futuretgper Posted April 9, 2006 Report Share Posted April 9, 2006 why dont turboed cars make boost when they are not under load!??! thanks i tried to find some enlightenment from google searches but couldn't find anything!! Quote Link to comment Share on other sites More sharing options...
Psych0matt Posted April 9, 2006 Report Share Posted April 9, 2006 from what i understand, the turbo isnt spooled up yet (spinning fast enough) to make any noticeable boost, and under more load, it spins fast enough to force the air in, creating boost (i could be totally wrong, but thats what i understand) Quote Link to comment Share on other sites More sharing options...
z284pwr Posted April 9, 2006 Report Share Posted April 9, 2006 from what i understand, the turbo isnt spooled up yet (spinning fast enough) to make any noticeable boost, and under more load, it spins fast enough to force the air in, creating boost (i could be totally wrong, but thats what i understand) Winner Winner chicken dinner Higher exhaust temperatures and exhaust flow will spin the turbine/compressor faster, which will flow more air eventually pressurizing the intake system. If the engine outflows the turbo, it won't pressurize it, just get the flow. This is why automatics are prefered with turbos for drag racing. You can power brake the car, putting a load/exhaust heat/exhaust flow on the turbo, spooling it up, so when you launch, you have instant powah!!!!! Quote Link to comment Share on other sites More sharing options...
Psych0matt Posted April 9, 2006 Report Share Posted April 9, 2006 Woohoo, I sound like I know something about something I have no experience with!!!! Quote Link to comment Share on other sites More sharing options...
futuretgper Posted April 9, 2006 Author Report Share Posted April 9, 2006 psycho...haha...i new they didn't make boost when not under load but i needed an explaination as to why......z284 thanks!! that makes sense i didn't even think about the tempature of the exhaust! Quote Link to comment Share on other sites More sharing options...
z284pwr Posted April 9, 2006 Report Share Posted April 9, 2006 psycho...haha...i new they didn't make boost when not under load but i needed an explaination as to why......z284 thanks!! that makes sense i didn't even think about the tempature of the exhaust! If you ever have an EGT gauge hooked up pre turbo you will notice it more....When I had one in our Beretta before the TGP with that engine, it has a "turbo" spec cam and DAMN it has some high EGTs Quote Link to comment Share on other sites More sharing options...
joberlee Posted April 10, 2006 Report Share Posted April 10, 2006 i'm just gonna go away now. All i'm trying to say is that if you take temperature out of the equation, you and look at just the flow caracteristics of a turbo, you could make of spool up with any temperature air. I underdstand that air expands when it heats, making it less dense, and this would increase volume of air through the turbo. However, if you look at some turbo designs, such as the twin turbo rx7, they reduce the size of the pipe and change the angle of the turbine blades to spool them up almost at idle. Oh, and does anyone know what rpm a turno "idles" at? btw: what happened to email notification of replies? this new format sucks Quote Link to comment Share on other sites More sharing options...
z284pwr Posted April 10, 2006 Report Share Posted April 10, 2006 um.. I really don't want to get into this arguement again, but the temperature has nothing to do with the turbo spooling up. It's all flow. When the throttle is closed it opens the waste gate or the blow off Valve, or both, to reduce the pressure. Otherwise the turbo would tear itself apart from the pressure building up with no where to go. The EGT increase is a by-product of the engine flowing more air through it, it does not increase boost. Umm, no, just no.... Throttle being closed has nothing to do with wastegate being opened or the BOV.. Wastegate opens after the intake tract has been pressurized to the spring pressure of the wastegate, then it opens to bleed off excess exhaust to prevent from overboosting. At idle the turbo wheels barely spin enough to do anything there is no way it would pressurize anything at idle... The BOV only opens when the throttle blade is closed and their is a pressue differential between pre and post TB. It bleeds off the excess boost before it reachs the closed TB blade so it doesn't rush back into the compressor. Quote Link to comment Share on other sites More sharing options...
futuretgper Posted April 10, 2006 Author Report Share Posted April 10, 2006 joberlee if youve ever read the acclaimed and highly informative Maximum Boost by Corky Bell you will know that you are not right and you do have nothing to argue that is why you won't "argue the point"......if the exhaust gas is hotter it contains more energy (if youve taked high school chemistry, you know that hot gases expand greatly) and therefore the gasses can do more work in a shorter amount of time than a cooler gas! so hotter air=more energy=faster spool up i would like to hear you reasoning though! also there is probably a small but noticable difference in you peak possible boost output! imagine how much slower and cooler the exhuast gases get as they travel past every extra square inch of the inside of the exhuast piping! i would imgaine that there is noticable difference in response and peak performance between an underhood mounted turbo setup and ones like the STS systems that are mounted near the rear axle! Quote Link to comment Share on other sites More sharing options...
