Zmanco

In my case the new wastegate housing extended farther back than the stock T3 and due to clearance issues the vband flange would be attached far into the curve not even close to parallel to the radius of the bend. The transition from the wastegate housing to the pipe would not be smooth.

So you're saying that you had a NA MSA header and 2.5" exhaust and now are going turbo? I just did the same thing last fall and in the end had a local guy build a custom 3" all the way back. He bought some 180 prebent pipes and cut/welded to make it fit. Took him most of a day but it turned out great. Probably not the answer you were looking for, but I searched for a long time for a downpipe I could adapt from vband to my existing 2.5" and couldn't find one.

Tony D, thanks for the further details. I went and read the grape ape racing article - great read! I follow that reasoning and agree with it. Yet I have to try one more time to clarify the question I'm asking because I suspect we're talking apples and oranges right now. My own experience with puking coolant is a bit different than yours. In brief, mine doesn't do it. I'm sure part of it might be that here in Colorado we rarely see days over 100F. And when I come off the track on a hot summer day I open the hood and let it idle for a few minutes until the temps are normal. But the point I'm trying to make is that regardless if I continue to use the stock 13 psi cap, or if I put a higher pressure cap on, since the cap is never opening up (meaning the radiator (not block) pressure isn't exceeding 13 psi) then what advantage would there be to putting a higher pressure cap on it? Again, I'm not challenging that the pressures in the head are higher and this helps prevent nucleate boiling - I understand all that. I'm just challenging the advice I've seen a few times here that putting a higher pressure cap on the radiator would help reduce detonation. I just don't see how that can be if the system has enough capacity (as mine does) to operate without venting with the stock 13 psi cap?

Here's my advance table. I've only driven it through about 180% which won't exactly correlate to you as it's referenced to Load instead of MAP and at my altitude, 100% load is around 81 kPa. I'd suggest pulling a lot out (at least 10-15 degrees) above 100 kPa and 3000 rpm and then slowly add it back. Much easier to approach it from below than above - as you are well aware by now

Interesting, it's probably there to help with potential noise issues. I've been running without it for a few months now with no issues. Still, not a big deal to add it - less than $1 at Radio Shack.

My experience is all with L28s in S30s, but I think you'll see that it applies to your Z31 too. I recently converted the NA FI L28 in my 240z to a turbo. The bottom end was having issues so I had to do something. I found an almost brand new complete factory 280zx turbo engine for a steal. But by the time I was through with upgrades (head, cam, turbo, ignition, exhaust, etc), the only part of factory turbo I used was the block with crank/rods/pistons. My point is that if you're planning on building it up beyond stock, you may as well start with what you have if the chassis is in good condition.

Is your tach one of the 70-73 current triggered types, or one of the later 75-78 voltage triggered tachs? If it's current triggered, there is no resistor. I don't know for sure for the voltage triggered, but I'll say that I just put one in my 73 without a resistor and it's working great. Perhaps you are referring to the resistor that's mounted near the coil in the engine compartment? That one is only to protect the points for non-electronic ignitions and is not needed once you install an HEI ignition. It is not needed for the tach to operate properly.

Ben, the situation I'm asking about is where the temperature as reported by a sensor in the thermostat housing (in my case read by Megasquirt) reads around 195 typical (I run with a 192F thermostat) and even under load on the track, the temps are not exceeding around 215F. I never see anything in the overflow tank, and if I pull the hose off the radiator nipple, it's dry. So my question is if the conditions never cause the 13 psi cap to vent, how would putting a higher pressure cap on reduce spot boiling in the head?

Thanks Guys, as you guys do this for a living, those of us weekend mechanics without formal training learn a lot from these sidebar discussions. We now return to the originally scheduled programming

ozconnection asks a question I was wondering about as well, but let me ask it a little differently: I follow how a higher pressure cap will allow the system to reach a higher temperature at thermal equilibrium without venting. However, I think it's also being suggested that a higher pressure cap will help reduce localized boiling that creates steam pockets in the head. If that occurs with a 13 psi cap that is not venting/overflowing, I don't understand how switching to a higher pressure cap would change it. Am I missing something?

Paul, a quick side question: for the stock turbo head bolts, is engine oil the proper lube to use when torquing to the factory torque specs? Reading your post made me question if I read that somewhere reputable, or otherwise. Hopefully this isn't too big of a threadjack ...thought it was worth clarifying for all of us following this thread.

Perhaps you can just take a picture of the screen with your camera if a screenshot is too difficult? Without seeing timing maps it's hard to make any recommendations. It also limits what the rest of us can learn from what you're going through.

Yes, there is the "standard" MSII firmware, and then there is the Extra version. If you like a lot of features and are willing to play around with them, Extra is the way to go. If you just want to get it to work, the standard code is ok. Keep in mind that moving from standard to Extra will involve retuning, so if you think you'll want Extra, start with it. Side note: I'm on Extra and your setup appears to be similar to mine (except for the cam) so you could start with my MSQ file as a baseline to get up the curve faster.

