My name is Russell Posted June 3, 2009 Share Posted June 3, 2009 Can anyone recommend some good articles, books to read to learn about these things? Basically I'm noob as with all this stuff and want to learn how they all communicate between each other etc and what needs to be done to get my settup running. Iv got 100s of small questions in my head but cant find any layman explanations i.e what vacum pipes need to be connected to n from what for say the wastegate. and what size / type of wastegate do i require etc etc. Cheers in advance. Link to comment Share on other sites More sharing options...
Mr.Mk1 Posted June 4, 2009 Share Posted June 4, 2009 Chur. Im often wondering such things. eg. How to determine wastgate size and what happens if its too big? How do plumb-back re-circ systems work? Can you put B.O.V's on any part of the piping? Link to comment Share on other sites More sharing options...
My name is Russell Posted June 4, 2009 Author Share Posted June 4, 2009 Yeah same here i just want some simple black n white instructions that say what you need to do etc Might ch ch check out the library yo for one of them haynes tuners books because im well noob Link to comment Share on other sites More sharing options...
My name is Russell Posted June 4, 2009 Author Share Posted June 4, 2009 Ok perhaps i will just dump helpfull diagrams n info i find in here for refernce and fellow noobs like myself. EXTERNAL WASTEGATES Im guessing the wastegate will be slightly more responsive if you plumb it as to the 1st diagram, near the turbo. "the theoretical stuff....... 1. The wastegate size is relevant to how much horsepower you are targeting 2. If you want to run high boost, then a smaller wastegate is better than a larger wastegate. The idea being that in order to generate high boost you need most of the exhaust gas going through the turbine, not through the wastegate. 3. If you want to run low boost then a larger wastegate is better than a smaller wastegate. The idea being that in order to keep the boost low you need a lot of the exhaust gas going through the wastegate not through the turbine. But what is high boost? Well for the sake of this discussion I have settled on 1.2 to 1.4 bar (18 to 21 psi) as being the divider, thus 1. 2 bar and under is low and 1.4 bar and above is high. How did I arrive at this number? Well based on the results of the surveys, this seems to be the most common point where the wastegate sizes change from theory 2 to theory 3 (above). The next bit of theory is that it takes 1 lb per minute of airflow to make 11 bhp in a current generation 4 valve engine. This is a pretty well established piece of turbo sizing philosophy. But how do we relate this to wastegate sizing? Well referring to the results of the surveys, it seems a straight 1 to 1 relationship is not too far from the average, so 1 lb of airflow = 1 mm of wastegate diameter. OK R31 Nismoid, let's use your car as a discussion starter..... 300 rwkw = 480 bhp 480 bhp = 44 lbs of airflow = 44 mm wastegate Now if you want to run 20 psi, then that's statistically the right size wastegate. My experience indicates that to get 300 rwkw out of a GT30 you would need to run around 1.5 bar (22psi). So using the draft formula... 44 / 22 X 19 = 38 mm. So based on the 75% success rate of the formula in the samples so far, I would say a 38 mm wastegate would be the go. Hi Steve and Dr Drift, I try Steve's question first............ What I am trying to do with the formula is give a baseline, something to think about. A 75% fit type of thing. At the moment there seems to be a majority of guys wanting external wastegates who don't even know where to start. They have been told for big horsepower you need a big wastegate, which is not necessarily true. They have been told you can't have too big a wastegate, which is definitely not true. They have been told for high boost you need a big wastegate, which again is not necessarily true. In order to do this there is one main assumption, that the turbo is pretty much the optimium size for the target power and boost. If it is totally wrong then whether the wastegate is sized correctly or not is really irrelevant. The turbo / engine mismatch is gunna kill horsepower / response anyway. The other issue is exhaust flow rates through the wastegate, some manufacturers claim very different flow rates for the same size inlet / outlet / valve. Now I haven't tested every wastegate out there, but I have yet to see any difference in popoff valve type