Scottie-GNZ

Hey, nice engine . What a difference mandrel-bent piping makes in appearance.

Do not know if there is still interest, but here is some more info to chew on: http://www.turbobuick.com/bb/Forum20/HTML/000643.html

RacerX, not sure I agree with your comment regarding the head on a SupraTT to make serious HP. Of course you did not define serious HP so I have no idea what that target is. I can tell you from personal experience that 400RWHP in a 1st-gen Z-car is serious. Now, note 2 things in that comment. I said RWHP and I said serious, not serious HP. 400RWHP in a 1st-gen Z-car is serious HP enough to run 11.0 1/4-mile at the track. On the street you can translate that to 0-120mph on less than 11-secs so the potential top-speed is insane because I can tell you that the Z is pulling HARD at that speed. That begs of some serious braking and suspension. The whole point of that diatribe is that if you plan on more than 400RWHP, your main concern should not be on the cost of the headwork to support that HP but the chassis/suspension/brakes needed to make the car safe. The SupraTT requires no internal work to support 400+RWHP and if you were planning on much more, you would have to open up the engine (or any engine for that matter). Someone else made an excellent point about the RBs. When you buy one used, you have no idea of the condition and of course the same applies to the SupraTT. However, if something goes wrong or you need to make upgrades, that is where the SupraTT has an advantage, IMO.

Not unless they are going to embarrass me .

one more time

One more time.

This is a test, only a test, blah, blah, blah.

Why not post them on the forum? I think others might also be interested.

Rick, at 23.8, the 225/50-15s will get you another 1". Another option is 215/60-14s. Do not about Nittos, but BFG has a 215-60-14 which is 24.15", is slighter wider than the 205s but will have a much larger contact patch with the added diameter.

I have to put any serious testing on hold for a short while as my BFG DRs have struck a chord with me, err, have the CORDS showing . I might try some 3rd gear acceleration testing but I will have to ease into the boost. All I have laying around are some 215/60HR15s and they are only good for holding the car up or cruising down the hi-way. Tim, I was tempted to disconnect the knock sensor Wed night but I did not have the b*lls and luckily I stopped as the tires were shot anyway. I sprung for a new sensor and if it continues, I can program the chip to ignore any knock to a certain MPH and 65mph will get me through the 2-3 shift. Clint, the soapy water is a good idea but my problem occurs in the upper RPM and boost range although I suppose a minor leak could manifest itself. What I have found in the past is that if I have a minor leak at a hose connection, that puppy comes flying off at 20# boost.

Pete, bookmark that one. As it says, "the best sportscars site on the web". This site and "Racer" magazine is a sportscar engineer's (or wannabees) dream.

I would have the heat shield ceramic-coated and a thermal dispersant on the intake unless you plan to polish it. My buddy does coatings and he has been seeing good results from the thermal dispersant on the I/C pipes and stock-location I/C. I think I can help you out. When you come down to run me, you can stay over and the next day while you are putting your doors back on, I can have him treat those pieces for ya . BTW, is mama and baby coming back this weekend? Is this a good weekend to come up?

Jim, is'nt time for another trip to FL? We could have a lot of fun chasing this down. I believe I have clearanced everything. I plan to replace the sensor, regardless. If I still get knock, I will detune it by running the chip in street mode but the richest fuel setting. That puts the timing at 18* and puts me in the less timing/more boost mode. I am also going to tee into the vacuum hose at the compressor to add another boost gauge to see the boost differential. My buddy just bought a new gadget and we will test it on my car. It is a digital device that accepts 2 temp probes and an EGT probe. The 2 temp probes will be placed at the turbo outlet and the TB to measure temp differential. The device also has an optional s/w package that can datalog the temps and EGT through the run and replay it on a laptop. Neat. "Great" minds think alike. I am running enough octane, only 21# boost , O2s indicate rich, everything clearanced, therefore it should not be knocking. Only thing we do not know is the inlet temp and whether or not I am losing boost and the compressor is really spinning at 30# Frustrating, but a heck of a learning experience and a lot of seat time. [ April 27, 2001: Message edited by: Scottie-GNZ ]

I am aware of the Autospeed article and if I recall it was done on an Audi. Same principle, different parts. I started out with just the adjustable wastegate rod. The reason why I do not rely on just the bleeder to adjust boost is because the stock GN cannister has a 12# spring and I did not want to rely on just a bleeder to double the boost. In addition, when I decided to use the relief valve, I wanted it set to 15 so I would have neeed the adjustable rod anyway. One thing I forgot to mention. Once I get the bleeder valve set, I do not like to fiddle with it so my plans for the street is to put an inline shutoff valve before the bleeder. When I am running pump gas, I close off the bleeder and limit the boost to 18# and when I get to the track I just open the valve and the bleeder becomes active. Another method is to disconnect the bleeder. I have the bleeder connected to the hose with a quick disconnect. I am looking for a quick disconnect cap so on the street I can quick disconnect the bleeder and put the cap on. Can you imagine disconnecting the bleeder and forgetting to put the cap on? KABOOOM The relief vale is made by one of the GN guys, but after seeing it, I probably could have gotten all the parts and made it myself, but it was only $30 shipped. A pic is worth a 1000 words. The cannister is hidden behind the compressor but you can see the rod going from the cannister to the puck. The adjustable part of the rod is also hidden. In front of the compressor you see the fitting for the boost sensing hose leading into the relief valve sitting on top of the blue silicone hose. The hose coming out of the relief valve goes into a grey plastic "Y". One connection from the "Y" eventually goes onto a small blue hose. That is a hard plastic line that goes to the bleeder valve in the car and is needed for the quick disconnect. The other part of the "Y" goes down to the cannister. [ April 26, 2001: Message edited by: Scottie-GNZ ]