A few things: - TunerStudio has a steeper learning curve, but is so much more powerful thank Megatune. Since you're starting from scratch, I'd go with TS. FYI, MT is pretty much at the end of its life - the developer is putting all his efforts into TS. - I'd recommend using MSII/Extra code. FYI, some of the features in the current beta release are only supported on Tunerstudio and not on Megatune. - Most people use an Innovative LC-1 wideband O2 sensor. I'd be really nervous about tuning a turbo with a narrow band. - I run the Ford 440cc injectors from the Mustang 5.0 with the stock fuel rail. You need to decide what type of injectors you will use upfront as you may have to machine the intake manifold to fit. There's a great sticky with details on a variety of injectors. - If you use the stock fuel rail, you can also use the stock fuel pressure regulator. - MS will support low impedance injectors without resistors. I had issues with the drivers overheating and shutting down during track use so added resistors to be safe. - I'd recommend you go with the GM IAT sensor that isn't the same as the coolant one. It responds much faster to changes in temp which is an issue when the underhood temps rise and cause heatsoak. Edit: you'll also find that the IAT rises as boost rises, even with an intercooler, and the coolant sensors won't react fast enough. - You'll need to swap to a FI fuel tank, or add a surge tank. I went with the latter and added a larger fuel return line from the engine compartment back to the surge tank. Like Mat was saying, there's a lot for you to read up on as each of these topics has more than one way to go with corresponding pros and cons. Good luck!

I've been thinking about changing to an eccentric pulley too. Any suggestions for one that can swap onto the 240SX TB? No offense taken - I've definitely modified how I use the throttle and shift points when driving sedately to compensate. But nonetheless it's hard to precisely modulate the throttle and boost when cornering, especially coming out of a corner in 2nd gear. I have a 4.11 diff so the boost comes on at slower speeds for me than most others. I know that to some degree this is a fact of life with a turbo motor, but if the throttle was less sensitive at small throttle openings, it would no doubt be easier to control. My daily driver is a turbo volvo and the boost comes on in a more linear fashion so that I don't have this issue to the same degree (although in fairness, it doesn't make as much torque in the mid range either). FYI, to my original question, I forgot that the rod on my actuator is bent just as it comes out of the housing, so this approach isn't going to work for me.

I'm currently running with a 7-8 psi wastegate and want to begin using Megasquirt to control boost. While it will allow me to run higher boost pressures, I also want to be able to limit to less than 8 psi when the TP is not WOT. I'm using the 60mm 240sx TB which is rather touchy (a little movement makes a big difference) especially in 1st and second. Limiting it to something less would make it easier to accelerate briskly without over doing it on the street. I saw this picture in PaulR's post about about his turbo build where he dropped the opening pressure of the WG down to 5 psi. Note the ring with set screws that holds the spring on the WG shaft. I love it! My question is how low can I set the WG actuator pressure via the spring and have it reliably keep the WG valve closed? I'm guessing it only needs to be a little more than the max exhaust pressure after the turbine in the WG housing? Do any of you have an idea what that would likely be? FYI, I'm running a Garrett T3/T4OE with internal WG and 3" DP and exhaust all the way back.

I just skimmed over the thread again but don't see the timing table. Perhaps you can post it? And are you sure that you have it calibrated properly? In other words, have you confirmed with a timing light that what you have entered in the table matches what you measure with the light?

The BOV is more or less an open/close valve that vents the pressure between compressor and throttle plate that can occur when the throttle is suddenly closed. Basically whenever the there is high intake manifold vacuum and boost pressure, the valve opens to vent it. The wastegate is a valve used to limit boost pressure to a precise amount by bypassing exhaust gasses around the turbine. In order to hold a set boost pressure, it must rapidly and continuously adjust the amount of exhaust bypassed. It's not a simple open/close function. There's a degree of precision in its operation that goes beyond what's required of the BOV.

Woops, you're right. Not paying enough attention

FYI, I found it cheaper to buy the intercooler piping as a "kit" on ebay (came with a variety of straight and bent pipes as well as silicon couplers and clamps) and it included a Greddy RS knock off including the pipe. I started out with it thinking I was going to chuck it and buy a name-brand, but so far it's worked perfectly so I've just kept it. Only problem is it's purple and looks ricey. Something for you to consider if you don't already have the piping...

Interesting, thanks, that's the kind of info I was hoping to see. How do treated rotors affect brake pad life?

Agreed. See my post #23 above. Even with the turbo installed, no muffler and 3" exhaust was way too loud to drive on the street.

I appreciate that you've disclosed your biases up front. I see this is your first post on the site, so welcome. If you plan on spending time here besides just this thread you'll find that while we all have opinions, it's when people provide evidence to support them that the rest of us pay attention. Without some evidence or data to back it up, this smells like snake oil, I'm sure even you will agree. I doubt you're able to make claims like that in the ASM journals without data to support them and still be taken seriously. Perhaps you can provide some objective data that supports a 200% to 500% improvement in brake life? Skeptical as I am, I'd really like to be proven wrong.

This is brilliant: http://mikemercury.home.att.net/carcover.htm

These are all-season tires. Fine for going to work/school and back, but not what you want for any kind of spirited/aggressive driving, never mind on the track. These are all season tires as well (except for the drag radial). Plus, this size is 13% larger (> 3.3") in diameter than stock! Except for the Pirelli, these are all-season tires, and the Pirelli is very dated technology and quite over-priced for what it is. If your goal is to build a car for performance driving that includes left and right turns and not just for show, none of these is a good solution. Here are some better tires in 16" and some are no more expensive than the 15"s. But they aren't the right choice for mud and snow http://www.tirerack.com/tires/TireSearchResults.jsp?width=225%2F&ratio=50&diameter=16&x=53&y=11