Tony D

I need photos to visualize how that trap-door AFM would even let the car run at anything but idle speed if installed 'backwards'... It would make no metering decisions at all other than being completely closed (idle position) all the time. It doesn't hinge backwards, there is no way that would have run the car down the road at all. Not the way I'm figuring it, anyways.

without increased fuel pressure (To effectively increase those stock fuel injector's flow capacity) I think you are treading on thin ice at anything over 10psi...

Nigel...now you see why I'm such a proponent of not screwing with the EVAP cannister, and keeping it intact, as well. Your example is a good one of something the factory engineers looked at an compensated for: enleanment under increased temperature. What does your fuel do when you heat it? Expand and turn to vapor. The Evap cannister's purge valves will hold several inches of water column in the tank before it 'relieves' pressure to the cannister for collection. While this is mostly an emissions concern after shutdown, it helps keep pump suction head higher running down the road. Unless you are seriously sucking fuel down (like NHRA Fuel Flows) the likelyhood of the fuel getting hot and expanding (and therefore resulting in a pressure rise in the tank) is greater than sucking a vacuum on the thing. This 'heat expansion' will allow for that pressurization on the fuel pump, and combat this kind of issue. What is also happening is 'hot fuel'---you can see this on Diesel Dynos, Detroits were notorious for this, as they gave a specific heat for the fuel when run on the dyno. Simply heat it from 70 to 108 F and you got all sorts of 'efficency increases'... This is a primary reason the Z31 box uses (and I believe all new vehicles currently) a fuel temperature sensor in a lookup table/compensation loop. The BTU content per fluid volume measure decreases dramatically with some of these fuels, and indeed 'cold fuel makes more power' because you get more into the chambe to combust. If you can't touch the fittings without feeling uncomfortable, you are in the 140F range. This is almost universal. See if you can touch your fuel rails and tank bottom after a long run. An Infra-Red Temp gun from AutoZone will open your eyes quite a bit. Once you buy one, you start using it on everything (everybody does it!) and start going "Hmmmm, Oh, Hmmmmm!" We run a 5 gallon cel on the Bonneville Car, have the fuel packed on ice as long as possible, fill the tank and keep the cool can filled with crushed ice to get the fuel as cold as possible. Our fuel rail will sweat at idle on the starting line! It keeps things consistent. I have always suggested that guys with A/C in their car run their fuel line ziptied to their A/C line, and then insulated. You loose some cooling efficiency in the cabin (you will never notice, the pump just runs slightly longer), but you can significantly affect your fuel temperatures everywhere in the system doing this. If it's hot enough for you to consider running A/C, it's hot enough to consider what it's doing to your fuel---works great.

Yes, I mentioned 20psi as I knew you could get caps with that rating relatively inexpensively. It's not a matter of keeping it flowing in the head, it's a matter of getting enough pump suction head that cavitation doesn't happen when you turn the impeller to fast, or exceed design tip speeds. This can happen with increased temperature at relatively slow speeds as well. It all interacts. But the increased static pressure prevents nucleate boiling like John said, and that is what can cause the cavitation in the impeller as well. (And when the pump cavitates, you cease flowing...meaning heat transfer, or carrying heat away more properly, ceases. Then you start that n-boiling, and from there, all is lost!)

We run the ERC Spec Fuel at Bonneville and El Mirage, and it's 110+ Leaded. And we run 14.75:1 CR on that.

Any hammer is fine---they're trash once they've been torqued anyway. They are a throway part. An arbor press can be used with a jig if you're doing production removal on large numbers of rods... but otherwise properly cribbed and a smart whack with any hammer should take them right out!

Just from personal observation, that G-Nose looks like an OEM version, which has been period modified to match the flared fenders. Mine was the same when I got it. It was a simple matter of work with a body saw to separate, then finish the edges to allow for removal of the valence. The G-Nose, if an original Urethane-Bumpered Version, is worth FAR more than anybody here is giving it credit for---add a "Zero" to the only post mentioning the price. If you think you can touch an OEM G-Nose for under $1500, you let me know where, I'll buy and pay shipping worldwide to get it to me.

Ahhhh, so it still does exist... My point was that previously every manufacturer of oil products made the claim---especially on Television Adverts. I don't see that claim being made public like that any more. I see galloping oil horses, but nothing about paying for the engine from an oil related failure. I think Arco Graphite's Ford Debacle started the decline in that claim. It's good to know Mobil still warrants against oil-related failure, but I see a $50K piece of litigation to get your $3K engine replaced.

