TimZ

Oh BTW, I used a hydraulic line lock for a parking brake for several years with my wilwood setup. I always had a problem in that the line lock would only hold for maybe a day, at best, and then let loose. This was why I finally went to the spot caliper this year, when the second line lock one failed (it seized up - presumably from sitting over the winter). I'd be interested to see if you have the same problem. In the mean time, I'd suggest always leaving your car in gear when parked as a safety backup. One really nice thing about the line lock, though - it seems to make for a great theft deterrent. Pretty much any time anybody else tried to drive the car, they couldn't figure out how to get the thing to move, since the rears were solidly locked. Seems nobody ever thinks to tap the brakes in this situation. [ July 29, 2001: Message edited by: TimZ ]

quote: Originally posted by scca: the rears will still work somewhat if the fronts rupture a line.. thats why cars now have separate reservoirs and in the 60's they didnt.....(early 60's) Although I have never tried this out myself, Mike is correct - you should be able to get the remaining circuit to work, but it does require pumping the brakes repeatedly, until some braking force comes back. Also, this is why most modern cars have a diagonal split, instead of front/rear, like on our Zs. Now, if you lose one circuit, you will always have one front and one rear brake that is still useable.

Just to defend the 280s a bit (since that's what I own )... As others have already mentioned, some of that weight difference comes from body reinforcements, resulting in an overall stiffer body. Some of the weight difference comes from the R200 (the 240s had the R180). If you are building a HybridZ, then you'll probably do an R200 swap anyway, so that weight difference is negated. Also, the 280's fuel system is already plumbed for a fuel injection system - the tank has a fuel return, and there is a high pressure pump, and associated wiring for it already there. Granted, you'll have to change the pump if you are doing a high boost turbo, but the mounting brackets are already there, and the pump swap can just about be a bolt-in.

It's probably the wiring - the wiring harness is pretty old at this point, and the contacts in the light switch, as well as all of the connections in between probably are somewhat corroded, causing a much larger voltage drop than when the car was new. Check the voltage at the headlamp, preferably between the contacts on the lamp itself. I wouldn't be surprised if you were only getting 9 or 10 volts at the lamp. If this is the case, wiring those relays for your stock lamps will probably help quite a bit. Also, this will make it pretty easy to upgrade to the H4 lamps later, if you want.

Probably the best rule that I have heard for sizing intercooler piping deals with limiting the maximum air velocity in the piping such that excessive drag is not generated. The design guideline that I had heard was to keep it below Mach 0.4, or about 450ft/sec (I just lifted this from 'Maximum Boost'). From this guideline, a 2.25" pipe would generate air velocity of about 360ft/sec at 600cfm (~400hp), and a 2.5" pipe would be about 290ft/sec. So, at ~400hp (flywheel), either size should work just fine - the 2.25" pipe should give better response, but the 2.5"pipe has more headroom. That said I use 2.5" pipe - mostly because that is the size of the outlet of my turbo, and it didn't make sense to me to make the pipe smaller than the turbo outlet. Also, I think that somebody already mentioned it, but it's generally easier to make the IC outlet pipe match the throttle body size than it is to have a transition in the pipe itself. [ July 28, 2001: Message edited by: TimZ ]

quote: Originally posted by Ross C: I'd have to have a lot of unloading to have my springs rattling I would think but we'll see. Keep telling yourself that... The rattling that I was referring was not occuring with an unloaded suspension. Rather, it would happen anytime that I hit a reasonably sharp compression bump. There is nothing there to damp any high frequency harmonics, so the spring would bounce on the perch. It did this noticeably every time I drove the car.

The noise problem stems more from the now complete lack of noise/vibration isolating materials in the spring perch assembly. Every noise that the suspension makes gets resonated into the ****pit, via the camber plates. The worst offenders in my case were squeaks from the suspension bushings and the shock absorbers, and chattering of the steel springs on the steel spring perches when I would hit medium to large bumps. I have been using the plates on the front for about 10 years, now, and have not seen a reliability problem at all with them, and this includes driving in Detroit for the last eight years. My problem was solely with the noise generated by the plates on the rear suspension. For me, it was just too annoying for a street driven car. For a dedicated race car, it would probably be just fine.

