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HT4100 4.1, 4.5, 4.9 Discussion, The "4.9 liter turbocharger, stage 1" thread. in Cadillac Engine Technical Discussion; You need to go over to www.fiero.nl and do a search for turbo 4.9, or just send PMs to PBJ ...
  1. #91
    Raze's Avatar
    Raze is offline Cadillac Owners Enthusiast
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    Re: The "4.9 liter turbocharger, stage 1" thread.

    You need to go over to www.fiero.nl and do a search for turbo 4.9, or just send PMs to PBJ and Her86GT (that's the car that does 12.2, there's video to prove it). Their build thread can be found here: http://www.fiero.nl/forum/Forum1/HTML/023354.html so that might interest you, it includes timeslips, but I cannot find where the videos are (they're sick). The fastest Cadero (Cadillac + Fiero = You get the picture) was made by Master Tuner Akimoto at least that's the claim, 11.97 on a highly tuned 4.9L, He also has a Turbo'd N* (one of about 2 actually functioning out there), PBJ is currently in the midst of a N* TT, though I havnen't seen any updates in a long time.

    Enjoy the reading, I know I did!

  2. #92
    Line Noise is offline Cadillac Owners Member
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    Re: The "4.9 liter turbocharger, stage 1" thread.

    Hey Raze Heres one of the video's your talking about. http://www.ghettosled.com/files/Vide...y@Stthomas.wmv
    PBJ did my motor swpa. he's a great guy.

  3. #93
    formula2m8 is offline Cadillac Owners Member
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    Re: The "4.9 liter turbocharger, stage 1" thread.

    Cool Video, nice production. Thanks for the links guys..and I'll be watching here as well to see how things progress.

  4. #94
    Raze's Avatar
    Raze is offline Cadillac Owners Enthusiast
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    Re: The "4.9 liter turbocharger, stage 1" thread.

    Thanks Line Noise, I couldn't find that darn link (was at work at the time without my bookmarks!)

  5. #95
    Line Noise is offline Cadillac Owners Member
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    Re: The "4.9 liter turbocharger, stage 1" thread.

    Quote Originally Posted by Raze
    Thanks Line Noise, I couldn't find that darn link (was at work at the time without my bookmarks!)
    No Problem was an easy link to find since it's on my web site

  6. #96
    94devilleDM5 is offline Cadillac Owners Member
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    Re: The "4.9 liter turbocharger, stage 1" thread.

    your my freakin hero, when its done make a video of you just melting a set of tires, please, that would be awesome

  7. #97
    formula2m8 is offline Cadillac Owners Member
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    Re: The "4.9 liter turbocharger, stage 1" thread.

    Just got a 30k mile 4.9 ($400.00)....also picked up a gm04 today ($100.00...in good shape!). Spare set of heads and intake are going out next week to be ported ($400.00). New revision MegaSquirt is on the way ($180.00), and cradle is being welded/modded this weekend (free). Not intending to brag here, but I can't believe how little (seemingly) this project appears to demand from my wallet! This is nothing like the other vehicles that I've built. Sorry to go on and on, but I'm TOTALLY FREAKIN' EXCITED ABOUT THIS CAR!!!

    How's everything going for you, Illumina?? Any updates?

  8. #98
    Stoneage_Caddy's Avatar
    Stoneage_Caddy is offline Cadillac Owners 10000+ Posts
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    Re: The "4.9 liter turbocharger, stage 1" thread.

    what are you doing as far as getting the exaust gasses to the turbo ?

    if i only knew if my t25 i have laying around would be big enough ...prolly not ...LOL....

    anyone suppose if i mounted the turbo up and then took the car to a muffler place that they could fab the rest ? i found a flange for the turbo online so ill buy thatand bolt it up to the turbo as i mount it where i want it (in place fo the stock airbox)

    im gonna go megasquirt too ....im hopeing to start this in 2006 , about mid febuary ...

  9. #99
    illumina's Avatar
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    Re: The "4.9 liter turbocharger, stage 1" thread.

    I have everything I need except for the Megasquirt system. I really don't want to put this thing together myself...But I will if needs be. Also needed is a new laptop computer: my curent laptop is cooked and I just need a newer one. I've been looking at Ebay for a good deal. I will likely order a newer laptop within the next few weeks.

    I'm also going to forgo intercooling for now. A friend of mine, as well as others really don't think that I'll need it.

    Once my '86 Deville Fleetwood is complete, I'll have nothing but free time to get this project underway and DONE.

