Tony D

Like John mentions, multiple structure ties are the key to keeping a rigid roof bar from punching through the floor. Each sanctioning body has requirements for this criteria, and what goes in one place may not be enough in another. I was at an FIA/KNAF Registered Roll Cage Engineereing Works the last weekend in September and took some snaps of their tie-ins on a 240. It was interesting how they worked the floor through and rocker panel into an integrated structure to accept the roll structure. I can post them on the site (the photos are on my laptop) or post them in another thread titled roll bar. I thought the 240 specific photos might be helpful later on when I was doing my cage...

Mileage for 17 mpg in commuter service was from about 26,000 miles in one year filling up the tank while driving to and from work in Brea, while living in Corona and tracking it as usual. Track numbers were taken after filling up trackside, running laps, measuring miles driven, then refilling and going "Oh, I guess the gas gauge gremlin is NOT rearing it's head and I CAN suck down 12 gallons in less than 70 miles!" (around 58 miles, in fact...) Depending on the temperature outside, I would have to be light-footed at 17psi, so what yerbetten says about 15psi is probably true. I don't run the best gas, either. At 12psi I was running Arco 87 octane at that advance level!

The 'power jet' may be a bit overated. VW's for years here in the USA used converted Dellortos with the spindle seals and special emulsion tubes that enrichened under boost. Which may be the 'power valve' they are referring to... I haven't seen a 'power valve' or see where they would even put it in the body. Send me the diagram of the 45M with the valve, I'd be interested in what it looks like and how it was fitted. The drivability problems I'm convinced are a byproduct of sh*tty plenum design. My mikuinis were flawless (er... as carbs can be...) with one plenum design. When I made the plenum smaller, drivability problems resulted. The VW's I worked with using Dells were always very drivable, same as my original Mikuini Build. I even got a set of DHLA's when I found them, so I could replicate my VW experiences on a Z. That never happened, EFI came along, and made it a non-starter (er...excuse the pun!) sharkie73z AT yahoo DOT com You will get the HKS photos this evening when I get home from the office, if the lighting holds out!

Because the difference in the 'stregnth' is not worth mentioning. It's immaterial.

I guess nobody evere had a mandrel made to do this expediently. You might try Power Brother's Machine in Paramount CA, they may still have the drawing for my mandrel. Line-to-Line fit (within 0.001") on the towers...stick 'em on, bolt em' down, and run it! From my 'centrifugal rotating equipment' knowledge database... Looks tight, though as stated running it will let you know what you need to do to make it turn easier.