I had them on all four corners, and as others have already said, they were too damned loud in the rear. I reverted back to the stock uppers, modified for the 2.5" id springs, and have been much happier. I do still have the plates on the front suspension though, and have no real complaints about that. Has anyone else noticed that you can't really increase the camber past the stock settings with these plates? The configuration of the mounting bolts prevents this. You can only decrease the camber from stock, unless you relocate the mounting bolt holes (guess what - you can do that without the plates ).

I must admit it's a bit fuzzy to me, too. I'll try to find the info and re-read it, and see if it makes any more sense.

Evan... This is going to sound like sacriledge, but I would just use motor oil, and use the 55 lb-ft number, instead. The reasoning behind this is that after you've run for a while, and need to retorque, you'll have a mix of whatever moly lube is left, and motor oil. Maybe you have that now. If you just stay with good old fashioned motor oil, it seems to me that you will actually end up with more predictable, repeatable results. I originally tried just using the moly lube and 35 lb-ft, and moly or not, that just felt SCARY loose. Also, unless you have a low-torque torque wrench, it's fairly hard to get consistent performance at the low end of the torque wrench's torque range (at least it is on my Crapsman wrench ). I was just much more comfortable using a higher torque setting, where it feels like I'm actually tightening something, and the torque wrench gives a nice, solid CLICK. [ July 19, 2001: Message edited by: TimZ ]

I had thought the same thing, Sleeper. That was why I had originally misinterpreted the instructions that I quoted earlier. I had originally torqued them in as you stated, but was then told that that was a bad thing, so I pulled them back out and installed them hand tight. I'm starting to think that nobody knows what you are actually supposed to do with these damned things. Actually, you are the first person that I have heard bring the pretensioning issue up. I had read the same thing, either in Maximum Boost, or one of Carrol Smith's books, but was starting to believe that I must have misread it.

Believe it or not that was what I was just going to suggest. Hopefully that's all it is.

James... I'll scan the sheet in tonight and e-mail it to you. Maybe you could put it up on your website, so that we could link the image here. I guess they thought I couldn't read?

BTW, you should notice that from these numbers, 100% of the fasteners yield strength happens at 60 lb-ft with Moly lube and 90 lb-ft with motor oil. I think that 100% of the yield strength is where the fastener breaks...

Expensive tools? A pressure port welded into the downpipe and a pressure gauge is all you need. I used a steel -4AN fitting in the downpipe, and ran some steel tubing a foot or two to get it away from the heat, and connected the pressure gauge to a fitting that I placed at the end of the steel tubing. You can kind of see it in this picture, the tubing goes to a fitting mounted on a small plate at the back of the intake manifold. It's capped off in this picture.

The 45/65 numbers are also on my ARP instruction sheet, but it appears that this is intended for iron heads. Here's the whole quote: PRELOAD (TORQUE) RECOMMENDATOIONS: (a) Torque values are based on 75% of the fasteners yield strength. Use the manufacturers torque sequence but do not use the engine manufacturers torque specs. Torque the studs to 45 ft lbs for ARP MOLY ASSEMBLY LUBRICANT (or ARP THREAD SEALER) or 65 ft lbs with motor oil. ( Due to the heat expansion rate of ALUMINUM, it is recommended that the preload on the fastener should be 60% of the fasteners yield strength. This torque is 35 ft lbs with ARP MOLY ASSEMBLY LUBRICANT (or ARP THREAD SEALER) or 55 ft lbs with motor oil. NOTE: If you do not feel comfortable using the 75% of yield figure, the 60% figure can be used but NEVER go below that percentage. After reading this, I think it's pretty evident why there is so much confusion - these instructions are not particularly clear. When I first read it, I thought they were talking about torquing the studs into the block in part (a), and the nut onto the stud in part (. This was not the case - it said elsewhere to 'hand tighten only' when installing the studs into the block. Maybe if I get some time later, I'll transcribe the whole sheet for everyone to see. The thing I don't get is that it seems like I'm the only one that ever got an installation instructions sheet with my studs. Are they not sending them out with instructions anymore? [ July 18, 2001: Message edited by: TimZ ]