wastegates that I have tested. So for this discussion and the formula I have ignored the manufacturers claims. The Turbonetics flap style wastegate is an exception, they flow much better than the same size popoff valve on our flow bench. Ok moving on to the good Dr's question, "So if he's chasing more in the future and had to bear that in mind something like the turbosmart 45mm racegate or similar would be a good option?" Sorry, but more what? Boost or horsepower? It is possible to make more horsepower with less boost ie; with a turbo capable of more airflow. In that case the formula says you would need a larger wastegate. If you wanted more boost (and therefore more horsepower) the same size wastegate may well be OK. You can get to the stage with "more boost" when a smaller wastegate is needed. Interesting discussion??? Try this; More power = more exhaust flow More boost = more exhaust flow through the turbine More boost = maybe the same exhaust though the wastegate, thus same size wastegate Lots more boost = less exhaust flow through the wastegate, thus smaller wastegate Moving onto Steve's question......... More power = more exhaust flow Less boost = less exhaust flow through the turbine More power = more exhaust flow the wastegate, thus larger wastegate required Steve, try the formula on your car "40mm, 1.7bar, 309rwkw" 309 rwkw = 520 bhp = 47 mm 47 mm / 1.7 bar X 1.4 bar = 39 mm So the 40 mm wastegate looks OK. I suggest you have play with the numbers you are thinking about for your car, post them up and we can discus. KamikazeR33, it doesn't matter how many cylinders you have. The logic is that it takes X amount of air and fuel to get X amount of horsepower. So whether the engine has 4, 5, 6, 8, 10 or 12 cylinders to make 500 bhp is irrelevant. The only issue occurs if there is varying efficiency amongst the engines. Since I am limiting this formula to production, DOHC, 4 valve engines, I seen no real big problems in using the same calculations. BTW this is also why RPM is not considered. I need a bit more information on your "hypothetical" to really give a decent fact based answer. I would need to know usual stuff, the BHP, boost and wastegate sizes. In the interim I'll try and answer this one.... Quote: Also, about this "response" of a wastegate. Just say you are "coming on boost" very rapidly (as most larger, aftermarket turbos tend to), wouldn't you think that a wastegate that only needs to travel ~5mm to maintain the desired boost level (i.e. a large gate) as opposed to a smaller wastegate that would need to travel ~10mm to vent the same volume of gas would be able to do this faster, hence be more "responsive"? I concede the smaller one would be able to be more accurate in it's flow limiting, but then again wouldn't an "intelligent" boost controller be able to manipulate these regardless? I am not sure that the travel "distance" of a wastegate is really an issue. Remembering that a 50mm wastegate valve is going to weigh twice as much as a 35 mm one. So there is an inertia issue to be considered. I think that is really the crux of the problem. The diaphram has to move twice as much weight, in and out very rapidly. This has 2 undersirable effects incomparison to a smaller (more correctly) sized wastegate. Firstly the too large a wastegate has to open and close more often, as it has too little exhaust flow when closed and too much exhaust flow when open. This wears the diaphram, due to the requirement for more movements and more weight. Secondly all this opening and closing of the wastegate affects the amount of exhaust flow though the turbine, this leads to fluctuations in the boost control. eg; I have seen a relatively low powered engine, with a very large wastegate, move up and down 0.3 bar in its boost as the boost control circuit struggles to keep up with this open, closed, open, closed requirement. Hope that helps Credits to Sydneykid from skylinesaustralia.com for this" Link to comment Share on other sites More sharing options...
FLAWLES Posted June 4, 2009 Share Posted June 4, 2009 im new to this turbo thing too when running a waste gate do you have to run with a air regulator like in the diagrams that low n slow posted? thinking about getting a aftermarket exh mani and tubrew set up for the 1j, but waste gates are beyond me Link to comment Share on other sites More sharing options...
Mr.Mk1 Posted June 4, 2009 Share Posted June 4, 2009 Air regulator = Boost tap? Link to comment Share on other sites More sharing options...