Read the application instructions on the RTV. Most of this stuff really needs to have clean and DRY surfaces. Some of the new oil resistant stuff will bond through a thin film of oil, but generally cleaning everywhere INCLUDING THE BOLT HOLES with a light quick evaporating solvent will make for a superior bond between metal gasket and dressing compound. People don't clean the holes out, and install the gasket forcing oil in the threads to exude out under pressure, creating a capillary where other oil can follow later. I think the 'wait 24 hours' camp is more of a get it up there wet, and semi-clamped, then install fully in the morning. This lets your bond get good, the RTV sets, and then when you tighten fully it compresses instead of gooing out in beads. Really, if you have excessive beads, you are using too much! Most directions will now tell you to let it 'skin' somewhat. But again the directions tell you what to do. Using chlorinated solvents, or good old brake cleaner, IPA, take your choice of residue free cleaners...and installing per the gasket maker's instructions has been foolproof for me for many years. I have to use RTV in gearbox installations for metal-metal fits and EVERYBODY overapplies the stuff. If you have more than a 1/8" bead that exudes out the joint you have used too much (generally speaking). Big gobs of this stuff breaking free and floating around the oil can make for bad things. Everything has a place, but read those directions and use sparingly and you will be amazed how well things seal up! You usually need a lot less than you think to accomplish the sealing once you are CLEAN AND DRY! Make sure the RTV is the newer generation oil resistant types. Older 732 and 736 style stuff can get softened over time and exposure to some oils. Really, with a thin gasket made of manila folder and some RTV you can seal the rail pretty effectively. Thick gaskets are for surface irregularities. Uniform torque allows them to semi compress in some areas and fully compress in others. If you have flat surfaces, the new generation of RTV's can seal without a gasket being in place. Done that as well. Preparation is the key, and proper application of the gasket/sealant system. Also, letting things cure properly for the requisite timefram helps immesaurably. On our oil tanks (containing Synthetic Oil in the 160F+ range, and aroudn 220 gallons on average) the SUBMERGED sections of inspection doors are sealed with ONLY RTV. Red 736 at that... This is a door that is approximately 36"x18", and has not only 20" of oil hydrostatic pressure on the joint, but 2-3PSI from a blanketing gas applied to the top of it. Straight RTV over a flat joint having less than 1" width around the perimiter of the door will seal it EVERY time, but if you have residual oil, oil in the bolt holes, oil on the door, or don't wait AT LEAST 2 hours before refilling the tank there is a very good chance you will get a 'seep' at first that starts attracting dust. Within a year you will have a mess at the door, and within 2 it will be a maintenance issue because of puddling on the floor beneath the joint. Considering they don't want to shut the thing down but once every 5 years, this is unacceptable. Flat-Dry-Follow Cure Time and Instructions for Application to the Letter-Do Not Overapply. Do that, and you should be good. Skip a step...things may get bleak! Good Luck! For our gearbox splitlines that have been set up using RTV, I will have to take grease and put it into a threaded hole on the splitline, then put a special 'o-ringed bolt' into the hole. This will allow me to screw a bolt in a hole, hydraulically compress the grease, and let it exude out under tremendous pressure to force it's way through the splitline joint and break the bond the RTV has on the two metal halves. I may have to do this in several spots before an overhead crane is capable of lifting the gearbox cover up and away from the lower half. When it's clean, dry, and properly applied ain't NOTHING short of a couple thousand PSI gonna work it's way through a metal to metal joint with cured RTV in it. Frankly, the use of a gasket in there is a potential weakpoint. If you have flat rails, and backup strips around the perimiter getting the pan OFF next time you need to do a bottom end will be more of a problem than leaks from the pan EVER will be!

who says you can't text while driving?

Brakes? Huh? What BRAKES? Please Substitute "Brakes" in the appropriate place in the following video clip:

My point is with well over 40K miles on a set of used N42 N/A pistons which have seen their fair share of detonation over the years, I'm still running with virtually the same compression and about 5% more leakdown than I had when I started. Actually, on #5, due to some stuck rings from extended storage before I installed the engine, I am up 10psi and down 20% on leakdown from when I originally started the engine the first time and took basealine readings. The N42 N/A piston is very durable. Nissan narrowed the rings to give 300,000 mile durability on an engine which was known for this kind of mileage lingevity by the time the turbo came out. It was an engineering decision to not compromise any longevity AT ALL when adding a turbo that may see constant borderline detonation for thousands of miles due to poor maintenance...and still hold up. We are not talking about that situation here. We are talking about seriously increasing the specific output of the engine well above the 200HP Nissan Designed around (yes, 200, not 180---the pistons in Euro Turbo Cars are the same P/N as North American Models...and they are 20HP more!) Under that assumption is that we will be running considerably more cylinder pressure, and if the fueling goes off the resultant detonation will be FAR more severe than what Nissan Designed the pistons for in EITHER case. If you ever heard Japanese LPG powered Bluebird Taxis and how they were lugged by the drivers, you would realize that the N/A pistons were designed around some SERIOUS parameters in regards to detonation. Make a stronger ring land, break the piston ring. Make a stronger piston ring, break the head gasket. Make a stronger head gasket, break the piston. Go forged pistons with even THICKER lands, THICKER rings, and O-Ring the block: BULLETPROOF? Detonate: Still break the piston. Detonation WILL break things, period. The difference between the turbo pistons and N/A pistons in service to 350HP to the rear wheels has been indecipherable to me to this point. If you are going higher than that, maybe turbo pistons are a good thing because of ring loading on the lands due to higher sustained cylinder pressures. But realistically do you see yourself running that build even 100,000 miles before expecting to overhaul or freshen it up? If not... But in either case, both machines will blow the ringlands when you detonate. I remind you JeffP ran lean at 8psi on two successive dyno pulls. TWO PULLS. Never heard it detonate or anything. Sunk 5 of six pistons rings and lands out of those expensive forged pistons. If it had a weaker head gasket, it would have blown. Maybe the rings would have held, maybe they would have gone... who knows, but if you make everything else airtight and 'bulletproof' you detonate and you will kill either piston: N/A-Cast, Turbo-Cast, Superdooper Unobtanium-Forged-Custom 6 Month Leadtime from Cosworth Racing-Forged. "You canna fight the laws of physics, Jim --- it's gonna blow!"

