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    Turbocharging FAQ By BOOSTEDSL2

    1. what is involved in a turbo set up? money

    2. what is the ideal turbo for a 1.9 DOHC? t3 super 60 for low boost, 50 trim t3/t4 or bigger for high boost

    3. what would be needed to make it a very reliable car but still have an ample amount of power on tap? about $4000 for low boost and $9000 for high boost

    4. how much would it cost to get a custom turbo manifold made? $250 to $750

    5. does anyone make a manifold for a saturn? titan, sms, me and a couple other people. if you find a twistec manifold don't buy it, study it. you can make a twistec manifold for under $150.

    6. would it be better to have an intercooler or not? intercoolers can cool the intake about 100 degrees. this makes more power, is safer, looks cool, allows you to run more boost and is more expensive.

    7. about what compression should the car be at to run boost safely? stock is fine for low boost, however it might be a better choice to go with 8.5:1 or a little lower for high boost. your much safer with lower compression.

    8. what exactly does a blow off valve do? it relieves pressure in the charge pipe that is built up after the throttle plate closes. it opens when its diaphram see vacume, aka vacume line from the intake. if you don't have one, boost levels can become high enough to spin the turbo the oposite way. this is called compressor surge and is a good way to toast a turbo.

    9. is there any way i could keep my AC if i threw a turbo under the hood? yes there is, but you have to ask manifold makers to make you one. the twistec style works too. just don't support twistec, they've bent a lot of people over in the past.

    10. what are the differences between the types of intercoolers? bar and plate is the best, if you can afford it buy one. if your trying be "cost effective" you might want to look at a used intercooler on ebay or a used intercooler off of a starion.

    11. would it be better to have a smaller turbo or a bigger one? bigger ones let you run more boost! seriously though, if you run a bigger turbo on small amounts of boost you can damage the seals because its not made to operate in that range of boost. the worst thing that can happen is that it will leak oil and you might need a rebuild a littler sooner. if you know your not going to upgrade, go with a smaller turbo.


    below are some compressor maps of turbos commonly used in our community.

    GT turbos!

    microsoft excel tool for matching compressors for an engine: ... -Tool.aspx

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  • #2
    Big turbos and me : boostedsl2

    1) big turbo is really efficent on lots of boost. now these you would not want to run at low boost, however when i'm refering to low boost, i'm talking about single digit boost amounts. these big boys are not made for high boost for a couple of reasons. first off, most "big" turbos we run have a smaller better half which usually is somwhere in the neighborhood of a t3. now because the turbine side is usually not matched to the big turbo, this increases shaft speed, which will ultimatly get the big compressor into the inefficency range faster.

    big turbos don't like to spin fast, so our fast spinning turbines don't help. this makes it easyer to run a big compressor, however its not what it was intentially designed for.

    you can get a huge turbo that at 10 psi will flow more then a peak flow rating on a t3 or small t3/t4. this is good! more air = more power.

    2) lower boost levels = increase longevity of our motors. less boost is less stress. while it would be nice to run 30psi, it is just not needed and there are way more things to go wrong on that amount of boost. everything is harder on the motor with those levels of boost.

    why not run lower boost and make the same power! there is usually more lag, however thats good.

    3) lag is good! why? traction thats why. big turbos are big and mean, but only on the top. i burn out at 6000 rpm at the top of third. this is cool and everything, but more importantly, it gives me that extra traction down low at lower speeds. our cars have a b!tch of a time keeping traction for many reasons and this is one way to aid that.

    spool is not everything. i don't want to give 10% throttle and make 30 psi. i just don't. with higher boost levels, you need more fuel. the more your in boost, the more fuel burned, which ultimatly means your running the car rich all the time and you have to spend a ton of cash on gas.

    i drive my car everyday, so i like getting 25~30 miles to the gallon. with a bigger turbo, the car only spools when i mash the peddle. its there when i need it. my car pretty much drives like a regular n/a saturn until i hammer it. just like i want it.

    quick spool also means more torque generally. if your peak torque is down really low in the power band, your are hurting your chances of making a lot of hp. our cars typically drop torque really fast at the top end, which gives us less hp. thats why you see a lot of dynos with equal or more torque values and lower combined power levels. the torque just dosn't hang around long enough.

    because torque falls and your chances of making high hp get worse, your also going to notice what most of us big dogs noticed a long time ago. SATURNS DIE ON THE TOP END WITH SMALL TURBOS! it sucks. you pull hard and then stop. it is mostly a cam problem, however most of you are not running cams, so YOU WILL RUN INTO THIS.

    i've been embaraced plenty of times before because of this. i run higher boost levels and pull at first and then stupid little hondas pass me on the top end. granted they have more rpm, but they also hold their torque a lot better. they generally make more power, which ultimatly makes you the faster car.

