bradyzq Posted May 8, 2013 Share Posted May 8, 2013 Great that the MAF looks like it will work out! I too have seen weirdness with MAF placement and dyno fans have also caused issues at lower flow (like idle and low RPM running). The voltage range on the MAP sensors are pretty much always 0-5Volts regardless of their rating. Offsets may vary a bit, but that's about it. So, yes it would run, but not without rescaling your load axes, the whole point of it being that you could get a max load under boost that is 100 or less, so ITB mode would work. Quote Link to comment Share on other sites More sharing options...
Xnke Posted May 9, 2013 Author Share Posted May 9, 2013 Well, here's the deal...ITB mode will not work with any pressure over atmospheric, because it checks baro on startup. It's hardcoded into the current system, and hasn't been changed yet. So far, the only way to get ITB mode to run with boost is dual map sensors, with the second sensor setup for "realtime baro correction", and install the baro sensor infront of the throttles, so it sees 100kpa on startup. As "atmospheric" pressure rises it increases fueling. It's not a perfect method...more akin to using a rising rate fuel pressure regulator on a stock ECU. Tomarrow I have to machine a new tensioner pulley and fit another brace on the tensioner bracket. Once that's done, most of the fabrication work is done, and it's just nitpicky stuff like getting the idle set correctly, tuning the pneumatic actuator for the bypass valve, and getting the MAP signal steady enough to reliably run the spark map. The transmission is still sitting in my floor... Quote Link to comment Share on other sites More sharing options...
Xnke Posted May 10, 2013 Author Share Posted May 10, 2013 Well, the MAF sensor does NOT like the fluttering bypass valve. The bypass valve is vacuum/boost operated, and is a 2" diameter butterfly valve. It uses a vacuum/boost actuator, with a vacuum signal on one side and a boost signal on the other side. At idle, the butterfly seems to "flutter", due to the noisy map signal from the cam plus ITB's. I should have gone with a single throttle...I'd be done tuning by now. I have a fuel filter inline with the MAP sensor line, but my MAP signal still sucks. It's clean enough after some smoothing, but I need to fix it. The car will cruise "OK", but as soon as you roll on the throttle and the bypass valve starts fluttering, the MAF goes nuts and the car throws a fit. All the way up to that point, though, it feels good. I don't have much option on the bypass...without one the super will start blowing pipes off on any kind of drop throttle event. I have to recirculate behind the MAF sensor in any case. Quote Link to comment Share on other sites More sharing options...
bradyzq Posted May 10, 2013 Share Posted May 10, 2013 So, let me get this straight. To clarify, even if you switch "Barometric Correction" to "None" from "Initial MAP Reading" and set "Default baro(kPa)" to 100, the MS still checks baro when in ITB mode? If the answer is "Yes," then WTH were the MS developers thinking?? If the answer is "No," then we can move on to the MAP sensor thing, which I explained badly. The idea is to keep the stock internal MAP sensor, but recalibrate the MS2 to think it's a 1 Bar sensor. That way, the picky ITB mode will never see boost. Basically, at atmospheric pressure, your indicated MAP will be 40ish kPa. Since you say the latest alpha code permits changing the MAP-Alpha-N switchpoint, you should be good to go, albeit with an odd, underscaled load axis. You would need to repopulate the fuel and spark tables to reflect this. But the load axis in ITB mode is a weird hybrid anyways, so that's no biggie. The most annoying thing would be having to always multiply the MAP by 2.5 in your head when logging or viewing data. Quote Link to comment Share on other sites More sharing options...