TGPilot Posted April 10, 2006 Report Share Posted April 10, 2006 This is going to get ugly fast! Quote Link to comment Share on other sites More sharing options...
joberlee Posted April 11, 2006 Report Share Posted April 11, 2006 edit, see above Quote Link to comment Share on other sites More sharing options...
futuretgper Posted April 11, 2006 Author Report Share Posted April 11, 2006 what a cop-out.......we cant have a discussion because it might "get ugly" im fine with ugly! its just the internet! and we are debating relevant material.........what the fuck are we here for if we cant have constructive arguements! if you know something i don't, don't spare my feelings just inform me where im wrong and show me the logic you used to obtain your conclusion and i will bow down and/or discuss further!! no pussyfooting Quote Link to comment Share on other sites More sharing options...
joberlee Posted April 11, 2006 Report Share Posted April 11, 2006 All i am trying to get across is that it is how the air flows and the volume of air, not temperature, that make a turbo work. Temp must be figured in when calculating the air volume due the expansion factor, but it is not a necessary part of the equation. That is why you can make a rear mount turbo setup that works. If you speed up the air by making the tube smaller just before the turbine you can make a turbo spool so fast that there is no noticable lag. This is what subaru figured out years ago. If you drive one of there newer turbo cars there is NO lag. You push down the gas and there is just a steady push, not a light push and then a slam. You will see exactly what I am talking about if you study a mazda twin turbo setup from the 93-95 RX7. They used two turbos in one housing, they have very different turbine and housing designs so while they are the same size they spool completely differently. Quote Link to comment Share on other sites More sharing options...
Jeff M Posted April 11, 2006 Report Share Posted April 11, 2006 All i am trying to get across is that it is how the air flows and the volume of air, not temperature, that make a turbo work. Temp must be figured in when calculating the air volume due the expansion factor, but it is not a necessary part of the equation. That is why you can make a rear mount turbo setup that works. If you speed up the air by making the tube smaller just before the turbine you can make a turbo spool so fast that there is no noticable lag. This is what subaru figured out years ago. If you drive one of there newer turbo cars there is NO lag. You push down the gas and there is just a steady push, not a light push and then a slam. You will see exactly what I am talking about if you study a mazda twin turbo setup from the 93-95 RX7. They used two turbos in one housing, they have very different turbine and housing designs so while they are the same size they spool completely differently. That's better Yes, talk, debate and such all you want to learn on here but anyone calling someone names with the intentions of insulting them and swearing is not learning, that will only offend and piss people off, I don't care if some people are not offended by this, others are including myself and most people I know, so its not the best way to talk over things!! Find other ways to stress your point other than insults and swearing, that's pretty easy right?! Jeff M Quote Link to comment Share on other sites More sharing options...
joberlee Posted April 12, 2006 Report Share Posted April 12, 2006 Good to hear from you Jeff. A friend of mine tried to argue that a turbo car would always have lag. He argued that it was not possible to eliminate lag because you need the heat from the engine/exhaust to spool up the turbo. He knows just enough about anything automotive to be really really dangerous to any car he works on. For example, he raised to compression ratio on his 3000 gt vr4 (that still doesn't run 5 years later) by having the heads and block (on a perfect condition j spec motor) machined with a cross hatch pattern to eliminate the head gaskets. If he ever does get the damn thing to run again he's gonna hit boost the first time and blow something. So, does anyone else know what i'm talking about with turbo design? And where the hell are the email notifications? Joe Quote Link to comment Share on other sites More sharing options...
