getoffmyinternet Posted July 29, 2008 Author Share Posted July 29, 2008 Andy: This is all relevant information, thanks. Sorry I haven't responded in a while, I've been having all kinds of side projects. We're still moving though. Well, I'm still waiting for my bpv, but the speed shop is making me a new throttle cable and the intake box is almost done (I really hope that works out, it's taking SO much effort to make!). It looks good so far though. Wondsparrow: Yes, the bov should recirc back to the turbo downstream of the maf, because if it goes upstream of the maf it is counted double and thus the ecu will overschedule fuel--ie. you might as well blow off to ambient. Recirculating back to the turbo doesn't really cool it or necessarily allow it to keep spinning, but rather to stop spinning on its own steam as opposed to spinning backwards from the backpressure created by closing the throttle plate suddenly and having pressure built up in the intake plenum. Once the air is downstream of the turbos, it combines and doesn't matter which bpv goes where--the only rule is that the recirculated air be evenly distributed between the two turbos so that neither stall. In fact, you don't necessarily need one bpv per turbo; the stock setup has two, but they immediately combine into one stream. The only thing I can't figure out yet is why there are two bpv's at all. For all we know, it's just to save space or have a common part between engine models. It's Al by the way. Al Gore. Now get off my internet!! Quote Link to comment Share on other sites More sharing options...
wondersparrow Posted July 29, 2008 Share Posted July 29, 2008 cool thanks! Coming from a piping and process background a question pops into my head. If you have a recirc like this (if it is big enough) would you need a wastegate at all if you had a properly sized turbo? would that not in theory encourage the turbo to keep spinning without increasing pressure and reduce lag? Sorry if I am straying off topic. hopefully soon i can find a z that is not all rusted out and answer my own questions by blowing things up Quote Link to comment Share on other sites More sharing options...
Careless Posted July 30, 2008 Share Posted July 30, 2008 cool thanks! Coming from a piping and process background a question pops into my head. If you have a recirc like this (if it is big enough) would you need a wastegate at all if you had a properly sized turbo? would that not in theory encourage the turbo to keep spinning without increasing pressure and reduce lag? Sorry if I am straying off topic. hopefully soon i can find a z that is not all rusted out and answer my own questions by blowing things up generally people use smaller exhaust housings to have turbocharges flick on like a light switch, and larger ones to make the transition to positive boost pressure a lot smoother. this has to do in part with the energy required to move the turbine wheel. if your exhaust flow/volume is not enough to continue to spin the turbo higher and higher, you will never reach the turbo's efficiency range at which it operates best on your application, and the accompanying compressor housing will be too large to build a strong boost level. adding to that, if you have it too small you will run passed the efficiency range to a point where the turbo setup falls off it's target along the compressor map, and the inverse of what happens on the previously mentioned setup happens to be what kills compressor wheels and housings when the units are too small. Too much pressure too fast, and they go boom. As a side note, the guys with the R33 skyline @ Exvitermini.com had a quote published in an article stating that they had no set waste-gate release pressure, as they ran no waste gates and just let the turbos do what they could do. This could be a case of over sizing the exhaust housing units just one step up from what they had calculated as ideal, so that they have room for more power on a cool day when everything is running better than usual. Quote Link to comment Share on other sites More sharing options...
getoffmyinternet Posted July 30, 2008 Author Share Posted July 30, 2008 That's actually what I once thought blow off valves were for. To me it seems that if you had a fixed wastegate, or none at all, aside from the turbo overspooling and blowing up given the right circumstances, consider that it would run very inefficiently. It might be okay for line racers, but having the turbo run at maximum capacity all the time only to blow the hot compressed air back into itself in a loop would be undesirable. Now because the bpv is releasing excess pressure, the turbo wouldn't necessarily be under a higher load, but regardless it would be spinning ridiculously fast and sucking in hot air from its own discharge and burning itself up. Also, the turbo would never shut down, as it would be spooling even at idle--to what pressure is hard to say; a balance between it's capacity at the current exhaust rate, and the load on the engine at which it would be caused to die. Does that make sense, or is it just 2am right now? Quote Link to comment Share on other sites More sharing options...