Xnke Posted May 12, 2013 Author Share Posted May 12, 2013 Unfortunately, it's become a moot point; after getting the setup to work on the MAF sensor I soon found out I had zero control of the bypass valve. The ITB system doesn't generate enough manifold vacuum to pop the valve, and more than once today I had a scary problem...the throttles were blown open. That was a deal killer...no throttle control and NO power brakes. The manifold has been converted from 45mm ITB's to a single 65mm throttle, Final vacuum line placement will finish up tomorrow morning; and tomorrow afternoon I should have the manifold back on the car and a usable speed-density tune setup again. I will use the MAF for datalogging purposes, for now. Right before the throttles got blown open, I was pushing 8.8lbs of boost at 3000RPM and 80*F IAT. Mass flow was 157g/second. Quote Link to comment Share on other sites More sharing options...
Tony D Posted May 12, 2013 Share Posted May 12, 2013 Indeed if he plates closed it should pop the bypass. If you have a tight spring though.... And the bypass, do you mean on the SC itself? That's just pressure ratio relief when the single body before the SC closes and so you don't make a 5:1CR across the SC trying to pump -15psi to -3psi (6"HG or so) at idle...making r 450F+ SC discharge temps! Quote Link to comment Share on other sites More sharing options...
Xnke Posted May 12, 2013 Author Share Posted May 12, 2013 (edited) Yes, I mean the one integrated into the Eaton M62. It's the same setup Magnuson uses when blowing through the throttle plates; although they don't build kits to do that, they do sell the exact same valve for this exact same purpose, plumbed in exactly the same way that I did, with the instruction to do it that way. Same with Harrop; those two just resell the Eaton product. Kenne Bell also sells a very similar unit, along with a low-vaccum model of the same unit. It does work well, when it *works*. But 80kpa is not enough to open the valve...70kpa is though. I was getting valve flutter at idle, the valve would close on acceleration, and then flutter once cruising was sustained. Cruising MAP is right about 76kpa...which meant the valve was being buffeted open and closed rapidly, causing MAF signal instability. Converting to a vacuum-only setup cured the flutter, but caused an unsafe condition where the supercharger doesn't get bypassed if the throttle is open to a throttle angle producing a higher manifold pressure than 80-ish kpa. It is an interesting feeling though, when you're moving from acceleration to cruise and you "feel" the blow off as well as hear the supercharger unload... Edited May 12, 2013 by Xnke Quote Link to comment Share on other sites More sharing options...
Tony D Posted May 12, 2013 Share Posted May 12, 2013 So no "Blowoff" actually in the line between the two... The SC setup I got on the 240 (in post 71) used the (surprised me) same bypass valve as is on the current supercharged Stillen 370's. Bosch Unit, I would think that would be a more reliable way to quick-dump the pressure on drop-throttle and positively activate the supercharger bypass to stopp parasitic lag. Quote Link to comment Share on other sites More sharing options...
Xnke Posted May 12, 2013 Author Share Posted May 12, 2013 Problem is that even a large blowoff valve for a centrifugal compressor can't dump fast enough for the positive displacement compressors, according to most manufacturers. I have a Bosch blowoff valve here; the 1" in and out kind. I will figure a way to plumb it in if the Single-Throttle intake can't do it either. I am getting cut deep though...I really wanted the ITB manifold to work well. I did N/A... That and my 15.5" runner length is now 13.5". Again, second choice. It will still work well, but it isn't what I originally wanted. We'll see how it goes...I got time yesterday to machine the 0.280" thick lash pads I was able to buy from Nissan down to the 0.215" that I'll need to run the new Isky cam profile. Quote Link to comment Share on other sites More sharing options...
redzedturbo Posted May 13, 2013 Share Posted May 13, 2013 This sucks jake but at least you still get to run the cool double plenum anyways. Also still have boost and now we can at least tune the thing with out coal black plugs and a flame thrower exhaust. You gotta get to the show and 2 weeks to tune out the 45mm itb's was not going to happen in that time frame man. Quote Link to comment Share on other sites More sharing options...