Scottie to Scott, come in I posted a write-up on what I am using for a boost controller but cannot find it anywhere, so here goes again. My system is home-made and somewhat complex because it has 3 components to it. It is, however, based on sound principles and it working well for me. Excuse me if I ramble and bore anyone but I think some basic turbo knowledge is required to fully understand how/why this works. A turbo with an internal wastegate has a valve (also referred to as a puck) in the turbine housing that opens to relieves pressure and help control boost levels. That puck is usualy controlled by a wastegate cannister that has a rod connected to a lever on the puck. The cannister has a diaphragm and a spring weighted for a certain pressure, lets say 12#. The cannister receives a boost signal, typically from the compressor housing and when the boost level reaches 12#, the diapraghm is moved and pulls the rod which opens the puck which relieves pressure in the turbine housing and helps maintains 12# boost. Despite a spring pressure of 12#, the puck actually starts opening sooner so the boost buildup is more gradual. The rod length is matched to the spring pressure and if you shorten the rod, more spring pressure is required to open the puck because the shorter rod puts a greater preload on the spring. One trick is to cut the rod, shorten it slightly, thread both ends and join them with a threaded connector with lock nuts on both sides. By adjusting the connector to shorten the rod, the compressor now has to put out say 14# to open the puck despite the cannister having only a 12# spring. When you are running a turbo with a bigger turbine housing/wheel, the slight early opening of the puck can hurt spoolup because the engine is not putting out a lot of HP at that point to spin the bigger/heavier wheel and pressure is already being bled off. In addition to having an adjustable wastegate rod, I also inserted a pressure relief valve in the hose that sends the boost signal to the cannister. The pressure relief valve typically is an inline checkball and spring setup and remains closed until a preset pressure is reached. I have my wastegate rod adjusted to 18# and the relief valve adjusted to 15#, so the cannister sees no boost signal and stays shut until the pressure relief valve opens at 15#. Instant spoolup. The 3rd device is a bleed-off valve that is inserted between the pressure relief valve and the cannister. When the relief valve opens and sends the signal to the cannister, the cannister starts to open the puck at 15# and has it fully open at 18#, but I run 21# and eventually 24#. By opening the bleed-off valve, I bleed of some of the signal pressure before it gets to the cannister and the compressor has to put out more boost before the cannister sees a signal of 18#. If I want to run more boost, I just open up the bleed-off valve some more. See, I told you it was simple . NOT RECOMMENDED FOR AUTOCROSSES or at least use more sane pressures. BTW, a lot of folks buy these industrial type bleed-off valves and find them too sensitive, like moving it 2 notches gets you 6# boost . That is because those valve are typically made for a pressure range of 0-150# or even more and you are trying to increase your boost in 1# increments. The answer is to take it apart and find a spring that is the same size but much, much softer to allow more granularity. There is no one answer as to which spring to get obviously, so it takes a little research based on the valve you have. I believe the stock Nissan cannister spring is rated for 7#. You have the option of making the rod adjustable and/or using a budget bleed off valve with the right spring or springing for an aftermarket unit for some big bucks that do the same thing. This is not a bolt up and go mod. It takes a lot of fine-tuning to get it just right for your setup. Ah, forgot if I even answered your question

Despite being confident that I have eliminated all possible causes of false knock, the problem persists. Took the car for a quick test last night and got the following results: 60' - 1.78 (.23 off my best) 1/8 ET - 7.26 1/8 MPH - 98.85 (new best) 1/4 ET - 11.25 1/4 MPH - 121.62 The ET between the 1/8 and 1/4 was 3.98, also a new best but still the computer is sensing knock and pulling out timing despite being rich. That was not a bad run considering and where the hell is my quick 60' times when I needed it? Coulda, shoulda, but a 1.60 60' would have consoled me some. Back to the drawing boards. Possible defective sensor, FP not putting enough at high RPMs or experimantal chip just not compatible with my setup. I made a couple more passes and gave up. On one pass I had 14.4* of retard on the 1-2 shift (car ran 11.22 @ 119.55) and on another I had tire spin and the 1-2 shift happened at 5600 and I had 19.2* retard (car ran 11.38 @ 119.23). I am only running a total of 24*! Did not think a car could run on only 4.8* much less flat out . I wonder how long it really takes for the engine to recover from that. Only positives were the cars I ran against. A nice S-charged early Mustang Cobra with slicks, the Impala SS I mentioned in another post and a big block Dodge Dart with Hilborn injection and huge slicks. His 11.57 @ 115.66 to my 11.45 @ 119.30 bucking all the way down the track I am having so much fun I could just SH*T, so with that, here is a little humor: http://www.turbobuick.com/bb/Forum13/HTML/011541.html

Is the NISMO catalog online? I was just looking at the specs on the "red car" posted by Eric N and noticed it had a NISMO LSD with 3:15:1 ratio. EXACTLY WHAT I NEED!!!! I will probably have my bubble busted when I see the price as my guess is $2K, but curious nonetheless.

Tease

quote Who are you referring to that has them?

Nion, very clean. Did you have to use a spacer with those wheels?

I resemble that picture

Stock Nissan part. After wasting more time than I care to mention searching boneyards, I broke down and spent $100 for the pair.

John, good to hear from you. All, John has a very healthy GNZ, not stock like mine, that has already gone 131+mph in the traps. He is also building a Fiero/GN.

HTH Maxima Bracket

Darn Pete, I reread my 2 paras 10 times and am confused what you are confused about If it is in reference to an L28T wheezing, I was referring to the sound.