I know no one cares/wants to hear/wants to read, etc... but please look at my prices
Oh my god, another one of these? So Sorry in advance.
As I build my kit, I want to be sure I'm using my knowledge to my advantage, but I don't know anything. ;) If you see any prices I've estimated that are incorrect, please let me know. I drive a 95 miata, and I'm looking to make around 300whp and have room to grow up to 350+. The basics: used t3/t4e 50trim .48a/r (300) BEGI t3 manifold (389) BEGI 5bolt mild steel downpipe (375) Rubber Oil Supply/drain + fittings (50) Ebay intercooler kit (200) IC/pipes/couplers/tbolts Screen as filter to start (0) Total: 1550 EMS/Support: 95 PNP megasquirt (600?) clutch good to 250 wtq (400?) walbro 255 (100) Injectors (200-400) what is the largest injector the stock fuel lines can support? Total: 1500 Grand total: 3050 I have to have forgotten shit. I just know it. I have a wideband and will be tuning the car myself. I doubt I'll be driving the car w/out a laptop handy, so I think I can save some cash on monitoring gauges (MAP/coolant/oil/etc). |
Megasquirt pricing at diyautotune.com
Don't forget the IAT sensor kit. Easy answer on the injectors is RX7 550's. ~$100 + cleaning/testing. KGP can take care of you on the injector cleaning & fuel pump. You'll need an BOV & exhaust. Don't know your timeframe, but I'm running a group buy for Enthuza now. C |
Youre missing stuff. Pressure sender adapter, pcv valve, wideband o2.
I wouldnt use rubber for the oil feed and fittings and stuff wont run you 50, probably 100. |
kind of a small turbine.
and you're probably missing $1000 worth of stuff |
You don't really need the fuel pump providing your OE pump is healthy.
If you are looking to make 300whp, you might want to make sure your clutch is up to the challenge. I'd go beyond what you think you'll need. I think you need to allocate more money for the I/C setup. I think you need to allocate more money for the oil/water fittings and line. Screen as a filter? You are fucking nuts. A laptop is great for datalogging, not so good at warning you and giving you a quick look into the health of your setup. Boost/WBO2/Oil Temp/EGT I think are all essential gauges to have. I hate to be driving in anger while trying to have a laptop display my AFR or oil temp. Doing a 300whp Miata on a budget is going to be a challenge. Cheaping out on anything might cost you a lot in the future. 300whp is a tall order. One thing few people point out is how much DIY will nickle and dime you. A few bucks here and there will eventually add up. It is amazing all the little bits and pieces that are included with a kit, that you will have to source yourself. Good luck, I think you will need it. Jay |
Originally Posted by chriscar
(Post 239997)
Megasquirt pricing at diyautotune.com
Don't forget the IAT sensor kit. Easy answer on the injectors is RX7 550's. ~$100 + cleaning/testing. KGP can take care of you on the injector cleaning & fuel pump. You'll need an BOV & exhaust. Don't know your timeframe, but I'm running a group buy for Enthuza now. C |
Originally Posted by jayc72
(Post 240002)
You don't really need the fuel pump providing your OE pump is healthy.