    3. as described above with torque and hp characteristics of slower spool, this makes a good combination for top end performance. yes we are limited to lower rpms, but i will garuntee you that top end is way better. its smother, faster and its pretty insane to feel rushes of torque at higher rpms.

    4. last point and probably the best. i've spent a sh!t load of money on my vehicle, not only to make it reliable, but to also make a ton of power. i don't want to limit myself to a small turbo from the get go. as it stands right now, i don't have to worry about my turbo, so it is one less thing to address.

    i also have money. yes, its a good thing and especially good when buying parts. it means i can get nice stuff and big turbos.

    its easy to compare a dsm to a saturn or a honda to a nissan, but the big problem with that is that they are all different setups. its been proven by many of us that t3's are good for low boost on saturns, but just don't cut it when your trying to make a ton of power on high boost.

    this is different for all cars and i guess it shouldn't be, but it is.

    o and a t3 is not the best turbo to run on our motors. most people will eventually crank the boost, and t3/t4's have been tested and moter approved for all boost levels. t3's die on the top end, where t3/t4's are pretty good with everything.

    t3/t3 50 trim. .60a/r compressor and .48 a/r turbine. stage 3 turbine wheel = best turbo for everything. this turbo is for your average enthusiast. good spool, good power and reliability.

    i'm not the only one that thinks this, so if your going to buy a turbo, buy this. if you want a little more power, 57 trim is the next best turbo. .63a/r turine and everything else the same. this is number 2 on my list (well, number 1 cause i don't care for smaller turbos and i like making more power!)

    i hope this gave a little insight to why bigger is better and i hope you realize what i'm trying for with my vehicle. each build is going to be different and each driver like different things about how a car responds and makes power.

    these ideals were conjured up by a immature speed freak. i like lots of power and i like going straight. i hate autocross and i don't like turns. i like racing on the track and the street and i'm highly competative.

    if you arn't like me or you have a different mind set, these ideas probably don't apply. if you are, keep tuned in, cause things are only going to get crazyer from hear out.


    Oil Lines

    most of the parts below can be found at almost any parts place. i choose jegs because they have everything in stock, same day shipping, and its only 2 days from me, ground. lines can be subtituted with cheaper rubber lines, but remember, these lines feed your turbo. better lines = less worry. ... y_Code=OIL
    - drain from turbo. this bolts to your turbo. ... y_Code=OIL
    gasket for oil return flange ... rmenbr=361
    - fitting off the block. this will fit right on the oil galley behind the block. make sure to take the rubber o-ring of the fitting before you install it. it doesn't serve a purpose for our application. if it falls off in oil galley, it can plug stuff up and your engine will go boom. ... rmenbr=361
    - reducer from fitting off block to -4an line. this fits righ on the fitting. the block fitting is a -6 which is a little too big. most people use -4. ... rmenbr=361
    - 2 of these. they attach to the block fitting and the turbo inlet. these will be permanently attached to the -4 braided line. ... rmenbr=361
    - 2 of these. they attach to the tubo drain fitting and the oil pan fitting. these will be attached to the -10 line. ... rmenbr=361
    - one of these. this is the feed line adapter. it screws into turbo. this is a 1/4" fitting, i think thats the one they use. check your turbo for correct pipe fitting on the feed side. ... rmenbr=361
    - this is the fitting for the drain. this will screw into the flange you get from atp. your oil pan is tapped. this might be the correct fitting for it, you'd have to check. so you might need two of these. they also have these fittings in angles (45, 90), you might need another angle for routing purposes. if you decide to ditch the tapped pan, you can take one of these fittings and cut the pip side off, scuff coating off and weld directly to the pan (drain oil and take pan off the car). ... rmenbr=361
    - for the feed. -4 line ... rmenbr=361
    - for the return. -10 line. you don't want to go below a -10 line for the drain. the bigger the better.

    hope this helps.