Simon Posted June 4, 2009 Share Posted June 4, 2009 Air regulator = Boost tap? Yeh, Ill be watching this. Simple things like should a bov be closer to turbo or throttle butterfly? Link to comment Share on other sites More sharing options...
My name is Russell Posted June 4, 2009 Author Share Posted June 4, 2009 Air regulator = Boost tap? Was wondering that too ... haha were are all the experts Link to comment Share on other sites More sharing options...
My name is Russell Posted June 4, 2009 Author Share Posted June 4, 2009 Air regulator = Boost tap? Yeh, Ill be watching this. Simple things like should a bov be closer to turbo or throttle butterfly? From what iv read so far its better to be closer to the turbo for response but iv seen / shown diagrams of both. Link to comment Share on other sites More sharing options...
kpr Posted June 4, 2009 Share Posted June 4, 2009 turbo stuff is pretty easy. compared to n/a ive been playing with turbo stuff for awhile. i can say its alot easyer to just throw some parts together and have it work fairly good. unlike n/a. have seen some pretty horrible turbo setups work not bad. i didnt read all that stuff above, but heres my understanding on how wastegates etc work, things that will effect wastegate size, power, boost level. exhaust housing size. but generaly you can just bang your standard 38mm size wastegate on most smaller engine setups, and will work fine. only when your making big power. or on large engines you'l need to go bigger. will be running a 38mm gate on my ae85, which will be around 200kw at wheels. allsorts of was to raise boost. bleed valve is usually just an air leak in the line to the actuator or bottom port on an external gate. so it just drops the pressure in the line to the waste gate so it opens later. pretty unreliable unstable way of doing it but cheap. if going with a fixed boost level the best way to do it is to use a stronger spring in the external gate. you can do similar thing with actuators, either swap to a stronger actuator or can add an external spring to it. may look hori but works a hell of alot better than a bleed if you add pressure to the top side of an external gate it will stop the gate opening. thats what they are doing in those pictures, with the regulator, your basicly adding to the spring pressure. add a few psi to the top port of the gate and it will add onto the spring pressure, hello more boost. electronic controllers basicly do the same thing but a better job than the manual stuff. bov's most people run them before thottle. so flow doesnt have to go backwards. but at the end of the day it doesnt really matter too much. you can run without them but can get a bit hard on the turbo im stick of typing now, Link to comment Share on other sites More sharing options...
QCADTA Posted June 4, 2009 Share Posted June 4, 2009 what turbo are you going to run? if you run a rb25 one just use the internal, the actuator opens a flap next to your exhaust turbine wheel to let excess gases past. under your bonnet of ya escort have you got enough room for an external waste gate? dependin on your certifier you probably eont be able to run a screamer pipe (sound crap any way) and will have to plumb it back into your exhaust. when setting up your tubo make sure you clock it so the oil drain points straight down or else youll start blowin oil out the exhaust wheel, and if its ball bearing run a restrictor or a smaller feed, they dont like full engine oil pressure Link to comment Share on other sites More sharing options...
My name is Russell Posted June 4, 2009 Author Share Posted June 4, 2009 what turbo are you going to run? if you run a rb25 one just use the internal, the actuator opens a flap next to your exhaust turbine wheel to let excess gases past. under your bonnet of ya escort have you got enough room for an external waste gate? dependin on your certifier you probably eont be able to run a screamer pipe (sound crap any way) and will have to plumb it back into your exhaust. when setting up your tubo make sure you clock it so the oil drain points straight down or else youll start blowin oil out the exhaust wheel, and if its ball bearing run a restrictor or a smaller feed, they dont like full engine oil pressure Yup RB25. its had the internal wastegate flapper removed. He had the Wastgate of the back of the turbo he said. I wonder if it would be allot easier / cheaper to just buy one with an internal wastegate, i could get a turbo in slightly better condition then also. I was going to run the wastegate of the back of the turbo as he said he did, i can picture how it would work (not how you could make it), but no one seems to do it of the back of the turbo. is this because there is issues keeping the two separated then re joining them down the exhaust? Yup my oil return has been modified so it drops straight down, the the bando is half welded over to restrict flow. (done by the tuner/engine builder) Link to comment Share on other sites More sharing options...
