Stock WRX turbo is not a 13G it is a 13T
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This is a discussion on Stock WRX turbo is not a 13G it is a 13T within the Engine Modifications forums, part of the Tech & Modifying & General Repairs category; The subaru community has believed (myself included) for a long time that the stock turbo on the WRX was a ...

  1. #1
    Registered User hotrod's Avatar
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    Stock WRX turbo is not a 13G it is a 13T

    The subaru community has believed (myself included) for a long time that the stock turbo on the WRX was a TD04L-13G. This was based on statements made by well respected members of the community back in early 2002 when the car first came out.

    The DSM community has been refering to it as a 13T for quite some time now, and since I just recently pulled my stock turbo off, I just pulled the compressor cover and measured the compressor.

    According to compressor dimensions published on :
    http://www.stealth316.com/2-turboguide.htm

    The compressor impeller measures out as a 13T, not as a 13G.

    My compressor measures 2.205 inches at the max diameter across the impellers, (exducer dia) compared to the expected 2.203 inch max dia on a 13T impeller.

    The minimum dia across the impellers (inducer diameter) measures 1.599 inches compared to the expected 1.597 inches for a 13T impeller.

    This shows a consistant bias of +.002 on the measurements ( using a very old vernier caliper that has not been calibrated in 25 years.

    It looks to me like we need to begin the long process of changing the urban legend that this is a 13G impeller because mine at least certainly measures out as a 13T.

    I suspect the basis of this is it is nearly impossible to find a compressor map for the 13T, and folks used the nearest thing they could find, and it took on a life of its own.

    FWIW

    Larry
    13.239@102.85 -- 5800 ft altitude
    on the stock TD04L-13T turbo

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  3. #2
    Registered User KoreanBeefcake's Avatar
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    i always thought it was just called "TD04" lol.

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    being nowhere near as educated on things like this as you, what does this mean to us in laymans terms?
    Vanitas vanitatum...et omnia vanitas

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    Registered User hotrod's Avatar
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    difference

    being nowhere near as educated on things like this as you, what does this mean to us in laymans terms?
    Basically the TD04L-13T will flow about 400 CFM ( compressor maps are hard to find for this one ). The TD04L-13G had a rated max flow of about 360 CFM.

    Bottom line, the turbo is capable of about 10% more hp than was widely believed based on rated max flow. Since we don't have a trustworthy compressor map, we have no solid info on exactly where it is most effecient. Some estimate it should behave about the same as the 15C, so that is a best guess for those who like to see compressor maps.

    And last but not least, the "Pro's" have probably known this for a long time, yet none of them bothered to tell the "masses". This means folks were buying upgrade turbos based on false information about the increase in performance to expect from the new turbo.

    I don't think that is an ethical way to do business, but I'm not a real fan of how the turbocharger industry does things anyway.

    Larry
    13.239@102.85 -- 5800 ft altitude
    on the stock TD04L-13T turbo

  6. #5
    Registered User UURX02's Avatar
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    That's very interesting. Nice work hotrod. Does this mean our TD04 actually isn't a Mitsubishi made turbo?
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    its still a mitsubishi, just different compressor that previously thought. .


    and10% is a pretty large number to be "overlooked"
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    Registered User UURX02's Avatar
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    Quote Originally Posted by gusto
    its still a mitsubishi, just different compressor that previously thought. .


    and10% is a pretty large number to be "overlooked"
    no kidding. How has this correction not been publically announced after 4 years? that seems a bit odd
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    Nice work Larry!
    FS: 02 WRX with JDM V7 RA-C

  10. #9
    Registered User bigwrxguy's Avatar
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    so how much hp is this turbo actually capable of then.

  11. #10
    Registered User hotrod's Avatar
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    max out put

    so how much hp is this turbo actually capable of then.
    That is a tough nut to crack at the moment. After comparing notes with Jlevy over on NASIOC I've decided to down grade my "guess" about the turbo's max flow. We used different ways to estimate the turbos potential. His frankly is more practical than mine and comes out about 385 CFM, mine gives a take no prisoners max flow rate up near 410 - 420 CFM.