If you are looking to make 300whp, you might want to make sure your clutch is up to the challenge. I'd go beyond what you think you'll need. I think you need to allocate more money for the I/C setup. I think you need to allocate more money for the oil/water fittings and line. Screen as a filter? You are fucking nuts. A laptop is great for datalogging, not so good at warning you and giving you a quick look into the health of your setup. Boost/WBO2/Oil Temp/EGT I think are all essential gauges to have. I hate to be driving in anger while trying to have a laptop display my AFR or oil temp. Doing a 300whp Miata on a budget is going to be a challenge. Cheaping out on anything might cost you a lot in the future. 300whp is a tall order. One thing few people point out is how much DIY will nickle and dime you. A few bucks here and there will eventually add up. It is amazing all the little bits and pieces that are included with a kit, that you will have to source yourself. Good luck, I think you will need it. Jay I'm trying to make this power on E85, can I safely assume the stock miata fuel pump is not up to the challenge of flowing 350whp worth of e85? I put a 250wtq clutch in my first post at 400 dollars, is that not sufficient? The ebay intercoolers are about 100 shipped and the beaded piping kits w/ tbolts are about 100 shipped, let's call the intercooler setup 250 dollars just for fun? How much do you think rubber oil lines will cost, if you noticed I'm not using a water cooled turbo. I've run w/ a screen on my turbo for years. Now what do you mean cheaping out can cost me a lot down the road? Like I popped an oil line and now there is a fire and my car burnt down? I'll play that risk, but what other risks have I put upon myself with my part selection? I recently built a 400whp Honda DIY with junkyard parts, so this isn't my first time around the block. (It's my second ;) ) I disagree with the bold type! |
Originally Posted by Saml01
(Post 239998)
Youre missing stuff. Pressure sender adapter, pcv valve, wideband o2.
I wouldnt use rubber for the oil feed and fittings and stuff wont run you 50, probably 100. I planned on just venting the crankcase to atmosphere from the valve cover, through a catch can. I have a wideband. |
Originally Posted by Ben
(Post 240001)
kind of a small turbine.
and you're probably missing $1000 worth of stuff |
I think your nuts for taking the risk of ingesting crap into your turbo. What's it cost to stick a K&N on the end of the turbo? $30-40? My engine/turbo is worth the investment. It's a retarded risk to take IMO.
As for E85 I must have missed that on your first post. No idea what size of FP you'll need. This is THE DIY place to be for Miata Turbos, how many guys here are running 300whp or over? Obviously there are few and it's not cheap nor simple. I don't know what it takes to get 400whp on a civic, bigger VTECK? Cheaping out is using rubber for oil lines. Again this comes down to risk vs cost. To me having a burst oil line NEXT to my turbo is worth a few $$$. As for being nickle and dimed ... at the end of your build you tally EVERYTHING and then we'll talk. Do you notice that few people here actually post what their entire build costs? Most don't want to know ... :) |
Originally Posted by opek
(Post 240009)
Well would you care to fill me in. ;) And what is wrong with the .48 exhaust housing? You certainly aren't referring to the wheel.
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Originally Posted by Ben
(Post 240027)
No, not really. There's enough info between this site flyinmiata.com and bellengineering.net for you to figure out what's missing.
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Ben, if a 1.6L can only produce about 14 lb/min out it's tailpipe, why use a turbine A/R that's max efficiency is at 21 lb/min.... a .48 T3 see max efficiency at 17 lb/min.
If the .63 T3 was the best choice, then you'd see more BEGi and FM kits using .86 housings on their T2 setups. here's a t3/t4 on a 1.8L: http://www.boostedmiata.com/dyno_day.../airbrush1.jpg guess what A/R turbine it's not using....... *cough*nota.63*cough* |
Originally Posted by opek
(Post 240031)
Why thanks. You are a nice fellow.
Ben's advice is good. |
He has a 1.8.
And wants to be spoon fed. And unless he produces hot nekkid pics of his wife, I suspect there will be bannage. |
even if i had a 1.8L i wouldn't go to a .63 myself. the only thing id be giving up is spoolup for possibly a tad more top-end. not worth it. again a 1.8L = 110 CI. 110CI * 7000RPM / 3456 / 14.47 = 15.4 lb/min....still under 17 lb/min.....
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hmm, maybe I'll just put a T04E compressor on my 48A/R turbine I already have.
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Originally Posted by Braineack
(Post 240037)
even if i had a 1.8L i wouldn't go to a .63 myself. the only thing id be giving up is spoolup for possibly a tad more top-end. not worth it. again a 1.8L = 110 CI. 110CI * 7000RPM / 3456 / 14.47 = 15.4 lb/min....still under 17 lb/min.....