Close. The lower rad hose doesn't really need to be called out as a box, and the recirc lines should all just go to the thick blue arrow coming from the radiator return. Technically, the Thermostat is not a block valve as drawn, but more properly drawn as a regulator with the flag for the sensing line on the engine side...but I look at this stuff all the time...for work....STOP MAKING THIS WORK! Some more information on the Diesel (LD28) Water Pump: Flow rate is 30.6gpm at 3400 rpm pump speed. Driven speed on the diesel is 1.32:1, with a maximum power occurring at 4600rpms, so you may deduce that the 30.6 GPM is being produced at a crankshaft speed of 2575 rpms...which is conincidentally 175 rpms higher than it's peak torque rating speed (2400 rpms crankshaft speed) In an industrial application the torque peak is rated at 2300 rpms crankshaft speed, and is down 9 ft-lbs from the automotive torque peak rating. If you look at the pump drive ratio, and recognise that the diesel is peak HP rated at 4600 rpms, you see the pump speed there is 6072 rpms. I don't know what speed cavitation will happen in this pump, given the NPSH present, but consideration of re-considering the actual drive speed of the pump and actually slowing it down may pay dividends in a more stable flow characteristic. As John Coffee stated, running a 20psi radiator cap would solve all the problems as well...and that may be something to look into; perhaps the non-diesel pumps are experiencing some higher speed cavitation and causing heat buildup problems. But for roadgoing street cars it looks like the diesel water pump may well indeed offer more flow without any penalty at the speeds the engine sees 85-95% of the time.

I found out some stuff on the LD28 regarding power, gearing, etc. For INDUSTRIAL use, the engine as is the norm is rated at 2600rpms (very near peak torque, or dropping back to peak torque under load...like industrial engines do. This would mean for ideal cruising and peak efficiency you would gear for this speed. For AUTOMOTIVE use, the engine has the following ratings: 92HP @ 4600 rpms 125 ft-lbs @ 2400 rpms The Maxima Wagon with a Manual 5 Speed to 6-82 came with a 3.545 Rear Gear. The Maxima Wagon with 4-Speed Autobox to 6-82 came with a 3.36 Rear Gear. The Maxima Wagon with 4-Speed Autobox 7-82 onward came with a 3.70 Rear Gear. This would mesh nicely with my testing on the 260, as the rear gearing is a 3.7, and my max speed would be 4750rpms with the late ZX Gearbox in there...coinciding nicely with Keith Bailey's Claim of 112mph 'all in' with the diesel---the 92HP would be near that point with the 3.9 he had (My recollection on his gearing may be faulty, but it did well on the Auto-X course!) So I'm thinking the 3.7 may be an near "OEM setup" as far as gearing goes with a late ZX transmission, and if you are running higher speeds then a 3.545 or even 3.36 rear gear would keep you in that high 30mpg / low 40mpg range similar to a Maxima when new (42/38 as I recall). Figured I'd post this in the spirit of completeness. Plus I found the LD Water Pump is rated at 30 5/8 GPM @ 3400 rpm pump speed...which I will add to another thread on L28 Turbo Cooling issues...

Adjust your valves, and hope you didn't nick the top of the piston and bust a valve guide/bend a valve in the process. BTW, what does "Fine" quantify to for the other cylinders?

Japanese racers would flop the air cleaner end-for-end as they didn't have some of our emissions related stovepipes on it...and then duct air from the cowl area through the grille at the base of the windshield. With no linkages in the way, they could do that. On a LHD car, it would be considerably more difficult.

"Nice Cool Gas Tank" only applies to after you fuel it from an underground tank. I have has heated fuel suction cavitation present out here when the tank level drops to 1/4 as the recirculation heats up the tank. Driving across the desert will have your tank at over 140 degrees in NO TIME! I took a Coleman Cooler, sized to hold a full 7# bag of ice, and made a 'cool can' for a 240 we drove up to vegas with...the bag would last about 2 hours of driving, and the water would be over 120F...same as the tank contents! Lower fuel levels just don't work as a heat sink. Even with a full tank, unless you cool the fuel on the way back to the tank it will start heating up. Just depends on the vapor characteristics of your fuel as to when it will cause flash-cavitation on the inlet of the pump. The high-speed electric pumps don't seem any less prone than the diaphragm pumps mounted to the block-even though they are usually much cooler, and nearer the fuel source. The reason to put the return line to the surge tank is when you start sucking air from the tank on your pre-pump, your surge tank still has fuel in it, allowing the main pump to remain flooded...all the fuel returning from the fuel rail keeps that surge tank full during that instant when you are sucking down the main reservior. If you returned it to the tank separately, you would need a much taller vessel, and sized larger in total volume capacity to accomodate the times when you are sucking air. On a track car where you have a single pickup, you could suck air on both right AND left handers, and that would mean a larger and larger fuel capacity in the surge tank for each expected incidence of booster pump starvation.