    Sorry people, I just haven't had the most time to do what I want to do and make the dates I figured things would be done by...But it's getting better now.

  10. #100
    CallMeCrazy is offline Cadillac Owners Member
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    Re: The "4.9 liter turbocharger, stage 1" thread.

    Quote Originally Posted by Stoneage_Caddy
    if i only knew if my t25 i have laying around would be big enough ...prolly not ...LOL...
    http://community.asiaosc.org/~zaliman/TurboSelector.htm

    In order to select a turbocharger, you must know how much air it must flow to reach your goal. You first need to figure the cubic feet per minute of air flowing through the engine at maximum rpm. The the formula to to this for a 4 stroke engine is:

    (CID RPM) 3456 = CFM

    For a 2 stroke you divide by 1728 rather than 3456. Lets assume that you are turbocharging a 350 cubic inch engine That will redline at 6000 rpm.

    (350 6000) 3456 = 607.6 CFM

    The engine will flow 607.6 CFM of air assuming a 100% volumetric efficiency. Most street engines will have an 80-90% VE, so the CFM will need to be adjusted. Lets assume our 350 has an 85% VE.

    607.6 0.85 = 516.5 CFM

    Our 350 will actually flow 516.5 CFM with an 85% VE.

    Presure Ratio

    The pressure ratio is simply the pressure in compared to the pressure out of the turbocharger. The pressure in is usually atmospheric pressure, but may be slightly lower if the intake system before the turbo is restrictive, the inlet pressure could be higher than atmospheric if there is more than 1 turbocharger in series. In that case the inlet let pressure will be the outlet pressure of the turbo before it. If we want 10 psi of boost with atmospheric pressure as the inlet pressure, the formula would look like this:

    (10 + 14.7) 14.7 = 1.68:1 pressure ratio

    Temperature Rise

    A compressor will raise the temperature of air as it compresses it. As temperature increases, the volume of air also increases. There is an ideal temperature rise which is a temperature rise equivalent to the amount of work that it takes to compress the air. The formula to figure the ideal outlet temperature is:

    T2 = T1 (P2 P1)0.283

    Where:
    T2 = Outlet Temperature R
    T1 = Inlet Temperature R
    R = F + 460
    P1 = Inlet Pressure Absolute
    P2 = Outlet Pressure Absolute

    Lets assume that the inlet temperature is 75 F and we're going to want 10 psi of boost pressure. To figure T1 in R, you will do this:

    T1 = 75 + 460 = 535R

    The P1 inlet pressure will be atmospheric in our case and the P2 outlet pressure will be 10 psi above atmospheric. Atmospheric pressure is 14.7 psi, so the inlet pressure will be 14.7 psi, to figure the outlet pressure add the boost pressure to the inlet pressure.

    P2 = 14.7 + 10 = 24.7 psi

    For our example, we now have everything we need to figure out the ideal outlet temperature. We must plug this info into out formula to figure out T2:

    T1 = 75
    P1 = 14.7
    P2 = 24.7

    The formula will now look like this:

    T2 = 535 (24.7 14.7)0.283 = 620 R

    You then need to subtract 460 to get F, so simply do this:

    620 - 460 = 160 F Ideal Outlet Temperature

    This is a temperature rise of 85 F.

    Adiabatic Efficiency

    The above formula assumes a 100% adiabatic efficiency (AE), no loss or gain of heat. The actual temperature rise will certainly be higher than that. How much higher will depend on the adiabatic efficiency of the compressor, usually 60-75%. To figure the actual outlet temperature, you need this formula:

    Ideal Outlet Temperature Rise AE = Actual Outlet Temperature Rise

    Lets assume the compressor we are looking at has a 70% adiabatic efficiency at the pressure ratio and flow range we're dealing with. The outlet temperature will then be 30% higher than ideal. So at 70% it using our example, we'd need to do this:

    85 0.7 = 121 F Actual Outlet Temperature Rise

    Now we must add the temperature rise to the inlet temperature:

    75 + 121 = 196 F Actual Outlet Temperature

    Density Ratio

    As air is heated it expands and becomes less dense. This makes an increase in volume and flow. To compare the inlet to outlet air flow, you must know the density ratio. To figure out this ratio, use this formula:

    (Inlet R Outlet R) (Outlet Pressure Inlet Pressure) = Density Ratio

    We have everything we need to figure this out. For our 350 example the formula will look like this:

    (535 656) (24.7 14.7) = 1.37 Density Ratio

    Compressor Inlet Airflow

    Using all the above information, you can figure out what the actual inlet flow in in CFM. Do do this, use this formula:

    Outlet CFM Density Ratio = Actual Inlet CFM

    Using the same 350 in our examples, it would look like this:

    516.5 CFM 1.37 = 707.6 CFM Inlet Air Flow

    That is about a 37% increase in airflow and the potential for 37% more power. When comparing to a compressor flow map that is in Pounds per Minute (lbs/min), multiply CFM by 0.069 to convert CFM to lbs/min.