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1 Attachment(s)
ok now you've gone and done it....
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Originally Posted by jayc72
(Post 240034)
You are making a mistake going down this road. Stop posting for a while and do some reading and get a feel for everyone here before you start into a pissing match on your 17th post.
Ben's advice is good. Your FAQ is great if you've never seen a car before, but I've put hundreds of hours into reading about how this stuff works. I helped write the FAQ over on a Honda site I post on. I'm asking for your experience, and for you to take your many years researching miatas and miata turbo systems and putting it out for me in just a couple of minutes. If someone tells me about their honda DIY turbo setup, I can answer address the fiscal reality as well as the overall potential of the setup. I don't think I am misunderstanding the overall potential of the setup I posted, but I don't have the five or six years reading on mazda forums to talk about the things unique to miatas. Why not have a FAQ that discusses such issues? Especially if they are so common that you wont even tell me about them. No one has written them down? Maybe we can turn this into a FAQ for people that have seen a car before. Hope that doesn't come off too mean. :) |
Originally Posted by Braineack
(Post 240053)
ok now you've gone and done it....
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you mean like the god damn fucking FAQ in my sig?
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Originally Posted by opek
(Post 240062)
:bowrofl::fawk:
what are you laughing at, the fact that you are now labeled in my mind as a complete moron? |
Originally Posted by Braineack
even if i had a 1.8L i wouldn't go to a .63 myself. the only thing id be giving up is spoolup for possibly a tad more top-end. not worth it. again a 1.8L = 110 CI. 110CI * 7000RPM / 3456 / 14.47 = 15.4 lb/min....still under 17 lb/min.....
7000rpm, for this sake it can stay constant. 3456 our wonderful constant We can assume temp is constant for this example, but 14.47 will not remain. In the conversion from volume/time to weight/time we need to account for density. I will not be pushing the limits of the .48 t3 turbine with a stage 3 wheel anytime soon without a nice big compressor attached to it pressurizing my intake stream. While I appreciate the fact that a 110CID motor theoretically flows 15lb/min @ 7000RPM at sea level at 120F, I think the amount of air I'll be flowing at 7000RPM is going to be mostly dependent on my compressor. |
^^^ Agreed. I was wondering if Brain's numbers account for the boost, as everything that goes in has to come out. Watching...
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14.47 is simply converting CFM to Lb./min
it doesn't matter how much airflow is coming into it. your engine can only displace so much airflow. The volume is always the same (97.7 C.I. per every cycle / VE), the poundage varies. |
Right, but in your math 14.7 represents a conversion from a volume/time to a weight/time using atmopsheric pressure at 120*F at sea level. My intake manifold will rarely see such conditions at 7000RPM.
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then apply the damned Ideal Gas Law and change the multiplier....is still doesn't change the fact that you can only displace so much air, regardless of how much boost. so while i may see 14 lb/min through my exhaust, you may see 12, who the fuck cares, what are you arguing again?
so to sum up: Shit ton of boost in the intake = 15 lb/min through the exhaust no boost in the intake = 15 lb/min through the exhaust |
Originally Posted by Braineack
(Post 240139)
then apply the damned Ideal Gas Law and change the multiplier....is still doesn't change the fact that you can only displace so much air, regardless of how much boost. so while i may see 14 lb/min through my exhaust, you may see 12, who the fuck cares, what are you arguing again?
so to sum up: Shit ton of boost in the intake = 15 lb/min through the exhaust no boost in the intake = 15 lb/min through the exhaust |
No, you are wrong. One cfm at sea level weighs more than one cfm at altitude. You are converting from volume/time to weight/time. density/volume = mass, mass * gravity = weight.
