i'm gonna do the 3" Gm mas w/ translator setup. I know you can tune fuel with this and i just wanted to know if i should go with some bigger injectors when i do this to aid my tuning. i have a walbro 255 and plan on getting that new FPR natedogg showed us.
the turbo will be an EVO 16G and i wanted to know if bigger injectors will help or harm. i know sometimes too much fuel can be just as bad as not enough. if so what size? 550cc? 650cc??

With a 16g you are going to have to go to at least 550 injectors. If you foresee a turbo larger than a 16g in the near future, the MAF translater will allow you to tune larger injectors in for your current needs.

a little away from topic but i just got a 3" blow through setup going, i have a 14b and stock 450s but it's working awesome! b.o.v is pretty intense also


but this might help...this is the chart you use to turn the knobs for fuel trim settings ... as you can see it really makes no difference what injectors you use ... so go with what ever will support your turbo/boost plans setup

Initial setup:

Set the MODE switch to match the vehicle configuration.

MODE SWITCH: set as follows
1 - OFF for 3” MAF ON for 3.5” MAF
2 - OFF for a 1G (90 - 94) vehicle ON for a 2G (95 - 99) vehicle
3 - OFF for NO Fuel Cut Limiter, ON to PREVENT FUEL CUT
4 - OFF for Flat AUX fuel control, ON for Contoured AUX fuel mode.

Set the BASE dial according to the table to match the installed injectors. If the vehicle ECU is equipped with a ‘CHIP’ that compensates for larger injectors, then calculate the BASE setting as follows.

% change = (1 - (Injector size of ECU / Injector size installed) * 100

eg. Stock ECU = 450, 550’s installed 1-(450/550) *100 = 19%
(the Translator must be set to 20% lean for 550’s. The BASE 4 setting is for 550’s)

BASE Switch: set to match injectors and fuel system.

Dial Setting % flow change Injector size Dial Setting % flow change Injector size
0 0 Stock (450) 8 -40% 750
1 -5% 475 9 -45% 820
2 -10% 500 A -50% 900
3 -15% 525 B -55% 1000
4 -20% 550 C -60% 1100
5 -25% 600 D -65% 1250
6 -30% 650 E +10% 400
7 -35% 700 F +5% 425





Idle, Mid, WOT, and AUX all follow the following table.

Dial Setting % flow change Dial Setting % flow change
0 0 8 35%
1 5% 9 -35%
2 10% A -30%
3 15% B -25%
4 20% C -20%
5 25% D -15%
6 30% E -10%
7 35% F -5%

I ran 17-18 psi on a 16g on my old car with the stock injectors, stock fuel pump, and stock fpr with little to no knock. 550's would definitely be good insurance, but in my case they weren't necessary. Of course I had a regular 16g, not an EVO III 16g. That one may flow enough to require larger injectors. In any case, if you've got the money, get the 550's.

550's will work just fine...some of the 20G guys (that can tune well) run 550's w/their turbos...the AFPR should help you out, in that regard, tremendously. Although, for that type of fine-tuning you'd need a SAFC. But 550's will be good for the Evo16G. You should also plan on an intercooler upgrade, too.

I'm not exactly sure why we always end up on differring opinions of a discussion Nate...It's disheartening though.

I'm sure there are few that will wring their cars and turbos out as far as I dare to, but in case you do keep in mind that I was consistently out flowing my stock injectors capabilities with a 14b and knock was always through the roof.

The only thing I disagree with in your original post is where you say he HAS to go with at least 550's. You know how well my car ran on the stock fuel system with the 16g. You logged it with me plenty of times. But like I indicated in my previous post I think 550's are a good idea, necessary or not, better to go with the insurance than to later find out you should have. So I did agree with you that its a good idea, just not that it may be absolutely necessary. Basically, giving my spin on it based on my experience with a 16g turbo.