    Injector Info

    so everyone wants to know what injectors to use in their vehicles and to tell you the truth there is more then enough info on this site to figure it out, however i'm going to get it right out in the open.

    first things first, don't look at a certain psi level or boost level, shoot for a certain hp level. 15 psi on different setups will net you different hp levels. i've seen 300whp on 15psi and i've also see 250whp on 15 psi, so 15 psi is not the goal, hp is.

    so now that you're shooting for a certain hp, you have somthing to base you injector sizing off. so there are some important thing to take into consideration besides hp. the first and more important is you BSFC, which ultimatly dictates how efficient you motor is. now this is kind of a confusing subject and it will be throughout your whole career as a super cool tuner.

    why? well, it has to do with the efficency of the motor. not just the drive train loss, because it has nothing to do with the drive train. the hp level you put into a calculator has to do with the crank hp, so don't worry about your drive train. now if your shooting for a whp number, just take your whp and multiply it by 1.15 and you'll get your crank hp. this is very loose, however it will get it close enough. the .15 is for 15% transmission lose and you can argue this until the cows come home, however i don't care and you can take a long walk off a short peer.

    well now you have your crank hp and everything i honky dory, now back to BSFC. this is a wierd one becuase it relys on everything on the motor, exhaust, intake, head, turbo and everything else. it basically stands for the efficency of the motor. some motors are generally more efficent then others so they will use a BSFC lower then yours. thats just the way things go, so don't get all hot and botherd. generally, a turbo car will have a BSFC of .6 to .65. naturally asperated motors are more like .4 to .5.

    so what does this mean? well, the lower the number, the more efficent. why are N/A cars more efficent? well turbos create heat and more stress, so they take more fuel. N/A cars don' t so generally they are more efficent. now, this doesn't mean that a N/A car is always going to be more efficnet, it just means that it usually is. these are all numbers based off of averages and tested cars of all kinds, so they are not specific.

    now that we have the BSFC, we need to look at a couple more things. number of injectors: well if your running 4 this is pretty easy, you just use four. well, what if your running an eic? well you take the total lb/hr that all the injectors can make and divide by four. that will give you the rating of 4 injectors. for example: stock injectors = 19 lb/hr and lets say and eic with 2 injectors rated at 50lbs/hr. so you would take (4*19) + (2*50) / 4 = (4) 44 lb/hr injectors. that will make things easyer on the calculator.

    so there is a couple more things that are important however, they are pretty easy. most of the time when you size injectors, you don't want to run them more the 80% duty cycle. what does this mean? well, its the % time the injector is open. if you go higher you run the risk of running the injector static, which means that is open all the time. injectors act like a toaster or a speaker. they are given current and then they do some work, ie, they open up. if you give current to them all the time (100% duty cycle) they will heat up and can somtimes melt. so don't plan on running your injectors more then 80%. with the ms, you will melt the ms before the injectors go, so be careful. its happend to me twice.

    fuel pressure is the last part of the equation. because most of you will run stock fuel pressure, just keep the value at 43.5 which is 3 bar. if you have an adjustable regulator on a stock fuel system, keep it where its at, the stock lines arn't made for high pressure. now if you have an upgraded fuel system (stainless lines and all the fixens) you can raise the fuel pressure to make the injectors "bigger". commen sense is all you need to comprehend this. with more pressure, more fuel is pushed out fo the injector, hence them being bigger. they are still the same size, however with more fuel pressure they push more fuel out at any given point.

    all injectors ratings are at a certain fuel pressure. for instance, my injectors are rated at 95 lb/hr at 43.5 psi. that is a pretty common fuel pressure among vehicles, so i'm all good. now the injectors from are mopar injectors, which use a 4 bar fuel pressure. so if they are rated at 52 lb/hr at 4 bar, then on our stock fuel pressure they will actually act smaller. so a 52 lb/hr injector at 4 bar is actually equal to a 45lb/hr injector at 3 bar, so be carefull when you buy injectors. make sure you know what flow rating is at what fuel pressure. its important, so look into it, otherwise you be doing a rebuild.

    so now that you have the numbers, now what do you do? well plug them into a calculator. where can you find one? well they are all over on the internet, however i happen to know a good one and its brought to use by our lovly friends at rc injectors. heres the link:

    now try out some different senarious and see what happens. its free so don't be worried. try seeing what changing the BFSC will do. it will change the injector size dramatically, so thats why it is the most important part and everything else is held constant.

    hope this helps you poor fools. later b!tches!

