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Discussion Starter #1
So i have been reading on doing this on my 7mgte and what I have seen is that if you use the lexus afm you have to use 550cc injectors to match so that your ecu will take this in right and this can be run on a stock ecu no tuning required. thats pretty awesome but question is why? is there a power gain in this at stock psi? or is it just nice for future tune-ability? oh and happy 4th of july everyone! :salute:
 

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I'm pretty sure there are no gains with this mod on stock boost. Also, as I understand it, you need an SAFC or your car is going to run rich as hell.
 

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From what I remember on this, with 550's and the matching AFM, you dont get more power stock, but you do get the ability to boost higher before hitting fuel cut.. I could be wrong though. I thought the lexus AFM let you run the larger injectors with out ecu issues/needing a AFC..
 

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Discussion Starter #4
IF-you dont want to spend the money on an AFC, and retain stock ECU, you have to retain 440/stock afm, or 55o/lexus afm combos, as stock computer cant adjust outside of its programmed learning curve. Whatever you do, you will need a good wideband to "tune" with. Unless everything else was given to you free, no reason at all not to have one already....
according to carfreak it does work with stock ecu
 

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Good to hear. I must've been thinking of something else. I'm pretty sure theres tons of threads on this subject on supramania.
 

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the afm for the Lexus v8 is larger diameter but otherwise a Karman vortex unit like the 7mgte stock afm so it's a cheap easy way to get some better breathing into your 7mgte and keep it relatively stock. Increasing injector size from 440 to 550 correspondingly increases the fuel delivery
 

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It does two things. First, you increase fuel and air delivery by 25%, so even at stock boost, you will see a power increase, figure 15-20% with stock ECUs "tuning" ability. Second, the larger diameter means a given volume of air moves slower past sensor, allowing more air to flow for a given sensor output. This means you can run higher boost levels before fuel cut sets in. On stock AFM, Fuel cut happened at 12 psi with my car. I still havent seen it at 18 psi with same turbo. Heres a very old link.http://www.suprasonic.org/public_html/lexusriemer/lexusnotes.html
 

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Discussion Starter #9
yeah im really wanting to do this little upgrade just still lookin for some good injectors. Im hoping by now everyone knows about venoms so thats out, I have seen alot of deschworks (sp) injectors around but to be honest i havent heard much about them, im probably just going to spend the money and get some rc ones soon cause they are reputable company.
 

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Discussion Starter #12
long story short from article.......use lexus maf housing but 7m sensor.....air goes through slower because afm housing is so much bigger.........ecu thinks less air is comming in because sensor reads less but is actually more than it knows and computer has to compensate to make it run not as lean........putting in bigger injectors (550cc) compensates for this accordingly. this helps keep you away from fuel cut, because your maf's normally stock readings set it off with the lexus one it reads much less so inturn..........WIN! Oh and according to article should run just as perfect as stock with strong idle.
 

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550's and lex afm are a waste of time if your still on stock ct26. IIRC damon had 440's with the lex afm running a little over 300rwhp on 12-14lbs of boost on the stock ct26.
 

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Buy an AFR, increase base fuel pressure by 10 lbs, injectors now function like 550s.. No need to pull intake.. done..
 

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Discussion Starter #16 (Edited)
meh intake mani is already off so i dont really care about that. So stock is 40 so bump it up to 50 and would be the same....but wouldnt it still be fairly close to duty cycle? its weird that 7mge is 44 and gte is 40 (just read that) and 300 is more than enough power for me for right now probably :p
 

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300 horsepower will get old in about a month....well got old for me in about 1 week. :)
 

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550's and lex afm are a waste of time if your still on stock ct26.
Not for me it wasnt. I started with 440/stock AFM. Then I put Lex AFM on and bumped fuel pressure 10 lbs or so. Then I bought 550s and lowered fuel pressure to stock. Each step was an upgrade, Ive got timing slips to show MPH increases. First step was 2-3 mph in quarter mile, second step was 4-5 more. Bumping fuel press with Lex/440s ruined my idle, and cut my mileage. I can also run even more boost with 550s, because fuel cut IS higher with 550/lex, than with 440/lex. No, it aint MR Fusion, but the 10 minutes it takes to change intake, and the hour it took to wire in Injectors IS well worth it....
 

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440's/lex combo gave me 10.6-11.2 afr's

550's/lex combo gave me 9.8-10.3 afr's.....PIG RICH

Both were ran with stock ct26 @14lbs with zeitronix wb. If i still had my old laptop i would post up my logs. With that being said each car is different, but if this guy only wants 300rwhp why would you even get the 550's unless you want to upgrade later??? 440's will suffice his little stock ct26.
 

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440's/lex combo gave me 10.6-11.2 afr's

550's/lex combo gave me 9.8-10.3 afr's.....PIG RICH

Both were ran with stock ct26 @14lbs with zeitronix wb. If i still had my old laptop i would post up my logs. With that being said each car is different, but if this guy only wants 300rwhp why would you even get the 550's unless you want to upgrade later??? 440's will suffice his little stock ct26.
I run 11.5 -1 with either setup, with 10 lbs less fuel press, and 5 lbs more boost with 550s. At each upgrade stage I tuned engine for VF correction, by changing fuel pressure. Then tuned for 11.5 WOT with AFC. Anyone with an AFPR, SAFC or equivalent , and wideband can do same. I got the 550s to allow for more boost, without upgrading turbo.
 
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