Tony D Posted May 13, 2013 Share Posted May 13, 2013 (edited) You don't need the BOV to dump the capacity of the SC... You just need it for that quick dump to get your throttles from being blown open so you hit 70kpa and the normal SC Bypass can open up... I think the dynamics f the drop-throttle situation (positive displacement) is causing the issue. Dump the positive pressure overboard, giving the bypass internally to the SC time to react, and you keep your ITB'S... I want I say resize the effective size of the diaphragm actuator on the SC Internal Bypass so it works more reliably at a higher kPa, but since you confessed to having a 1" Bosch already laying around what do you have to lose by trying it and seeing if it helps the internal valve work better? Edited May 13, 2013 by Tony D Quote Link to comment Share on other sites More sharing options...
Xnke Posted May 14, 2013 Author Share Posted May 14, 2013 Well, now that the intake has been converted to the single-throttle intake (not that it couldn't be converted back...) it's been sidestepped for now. Back to speed-density tuning, and weird vacuum. Driving around today on the same runners, same plenum, but with at 65mm ford throttle body bolted to the front of the plenum, I'm cruising at 83-84kpa! WHAT THE HELL!? Even my old twin-50mm intake manifold cruised at 72-73kpa. Hell, the ITB'S cruised at 78kpa! There has got to be a vacuum leak somewhere. I'm still N/A at the moment, trying to get the S/C cam swapped over and broken in. Something is not right. That, and my 70mph vibration is getting worse...I think the trans is really starting to go now. Cam goes in tomarrow night, and transmission goes in as soon as possible. Quote Link to comment Share on other sites More sharing options...
Tony D Posted May 14, 2013 Share Posted May 14, 2013 Check that rear tranny mount well when underneath, that was where my thrumming vibratin was coming from, tail shaft was moving putting angularity in the card an joint...and vibration! Quote Link to comment Share on other sites More sharing options...
Xnke Posted May 16, 2013 Author Share Posted May 16, 2013 Cam swap complete; engine has been run in at 2000RPM for 20 minutes; although a cooling deficiency has arisen. Starting from cold, the engine was brought up to 2000RPM and the idle stop was set to hold the engine there. After 15 minutes, coolant temp was 210F degrees, and slowly climbing...by the end of the 20 minute run-in, coolant temp was 216F. I am running a 185* thermostat; from back when the engine would just barely come up to temperature with the 3-row copper radiator and a 160F thermostat. Now, with a thinner 2 row aluminum, I will move back to the 160F thermostat. Quote Link to comment Share on other sites More sharing options...
Xnke Posted May 17, 2013 Author Share Posted May 17, 2013 160F thermostat didn't cut it. It got up to 85F today; the engine was borderline too hot. Now I'm kicking myself for installing a radiator from a car with a similar displacement engine known for overheating... I am going to run a test with no thermostat or restrictor at all and see if I still overheat. Quote Link to comment Share on other sites More sharing options...
Tony D Posted May 17, 2013 Share Posted May 17, 2013 Standard, unglamorous four core copper & brass, man! Andy Flagg had a killer five-core five pass radiator built for dyno time... Also works well to cool his 10 second Cadillac Powered 240Z on the street when not needed for Bonneville car dyno runs. For the B'ville car, we run a standard MSA Three Core unit at the salt... Quote Link to comment Share on other sites More sharing options...
Xnke Posted May 18, 2013 Author Share Posted May 18, 2013 I would gladly run the stock radiator...but I will need to shove the engine back at least 1 5/8" to do so. Belt clearance, fan clearance, ect. More testing yielded a cylinder-to-water jacket leak. The radiator builds up to 20+PSI in under a minute from a cold start. Quote Link to comment Share on other sites More sharing options...
