EVO III 16g,MAFT GEN II, fuel injector suggestions w/ setup

[micahmr2]

Need some help, have done alot of research, but heres my question. With my setup, not sure if I should go with 550's or 660's. My thoughts are with a GEN 2 MAFT (more or less a translator w/ an AFC built in, for those that don't know) I don't plan on buying a DSM link, plan on selling car within 6 months. 550's might not be enough to run 20 psi daily driving, 660's are pushing the limits of the MAFT gen II. Any thoughts

 

[v2ner]

I assume you'll be runnin pump gas. See if you can grab a hold of EVO 8 injectors(560cc). If you're going to sell it, I suggest you should only run 18psi at the most. I also don't know how good your tuning skills are.

 

[micahmr2]

I thought about that but for the price I can get 660's for a little more. Plus I want that extra safety cushion, why only 18 psi? Or will those injectors max out.

 

[v2ner]

Because 93 octane doesn't like anything pass 18psi much. Your extra cushion is a fuel pump and AFPR.

 

[micahmr2]

Which I have, undertandable. So 660,s too much, I kinda thought that would be bordine for tunabilty. Thanks

 

[v2ner]

Well, what I'm saying is that you can do it safely on 560ccs. If you can get 660cc for the same price than you might as well go for it. Most people will say 660cc will be the limit for the S-AFC but even 720cc is ok.

 

[micahmr2]

Whats the percentage difference on 660's like 67 %

 

[dsm-onster]

Because 93 octane doesn't like anything pass 18psi much. Your extra cushion is a fuel pump and AFPR.

I am not flaming, but pump gas can do lots more. . .

I ran fine w/ my maft a PTE 660s. Back when I had them... You have to accept that deadtime is a part of injector upgrades... Therefore you'll have to tune your maft rich for idle (not rich running, increasing your idle airflow sent to the ecu is what I mean) to get it to run right. It was fun and quick spooling. I ran my small 16G and loved it at 20 psi!!!

You have an intercooler upgrade. You may not want to sell once you get a decent BASE tune...

 

[dsm-onster]

(450cc/660cc) - 1.0 = 0.682 -1.0 = -0.32 = -32% offset

Definately not 67%. 100% - 67% = 33% (or 32% as above considering all the rounding I did). You have to think the other way around .

 

[micahmr2]

Sorry for the delayed response.

The gen II MAFT has adjustment just like an AFC, so you can tune main scale and individaul rpms points like 14 I think. I just didn't want to go to big (660's) for timing issues. Any suggestions on setting base timing going either way 550's or 660's

 

[dsm-onster]

Leave your base timing alone (stock). Your off idle and less-than-boost light acceleration will suffer. Been there, done that . Timing advance from 650cc offset is GYOOOD . Unless you can't maintain control of the knock. You have a decent fmic. Don't shoot for super high boost just low air temps, high timing, and a lean clean tune. It will be fun. And make anyone want to buy, even yourself !!!

 

[micahmr2]

Thanks, 650's for me. Ill go for that. Bought a truck, car's gotta, don't want it to go, trust, wife says so. She's the boss

 

[dsm-onster]

How much is the car costing you? Will it be used for paying back the budget for the truck? I know where you're coming from. My wife hates my car. . . look at my mods !

 

[oldman]

Whats the percentage difference on 660's like 67 %

I'm going to guess that math was not your favor subject.

 

[micahmr2]

Tha car is costing me no money, other than insurance, other than normal DSM repairs, but the return on the car will put a dent in the price of the truck. Though if I don't get what I want then it's not worth selling.


Oh and by the way, you're right oldman math was not a strong point, worse since I'm getting old.

 

[DEEB0rider]

i have no experience using this for tuning...but i am pretty solid on the math and i think you are both wrong

should be (660-450)/450 = +46.7% offset

or can be interpretted as 450 x 1.467 = 660

 

[JWoodley]

I'd run the EVO injectors. From what I'm gathering they perform close to a 600cc injector (read 590cc). Goodluck with the car! When you get her running well you aren't going to want to sell it. Been there, done that...