wondersparrow Posted July 30, 2008 Share Posted July 30, 2008 makes total sense to me now Quote Link to comment Share on other sites More sharing options...
ww Posted August 8, 2008 Share Posted August 8, 2008 Wastegate = Prevents the turbo from boosting beyond it's efficiency envelope or exceeding the design limits of the components under pressure while under positive throttle. I've never actually seen a running turbo car without one. Doesn't mean they aren't out there, just doesn't mean I've seen one. I don't believe it is prudent to design a turbo installation without one. BOV/BPV/Pop-Off Valve (Blow Off Valve/Boost Pressure Valve) = prevents compressor surge resulting from a throttle engaged boost condition to a throttle disengaged condition where the latency between on throttle and off throttle allows the boost to continue to be produced against a closed throttle plate. Can either inefficiently vent to atmosphere (easiest to install) or efficiently recirculate the boost pressure after the throttle plat and in front of the turbo inlet to allow the turbo to "free wheel" either between shifts or on sudden throttle off deceleration. Quote Link to comment Share on other sites More sharing options...
getoffmyinternet Posted August 24, 2008 Author Share Posted August 24, 2008 Sadly, in light of the complications accompanying the new bpv, I have to abandon the air box and just get twin cone filters for now. The fuel pump is working now, but I found out I need new o-rings on the injectors because two were leaking. Also, my so-called engine paint isn't exactly fuel-proof, so I'm going to end up lp'ing the fuel rail black. Meanwhile, I got anxious and already started on the sound system, which I know is a completely unrelated topic and should be its own thread altogether, but I'm pretty excited about it because it's the first time I've been able to buy quality ingredients all at once and hopefully be a one stop shop. On the last car I ended up spending just as much on the cheap stuff because I kept changing my mind and whatnot. Also, when you have a soft top things tend to get stolen. So it's a 12" pioneer "thin series" sub that I made my own box for (as close to spec as I could get: sealed offset rectangle ~.75 cu. ft.). I hope I don't get any flat tires because that's right, it's going in the wheel tub. Two rear mounted pioneer 6x9s and an alpine deck with imprint powered by an alpine 5 channel amp on the contingency that I might end up needing two small speakers up front as well (If there's one thing I hated about the past systems it was that I always seemed to have to buy a new amp or replace one when I upgraded or bought new speakers.) Pioneer has some good amps but no 5 channels so no matter what I would need two; plus the new alpine amps are tiny. AAAnyway, the line for the bpv is still tentative so I don't want to post pictures yet, but I'm getting close to summing that up. The way I keep adding more and more lines and crap under the hood this is turning into a new car where everything is hard to get to. Quote Link to comment Share on other sites More sharing options...
Bishopsrock Posted August 28, 2008 Share Posted August 28, 2008 The way I keep adding more and more lines and crap under the hood this is turning into a new car where everything is hard to get to. Yes I have been thinking the same thing today - i.e. that I will have to dismantle half the engine bay in order to fix something fairly simple - like fitting the 240z oil pressure sensor that I forgot to fit! When I lift the hood now, all I see is an impenetrable wall of pipes and cables. Glad to see that you are still crossing the jobs off the list though. Anyway, I have been on vacation for a while but am back now - so I will try to post the recirc stuff in the next week or so. Quote Link to comment Share on other sites More sharing options...
getoffmyinternet Posted August 29, 2008 Author Share Posted August 29, 2008 The filters I got came today, a bit of an overkill again on my part. They looked smaller on paper! I hope they fit... Quote Link to comment Share on other sites More sharing options...
getoffmyinternet Posted September 7, 2008 Author Share Posted September 7, 2008 I don't like the way those filters are fitting, it's so snug that I'm certain over time they would rub holes into each other. I've returned them and ordered smaller ones. Also, I retook a picture of the fuel pump because I believe since the last time I posted one, I switched it around. The original install had it pointing the wrong way! The bov is installed and I'm ordering some high heat flexible hose from mcmaster to hook it up to the intake. Note that the front turbo flange has also changed, as well as the plug for the rear intake (needed that recirc port). Here are the individual homemade pieces, as well as the new maf flange. I've cut up the silicone tubes for the mafs already (removed legs, increased angles), here's how they sit. Updated the overflow line so it fits properly. Installed the new custom throttle cable. Much easier than i thought it would be (uses mostly original mounting with a new ball up top). Misc: The battery is in, everything in that corner seems to fit nicely so far. I jumped to the radio to test out my sound system freshly installed. Pretty sweet I'll say. First try, I like that Quote Link to comment Share on other sites More sharing options...
