1.5T Power Metrics & Limitations for 1.5L Turbo (Non Si models)

  1. Hollywoo0220

    Hollywoo0220 Customer Service oriented (most of the time) :-)

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    #1 Hollywoo0220, Feb 17, 2019
    Last edited: Jul 5, 2019
    For understanding purposes only:

    FACTS

    * Stock exhaust system is more than capable of supporting maxing out the turbo's capability. Pre-Cat is large, Mid-Pipe is 2.125" and exhaust is 2". Stock Turbo is the shortfall.
    ** The WG is is electronically controlled and the ECU uses "slope logic" to bring in spool. You can achieve increased spool with base tunes by adjusting the level of Ramp Rate already.

    Previous testing of a downpipe system showed a reasonable bottom end to midrange improvement, but nowhere near the gains an ECU reprogram delivers. (et al Hondata)
    *** Not one tuner or developer has posted dyno tunes on an upgraded turbo with a CVT model (as of this date).
    This is placed here to dispel rumors of anyone making "vague" claims without engineering data and/or reliability.
    There are erronious claims of power, in which the tuner's are changing values to show false #'s.


    THEORY

    * The CVT has been tested for "capability"; however, no hard data has been reported as of this date.
    WHAT is "Maximum" Torque? My estimation stands with a reputable individual that guesstimated approx 230-240lb/ft. Is that V6 levels of torque? The lower (under the threshold) the torque is kept, the more reliable the CVT will be over time.
    ** It is also important that when increasing torque, that the RPM band from which it is generated be moved further right. This is easier to achieve on upgraded turbos.

    ** The M/T is about at the same level (+/-10%) for stock clutch safe operation (in guesstimation).

    1) Let's determine our Maximum Turbo Efficiency:

    Maximum turbo CFM output = (3.14)(turbo compressor wheel size ÷ 2)2 / 3
    So:
    (3.14) x (39.1mm stock compressor wheel / 2) = (3.14) x (19.55)2
    (3.14) x (18.5 x 18.5) = (3.14) x (382.20)
    (3.14) x (382.20) = 1,200.11

    Now, divide 1,200.11 by 3 = 400 (corrected)
    Thus, the Maxium Turbo CFM output of the non-si turbo is 400 CFM.

    a) A stock set-up is more than capable of handling the power that the turbo can produce effectively.
    Using the highest Octane possible will get you to those numbers (i.e. Race Fuel, E-Blend, etc...)
    b) **Max Flow DOES NOT equal "efficient" flow.
    - If the turbo is able to operate at a good efficiency of 75% at the boost level you choose, then you would in essence decrease the air flow to 300CFM.
    c) From factory @5500rpm HP reaches it's peak; to get past that hump a more efficient turbo is required. This is the tranistion from boost is higher than exhaust back pressure TO exhaust pressure higher than boost. The power capability remains in the turbo's ability to push and pull.
    d
    ) Non-Si Turbo Exhaust Exducers are "11" Blades as opposed to "9" on the CRV & Si models.
    - The lesser blade # can exspel exhaust gases more efficiently; thus higher RPM power.


    2) Let's determine Spool time:

    Spool time in seconds = turbo compressor wheel size2 / (exhaust PSI)(100)
    So:
    (39.1mm x 39.1mm) = 1529
    (14.7psi barometric + 16.5psi Max Stock level x 100) = 3120
    1529 / 3120 = .49
    .49secs is your spool time


    a) You can add your tuned PSI into the equation and see how your spool time is dropped at that level.

    3) CONCLUSIONS:

    Downpipes and aftermarket exhausts do not add favorable power gains with the stock turbos. Aftermarket intakes are a "preference", not required.
    --It is ideal to keep with the designed Bypass Valve and not migrate to a Vent to Atmosphere.

    #1 An Upgraded IC would be advantages in racing applications OR increased spirited driving, but not required for regular street driving.

    Note: In a FI vehicle, the air entering the combustion is after the IC. So, adding an aftermarket intake (claiming to provide more "cold air") is a moot subject. That colder air is being compressed and heated up by the compressor, then through the IC to be cooled - before being added to the combustion. A higher efficiency drop-in filter would function just the same (especially on a limited turbo). All that is needed is to have increased velocity.
    By using after market MAF's, the ability to get more power is possible - but, that power will only be available very high in the power band and for a very short time (before shift).

    #2 Upgrading the charge hoses (when increasing PSI) will decrease radiating heat, premature wear and provide longer lifespan (dependability).

    #3 By adjusting ignition, fueling and VTC, the Base Tunes (of both Hondata / KTuner) provide safe performance - even on a completely stock vehicle.

    Things can be pushed a bit further with custom tunes and increased octane.

    Just understand the limitations.