The miata motor at sea level with 120* air in the intake manifold, based on only it's CID, flows 15lb/min. Once you pressurize that air, it is heavier. You are flowing more dense air through the same volume over time, which results in more corrected CFM or more corrected lb/min. There is more air. Arguing about what?? I politely responded to your lame point, made using some fancy mathematics most people probably don't bother to understand, and you called me a moron. Nice. Your point is lame because the airflow of the stock motor at sea level in 120* air is not nearly as relevant to turbine selection as power goals or the compressor. IMO it's not worth a damn to say, "this turbine is OK because during these completely arbitrary conditions you will never encounter that aren't even related to making power (who puts a turbo on and runs atmospheric pressure in the intake manifold?) you will be flowing less air than the turbine is rated to." What's a t04e 50 trim flow compressor flow? 40lb/min? |
You displace the same VOLUME of air all the time. To change that, boost increases density so that the same volume has more pounds of air in it. You could move an infinite amount amount of air in lbs/min by increasing boost until something breaks.
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Just so we are clear my reply was directed at the Brain.
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Originally Posted by Ben
(Post 240001)
kind of a small turbine.
The .48 doesn't seem to breath for shit in the top end and I'm only at 214 whp. I may change my mind on this after the new downpipe and exhaust arrive. |
Just to throw in my extremely uneducated 2 cents...
For 300 whp don't the internals have to be beefed up? Rods and Pistons? Pissing match aside it's one thing to make 300+ whp, it's another to make it hold together. Am I wrong about this? |
Originally Posted by opek
(Post 240151)
IMO it's not worth a damn to say, "this turbine is OK because during these completely arbitrary conditions you will never encounter that aren't even related to making power (who puts a turbo on and runs atmospheric pressure in the intake manifold?) you will be flowing less air than the turbine is rated to."
What's a t04e 50 trim flow compressor flow? 40lb/min? the more pounds of air you move, the more power you will make. pounds = mass. not volume; the volume will always stay the same. you're not increase the displacement of the motor. you know damn well you can easily factor in your atmospheric conditions and temps, stop being a fucking douche. |
Originally Posted by Arkmage
(Post 240164)
The .48 doesn't seem to breath for shit in the top end and I'm only at 214 whp. I may change my mind on this after the new downpipe and exhaust arrive.
Originally Posted by cueball1
(Post 240186)
For 300 whp don't the internals have to be beefed up? Rods and Pistons? Pissing match aside it's one thing to make 300+ whp, it's another to make it hold together. Am I wrong about this?
yes, the rods wont hold up. We typically start to thinking about beefing them up at 200-220rwtq. |
Originally Posted by Braineack
(Post 240037)
even if i had a 1.8L i wouldn't go to a .63 myself. the only thing id be giving up is spoolup for possibly a tad more top-end. not worth it. again a 1.8L = 110 CI. 110CI * 7000RPM / 3456 / 14.47 = 15.4 lb/min....still under 17 lb/min.....
Originally Posted by Braineack
(Post 240139)
then apply the damned Ideal Gas Law and change the multiplier....is still doesn't change the fact that you can only displace so much air, regardless of how much boost. so while i may see 14 lb/min through my exhaust, you may see 12, who the fuck cares, what are you arguing again?
so to sum up: Shit ton of boost in the intake = 15 lb/min through the exhaust no boost in the intake = 15 lb/min through the exhaust |
Originally Posted by Braineack
(Post 240192)
more boost doesn't mean that you'll displace more air. It's a simple equation to determine a good size A/R turbine based on your displacement and airflow volume.