I attributed much of your knock to running 19 to 20 psi on a 14b turbo. Way out of its efficiency range, esp. on a stock sidemount IC. Not necessarily overrunning your injectors. You may remember still knocking like a whore even when you switched up to 550's. Buuut 19-20 psi felt better to the famed butt-o-meter, so that's what we stuck with. (Disclaimer: it felt faster to me too, yet at the expense of another engine, but that's cool because the ragged edge is your thing and I respect that.) Remember I was only running 17-18 psi on my 16g, which is even still a more efficient turbo than a 14b. This helped keep my knock down even on the stock fuel system.

Also, the fact that WI helped knock down your knock counts by cooling the air charge, lends itself to an inefficiently hot air discharge from your turbo causing the nasty detonation, rather than insufficient fuel supply.

See you just don't stop...

After the things I've seen...I am not giving out advice for anyone else that may cause engine failure if I can help it. I on the other hand will probably continue to run as lean and as fast as the motor will take.

My writting skills didn't lend themselves very well to my point earlier, but I wasn't implying that the knock was totally from fuel starvation. Sorry if that's the way it came out. I write much clearer with pictures graphs and tables so let me try something like that:

Fact: I wring my car and turbo out as far as possible for speed (def: lean and hot due to funds and high psi)
Fact: My 450 injecector duty cycle was always over 100%, If I remeber right it was in the 110% range
Fact: I have burned holes in the number one piston twice due to lean condition (Once with water injection)
Fact: Knock in third and forth gear were almost always above 30 and into the 40 range even with WI
Fact: I ran at a regular level of 17-18psi on the street (Some other moments included 20 and 24 at 12.67)

My Conclusion (and closer to topic): More fuel could have prevented engine failure a 'friend' of mine used to tell me ALL the time. So I'm passing out that advice to others that may otherwise unknowingly torch a piston and wonder WTF happened!? I knew what would happen and I can and am living with it...no sweat. But for me, it aint fun unless it's ragged edge fast. Sick isn't it.

BTW - Thank you for substantiating my claim that we both were able to feel the car accelerate quicker by the Ass-meter once we had it close with the loggers readings. And actually that second engine didn't bite the dust until I cranked the boost back up to 24ish with race gas on the hot humid summer night at Cordova's Midnight Mayhem.

i was running this all the time

i was hitting a nasty fuel cut with stock injectors but when I upgraded to my 550cc injectors, I was good to go, stock sm intercooler, stock 14b turbo.

I understand your side of the story, Marcus. In my experience with logging other 14b DSM's none of them have ever knocked as much as yours. Take either Dan's GST or GSX for instance. Take my old GST for instance. For some reason your car always ran hotter and leaner. I don't know if this has to do with your worked head or the fact that you like to manually advance your timing or some strange possesion of an evil detonation spirit. You may have had your boost set at 17 psi but as is usual on a 14b at those levels it crept higher as I remember from logging anyway. More fuel may have been a decent bandaid for the gobs of hot air that the 14b was blowing, but thats all it was even when I was suggesting it. You knew you were running the 14b out of its efficiency range so I figured I'd offer any advice that could be helpful. Even though we both knew you just needed a larger turbo or at least a fmic for the boost levels you were running and the knock counts we were seeing, even after you had upgraded to 550cc injectors, which are more than enough for any 14b.

BTW, I have some of your logs sitting right here in front of me though and every time your car tried to edge over 100% DC you hit fuel cut, none of the ones I'm looking at show your car hitting 110%. But some have been deleted, so I may be missing some.

Yeah, you had varying experiences with the 14b on varying fuel and cooling setups I had a good experience with the 16g on my stock fuel system, which was my original point. I'm not saying everyone will, but I did. I'm currently having a great experience with the BR500 on a far from stock fuel system and soon you will too.

Hhaha...yeah I think evil spirtits is a possibility.

And on those logger runs with the 100% inj duty cycle. Those had to be with the 550's because I never hit fuel cut until I got the MAFT and the 550's. Go figure. Oh and spikes...definitely to 20psi!

I think it's funny how you are saying fuel can be a bandaid like I always said and I'm trying to tell people to be consrvative with their fuel management like you always preached. Crazy.

I hear ya.

Hahaha! Yeah, good point. I love these discussions. Keeps things from being mundane.