 

[oldman]

i have no experience using this for tuning...but i am pretty solid on the math and i think you are both wrong

should be (660-450)/450 = +46.7% offset

or can be interpretted as 450 x 1.467 = 660

This is not correct.

It's either (660-450)/660 = .318 =31.8% or

450/660 - 1 = -.318 = -31.8% adjustment.

 

[DEEB0rider]

i still dont agree with that math...660 is offset from a base of 450. 31.8% of 450 is 143.1. if you do 450 + 143.1 you get 593.1 and not 660 like you would expect. however 46.7% of 450 is 210. 450 + 210 = 660

According to the MAFT manual, in order to adjust for 660s.... you set the base knob to 8 (+35%) and the AUX knob to 5 (+10%). this results in an overall offset of +48.5% (1 x 1.35 x 1.10 = 1.485)

check for yourself

http://www.fullthrottletech.com/attachment.php?attachmentid=72&d=1103666303

 

[dsm-onster]

i still dont agree with that math...660 is offset from a base of 450. 31.8% of 450 is 143.1. if you do 450 + 143.1 you get 593.1 and not 660 like you would expect. however 46.7% of 450 is 210. 450 + 210 = 660



http://www.fullthrottletech.com/attachment.php?attachmentid=72&d=1103666303

My and Oldman's math comes straight from the DSMLink manual which discribes injector offset as piggy backs generally do. As I know the MAFT does. I used the math to get my 1000cc injectors dialed in to w/in 5% in the fuel trims. See DSMLink User Guide on the dsmling website. If I use your math I wouldn't even be able to idle

According to the MAFT manual, in order to adjust for 660s.... you set the base knob to 8 (+35%) and the AUX knob to 5 (+10%). this results in an overall offset of +48.5% (1 x 1.35 x 1.10 = 1.485)

WTF ! This guy is a 1G so why are you discussing a 2G postion of 5 for 660 injectors. I was shipped a paper copy of that manual when I bought the maft. . .

check for yourself

I did. I ran 660s and maft for years. It refers to using position marked "1" for 660 cc injectors. You really should do more research before you assume that your logic is in fact logical. Remember:

i have no experience using this for tuning

Just because it makes sense to you, . . .

I've used position 1 on the auxilary for MY 660cc injectors and ALL of EVERY person (who uses 660s and a MAFt) tune w/ the 1 position on the auxilary knob. . .

 

[oldman]

i still dont agree with that math...660 is offset from a base of 450. 31.8% of 450 is 143.1. if you do 450 + 143.1 you get 593.1 and not 660 like you would expect. however 46.7% of 450 is 210. 450 + 210 = 660

According to the MAFT manual, in order to adjust for 660s.... you set the base knob to 8 (+35%) and the AUX knob to 5 (+10%). this results in an overall offset of +48.5% (1 x 1.35 x 1.10 = 1.485)

check for yourself

http://www.fullthrottletech.com/attachment.php?attachmentid=72&d=1103666303

The way injector compensation work on devices like SAFC, DSMLink....etc. is that you're calculating what is the percentage DECREASE required to make the 660s flow like 450s, not the percentage INCEASE required to make 450s flow like 660s, because compensation is done by subtracting airflow, not by adding fuel. For example, one needs to substract 31.8% of 660 from 660 to make it flow 450. 660-(660*.318) = 660-210 =450.

I have always been under the impression that MAFT operates under the same parameters although I have never had the opportunity to tune with MAFT personally, I will study the MAFT manual you linked tonight and give you a better answer.

edit: Matt answered your question on MAFT, no reading for me tonight yeah...

 

[DEEB0rider]

The way injector compensation work on devices like SAFC, DSMLink....etc. is that you're calculating what is the percentage DECREASE required to make the 660s flow like 450s, not the percentage INCEASE required to make 450s flow like 660s

this is where i got confused...like i said, i havent used this to tune anything before and to me it goes contrary to logic and it may have come across the same way to others. but now it is clear to me, thanks fellas

 

[oldman]

No problem.