less loss, especially at high velocities as the valve leaves the seat or is coming back in contact with the seat, if flow is still high in that region. These two pics should help illustrate that more clearly; Courtesy of WS6transam.org Any automotive machine shop that grinds valve can do this operation. Some of the later Nissan intake valves come already with the back cut. When a machine shop is doing this, they need to know how far to go so they don't cut into where the actual valve sat is at. They need to leave some margin. If the the shop has the head as well and the seats are faced, (ground/cut), they can simply lap them to see where the face is at and back cut to just shy of that. Hope that helps, Paul

Datsun 2 door 810/Maxima; Courtesy of JapaneseNastalgicCar, Chickenwing/datsunfreak;

Does this help? http://forums.hybridz.org/index.php/topic/57387-“how-to”-post-pictures-on-hybridz-the-easy-way…/

How'd I miss this! Gorgeous car. Are there many if any V8 converted 2 door 810/Maxima's running around?