A collar that is too long can be compensated for by adjusting the slave rod approximately 1/4" shorter. A collar that is to short may run out of rod length, or throw in the bellhousing opening to adequately release the clutch at some point. As your girlfriend once said: "Longer is Better" I made the mistake of a too-long collar and simply was too lazy to take the tranny back down...that's when I found out the 91 240SX Slave Rod is considerably shorter than the one I had in the 280Z...and since I had already cut down my old 280 rod...they looked identical, so there are two options. Adjustable rod makes this one a no-brainer, go long, adjust shorter if you have to. Likely 5mm (1/4") will get the clutch engaged so you can move the car. Too long collar results in a clutch that will not engage, and the car will not move. Too short a collar results in an inability to get into gear, or start the car in gear. (Clutch disc always partially clamped by pressure plate, even with pedal all the way to the floor.) Hope that clears the logic behind what you have in front of you. Good Luck!

This link, of course, has been forwarded to The Boy under the subject heading "Why aren't you doing something constructive like this?"

It all depends on what speed and load they are generating. Do a dyno pull from 1000 rpms in 4th gear and look at the power generation of that engine. Plot 25HP. Then extrapolate 5th gear and 25hp. That's as low as you can go and likely keep forward momentum on a level highway at 65-70mph. Now, put a load like a 5% grade. Just add boost. Right? It's an extreme, but demonstrates that while you might be able to do some things, it may not be best advisable. Shifting to 5th gear at below 45mph is lugging the engine. But you can do it. Now climb a hill with it. Just add boost, right?

WATCH ME! I've taken bats away from a lot bigger people than some spoiled brat on a rampage...

Actually, I was thinking more on the lines of condom commercials than spanking...

Good point on the distributor. I cut my plate to allow reverse rotation so underboost the breaker plate moved backwards and retarded timing. I think I was set at 24 total under 10psi of boost. That was pretty agressive, I ended up dialing it back to 18 and could run on normal gas then. I got 5mpg on boost as well...17 in daily commuter duty though. Not bad for as heavy a foot as I have.