    707.6 CFM 0.069 = 48.8 lbs/min

    Now you can use these formula's along with flow maps to select a compressor to match your engine. You should play with a few adiabatic efficiency numbers and pressure ratios to get good results. For twin turbo's, remember that each turbo will only flow 1/2 the total airflow.

  11. #101
    CallMeCrazy is offline Cadillac Owners Member
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    Re: The "4.9 liter turbocharger, stage 1" thread.

    This is the main problem I have been having with the GM series turbocharger, trying to track down/build an accurate compressor flow map, compressor ratio, and correct A/R of the turbo itself. This is why my measurments/data is so important. When turbocharging, you HAVE to know these numbers and be able to plug them in mathematically. if you have an ill suited turbo, all the fuel in the world isn't going to help. By building a compressor map, I can figure out the turbo efficiency and even calculate how many cfm it pushes at various rpms and at different levels of boost as well. I found this thread by accident and to date it looks like I am the only one lookign to do any real calculations on this turbo, the rest of you plan on just slapping it on and crossing your fingers? lol

  12. #102
    illumina's Avatar
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    Re: The "4.9 liter turbocharger, stage 1" thread.

    Quote Originally Posted by CallMeCrazy
    This is the main problem I have been having with the GM series turbocharger, trying to track down/build an accurate compressor flow map, compressor ratio, and correct A/R of the turbo itself. This is why my measurments/data is so important. When turbocharging, you HAVE to know these numbers and be able to plug them in mathematically. if you have an ill suited turbo, all the fuel in the world isn't going to help. By building a compressor map, I can figure out the turbo efficiency and even calculate how many cfm it pushes at various rpms and at different levels of boost as well. I found this thread by accident and to date it looks like I am the only one lookign to do any real calculations on this turbo, the rest of you plan on just slapping it on and crossing your fingers? lol
    No, I'm not going to build a compressor map, we have you to do that for us

    Also, and I've stressed this several time before, I am basing this project off of the Fiero project that was done with the same turbocharger attached to the same engine. They did their research and they came up with the said GM turbochargers being the best suited for the job. I'll take them apples for now.

  13. #103
    CallMeCrazy is offline Cadillac Owners Member
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    Note this is NOT the GM A/R

    As far as calculating A/R:
    http://www.turbomaster.info/eng/turbos/concepts_ar.php

    A/R (Area/Radius) describes a geometric characteristic of all compressor and turbine housings. Technically, it is defined as:

    the inlet (or, for compressor housings, the discharge) cross-sectional area divided by the radius from the turbo centerline to the centroid of that area (see Figure 2.).




    And from Garrett:


    Now how to calculate A/R?

    I took what is known as a 63 A/R exhaust side as an example:


    Looks like roughly 40mm eh?:


    And roughly 50mm too eh?:



    But we need to be more precise as there is room for error:


    Nope, no error here, 50 mm:


    Same thing on the inside:



  14. #104
    CallMeCrazy is offline Cadillac Owners Member
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    Re: The "4.9 liter turbocharger, stage 1" thread.


















    1243.47/1962.50=.63!!!!



    Just so you know that my calculations will be correct when it comes to the GM series. I have it all apart and will try to figure it out this weekend, it's either figure out the A/R of a turbo or go to San Francisco with my GF....stay tuned for the exciting conclusion

  15. #105
    CallMeCrazy is offline Cadillac Owners Member
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    Re: The "4.9 liter turbocharger, stage 1" thread.

    Illumina- I need you to do me a big big favor!!!! I was trying to calculate A/R last night and by the design of the exhaust housing, couldn't get an accurate set of numbers (I need to buy some telescoping calipers to measure the inside diameter)

    Anyways, while I was measuring, I realized that the answer might be right in front of me:

    It looks like it might say A/R right? And the numbers next to it appear to be 74, BUT, mine is severely worn and I can't make it out. I want to be SURE!!!

    Can you please check yours and see if yours has a set of numbers?????????

    Here is where the numbers should be:

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