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    • #3
      MegaSquirt Info
      also by BoostedSL2

      alrighty, here goes.

      so joe and myself were having some issues with not getting the ms to read the tach wire on his 99 dohc sl2. this is beacuse its a dirty wh0re. so what would happen is that when the ms was plugged in and reading off the stock tach output the stock gauge would quit working.

      the solution to this problem was to buy this nifty little box from msd called a tach driver. the part number is MSD-8913 and you can buy it at summit for about $60.

      this little box is a dandy. all you have to do is find the positive wire to the ignitian wire, which in our case was the pink one. snip that little bastard then wire the red wire to the side away from the ignitian modual and wire the red/green wire to the side going to ignitian modual.

      hook up your ground and run the gray output wire to the ms. this worked like a charm and took longer to mount, then to actually hook up.

      in addition to the tach driver beeing needed, heres a list of the wires i used to get it to work.

      Wiring for 99 dohc sl2
      clt - sensor included
      ait - sensor included
      tps - a6, dark blue
      o2 - c14, purple
      tach - msd-8913 tack driver
      inj1 - b2, black
      inj2 - a3, light gree/black
      inj3 - a1, pink/ black
      inj4 - a2, light blue/ black
      power - c12, pink
      ground - b9, black/white
      [img width=600 height=150][/img]<br />99SL2 w/97SC2M Engine/Trans Swap, CAI, 2.25 Custom Exhaust


      • #4
        good shiet
        2005 Legacy GT
        2004 Vue V6 AWD
        1995 SL1


        • #5
          thats a lot of good info there
          <br /><br />


          • #6
            who's gonna help with ions?
            AC 66Bronco: holly shit a bmw 850 is in a porno<br /><br /><br />Erik: there is a train going by<br />me:im on a train<br />Erik: OH MY GOD! IM TALKING TO SOME1 WHO IS ON A TRAIN....<br /><br />&quot;The fun was ended when a dour-faced man smashed the penis out of the air.&quot;<br /><br />If I had a dollar for every time I read that phrase...


            • #7
              Originally posted by blueiondubv
              who's gonna help with ions?
              except for the Megasquirt info, all of it is generally the same. However, as far as the specifics for Ions, we're working on it.


              • #8
                Originally posted by Schizzo97SC2
                Originally posted by blueiondubv
                who's gonna help with ions?
                except for the Megasquirt info, all of it is generally the same. However, as far as the specifics for Ions, we're working on it.
                Actually Mike (boostedsl2) is gonna work on building a kit. He mentioned it over at TSN. Look out baby!!
                I Only Worry When My SES Light Goes Out....

                I'm Officially in the 200,000+ mile club


                • #9
                  Yeah I read about that, but we're nowhere near close to having as much info for Ions as we are on S-series, that's what I meant.


                  • #10
                    I know you

                    whats up mike!! its Jesse ??


                    • #11
                      Re: I know you

                      Originally posted by bad ass saturn
                      whats up mike!! its Jesse ??
                      use pm's!!!!!!!!!!!!! [img]{SMILIES_PATH}/evil.gif[/img]
                      Jeff W.
                      Old Fella Nobody Remembers


                      • #12
                        The jegs links don't work anymore for the turbo feed and drain.

                        The block fitting for the oil feed is 16mmx1.50 to -6AN


                        • #13
                          larger turbo Q?

                          Hey mike, had a few questions after reading your write up in turbo secton on turbo's. I was runing a .57 trim t3/to4e it had a stage 3 turbine. Well it caused my car to smoke like a frieght train after about 2yrs of use. I ended up buying a turbo xs turbo from a buddy same turbo but a .50trim compressor. Its running good, but i pnly run 10 psi max (cause im afraid to crack my ring lands). I am running sohc sealed power pistons on shot peened and polished stock rods. So should i downgrade my turbo, im afriad that i caused the first turbo to craped out cause i wasn't spinning it fast enough. I was planning on building a custom t3/to4b with the standard .48 turbine and the .60 a/r compressor thinking it would be more happy on 10psi. But after reading what you wrote i may go to a t3 supa 60. anyway thanks for any advice, i trust you, thats why i always pm your ass as apose to others. Thanks Bill

                          p.s. how much boost you think i can get away with, on my ride? Its seen 14psi spike, and 12psi @ 140mph....which my buddy was drivin and didn't watch the boost gauge to let off [img]{SMILIES_PATH}/evil.gif[/img] . she's still runnin luckally.


                          • #14
                            Very nice, i have been asking these questions to myself, but didnt want to post for fear of a flaming.
                            Now i think we need a site backup so we dont lose this.
                            Sometimes I Like To Pretend My Car Is Fast..


                            • #15
                              Re: LOTS OF GREAT TURBO INFO

                              the turbo saturn on the cardomain what really cool i like it . i cant wait to do it to my saturn but i will never have that kind of money


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