futuretgper Posted April 12, 2006 Author Report Share Posted April 12, 2006 your point about decreasing exhuast diameter is valid for boost response.....but it only hinders the top-end performance by cuasing a ton of back pressure! yes the remote turbos work but not as efficienty as one located near the hotter gasses that contain alot more energy! joberlee can you explain why a turbo car doesn't make boost in neutral!?!? the only answer i got was that load cuases hotter exhuast which spools the turbo more than when just reving does! this does seem valid..........if temperature change is not the x factor what is??? any turbo car does have lag......just not always noticable........ive never heard of a car that was in boost at idle! and you surely cannot argue that the instant you hit the gas your hitting boost.......my cuzin has an 05 subaru 2.5gt turbo......its top o line and it has lag! a steady russ is still lag it could be in boost very early but ramp linearly till peak but until peak its still lag...so you get smooth rush of power up till peak! not like an NA car that you stab the gas and instantly get spanked from behind! Temp must be figured in when calculating the air volume due the expansion factor, but it is not a necessary part of the equation i find that contradictory. first you say you must, then you say its not necessary...maby you could elaborate. you must always factor temperature when dealing in gases...you calculate the volume of gas by by taking into account temps...but this volume isn't constant as it travels away from the egine....once the gases begin to cool the volume also goes down...just like an intercooler! so you will have less volume and less velocity = less flow (Vol x Vel if both or one go down, in our case both go down, flow must also go down)! so flow is the final answer but temperature and the distance the exhuast must travel effects its greatly! is my logic flawed? is there something im not seeing? oh i see that you revised your first post!! you totaly took the wind out of the whole thing ahaha!! i agree with you revised statements! and yes i know of the rx7 setup.....its sequetial twin turbo.......one smaller resposive turbo spools the larger turbo for a good low end and better high end! with todays turbos this isn't really nessary and if you read enough you will see that the majority of fast rx7s are switching over to single turbo.....becuse they spool almost as fast and can make more power on the top end (less exhuast restricion associated sequential setups and the same applies for reduced exhuast diameter preturbo! as this also hinder the flow you basing you arguement upon!) let just say there are no competative proffesionals running turbos mounted in the rear of the car (unless thats where the engine is) i would tend to follow the leading edge of hi-perf turbo cars! and there is alot of information to back up their cases for using underhood setups! Quote Link to comment Share on other sites More sharing options...
Garrett Powered Posted April 12, 2006 Report Share Posted April 12, 2006 You JErk! you made all the ricers and f-body wannabes cry Quote Link to comment Share on other sites More sharing options...
TGPilot Posted April 12, 2006 Report Share Posted April 12, 2006 Ok guys...think about what some of you are saying. Smaller pipes before the turbine makes lag less? How? It is impossible to make boost in neutral? Hotter exhaust gasses are better/worse for making boost? You need hot exhaust to make boost? When you make statements like this you need to explain your statement. Are we talking on an LG5 or ALL turbo applications no matter make, model, year, head design, exhaust design, turbo location, turbo size, how many compressor wheels and if they are sequential, ambient temp, etc. There are TONS of factors when applying a turbo that will help or hinder it's ability to work efficiently. The discussion I see is EXTREMELY VAGUE in it's arguement. Not trying to sound like a dick...but reading one book does not make an expert in any field. Until you put what you learned into real world application and test...you have no true idea what will happen. Anyone ever done a port job on intake and heads and LOST boost to a point where a larger turbo was so in-efficient that you had knock? Or opened an exhaust system inside diameter to a point where the car would choke itself out and die as soon as you touched the throttle? Does Corky talk about any of that? I have not read the book but have ordered it to enlighten myself. Quote Link to comment Share on other sites More sharing options...
futuretgper Posted April 12, 2006 Author Report Share Posted April 12, 2006 Smaller pipes before the turbine makes lag less? How? tgpilot he said that smaller diamter piping increases velocity of gases...which may be true, but your right to question it, i don't think i could be anywhere near sure of this assumption! if you read my above statement i said the same applies for reduced exhuast diameter preturbo! as this also hinders the flow your basing your arguement upon!) It is impossible to make boost in neutral thas what ive been told from others on here (and other places) Hotter exhaust gasses are better/worse for making boost? nobody said it was worse.....only better which from my understanding is true (and i explained my sources and logic specificaly on this point, no vagueness) You need hot exhaust to make boost? thats an explaination that was thrown in to answer my original question as to why we don't get boost in neutral (or any manual turbo car with cllutch depressed) it is unconfirmed and still open to further explaination.....if you do know of a different reason why we make boost only when the engine is under load....out with it! (i honestly don't know if thats right but right now its the only thing anyone has come up with) The discussion I see is EXTREMELY VAGUE in it's arguement yeah the orignal question was pretty fundamental and the topic being discussed is very universal so particulars are unneeded. i thought the explainations behind my point of vew were direct and certainly not vague(imo) you could come up with some deatails to input on either side of the debate if you want! don't just be a sideliner and downplay the substance.....join in and come up with some new info for us to chew on if the discussion isn't to your satisfaction! Quote Link to comment Share on other sites More sharing options...
Guest TurboSedan Posted April 12, 2006 Report Share Posted April 12, 2006 lol Quote Link to comment Share on other sites More sharing options...
