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PostPosted: Thu Sep 22, 2011 4:42 am 
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Joined: Sun Sep 11, 2011 4:41 am
Posts: 4
Location: new zealand
i have brought i mitsi cyborg 4g61t with 4g63t injectors which means its gone from 390cc to 450cc size injectors :toimonster: , but thats all, so its running very rich at the moment and has sucky proformance, i recently brought a adjustable fuel reg and am now just waiting for the adaptor in the mail along with a boost tap, does anyone knw a cheaper way to make use of this extra fuel rate? as im an apprentice and cant afford dyno tuning and think itd be a waste to down grade back to stock :( would a airflow meter help? or would i need the ecu to? if i do, does anyone know how to rewire for this different ecu?


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PostPosted: Thu Sep 22, 2011 8:40 pm 
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The Silent Administrator
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Joined: Wed Dec 24, 2003 3:32 pm
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Location: Ottawa, ON, Canada
If you have the stock motor and no complimentary upgrades to follow with the 450cc's (or 1G style injectors), then put the 390 cc's back in.


What you need to make the 450cc work properly and without much consequence is as follows:

1G 4g63t ECU (main computer behind/below the factory radio)
1G FPR (fuel pressure regulator)
1G 450cc injectors
1G MAF (mass airflow sensor)
Fuel pump rewire kit
Intercooler and piping
Boost gauge
Full width 4g61t radiator and fan(s) if you only have the half size

If you want to up the boost you can add:

MBC (manual boost controller)
1G early or later model ECU with EPROM and tuning for larger injectors and deadtimes, fuel maps for higher boost ceiling, MAS upgrades, etc)
1G cams
2G MAS
Wideband 02 sensor and gauge

This is the safest approach currently available, where no tuning is required and will be turn key and go, if all parts are working properly.
Once you get into random cams, higher boost, datalogging (well you should have this anyways), AFPR (aftermarket fuel pressure regulators) and so forth, it becomes quite complicated and less fun in my books.

Stay close to stock in terms of components and it will be easier to replace, repair and still bring lots of smiles to your face.
If you cannot afford to break it ....

Manuals here:
www.lilevo.com/mirage/
www.lilevo.com/mirage/Manuals/

Get the engine running correctly on the stock sized and matching components then move forward.


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PostPosted: Thu Sep 22, 2011 9:09 pm 
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Spends Too Much Time Under The Hood
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Joined: Sun Apr 20, 2008 1:00 am
Posts: 375
Location: Tacoma, WA
If it were me, since you already have the 450s installed and have an adjustable FPR, I'd install it and try turning down the fuel pressure a bit. Stock 390s are set at 36.3psi base fuel pressure. Its certainly not optimal but I'd try lowering the base fuel pressure to 34psi, see how it runs, 33psi, etc. I'd be cautious when going lower than 30psi base pressure. Make sure you drive it easy and see how its running. 30psi on a 450cc injector equals 409cc which is a lot closer to the 390s.

RC Engineering has great injector calculations on their website. http://www.rceng.com/technical.aspx?Use ... oEfFxqqrxf

_________________
'89 Colt GT w/bigger than stock turbo
'91 Talon AWD w/bigger than stock turbo
'05 Dodge diesel w/bigger than stock turbo


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PostPosted: Thu Sep 22, 2011 9:17 pm 
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Joined: Sun Apr 20, 2008 1:00 am
Posts: 375
Location: Tacoma, WA
Another "old school" mod from back in the early '90s is to just lean out the airflow meter. If I remember right a turbo CSM MAF doesn't have a lower honeycomb (someone correct me if I'm wrong). If it does you can remove it (JUST the lower one though, the larger upper one HAS to straighten out the airflow or else the meter won't measure air correctly). If not, then you can also back out the large plastic "fine tuning" screw that goes into the bottom of the MAF bypass chamber. Just back it out so it's flush, don't totally remove it or it'll allow unfiltered air into the turbo. And from there you can cut out the middle divider, and/or hollow out the lower chamber more to increase bypass air. Then last but not least you can totally hack that lower chamber totally off. :D But the more you free up airflow through that bottom chamber, the more air is entering the engine that is UNmetered. That leans out the a/f ratio and if you go too much you will need something to compensate, like ECM Link, old AFC, SAFC, etc.

_________________
'89 Colt GT w/bigger than stock turbo
'91 Talon AWD w/bigger than stock turbo
'05 Dodge diesel w/bigger than stock turbo


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PostPosted: Thu Oct 20, 2011 2:31 am 
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Joined: Sun Sep 11, 2011 4:41 am
Posts: 4
Location: new zealand
thanks eveyone for your help, will work on car a nd see what happens :)


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