    ***For the Si and 6MT models, the sky is the limit with correct modification(s).

    Now for a little entertainment:
    It has become apparent that our vehicles may very well be equipped with TD025 turbos. However, given the boost levels of Base Tunes available from the two prominent tuners, we are more so likely on a TD03 turbo (as claimed by Honda). Let's look at the information available for both the TD025 and TD03:

    upload_2019-3-6_9-39-20.png


    TD025:
    The Max Pressure Ratio is 2.2.
    So, if we were on a 21psi Tune then:

    Pressure Ratio = Absolute Discharge Pressure / Absolute Turbo Inlet Pressure
    (14.7psi + 21psi) / 14.7

    35.7 / 14.7 = 2.42

    The arguement here is:
    How can our turbo achieve a Pressure Ratio of 2.42 if it is a TD025?

    TD03:
    The Max Pressure Ratio is 2.9
    So, if we were on a 21psi Tune then the 2.42 Pressure Ratio falls within the capability of the turbo.
    That is engineering logic.

    ***There is also contention, that the stock turbos are TD025's (based on labling); but, if they are - then they are certainly a "hybrid" of some sort that have a higher PR than the standard models.

    With a Pressure Ratio of 2.4 on a turbo with a ceiling of 2.9, you will be in the higher efficiency islands of the compressor map more sustainably; without maxing out the stock turbo capability.

    "So, why aren't we seeing that 21psi?" as some might say. Well, you are not seeing it. What you are seeing is the MAP pressure, not what the turbo is actually boosting. The compressor is operating at 21psi, but you may only be registering 18.5psi on the MAP reading. That difference is "System Pressure Loss" and is a thermodynamic principle; better known as Bernoulli's principle. Which in simple terms means that when you draw air from outside, you are drawing air in at atmospheric pressure. However when it gets pulled through the filter and air tubing, the pressure actually drops BELOW atmospheric. So, your MAP might show you you are reaching 18.5psi, but your compressor would be producing 21psi (for example).

    I would also like to point out that Honda (or any other manufacturer) are in fact providing you correct technical information as it pertains to boost pressure. Just understand that from this point forward, as you are reading the MAP level on your tuner or datalog - that your turbo is actually producing more PSI than that to achieve the target.

    Hope that helps....

    *Article Update as of 5JUL19
     
  2. Myx

    Myx Senior Member

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    #2 Myx, May 17, 2019
    Last edited: May 17, 2019
    @Hollywoo0220 Big thanks for this post.

    I just happen to be looking for max torque numbers the CVT can hold and max horsepower the turbo can make to determine my full modification route. This post/thread is gold. Kudos!

    And thanks for stating what I'm trying to do with my current setup. I actually posted a thread asking about pressure loses and you answered it. I am currently trying to reduce any pressure lose associated with everything from the air filter to the throttle body. I just purchased a manometer to check this (Never used one before) but I procrastinate.
     
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  3. Hondanickx

    Hondanickx Senior Member

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    Where's the proof a stock exhaust isn't a restriction? I've seen several people going from stock 182hp to 200hp with just a 2.5" exhaust ,everything else stock.
     
  4. Myx

    Myx Senior Member

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    #4 Myx, May 17, 2019
    Last edited: May 17, 2019

    Where did you see this?
     
  5. charleswrivers

    charleswrivers Senior Member

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    Good stuff. Everything I've seen on our turbos has shown they've been either HP or LP variants of TD025s. Could they actually be a hybrid of the two? (shrug) maybe. I'd heard the Accords with their K20C4s also had conflicting info as to what turbo that had compared to what Honda advertised.

    TD025Tag.jpg IMG_20171230_135417.jpg UfG70eh.jpg 20171229_104114.jpg IMG_20180121_110129_778.jpg

    In the end... we got what we got. It's responsible for a quick spool when you get rid of the slow ramp up and makes for rapid massive midrange power... it just can't flow enough to make the top end power match other competitors that have 2L engines mated to ~TD04 sized turbos that are tuned on pump gas.

    I still am very interested if Honda decides to recycle the L15 engine if they did testing with a larger turbo to make well more the 200 hp but intentionally gimped gen 10 to leave a little more on the table for a gen 11 car. We're still a couple years out from knowing. Unless Honda is looking at variable compression or HCCI, I'm not sure what other tricks they have to improve economy on the L-engine for gen 11. I thought the number to reach was 50 mpgs by 2025. We'll have had the Si stuck at ~200 flywheel HP for over 20 years by the time gen 11 hits. I'm not sure where Honda will go next. I imagine they'll target more efficiency before power.
     