WOW! And I thought a Diesel Sentra was a neat find!

Alan, I have sent you a P.M.

Curiously I took a look at my freshly-bought Shell Delo oil for The Boy's 510 when we were in the parts store this weekend. We are getting ready for fire-up and break-in and noticed that the oil I picked up was only "SJ" rated! Which I thought odd, as it had the latest "C" rating for diesels... So that would run in line with what you were told, as I checked all the other oils on the shelf that were available (even AutoZone Generic) and they all had much later "S" ratings, though some without a "C" designation, or one that was lower than the Delo. There seems to be specialization in oils now and branches of 'diesel specific' and 'passenger car specific' oils are being marketed. I wondered out loud if this SL-SM Change conincided with the cessation of the marketing hype around 'We will warrant your engine against oil-related failures for the life of your car if you use our oil' type of warranties from the oil companies out there. Anybody else notice the 'fading away' of that warranty claim? Curious if any of them still offer that kind of warranty? That tells me they recognized something critical had changed, and they limited their exposure accordingly.

I will have to look into that...

lol! I see money is boing renegotiated! If you can get more money out of him, tell him to send me the $$$ for the bearings he burned up in his last motor...BWAHAHAHAHAHAHAHA! I may be in Morocco for Spa...BAH! I am trying to play with the numbers and dates as one way or another I have to be in Morocco before Spa, and then go to Nigeria on or around the 27th... And there aren't many direct flights. Having to fly to Paris to fly BACK to Africa is insane...but this may work to my advantage!

I don't know where you get 3500rpms, the Nissan OHC is not a Detroit. The rev limit is not 3500rpms, it's closer to 4500 or 5400 as I recall! I know Keith Bailey could do 112mph in his LD powered 240Z. A stock tired car with a late ZX gearbox and 3.36 rear gear will turn 2000 rpms for 50mph, and by 3000rpms you will pretty much pass everybody! So gearing is not an issue. I have not checked the pumpkin in the last Diesel Maxima I dissected, but I really should. I'm curious to see how they were geared. I know the automatics used a different sun cluster up front than gasoline cars...and for guys running N/A Petrol L-Engines with a four speed autobox that gear cluster makes for some interesting combinations with something like a 4.38 rear gear (considering the .67 overdrive in the slushbox!)

How is six times in the past two years (with someone else finding similar finds on equal basis) a fluke? Last weekend JeffP bought the crankshaft from an LD for under $40, as it happened to be 'half price day' at the JY. Last time I bought just the crank, it was $39 with the harmonic balancer and flywheel attached. You can buy the whole Maxima on the street for under $2000. There's one in Craigslist right now I see for $1200 asking. That's an average of one crank a month...but two guys who don't have time to 'scour' the JY like they did in their youth. $170 for the engine, with a $40 core. Last one I bought complete for $275 no core, outright. There is a reason the cranks only sell for $250 on E-Bay (or thereabouts)---they're not all that rare! Same for the complete engine. Maybe SoCal is a geographic anomaly---but the vendors selling in SoCal are apparently preying on those who don't want to spend a day walking through a junkyard to find something they want/need. I think $2000 for a used Maxima engine is outrageous when the car can be bought whole for less than that.

Darn, I thought I'd see John making a comment about 'cheating' with an overbored L24 in a FIA Regulated Class. I was so hoping to show Miroux's Red 240Z entry that they 'swore' had an L24 in it, and was a 240Z... I commented to them "You really should grind the F54 off the block, then!"

When an LD28 is $170...it kind of makes paying $2000 look a bit foolish, no?

Yeah, in first and second I can bang the next gear at 6500 because of the gearing's mechanical advantage, but once you hit 3rd gear with a stocker L28, you will be running through the traps on a 1/4 mile well before upshift time to fourth, somewhere around 90mph. You will notice the loss of power above around 5500 at that point, and realize you just got to get to 6000 to be able to upshift and still get some sort of decent pull out of the next gear....

If you aren't doing it on a regular basis, it's not worth the hassle IMO. Leave earlier, and pray... Or call 'Supershuttle' and send your bud off with them, and a bottle of Bud for the ride (put it in a vernor's ginger ale 2-liter bottle, they will never know!) He's happy, you don't deal with traffic both ways, and if he missed the flight, Supershuttle is the recourse! Win, Win, WIN! ;^)

Most of the rock crawler guys love EFI as it's much more resistant to fueling issues at extreme angles than something with hinged floats in it. Proper Surge Tank will go a long way to making an EFI unit 'stall proof' at 45 degrees. Some carbs will either die or flood out at that kind of approach/departure angle.