getoffmyinternet Posted September 10, 2008 Author Share Posted September 10, 2008 Just picked up the filters and it looks like they're good to go, I just have to get a few more clamps and secure the tube for the rear filter so it doesn't bounce around so much. The front filter hangs kinda low, so unfortunately it will get dirty much quicker, but on the plus side it won't be as hot. I just can't drive through any deep puddles. Quote Link to comment Share on other sites More sharing options...
getoffmyinternet Posted September 12, 2008 Author Share Posted September 12, 2008 This is the last time I change my mind on filter placement, I swear! At least for now. I was able to mount the front filter pointing up after all without being in the way of the rear filter--due to the implementation of that modified flange for the rear filter (adding a 30 degree angle) making it possible to stick it near the strut. Note that the filters themselves have a 10 degree angle at the flange. I don't remember ordering this option, but it ended up serving me well. Quote Link to comment Share on other sites More sharing options...
getoffmyinternet Posted September 22, 2008 Author Share Posted September 22, 2008 The filters are in for good now, I think. The bpv lines are in and looking fine, pics coming soon. I filled it with oil and water... my water pump is weeping! :'( Does anyone know if it's easy to press these apart and replace the seals or do I have to buy a new one? I bet half of you guys have one to "give away" since everybody is upgrading to the N1, right? Pm me! Quote Link to comment Share on other sites More sharing options...
getoffmyinternet Posted September 23, 2008 Author Share Posted September 23, 2008 Sure wish I had figured out about the water pump sooner. The bottom cover, thus the top cover and the belt, thus the balancer, thus the radiator, must now come out. Quote Link to comment Share on other sites More sharing options...
stony Posted September 23, 2008 Share Posted September 23, 2008 Yep pretty typical of a motor that has sat for a while. Mine was good while on okinawa. (running for 2 weeks) but once it made it here to alaska it went bad. Make sure you follow the FSM and torque everything to specs. I have seen way too many people loose timing belts because a boilt came loose after. Quote Link to comment Share on other sites More sharing options...
mtnickel Posted September 23, 2008 Share Posted September 23, 2008 Installed the new custom throttle cable. Much easier than i thought it would be (uses mostly original mounting with a new ball up top). Where did you get this Throttle cable...with the new ball and all. what length? Thanks Mark Quote Link to comment Share on other sites More sharing options...
getoffmyinternet Posted September 23, 2008 Author Share Posted September 23, 2008 Well, I refuse to buy the special tool to take off and put on the idlers, but yeah. I'm debating also having the covers lp'd since I'm already having to go through the trouble. That engine paint really let me down something powerful. I got the throttle cable from a local control cable shop. 4 ft. even and fits just right. Standard 3" travel if I remember right. Those shops can make just about anything in a couple days if you know what you want. The ball is just a universal type, about the size of a zerk fitting. The end of the cable isn't attached to it, rather it is a bored cylinder with a spring loaded sheath that snaps over the ball loosely but doesn't let go. 35usd Quote Link to comment Share on other sites More sharing options...
getoffmyinternet Posted September 23, 2008 Author Share Posted September 23, 2008 By the way, I feel like your location keeps changing, stony. Didn't you start out in nz or some paradise like that? I guess your car uses all weather coolant. Quote Link to comment Share on other sites More sharing options...
getoffmyinternet Posted September 23, 2008 Author Share Posted September 23, 2008 And another thing, does anyone know if the water pumps are interchangeable between rb20-25-26? The ones on ebay all look exactly the same except the "26" ones cost more. To make it more confusing, the p/n for the 26 pump on ebay is different than the one I found in fast. ??? Quote Link to comment Share on other sites More sharing options...
stony Posted September 23, 2008 Share Posted September 23, 2008 Was stationed on okinawa (where i built the red rb26Z) then moved to alaska. Quote Link to comment Share on other sites More sharing options...
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