the more pounds of air you move, the more power you will make. pounds = mass. not volume; the volume will always stay the same. you're not increase the displacement of the motor. you know damn well you can easily factor in your atmospheric conditions and temps, stop being a fucking douche. Why do you keep saying pounds = mass and not volume, clearly I understand that. My first post addresses the relevancy of using a simple cfm -> lb/min conversion to a turbocharged motor. "You know damn well you can easily factor in your atmospheric conditions and temps, stop being a fucking douche." :bang: Ok, let me try again. I don't think I am explaining myself very well. The conversion you used factors in pressure and temperature, but the pressure you use in your calculations is 0lb. I don't care if the turbine can flow 0lb of boost, I care if it can flow 24lb of boost. An equation to determine ideal turbine size must take into account desired airflow. |
Originally Posted by patsmx5
(Post 240213)
Originally Posted by Braineak
Shit ton of boost in the intake = 15 lb/min through the exhaust
no boost in the intake = 15 lb/min through the exhaust lb/min is weight/min; and since we know what gravity is all about we know what is the mass of the air we are using. 15lb/min is 15lb/min always, but 300cfm can be 15lb/min or 30lb/min depending on it's density. A pressurized intake manifold does change the lb/min out of the tailpipe, and will also change the corrected CFM. (corrected for density). |
Can we talk about my turbo kit again?
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Keep in mind that you can get several different sized turbine wheels in the 48 housing. Most of the OE t3 housing are stage 1 48AR and can be cut "up" to a stage 2, or 3. I'm running an OE Mercedes 48AR with a stage 3 wheel now. The bigger wheel helps relieve some of the top end flow issues associated with the smaller housing.
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Yes we can. I'd like to know why E85? I'm pretty sure I read that there's less specific energy in E85 than regular gasoline... something like 20%... which means you're gonna need a lot more liquid. I don't think 550's are going to get you 300whp if you need 20%more fuel than gasoline. And 350whp seems like more.
You might be looking into some big RC's which are gonna cost $$$. Do a search for "mild build". There are several good threads out there that tell you how to build a motor to handle 300whp. Rods, pistons, rings, and some headwork are almost mandatory. OEM pistons are pretty strong if you keep the knock under control. Most guys see stock rods bend before the pistons melt during a knock event. Forged rods, tri-coated stock pistons, upgraded rings, and a 3angle valve job will see you safely able to push 300whp for a long time. For a goal of 350whp, you're definitely in the realm of forged low-compression Wiseco pistons. The going rate for a mild build, without forged pistons is $2500-$2800 with somebody else doing the work. If you're gonna go with forged pistons and get a little fancier with the port/polish and maybe an upgraded valvetrain, ARP studs, you're looking at $4k... but that gets you 400whp and some longevity. Try not to gauge your build around your Honda experience too much or you'll be disappointed in how much $$ it takes to make RELIABLE hp in these cars. The BP head is early 80's engineering and is the weak point in making power... it simply runs out of flow. Nothing about the Honda head will translate. You can make up a lot of ground in the head with somebody who is a magician with a Dremel... but even a $2k BP head won't flow what a stock Honda B series will. The clutch to hold 300+whp is gonna be $400+. The 5spd tranny is at it's limits at 300whp unless you drive like Grandma. The 6spd are known to handle 400whp. For that power, a 3.6 dif will get you back the use of 1st and 2nd, but a 4.30 or even 4.10 just means 1st=$$$straight to Tire Rack. Wheels and tires to put 300whp down safely are gonna run you $1k. A little suspension work might be in order... shocks and sways at a minimum... $500-$2000 depending on new/used/choice. I'd go with some brakelines and pads for safety. Rollbar? Tranny/Dif fluid=$75 3" Enthuza=$400 |
Originally Posted by Braineack
(Post 240196)
There's something wrong on your setup then, even with my extremely restrictive exhaust i never saw boost or torque drop.
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Originally Posted by samnavy
(Post 240283)
I'd like to know why E85?
The problem with E85 is that it has a high sensitivity rating, that is it's resistance to detonation decreases with load. |
Originally Posted by Arkmage
(Post 240295)
I'll find out soon enough. I suspect it could be either my 2.25" crush bent cat back and 2.25" cat, or a problem with the turbo XS bleeder type MBC. We'll see, when the enthuza and BEGi gear arrives.