quote: Originally posted by Evan Purple240zt: OH btw, why to studs torque so much better than a bolt? Evan My understanding is that it is due to a couple of effects. First, since you are tightening a nut onto a stationary stud, there is considerably less friction, compared to threading a bolt into a hole. With the bolt, you have more threads making contact as it is screwed into the block. Part of the tightening torque gets used overcoming this friction. Also, because the thread pitch is finer on the head studs, a given torque at the nut translates into more clamping force, from the greater leverage the fine pitch provides. Maybe a metallurgist or fastener expert can chime in now, and correct any misrepresentations I have made...

quote: Originally posted by Evan Purple240zt: Whoa scary scary stuff, i way overtorqued the head then. Man, i heard about 900 different torque values for the studs. Well, if you only went to 60lb-ft, you weren't too far off. I've heard lots of people quote higher values, too, but as far as I can tell, the values ARP recommends are what I quoted. It wouldn't hurt to double check with them, though. I do know that someone on this list followed the advice of TEP, and torqued his head studs to something like 85 or 90 lb-ft, and promptly broke one of them off in his block. quote: Tim, assuming I didnt damage my studs when i bolted on the head, is it safe to retorque them to the proper specs? Its not even really a leak, it just looks wet. Maybe im not TOO screwed! If you haven't broken them yet, you are probably alright . You did just go to 60lb-ft, right? Anyway, I would think that you should have no problems retorquing to the proper specs.

On the fuel pump - 270hp is going to require a pump capable of about 155 lb/hr of fuel flow (I assumed a .5 BSFC, and 15% safety margin). It's very important to know what operating pressures you will need to run. 270hp should put you in the neighborhood of 10psi of boost. This means that your pump will need to produce 10psi over the baseline fuel pressure, assuming that you are using properly sized injectors. So, if you are running 35psi baseline fuel pressure, your pump will need to supply 155lb/hr, at 45psi. If you are using stock injectors and a rising rate FPR, you will need that same 155 lb/hr at even higher fuel pressures. As I recall, the stock fuel injectors are good for 19 lb/hr at 45psi. So to make them flow enough fuel to make 270hp, you will need to run in the neighborhood of 75psi at the pump. So in this case your fuel pump will need to flow 155lb/hr at 75psi. This is a huge difference in requirements for the pump. In general, a fuel pump's output flow drops dramatically as it's output pressure rises. In the end, these are the requirements that you will need to specify, NOT how much horsepower the pump is capable of. There are lots of pumps out there that will flow 155lb/hr at 6psi, or even at 45psi, but there are considerably fewer that will do the same at 75psi (or that can make 75psi at all, for that matter). On the distributor - You can use the Euro distributor, provided you can add some sort of method of retarding the timing as boost rises. Does the ignition you are using have an option of adding something similar to the MSD Boost Timing Master? If so, then you should be okay. Otherwise, maybe you should consider changing the electronics over to MSD, or similar, with this capability. [ July 17, 2001: Message edited by: TimZ ] [ July 17, 2001: Message edited by: TimZ ]