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  6. Hondanickx

    Hondanickx Senior Member

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    #6 Hondanickx, May 17, 2019
    Last edited: May 18, 2019

    Stock with 2.5" exhaust https://www.civicx.com/threads/apexi-n1-x-exhaust-for-hatchback-review-with-dyno.32041/

    Post from Kytos https://www.civicx.com/threads/ktun...p-switching-and-more.35199/page-3#post-592596
    First dyno is stock (stock ecu) with 2.5" exhaust And k&n drop in filter
    https://civicx.club/t/votacion-de-estimacion-de-potencia-stage-1-y-stage-2-ktuner/1875/10

    TDI North (UK) tuning this fk7 stock car with spoon 2.5" exhaust.Dashed line is stock ( and stock Ecu ) with 2.5" exhaust

    TDI north tuning fk7 spoon 2 .jpg
     
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  7. 360glitch

    360glitch Moderator
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    "*** Not one tuner or developer has tested an upgraded turbo on a CVT model (as of this date)."

    I realize several months have passed but I believe a PRL customer has their big turbo kit on a 1.5 CVT car now.
     
  8. OP
    OP
    Hollywoo0220

    Hollywoo0220 Customer Service oriented (most of the time) :-)

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    This 2.5” Exhaust talk is relative to the Si - that’s what I see.
    Like the “Metric” reads:
    You can gain the same power with the stock exhaust - it is not restrictive. The difference is “Tuning”, not just simply throwing on exhaust and getting power.
    The Si & CR-V can expel a bit more exhaust than the non-Si variants. Neither model however, have restrictive exhausts.
     
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  9. OP
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    Hollywoo0220

    Hollywoo0220 Customer Service oriented (most of the time) :-)

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    Have not seen any reports of that matter.
     
  10. Hondanickx

    Hondanickx Senior Member

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    #10 Hondanickx, May 17, 2019
    Last edited: May 17, 2019
    You are blind , they are all Untuned , and all FK7's so where does this even come from....?:dunno:

    However it could be that the restriction is from the downpipe/cat and that a bigger exhaust helps to extract more exhaust gasses and the gain is from that. All these dyno's are with a stock " restrictive " cat.The theory of what a certain size exhaust flows can't tell you if the whole exhaust system isn't restrictive somewhere.All oem honda exhausts are made tapered because exhaust gasses cool down the further away they go and they take up less space in the exhaust.To keep the exhaust pulses going at the same velocity the exhaust size gets smaller.
     
  11. OP
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    Hollywoo0220

    Hollywoo0220 Customer Service oriented (most of the time) :-)

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    Let’s try this again.
    Swapping the stock exhaust for a 2.5” is not going to net more power by itself.
    Be mindful of what you read and question everything you only see.
    You can achieve 280-290hp from a 2” exhaust, if you have a turbo that will get you there. Try maxing the turbo first before adding many another item.
     
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  12. gtman

    gtman Senior Member

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    What he said.

    No way just increasing exhaust piping a half inch and using aftermarket mufflers on an otherwise stock base Civic is legitimately adding 18 hp in and of itself.

    If that was the case, 2.5" aftermarket exhausts would be selling like hotcakes.
     
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  13. Hondanickx

    Hondanickx Senior Member

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    #13 Hondanickx, May 18, 2019
    Last edited: May 18, 2019

    That's theory of what a 2" pipe can flow max .You can never achieve that if the exhaust is 2" right after the downpipe (cat). .All of them who get 280-290hp enlarge the downpipe and/or front pipe .
     
  14. Myx

    Myx Senior Member

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    This all is making for some interesting discussion. I'm only running a PRL Downpipe as my PRL front pipe was damaged from a bad install. The dyno chart above is interesting as well.

    I'm still looking for the dyno post/link/thread that PRL stated (It was PRL If I remembered right) when they removed the piping from the front pipe, no horsepower was gained. This was why they never developed an exhaust for the Non-Si. Can't find it at the moment though. I purchased a 3" Injen despite that, that I had modified to be 3" from the front pipe back but I never ran a faster 1/4 mile time or trap speed with it. I didn't run a worse time, just not faster than my stock piping.
     
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  15. Hondanickx

    Hondanickx Senior Member

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    #15 Hondanickx, May 18, 2019
    Last edited: May 18, 2019
    It was PRL that said that indeed and is still the only one that says that.27Won says it is a restriction ,and others as wel.Most tuners i know around here also say it's a restriction.
    Imo they never tested it properly, a full (larger) exhaust vs a stock exhaust would be a good test.Unbolting a stock exhaust after the front pipe isn't.
    For me the best front pipe or downpipe would be tapered in size .For example starting at 3" at the turbo flange going true the cat into 2.75" then into the front pipe going from 2.75" to 2.5" .After that the exhaust can go from 2.5" to 2.36" and end up into a twin 2" or single 2.36" pipe. This keeps the exhaust pulses going and exhaust velocity up .Unbolting after the front pipe ,slows down the exhaust pulses into a very large area which could also mean hp loss.
     
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