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the equation is to measure to amount of airflow volume that your displacement assuming 100% VE can displace.
the formula is: Volume of Air (CFM) = RPM X Cubic Inches / (1728 x 2) The displacement of our 1.6L is 97.7 cu.in. We have a four stroke engine; the intake valve on a cylinder opens once every 2 revolutions of the engine. So, for every 2 revs the engine takes in 97.7 cu.in. of air.
Originally Posted by opek
(Post 240240)
Why do you keep saying pounds = mass and not volume, clearly I understand that. My first post addresses the relevancy of using a simple cfm -> lb/min conversion to a turbocharged motor.
example: http://www.turbobygarrett.com/turbob..._2_turbo_e.gif
Originally Posted by opek
(Post 240240)
Ok, let me try again. I don't think I am explaining myself very well. The conversion you used factors in pressure and temperature, but the pressure you use in your calculations is 0lb. I don't care if the turbine can flow 0lb of boost, I care if it can flow 24lb of boost. An equation to determine ideal turbine size must take into account desired airflow.
If you wanted to take those factors into account to get a closer idea of the exact volume, then you'd apply the Ideal Gas Law to the CFM you first calulated. The Ideal Gas Law is: PV = nRT Where P is the absolute pressure, V is the volume, n is related to the number of air molecules, which is an indication of the mass (or pounds) of air, R is a constant number, and T is the absolute temperature (460 + intake temps) . To get pounds of air: n (lbs/min) = P (psia) x V (CFM) x 29 / (10.73 x T) To get the volume of air: V (CFM) = n(lbs/min) x 10.73 x T / 29 x P (psia)) To take is a step further, since the actual amount of air that flows into the cylinder is somewhat less than ideal. We factor in volumetric efficiency. 15psi in your intake manifold doesn't mean 15psi filled into the chamber before ignition. So we determined that we can flow 198 CFM through the engine....but alas maybe the engine also sees 90% VE. so therefore, the flow through the engine may only be (198 x .9) 178 CFM.
Originally Posted by opek
(Post 240240)
I guess I just don't understand how this equation tells us anything about the turbine to suit my goals vs. someone who is looking for 200whp. Right, volume and weight are different. The more air you move, the more power you make; MAP is a function of the turbine as much as it is of the exhaust, head, cams, and manifold itself.
How does it relate to your turbine? because your fucking exhaust spins the damned turbine, which determines the speed of your compressor wheel. If you look at the turbine map, you see two axises. PR and Flow. You will always flow 198 CFM at 7000RPM, and plot it against the PR. So, it's import to know you have a turbine that working within it's efficiency so it spins faster and spools quicker without being too large or too small. Pick one too small and you'll choke it up and you'll suffer from boost drop and increased temps. Too large and it may not spool how you want it, but it will make more power once it does spool. |
Negatory. Why do you think you need a t4 turbine wheel and a large t4 housing to make 800whp on a 1.8liter honda motor?
let me edit a hint in for you: It's not because the 110CID honda motor is flowing 15lb/min at 7000rpm. |
2 Attachment(s)
this is why; larger a/rs make more power & you need a larger turbine wheel exducer diameter to drive a compressor at various air flow rates.
again, approximately the same volume of air is drawn in as the piston moves down regardless of engine speed, load, or intake manifold pressure. The volume is the cylinder displacement. However, the density of the air that is drawn in varies quite a bit. |
Right, and your dumb ass said that regardless of how much air the compressor is flowing into the engine, the exhaust pipe sees 15 lb/min. That is fucking so incorrect, I don't konw how you haven't apologized for saying it. You go to a t4 turbine wheel and housing not because a t3/t4 can't spool, but because no t3 wheel/housing combo is going to efficiently flow the 80lb/min the compressor is sending into the motor.
