Boost lag
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This is a discussion on Boost lag within the Engine Modifications forums, part of the Tech & Modifying & General Repairs category; I have an 05 wrx with an ej22 engine swap. I also have larger injectors an 18 t bloushe turbo. ...

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    Boost lag

    I have an 05 wrx with an ej22 engine swap. I also have larger injectors an 18 t bloushe turbo. I don't hit boost until like 4000 rpms right now. I feel like it used to be better when I first got it. I'm going to a front mount intercooler in a month or two. I'm wondering if this would help. I also have been considering an engine management system other then my stock reflash but I have no idea what to buy. I haven't had it tuned in 5 or 6 months.

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    Registered User Ingo's Avatar
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    FMIC will likely inrease you lag, not decrease...
    I have the 2.5L with an 18g (I think) and FMIC, it starts to whine at under 1.5KRpM and really goes to work at RpMs after 3K. At 4K is probably the most push. But in all actuality the boost starts probably at about 2K, then gets stronger and peaks at about 4K.
    You can't have everything - where would you put it?

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    Pro Manscaper Mikie13's Avatar
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    If you move to a different Intercooler, you should have it tuned again. But you will notice more lag if you go FMIC. You'd be better off running an upgraded TMIC.

    Also, what kind of a boost control system are you running?
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    Well I don't have a manual boost controller so I'm assuming whatever comes stock. Well why does everyone run fmic if it creates more lag?

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    MAINEiac 11blackSTi's Avatar
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    Quote Originally Posted by Chas View Post
    Well I don't have a manual boost controller so I'm assuming whatever comes stock. Well why does everyone run fmic if it creates more lag?
    Everyone doesn't, but if you are running a rotated turbo then fitting to a top mount intercooler usually won't work.

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    \_(ツ)_/ Rambo's Avatar
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    Quote Originally Posted by Chas View Post
    Well I don't have a manual boost controller so I'm assuming whatever comes stock. Well why does everyone run fmic if it creates more lag?
    There is a ton of writeups on TMIC vs. FMICs. No need to rehash information that is already widely available. Here's a solid article on the topic: Why you don't need a Front Mount Intercooler on WRX STI | R U Subaru? - Tuning Forced Induction Cars and Alcohol Injection

    As for your spool, you would do well to post some log files to shed a better light on what's really going on. It sounds like your tune is the biggest culprit. If you decide to have the tune revised, adding a EBCS and tuning for that should help improve spool, although with your engine swap, you'd have to be sure the EBCS you chose was compatible.
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    Master Baiter EJ257's Avatar
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    Quote Originally Posted by Rambo
    There is a ton of writeups on TMIC vs. FMICs. No need to rehash information that is already widely available. Here's a solid article on the topic: Why you don't need a Front Mount Intercooler on WRX STI | R U Subaru? - Tuning Forced Induction Cars and Alcohol Injection
    There are some things that I disagree with in that article (specific values, but agree with the theories behind them), based on my experiences. An 18G turbo shouldn't demand more cooling than a good TMIC, though, so a FMIC would not be my recommendation unless you're looking for drag racing setup, in which you'll be able to run a bit more aggressive tune (with the same safety margin) with a FMIC vs TMIC.

    Quote Originally Posted by Rambo
    As for your spool, you would do well to post some log files to shed a better light on what's really going on.
    Yes. What do you have the ability to log with? I can give you a list of parameters to log, so you're not logging extraneous data and wasting bandwidth.

    Quote Originally Posted by Chas
    I also have been considering an engine management system other then my stock reflash but I have no idea what to buy.
    A standalone ECU will yield little/no benefit on your setup. The OE ECU logic is more than capable of handling your setup.

    Quote Originally Posted by Chas
    I haven't had it tuned in 5 or 6 months.
    Who did the tune? Did the tune include road datalogs/reflashes?
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    Pro Manscaper Mikie13's Avatar
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    Quote Originally Posted by Chas View Post
    Well I don't have a manual boost controller so I'm assuming whatever comes stock. Well why does everyone run fmic if it creates more lag?
    Not everyone does run an FMIC...and to be honest, a lot of the people that run it will run it for the "bling" factor of having an awesome looking FMIC for everyone else to see.

    I only ask about the boost control set up because there are a couple options you can play with that can increase some spool, main one being a Hybrid boost control setup with an aftermarket manually boost controller and an EBCS. This is something that would need to be tuned for completely though.
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    Registered User Heide264's Avatar
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    Aside from the FMIC debate (I wouldn't recommend one), go get a good tune. Look around for somebody that does Open Source tunes - otherwise you have to pay for a Cobb AP.
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    OMG WTF MainFrame's Avatar
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    If you want less lag, get a bigger engine, or a smaller turbo.. anything else will only produce negligible gains (unless you are experiencing some sort of mechanical issue, or a crappy tune).

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    Right now I have some crappy Chinese TMIC I believe because when I got it it was painted and said grimspeed on it. Pretty sure grimspeed doesn't make them. I'm wondering if a good top mount is in order. And as for the Cobb access port should I get one because my friend got one and he said the tunes available on the access port made his car slower then the one he had before.

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    OMG WTF MainFrame's Avatar
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    Quote Originally Posted by Chas View Post
    Right now I have some crappy Chinese TMIC I believe because when I got it it was painted and said grimspeed on it. Pretty sure grimspeed doesn't make them. I'm wondering if a good top mount is in order. And as for the Cobb access port should I get one because my friend got one and he said the tunes available on the access port made his car slower then the one he had before.


    A good TMIC, (like the Process West one) would probably be a good thing.



    As far as the Access Port, Cobb does not make a map for your modifications, and even if they did, no off the shelf map would be as good as a real tune. You could still use an AP, but you would need to pay someone to tune it.. in which case the AP is not really a cost effective way to go.

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