    I think those are reasonable bounds to work with right now. For every 15 CFM increase in flow rate the turbo's max potential hp goes up by about 10 hp.

    The max flow for the 13G was 360 CFM that gave a max hp of about 240 hp. Everyone recognized this seemed low, but we just wrote it off to poor effeciency. A few tuners got very close to 300 hp out of the stock turbo, but these were ragged edge tunes on high octane fuel.

    The current guess of 385 CFM implies a max power output potential of about 260 which is still low by my estimate. My max flow of 410 CFM implies a max power output of about 275 hp which is pretty close to the best numbers folks have achieved with the stock turbo.

    Of course this all depends on how lean an air fuel mixture a tuner can get away with using his tuning techniques.

    The most important issue to me, is that with the new flow data on the stock turbo, the small IHI turbo's are basically replacement turbos not upgrade turbos. The VF23 for example is supposed to flow about 430 CFM so it is very close to the max flow of the stock turbo, not a meaningful upgrade as many folks thought. If I'd spent $900 for a VF23 and only got a 2%-3% increase in power potential I'd be upset!

    In fairness the stock turbo does not live long if pushed this hard, but I'm not sure the small IHI's do much better if run at 18 -20 psi everyday either.

    Larry
    Last edited by hotrod; 01-18-2005 at 04:24 AM.
    13.239@102.85 -- 5800 ft altitude
    on the stock TD04L-13T turbo

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    I have a vf23 turbo running 20psi and 22 or so at the track.
    My 04 wagon went for a 12.9 at 105.
    The vf23 has more top end then the stock but its still not great. Stock I ran a 13.3 @ about 102 stock turbo. The vf23 should be able to run 20psi at 7000rpm or so i have heard.
    My tuning says that the turbo can only hang on to 16-18psi at redline.
    its a great mid range turbo, hits hard and falls off on top end.
    I went with this turbo because I got it cheap and I want my tranny to last a little longer.

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    Lol... Well new info for me.. Thanks I told you my 21psi of boost works greate on my stock turbo
    Silver -02 Impreza WRX

  14. #13
    Registered User bigwrxguy's Avatar
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    This is intresting, so it can make as much power as a VF34 and would spool just as fast. But you wouldn't really get the top end of a VF34?

    So would going with bigger injectors and fuel pump on a much more aggressive tune work for this turbo.

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    Banned dark_rex's Avatar
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    great info as always larry. thanks.

    dR

  16. #15
    Registered User hotrod's Avatar
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    easy guys

    This is intresting, so it can make as much power as a VF34 and would spool just as fast. But you wouldn't really get the top end of a VF34?

    So would going with bigger injectors and fuel pump on a much more aggressive tune work for this turbo.
    EASY!!! there folks ---- lets not jump out of the pan into the fire.

    Plain and simple -- we have no clue how much the 13T can flow ---

    WE know it flows more than the 360 CFM of the 13G we thought it was can.
    we can guess that if you spin its guts out you might get 410 CFM out of it.

    The VF30/34 is generally thought to flow about 460 CFM at 18 psi, and they are clearly superior to the stock turbo.

    Its the small IHI's that are not really much of an upgrade.

    In 2003 and 04 when folks started to run high 12's with the stock turbo no one would believe it was possible because the implied limits of the 13G did not fit with the actual performance they were getting.

    The reason this mix up occured, is a few knowledable people took an educated guess about the compressor on the stock turbo. As urban legends always do, if repeated often enough, they begin to be accepted as fact. The few who ever actually measured the compressor and dicovered it did not match up with the communities conventional wisdom, just kept the info to themselves and let everyone else stumble along with a false impression about the limits of the stock turbo.

    That is one of the reasons that only a handful of us have ever really explored its limits. Most folks accepted the conventional wisdom at face value, threw money at the problem and assumed the new turbo they just bought was a significant upgrade. In many cases it was probably a minor upgrade and if they had known how small of a gain in performance it was, they would have either gotten a bigger turbo or not spent the money at all.

    Lets give the grape vine some time to try to dig up authoritative info on the 13T then we can make intellegent decisions.

    Larry
    13.239@102.85 -- 5800 ft altitude
    on the stock TD04L-13T turbo

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