"Shifted to second gear at 7000 rpm and then the engine surged, suspected vapor lock. Stopped car, looked at the float windows and as I suspected from the engine reaction they were empty, no fuel. Back to the garage again adjusted the fuel pressure regulator to the maximum pressure setting, tried the same drive again and vapor lock a second after shifting to second gear at W.O.T." I agree with yerbetten! You need something that will produce at least 3.5 psi more than the boost level you intend to run. I know a kid in AZ that was going through L28ET's like there was no tomorrow runing a Holley Red...everytime he got to 12psi of boost, BOOM the thing ran lean and detonated to death! Holly only produces 15psi at best conditions! HE was overpowering the fuel pump with boost and the air was going backwards down the fuel line! This is the same scenario with yours. If you look at the Lotus Esprit Photo I posted, you will see in the lower right hand corner a small pressure regulator, that is what you need. It will reference boost pressure and keep fuel pressure a set delta-p above it to prevent gradual running lean as boost comes on... This was a very common occurance in the VW world decades ago---there was a misconception that you couldn't run boost more than 2-3 psi because 'the fuel pump won't keep up'---wrong. They are sealed on the VW, and you can vent boost to the lower chamber of the fuel pump to make the mechanical unit boost regulated to 3.5 psi over boost pressure on them, no problem! But if you don't they only make aroudn 5psi terminally and once you hit 2-3 psi you start running lean. Do it hard run style and you blow air into the tank! (Or at least stop it from entering the carb at all as the pump can't overcome the air pressure!) YOU GOT LUCKY THIS FAR! IMO you're running on borrowed time, runing dry on a turbo causes exactly what yerbetten stated: "ping bang boom!" That's just about all the warning you will get one of these times. Could be the next time, the time after, but eventually it WILL happen if you don't get a pressure and flow capable pump. Most carb rated pumps are only good to 9-12 psi because they are terminally rated to produce 12-15psi. EFI pumps are great because they're everywhere flow like crazy at 20 psi, and are quieter than most carb pumps. Hell, a stock N/A pump works GREAT! (Cheap, and readily available, too!)

I learned years ago to carry an extra pair of socks in the car... Sometimes you get this feeling at a remote desert filling station about how often their premium tank is actually turned over... So you whip out the old nozzle, slip a double sock on it, and GO FOR IT! Live life on the edge... Later, as you realize the red stains on the socks were not from the last time you walked barefoot from the tent to the Z in a stupor...as the car vapor locks and comes to a stop on the hills outside ABQ NM... That maybe, just maybe you got a bad tank of gas. And even going in with protection didn't stop the gas crabs from making your day terrible. Then you get to lie on your back changing the large filter you just installed before the trip, thinking it was big enough to 'last a lifetime' but in reality it only took one dirty deed in the remote desert wilds of Arizona to make your nozzles do nothing but drip drip drip with a reddish tinge and a full heart of regret for what you did the night before...

Mr. Bell and I have some disagreements on other aspects of his published works...

I've run N42 stock Nissan Pistons in my turbo car for over 40K miles... If you are sinking rings and lands, it's NOT the pistons' fault! I've run 21psi on the stock N42 pistons, though most of the time I'm running in anywhere from the 12 to 17psi range. The engine started at 12psi, and it's the lowest boost it's seen since startup. This is a JDM engine, that came out of a car, so it's not like these were new parts I was starting with, either. I think the point XNKE makes is valid. Sometimes people get blinders on to the forest, and then can't see it because of all the trees in the way!

Critical for a proper compression of the gasket. The MSA super duper gasket is more designed for rigid cast pans than sheetmetal ones. If you insist on using it, you need the rail reinforcements. Frankly, I cut and made my own out of strap steel, from Lowes (Or Home Depot, I forget now) Combined with the stock L28ET reinforcements the entire pan is girded with a nice thick support. It sandwiched the pan and gasket against the block. I also made my own stud kit, and use flanged-headed nuts with serrated anti-loosening feature so once they were tight, they didnt' slacken off. Worked well to this point. Then again, I believe I used a cheap cork gasket like originally in place and that worked for 100K plus miles before I opened it up! I got a super dooper MSA gasket hanging on the wall---they make a GREAT pattern for transferring bolt patterns when you make your own pan stiffener rails!

Lotus did it better, though, and more completley dominating! Everything you want to know about blowthrough applications can be learned from closely studying the BiTurbo and especially the Turbo Lotus Esprit!

"This posting has been deleted by its author." Too late for me, I guess!

