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SEM manifold works better at higher boost/power.

Discussion in 'Engine Discussion and Tuning (archive)' started by RobDon, May 15, 2011.

  1. Don R

    Don R Guest

    An independent K04 test was done...
    [​IMG]

    Even my own dyno testing showed gains @ only 15 psi, 20 min swap between intakes.
    [​IMG]

    There's a possibility the mapping you gents have is inhibiting the power from timing correction. This would be based on increase in MAF and Trq values...
     
  2. ibizacupra

    ibizacupra Jack-RIP my little Friend
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    do you have the afr, boost plots which should have gone with the power plots don?
     
  3. Don R

    Don R Guest

    Sorry boss, the only info I know is the blue and red curves are before and after at 18 psi and the orange curve is 22-24 spike and tapering off up top.
     
  4. RobDon

    RobDon Pro Detailer

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    So the boost was increased when the SEM was fitted, for the orange run only? There is also different temperatures and correction factors between the blue and red - that's not right either. Also, look at the dates between the red and blue runs. There is only 5bhp difference at the wheels between the red and blue runs, if that's before and after fitting a SEM on a K04 car then it proves my point.

    Is your turbo not a GT30 Don?

    I'm not trying to discredit the SEM, but I firmly believe that it will only show decent, cost-effective gains on a turbo larger than a GT2871R.
     
    #44 RobDon, Jun 28, 2011
    Last edited: Jun 28, 2011
  5. Don R

    Don R Guest

    Please re-read, Red and Blue are before and after @ 18 psi. Boost was increased on the orange curve.

    Again, this was an independent test and can only be taken as information only.

    Simple facts to consider with stock vs SEM intake design:
    - The stock 1.8T intake manifold is less in displacement than the actual motor, if I recall 1.3 Liters vs 1.8L engine. This will definitely choke up top. The SEM is 2.75L in plenum volume.

    - Flow characteristics are very poor with the stock intake while the SEM flows well within 1.5% from highest to lowest. This was an independent test commissioned by Bill and conducted by JNL-Racing.

    To re-iterate:

    From: JNL Racing <jnlracing@googlemail.com>
    Subject: SEM Manifold test results
    To: "BILL BROCKBANK" <bill.brockbank@btopenworld.com>
    Date: Wednesday, 15 October, 2008, 12:21 AM
    SEM Manifold Report

    Overview

    Mathematically the internal runner size on each runner has an identical cross sectional area to the intake mouth of a big port head if we make the assumption it is a perfect rectangle. Obviously we are in a scenario where in real life the intake has radiused sides so there is mathematically scope to open the mouth of the cylinderhead port further than the standard port mouth size without loss of flow. Further experimentation would have to be done to actually work out what the threshold is and as to how much effect the port design has on it.

    Testing Method

    The flow results of each individual runner Number 1 being closest to the throttle body which in this case cyl number 4 closest to the gearbox. All flow figures have been pulled at 10" on a digital bench calibrated to a superflow 110 with allowances for atmospheric conditions whilst tested. A calculated equivalent using a 1.673 correction factor has also been made for a 28" test pressure result for comparison with existing results from other sources. From experience time and time again the mathematical 10" to 28" conversion actually yields results 1-1.5% lower than an actual tested 28" at flow figures between 250-300cfm. On the individual runners 3 seperate pulls where made at different bench operating temperatures (heat build up over time from extended running of the motors) and an average taken from the results.

    CFM Report

    Percentage variation between each of the individual runners is a maximum of 1.54% between the highest and lowest. An acceptable variation for high performance mapping purposes when using a single lambda probe to determine the average of 4 cylinders is considered to be 3-4% deviation from minimum to maximum. So the manifold falls well below this safety range.

    FPS Report

    At 10" test pressure port/runner velocity is considered at choke at 209fps which equates to 350fps at 28". The runner velocities where measured as central as possible to the runner at the cylinderhead flange exit/entry point. Higher velocities where recorded towards the sides however it was difficult to record a constant across the 4 runners for comparison so it was decided to take the lowest velocity found at the centre of the runner as the comparison point.