Honda Ass Dragger Posted June 4, 2009 Share Posted June 4, 2009 For what you are doing internal gate FTW Most of the time externals are not nessicary and unless theya re plumbed back into the exhuast make a noise thats imo is fucking gay Link to comment Share on other sites More sharing options...
My name is Russell Posted June 4, 2009 Author Share Posted June 4, 2009 what is the advantage of an external wastegate? Link to comment Share on other sites More sharing options...
Simon Posted June 4, 2009 Share Posted June 4, 2009 ^ maybe cos aftermarket turbos come with no internal so you use an external? Plus you can easily have a screamer, where as its not so easy to make a screamer with an internal gate? I dont really know but cos most are noobs here might as well say something that someone else can correct... I reckon a gate plumbed back into a sweet exhaust sounds way better than screamer. Link to comment Share on other sites More sharing options...
Hemi Posted June 4, 2009 Share Posted June 4, 2009 some turbo's dont actully come with wastegates , annnnd sometimes the int wastegate cant let enough out .. although that would be very rare!. also this is just me thinking but i reckon the bov should be just before the throttleplate to get rid of the pressure wave that is the reason you have a bov for ..? i could be wrong though cos all the turbo stuff i work on dosnt have thorttle plates oh and plumbed back bov's stop your afm getting confused .. if it gets vented the afm says x air has gone through sweet . then you vent y air into atmosphere .. the comp still thinks it has that x air and provides z fuel metered for x air not y air . Link to comment Share on other sites More sharing options...
kpr Posted June 4, 2009 Share Posted June 4, 2009 as above, most internal gates will work sweet. some will become shit and cause boost issues when you wind up the boost. external gate will give better control. when running high boost. alot of the bigger turbos have no internal gate. anything bigger the t3 size usually doesn't running an external off the back off the turbo from the stock wastegate port is gonna restrict you to the internal gate hole size , unless hes die grinded the shit out of it. cant remember what the ex housing on a rb25 turbo looks like, but unless it has 2 separate outlets for ex wheel and wastegate. it wont work off back of turbo anyway. Link to comment Share on other sites More sharing options...
Hemi Posted June 4, 2009 Share Posted June 4, 2009 back of turbo anyway. i was about to say lol Link to comment Share on other sites More sharing options...
OSM Garage Posted June 4, 2009 Share Posted June 4, 2009 also this is just me thinking but i reckon the bov should be just before the throttleplate to get rid of the pressure wave that is the reason you have a bov for ..? Im not too sure of position of a BOV, but im sure its to prevent compressor surge. Vents the compressed air so it doesnt rush back to the turbo, and stall/damage the turbo. Shit, you could run 2 BOV if you wanted. 1 on each side of the intercooler. But that raises another question on if running 2 BOV is too much. External Wastegates do control boost levels more accurately and are adjustable via spring rates. I dont mind the "Vent to atmosphere" scream. Makes ya look! Link to comment Share on other sites More sharing options...
Hemi Posted June 4, 2009 Share Posted June 4, 2009 also this is just me thinking but i reckon the bov should be just before the throttleplate to get rid of the pressure wave that is the reason you have a bov for ..? Im not too sure of position of a BOV, but im sure its to prevent compressor surge. Vents the compressed air so it doesnt rush back to the turbo, and stall/damage the turbo. Shit, you could run 2 BOV if you wanted. 1 on each side of the intercooler. But that raises another question on if running 2 BOV is too much. External Wastegates do control boost levels more accurately and are adjustable via spring rates. I dont mind the "Vent to atmosphere" scream. Makes ya look! yup that what they are for not having one is a good way to split the shaft in half . and screamers need to die Link to comment Share on other sites More sharing options...
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