We had a 240Z that was vapor locking in daily driving only after highway runs. We put a makeshift fuel cooler into the car that was constructed out of a one-gallon igloo cooler and copper coils, we could put a whole 7# bag of ice in there, and it would prevent (ABSOLUTELY) any vapor locking of the vechile under any conditions. One thing we noticed was that after 2 hours of highway driving the ice was totally gone and the water was up to near ambient temperature in the engine bay (around 140 on a 90-100 degree day). We realized that as the tank got lower, the ability of the fuel in the tank to act as a heat sink and dissipate absorbed heat picked up from the engine bay was less and less. People with EFI cars have noticed their AFR's go crazy sometimes when they operate high specific output cars with less than 1/2 or 1/4 of a tank. The fuel heating affects the heat content of the fuel (BTU's)---this is the impetus for requiring fuel dispensers to be temperature compensated. Fueling stations make money selling 'hot fuel' later in the day than they do in the morning and overnight when the fuel can be as cool as 58F. Even small changes in gasoline can make for a large (up to 10+%) difference in volume. When everyone says their injectors are 550cc, do they mean at 60F, or a 160F. The heating value of the 550ccs delivered at 60F will be far different than 550CC's at 160F. We generally use volume delivery systems, which are uncompensated for temperature (air temp on EFI helps). When you do that, your power levels are inconsistent. Drag racers chill the fuel not only for maximum density, but for maximum consistency---taking fuel temperature out of the equation leaves only air density, and they measure that and jet accordingly. No cool can and your air density measurement is a guess in the dark! Depending on the temperature of the fuel delivered, it's heating content can vary GREATLY! Combined with air density that will not be changing at the same relative rate... and you have an issue. Small power steering coolers were always on my mind as fuel coolers. The factory rally cars in European Winter Campaigns had differential coolers in the fuel tanks! Helped keep the fuel warmer to prevent icing of the tripple carbs in winter rallys. In short, if the cooler is on the return, the goal is to lower the temperature on the return and keep it from rising above ambient (the assumption that fuel in the tank is at ambient temperature is seriously flawed, get a temp gun and take a reading sometime, the only time It's at ambient is before you start the car in the AM. After that, it is consistently, and in some cases considerably above ambient temperature!) If the cooler is on the fuel feed side, it has to incorporate some sort of artifical cooling (running the line along the A/C Cold Line, inside the insulation for instance, or ice bath coolers) to lower fuel temperatures for highest density and consistent fuel delivery temperatures. Note the Z31 computer uses a fuel temperature sensor, and has a compensation table to go with it... Even Nissan acknowledge there was an effect on emissions and power that is related to the temperature of the fuel.

That's a generous and flawed assumption to make based on an engine output plaque. Manufacturing difference can mean as much horsepower is lost in transmission as from production tolerances. Taking a factory HP rating from an era when there were no standards for measuring it, and then comparing the results to current dyno comparisons is foolish. What if the rear wheel said 127HP, then this car only lost 23HP---then how do you account for a 45 HP loss on one vehicle, and another identical vehicle in similar trim makes 127 on the same dyno, or on a different dyno for that matter? What of a power peak different than claimed on the factory documentation, frictional losses building as speeds climb skewing it downward (if I'm reading your post correctly)? The rating on the plate is useless. And certianly is not a basis for making a claim of 45 HP lost through the driveline. That is just foolishness. Good to see the OP got the thing dialed in, looks like it was a Tachometer Error. As for loafing along at 2800 in a turbocharged car, hope your oil pump is up to the challenge. Most people are looking for a 2000 rpms cruise speed, and that just doesnt' supply required oil flows for longevity IMO. You can do what you want, but oil pump performance curves and bearing loads are very definite science. And lugging an engine is lugging an engine.

Jobs nobody talks about but someone has to do: Wale Moyle. Pay isn't great... BUT THE TIPS ARE BIG! Yadayadayada, I'll be here all week, you've been a great audience, don't forget to remember your table attendants, I get a cut!