    SEM Manifold Results
    Test Pitot SCFM
    Intake Pressure FPS
    1 10 269 162.3
    2 10 282 164.5
    3 10 287 164.8
    4 10 288 162.4

    Test Pitot SCFM
    Intake Pressure FPS
    1 28 450 271.6
    2 28 472 275.3
    3 28 480 275.8
    4 28 482 271.7


    Flow test involving a mildly ported testhead
    As an experiment we have also taken a mildly ported large port head with standard port mouth sizes to mate up to the SEM manifold. (Again flowed at a 10" test pressure). As you can see although there is a drop it is considered quite minor in the grant scheme of things averaging between 2.5-3% drop across the complete lift range.

    The most surprising thing here though is that although runner 1 flows physically worse than runner 3 it only exhibits a 2.5% drop across the range against the 2.9% drop of runner 3 which will be down to the slower runner velocities that were recorded. Which goes to show that runner flow without the equation of the head can be quite deceptive and should only be taken as a guideline as to how well they are matched to each other not of their final ability. I also shows that port/runner velocity plays an important part in final combinations.

    Common to both runners tested on the head; when measuring port/runner velocity at the port mouth of the head with the intake bolted on the port velocity became approximately the average of the two items when tested individually.
    For example runner one measured 269fps on it's own and port 1 measured 227fps on it's own. Once the intake was bolted onto the head the port/runner velocity averaged out at 245fps. (All three velocity measurements taken as central to the runner/port as possible).


    Final Overview

    The SEM manifold for use on a standard head application will potentially see small gains in tq and hp in the mid to top range over a standard manifold due to the high runner velocities, providing it is correctly matched with the right throttle body (not too large) there will be improved throttle response over a standard manifold. There may be a small sacrifice of power in the low rev range as it will take extra time to fill the larger plenumb chamber however this would have to be tested on a dyno to verify.
    For big power/high rpm application it would be considered a highly desirable manifold to have specifically because of the large plenumb chamber giving a large storage capacity of boost pressure for the cylinders to draw from. This means less of a pressure drop during gear changes and would be ideally suited to track orientated vehicles whether drag or circuit. For drag race/big turbo - high boost application it would be advised to open the ports up to slow the runner velocities down accordingly, whereas circuit cars with smaller turbo's and lower boost settings will benefit from the higher velocities for out of the corner throttle response on the standard port/runner size. Comparing the figures of the SEM manifold against existing test results floating around the net not only does it outflow the best manifolds out there at the moment but it is also the most consistant across all four runners even outdoing my previously favoured RMR manifold which has a 2.8% variation across the runners.

    Courtesy of www.JNLRacing.com

    Kind regards

    Jean-Paul

    www.JNLRacing.com

    JP is indeed one of most qualified people I've ever had the pleasure in dealing with. His analysis confirms most of my R&D. Please feel free to email him about his assessment of the SEM intake.

    Thanks again Bill for commissioning the test.
     
  6. RobDon

    RobDon Pro Detailer

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    As said previously, the SEM's credentials are not in question, it's all down to price vs performance, as JNL said you'll only see small gains on a stock smallport head. The bigger the turbo the bigger the gains.

    On a cost vs gains you'll only see bigger gains on bigger turbos - my point is spending £750 for minimal gains on smaller turbos just isn't worth it - £750 for 5whp? Nobody is saying the SEM doesn't work, it just works alot better on bigger turbos with ported, flowed heads.
     
    #46 RobDon, Jun 28, 2011
    Last edited: Jun 28, 2011
  7. JNL

    JNL Guest

    Couple of things to note on this thread.

    First of opening a small port head to big port spec to fit a big port SEM is going to counteract anything it's capable of in the midrange where you feel it unless professionally done as opening the small port ports can really b*gger things up relative to airspeed.
    Any turbulence introduced into the airstream will counteract flow and end power gains.

    If you have a small port head buy a small port intake end of. Unless the small port versions are no longer available in which case buy a transfer flange.

    Next what is it with pub figures in this country? I look at the shape of the curve's of the comparison at the top of the page and think wow, smoother power delivery and more driveable across the range, not it only made an extra 5hp at peak.

    Currently I'm running in a fresh engine at 0.85bar of boost it produces just over 400hp. Previously I ran a different configuration at 2.1bar and made 528hp.

    The fresh engine at low boost is faster and more useable on the street.