Tony D Posted May 18, 2013 Share Posted May 18, 2013 (edited) Detonation...bummer! What fan are you using? The early fans fit better than the 280ZX fans, and they are about that different. The engine bay photo I posted in 71 shows almost identical positioning with the stock three core MSA unit. The SC serpentine belt runs off the front of a secondary pulley about where the ARA York AC Compressor used to reside (fitting since that was the first sacrificial bracket used to mount the SC!) of course it's currently unintercooled.... Meaning fans in front can be a viable option. I reviewed those engine bay pics you posted I'm trying to picture why there is a clearance issue other than positioning of two smaller, relatively thick fans. I didn't see a shroud installed photo. Your pulley/drive is almost identically positioned as mine, and we both know that 160F thermostat and cooling mod to the head helps... But how to get a working, efficient fan to fit in that space.... Are you confident the two row can cool you when all is right? Copper and Brass is workable at just about any radiator shop, a couple of Corvette end tanks, you could have a multiple-pass (3 or 5) fabbed for under $400 which could be thin like you currently have but have much better heat rejection properties. With a three pass, that top pass left-to-right would be above your I/C so the most cooling would go on there...the next two incrementally less. There is always the possibility of a three way temperature control valve running "bypass to cooler" arrangement, which means all internal coolant bypasses could be plugged permanently giving 100% capacity to cooling of the engine. But plumbing a 25-30mm tube and valve placement would be a definite challenge!!! Edited May 18, 2013 by Tony D Quote Link to comment Share on other sites More sharing options...
Xnke Posted May 18, 2013 Author Share Posted May 18, 2013 (edited) The stock radiator kept the car quite cool, it's actually a copper 240Z-core-height 3-row unit. The two electric fans are only 2.20" thick from mounting face to the tit on the back of the fan motor; they're the slimmest fans I've found. I currently have 0.5" between the belt tensioner stud and the 10" electric auxiliary fan, and about 1" between the A/C compressor clutch and the 12" main fan. Nothing hits, even on a hard decel, and the 12/10" combo worked fine with the stock radiator. Stocker is 2.5" from core support to the fan shroud mounts, and I didn't run a shroud with the stocker, just had the fans pulled tight to the core. Core size is 24"x14"x2" thick. MkIII Supra aluminum unit is 1.875" from the core support to the fan shroud mounts; and the radiator has a flat aluminum shroud sealed to the back face, standing off the core 0.375". The fans are mounted to the shroud. Core is 25.25"x16.2"x1.25" thick. According to all the literature I can find...the supra radiator should handle this. I am wary of it still, but the BHG plus less than optimal airflow of having the A/C core and intercooler stacked in front of it, plus the gap between air dam and core support. The A/C core is ducted to the radiator; and the IC stands off the A/C core by 1.25". The core support is sealed up, but the seal plate between the air dam and core support is not finished...working on it tomorrow after making sure the BHG is really fixed. This radiator cooled the car fine with the IC and condenser core in place all the way up to the likely BHG event. I'm jumpy because of my timeframe...getting short! Had to take a step back and cool my jets so I didn't just rip it all apart and start over... Money is starting to get tight too. Need to be saving up to make the gas money to get there, but the car just keeps sucking it down. Still need gear lube, argon for the TIG, fuel for tuning, ect... Edited May 18, 2013 by Xnke Quote Link to comment Share on other sites More sharing options...
Tony D Posted May 18, 2013 Share Posted May 18, 2013 (edited) <p>Too Bad you didn't have a G-Nose...<br /> <br /> You could lay the AC Coil Down horizontal and use pancake fans to cool it separately.<br /> <br /> Not that I knew anybody that did that...<br /> <br /> <br /> You got the test down, decel is where everything gets ground up...a limit bracket on the back side of the motor mount works well to make sure it doesn't move and still keep rubber mounts. The ZX Isolators do it, but they're kinda mushy and let the engine move more than I like.<br /> <br /> Core sizing sounds about right for what I had. The 12 x 10 fan was exactly what I did, then found some reeally high-capacity 10's that I replaced them with. Staggered one up high, the other down lower for similar clearance issues on another car.<br /> <br /> I start sympathising with the Japanese Builders who just cut the damn radiator support out and tilted the whole arrangement forward to get clearance! My black car is about "this" close from having that done behind the G-Nose...</p> Edited May 18, 2013 by Tony D Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.