Because MAP depends on the turbine and the compressor, you can't just talk about one side of it. |
Originally Posted by Braineack
(Post 240139)
then apply the damned Ideal Gas Law and change the multiplier....is still doesn't change the fact that you can only displace so much air, regardless of how much boost. so while i may see 14 lb/min through my exhaust, you may see 12, who the fuck cares, what are you arguing again?
so to sum up: Shit ton of boost in the intake = 15 lb/min through the exhaust no boost in the intake = 15 lb/min through the exhaust |
one here's one less.
turbos don't increase your displacement. they may increase your VE, not your displacement. |
aww come on Scott. I like this guy.
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15psi in the IM means we completely fill the cylinder up with 15psi of boost and shoots straight into the exhaust during overlap....Hell, boost shoots out of the exhaust, duh. We drive the car on boost, the boost pushes the pistons down (creating torque) and spins the turbo at the same time.
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The guy had a point scott, I hope you didn't ban him for that. I still think he's right to, and your comments about flow earlier were wrong. You could admit you were wrong instead of draging on about "displacement", volume, and all that. I'm still hung up on how you think the same poundage goes through the exhaust irrelevant of what goes in the intake. I'm pretty sure that poundage that goes in tries to expand back when it comes out, but builds up pressure because of the restriction (turbine) in its way.
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Why was this guy banned again...?
Booo |
im not wrong. opek had no points other than i was wrong. explain to me why im wrong.
DISPLACEMENT = VOLUME MAP = PRESSURE PRESSURE :ne: VOLUME I only converted engine CFM to lb/min since the garrett turbine flow maps are in lb/min. still flow. the temp and pressure of the air must be know to correctly convert this. however it's the density ratio, not the pressure ratio you use for the conversion....so again, boost pressure does not factor in. |
Originally Posted by Braineack
(Post 240564)
im not wrong. opek had no points other than i was wrong. explain to me why im wrong.
DISPLACEMENT = VOLUME MAP = PRESSURE PRESSURE :ne: VOLUME Mass != volume, right. That is why your point in this thread is moot, because you are not considering dynamic pressure in the intake manifold. My point is that you need to consider desired airflow (or power) to decide on a turbine. The turbine is more concerned with being able to flow the air the compressor pumps, rather than the air a naturally aspirated 1.8l is flowing. Of course I'm right, braineack said 1 bar absolute pressure in the intake manifold produces the same amount of exhaust flow (mass/time) as 2 bar aboslute pressure in the intake manifold. rofl.:bowrofl::bowrofl::bowrofl::jerkit::noob: And he also called me a complete moron, after he used a bunch of math he doesn't quite understand. :eek5: |
this is the part where it all gets messy,
every one stay tuned, brain and opek round 2 |
next time ill ask Garrett to post their turbine air flow rates in cfm versus lb/min.
I don't need to factor in the pressure ratio in the intake manifold. only the density ratio of the air outside the car. the compressor compresses air to fill a certain volume in the intake. the pistons further compress this air with fuel, and displace a certain amount of volume, this exhaust spins the turbine. |
But you didn't account for that! holy shit man, just say "I'm sorry I was wrong."
You still haven't responded to my point, and keep saying I have none. You need to consider power or flow goals to choose a turbine, not the flow of a naturally aspirated motor at sea level. And just to be an asshole, think about the dynamics of the system. What determines airflow? How we measure airflow may be a better question, speed/density or mass air flow. What determines density? Is it related to MAP? Directly related? Density is a function of the turbine and the compressor, and the head and exhaust and intake manifold and cams and etc. Your math assumes the density of the air in the motor is equal to 1 bar at 120*F. That's absurd, we are concerned with a dynamic system that will be flowing 30+lb/min into the motor and the density is going to be dependent on the turbine. For that reason we must focus on turbine flow with relation to desired power output. The Pressure Ratio that you are referring to is a way to describe the efficiency of the compressor, but you used sea level and 120* F as a measure of the air IN THE INTAKE MANIFOLD. No one is concerned with the pressure ratio in the intake manifold. Ratio with respect to what? Ambient air? Exhaust manifold? Cylinder at x crank angle and y cam angle? Come on, man. |
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