    The difference.....
    The high boost setup was a GT3076 with a 0.63 hotside on a 2.2. Thing was rapid and had a real kick to it.

    The low boost is the same 3076 with a 0.82 hotside but this time bolted to a 2.5ltr. Although less peak power the torque curve is flat from when it's on boost till redline and starts 750rpm earlier. more driveable feeling slower as there is no kick that you get from a poorly matched setup with respect to flow but you can see your speedo moving quicker then it has ever done before until wind resistance takes it's toll. I can't wait to stick the modded turbo on and turn up the boost.

    Everyone seams to be more fixated with what their car makes on a dyno then what it actually does in real life. Go to the quarter the poor man's dyno. Yes that's right for those that never realised there is a direct mathematical correlation between hp, weight of vehicle and quarter mile results. This is why when someone gives me a hp figure for a specific car I'll look at the timing slip keep in account traction (60ft) and the expected quarter mile time vs trap speed relative to the weight of the car. from the timing slip I'll deduce the driveability and hp of the vehicle.

    Rant over :D


    ****EDIT***** ^^^^^replied during my essay :p
     
  8. RobDon

    RobDon Pro Detailer

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    I agree that the open road is the best place, not a dyno, and I feel pretty much zero difference going back to the stock intake manifold and TB from the largeport SEM and 70mm TB on a GT2860RS turbo.

    SEM do a smallport version?

    1/4 mile - FWD - traction off the line? Not really the best test of a FWD car.
     
  9. ibizacupra

    ibizacupra Jack-RIP my little Friend
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    yea, SEM available in smallport or largeport.. in stock 60mm tbody and 80mm tbody sizing..
     
  10. RobDon

    RobDon Pro Detailer

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    Well after being told to go for the largeport by Don, Issam, etc. it sounds like that was the wrong choice then. If I ever get another one I will go for the smallport version.
     
  11. ibizacupra

    ibizacupra Jack-RIP my little Friend
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    I dont think it was the wrong decision rob.. It gave the option of largeport head at a later date if further mods/plans were ever hatched.

    The gains as I have said are proportional to power/airflow thru the motor at the end of the day
     
  12. RobDon

    RobDon Pro Detailer

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    I was never planning on changing the head or going above say a GT2871R so I think I should have stuck with a smallport manifold. With the OE smallport manifold on now I feel I have better midrange torque than I did with the largeport SEM.

    What I would like to do is dyno my car now with the OE manifold and TB, fit a smallport SEM with 70mm TB then go back and dyno it at the same place and see if there are any gains. If there are substantial gains then I would take everything back I have said (apart from going largeport was wrong).
     
    #52 RobDon, Jun 30, 2011
    Last edited: Jun 30, 2011
  13. INA

    INA Garrett Super STAR!

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    Rob,
    what about the transition phenolic spacer?
     
  14. RobDon

    RobDon Pro Detailer

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    What about it Issam?
     
  15. INA

    INA Garrett Super STAR!

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    You would prefer a small port manifold than a big port + phenolic?
     
  16. RobDon

    RobDon Pro Detailer

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    To quote JNL: "If you have a small port head buy a small port intake end of."

    So yes, I'd stick with a smallport SEM.
     
  17. ryan_s3

    ryan_s3 Full Member

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    There is very little wrong with a stock evo intake manifold, having a very large intake adds 15whp but at the 450-500whp range but adds a fair chunk of lag.
     
  18. Gulfstream

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    Hi, dont want to be a hijacker so dont squawk 7500 just yet. I have a bigport AGU 9.5:1CR motor with bigport SEM / 70mm TB and a billet 3071R. 413whp @ 27psi. I just want ppl here to see the power and boost curves I got from this setup and see for themselves if they think its laggy or what.

    [​IMG]
    [​IMG]
     
  19. RobDon

    RobDon Pro Detailer

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    Don - could you give me a definitive answer to this question please?

    Smallport head and GT2860RS turbo - smallport SEM and 70mm TB is the best choice?

    Any point in going with a largeport SEM flowing into a smallport head? The inlet ports on my head have been opened up a bit but nothing wild.

    My goal is fast throttle response, quick spool and good midrange torque.
     
  20. caney

    caney Full Member

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    @jnl,ok what would you say my bhp is trapping 122mph terminals in a car weighing 1510 kg with me in it?
     

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