TGPilot Posted April 12, 2006 Report Share Posted April 12, 2006 Alright...I am not going to answer line by line like you...but I will answer what I know from being around turbos and turbo applications for close to 20 years. I am NOT an expert...but basing my answers on what I have seen in the real world. Physics and real world often conflict! I am going to ask questions to answer questions. Get's the brain juices flowing. Look at what you own as an example. Ok...to reduce the pipe diameter pre turbine to increase velocity. What about increased backpressure in the cylinder? An LG5 platform as an example...have you looked at the size difference where the gases enter the turbine in comparison to the pipe diameter leaving the head through to the cross-over? Why does the LG5 have one of the worst backpressure ratios of most factory produced turbo cars? Why does the LG5 with stock turbo spool at such a low RPM compared to loss of flow at high RPM? What is the IDEAL backpressure ratio for a turbo application? Boost in neutral. You can build boost in neutral with some assistance. You have heard of a two step right? How does a two step work? Back to a question that was asked but not really answered from what I saw. What MAKES BOOST? The mere flow of exhaust gases will turn the turbine. When does resistance to flow take effect? What is a BTU? Why does a BTU effect flow? Other than under hood heat control...why is header wrap or ceramic coating (keeping heat in the pipe as long as possible) important? Why does that then tie into the BTU again? I can sit here and write you an entire explaination of my qestions...but I am curious to know if Corky answered any of those questions for you. I need to sit down and read the book to see what I have missed over the years and what I have seen if they are common to him. Very possible that what I have seen over the years has reasonings that I could not answer for myself. Quote Link to comment Share on other sites More sharing options...
joberlee Posted April 12, 2006 Report Share Posted April 12, 2006 you're right, i worded that one statement incorrectly. Temperature must be figured in when calculating the volume, but, if you have the same volume of air moving through a pipe it doesn't matter what the temperature of the air is. All that matters is the volume. Turbo engines will make boost in nuetral. It is possible, it can and does happen. Unless you have a computer control of any sort, then they program it not to do that in order to save wear on the engine and turbo. I had a 79' Riviera Type S which had a 3.8 v6 turbo 4 barrel carb and an automatic trans. That car would make boost in park nuetral reverse, whatever. (made for really fun reverse donuts in the snow ) Ever notice that most turbo cars won't make boost in reverse? They come up to zero, but won't go into boost. This is all in the computer control. damn computers Quote Link to comment Share on other sites More sharing options...
TGPilot Posted April 12, 2006 Report Share Posted April 12, 2006 if you have the same volume of air moving through a pipe it doesn't matter what the temperature of the air is. All that matters is the volume. But which works more efficiently to produce energy/power...hot or cold? Again...what is a BTU and how does it effect tuning an engine with a turbo? This thread should be renamed... Turbo Q (question)...LONG, Detailed, Questioned one! Quote Link to comment Share on other sites More sharing options...
futuretgper Posted April 13, 2006 Author Report Share Posted April 13, 2006 tgpilot enough questions......if you have something to help out feel free but i don't think what your doing is constructive.......the things you mention like BTU's aren't even relevant.....its a british thermal unit...but it isn't necessary to know what that is to discuss the topic.... you don't know the answer to the first question and you have nothing new to add to the discussion...what point are you trying to make by posting! your using "questions" as a crutch becuase either A: you don't have anything with substance to contribute or B: your too lazy to put in writing what your thinking.....either way your no help so don't play the games....so far you responses have been utterly pointless....it sounds like you haven't even been reading what has been written . example: But which works more efficiently to produce energy/power...hot or cold? ive given my reasons for hotter gasses being more efficient in the previous posts....why would you pose this question again!?! either agree or disagree and state why don't just ask it again. this is all we can come up with??!! still no direct proof or disproof of the hotter exhuast gasses being responsible for being able to create boost on the line!! but its the only posed idea that we have and it seems plausible and highly likely!! even in a manual car with a manual boost controler (ruling out computer controled boost) you don't make boost in neutral! so what is the X factor if not the extra heat!??! Quote Link to comment Share on other sites More sharing options...
joberlee Posted April 13, 2006 Report Share Posted April 13, 2006 I know for a fact that my 79 riviera turbo would register boost in park, reverse, and neutral as well as the forward gears. That car had only mechanical control over the turbo. The turbo bolted directly to the intake and had very short path from the exhaust ports to the inlet. However, it had a HUGE turbo on it and had horrible lag, unless you knew how to prespool it. Put it in nuetral, and kind of feather the gas until the boost lights start to flicker on, then let off the gas for a second, drop it in gear and punch it. Still had a little lag, but then the 4 barrel would kick in and all hell would break loose. The car made boost in neutral. Quote Link to comment Share on other sites More sharing options...
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