Okay - if I'm understanding this correctly, it goes to 14psi, then drops to 11, then to 10. Is that right? If so, then I think that you may have already found the limit of how much boost the stock turbo can supply. The turbo can make 14psi at lower RPM, because it requires less airflow to make boost at low RPM. As the revs rise, the airflow out of the turbo doesn't, so the boost pressure drops. At 14psi, you really should be doing something to augment the fuel flow. Tweaking the AFM won't do it - the injectors simply aren't big enough to flow that much fuel at the stock fuel pressure. You will either need to go to bigger fuel injectors, or a rising rate FPR if you intend to run that much boost. Also, you will most likely need a fuel pump that is capable of delivering enough fuel at the required pressures. This is especially true if you use the rising rate FPR, since it will need to raise the fuel pressures to around 80-90psi when you are under full boost. The stock turbo fuel pump has an internal pressure relief valve that opens at 65psi, as I recall. The stock n/a pump opens at 55psi.

quote: Originally posted by Evan Purple240zt: I used 60ft lb for final torque. Seems to be leaking from the water jackets slightly. Someone mentioned 80ft lb. Help!!!! Evan NO. 60 lb-ft is about as high as you should go with the ARP head studs. Actually, it's a little higher that they recommend. For an aluminum head, my ARP instructions say to torque to 35lb-ft if you use the ARP moly lubricant, and 55lb-ft if you use motor oil for the lubricant. Tightening torque has little to do with clamping force when you are talking about head studs vs. head bolts. The studs will offer considerably more clamping force at 55lb-ft than the stock head bolts did at 65lb-ft. It seems to be pretty common for the metal head gaskets to have oil/water sealing problems. Did you use any kind of sealer/coating on the gasket before you installed it? I know James uses the spray on copper coating, and doesn't seem to have any problems. Also, after running the engine up to it's normal operating temp, it's a very good idea to let it cool back down (overnight) and retorque the head studs. Back each one off about 1/8 turn, and retorque. This usually helps the gasket to seal, as the expansion/contraction of the warm engine crushes the combustion chamber sealing ridges a bit. The sealing ridges around the combustion chambers is most likely what is keeping the oil/water passages from sealing properly, BTW. I usually retorque the head two to three times after installing a new gasket, just to be safe. [ July 17, 2001: Message edited by: TimZ ]

Scotty... From your description, it sounded like you were saying that when you first see boost, you get around 14psi, then as you stay in the throttle and the RPM rises, the boost drops off to round 11psi. Is that what you were trying to say?

Yes, they still work just fine. The check valve keps any boost from getting into the booster, so it's pretty much the same as n/a. Actually, since the cam profiles are generally more conservative for a turbo, they usually have very good off-boost vacuum, so the brake performance does not suffer like it does with a long duration cam on a n/a car.

If it's below 75degF, mine will do that in 2nd. If it's below 60 degF, sometimes it'll do it in 3rd . Okay - bragging over . I can't remember - are you using an intercooler? If not, your intake temps are probably rising, since you stay in boost progressively longer in each higher gear. If you are lucky, all this will do is make it go flat in the higher gears. If you are not so lucky, it could cause detonation.

quote: Originally posted by Scottie-GNZ: You might all have have L28Ts but believe me, there are so many variables, every engine will react differently. Turbo size, gas quality, I/C efficiency, exhaust backpresure, etc, all play a little part in making the engines react differently. Never have truer words been spoken (okay, never is a strong word - I'm adding some artistic license here ). Timing curves are not too bad to pass around, but fuel maps are pretty much a waste of time. Unless you have a spec engine that is EXACTLY the same as another, the fuel delivery curves probably won't 'trade' very well. Hell, I've had to completely remap my VE curves just from changing my cam timing 3 degrees. Scottie - I agree that my timing on boost is conservative. I had to dial it back to that for the dyno runs that I did last month, because the intake temps were running so high (96 deg ambient). I've left it alone, just because it's still running pretty strong, and it never seems to detonate, now. Also, my EGTs are not through the roof under boost, so I'm going to leave it alone for now. I'm looking at upgrading my TEC PROM, as the newer versions have a feature that can retard timing with increasing intake temps. That way, I could run higher advance in cooler weather, and still not detonate when it gets really hot out. [ July 15, 2001: Message edited by: TimZ ]