What size injectors do I need?

[toomanymodz]

Well, I just installed a new WB 02 sensor to see where my A/F ratios are. Under WOT, the A/F's were around 11.6 to 12.0, which is a little on the lean side for sure. My injector duty cycles were between 94% and 99%. (Yikes! I know!). I'm running 23# of boost with 110 leaded fuel. I'm getting a small amount of retard (around 2.5 degrees). So I decided to see if I could add a little fuel to richen it up a bit. I moved the Max Effort thumbwheel from position C to position D to add WOT fuel. This helped the A/F's a little, putting it at 11.4 to 11.7, but my injector duty cycle worsened and hit as high as 102.2% (never knew it could exceed 100 percent). Knock retard got a little worse and hit 3.2 degrees. I would like to see A/F's between 10.9 and 11.3, but there is no way these injectors can do that.

I'm running a stock shortblock, stock cam. Ported irons, PTE-51 turbo, stock MAF, huge FM intercooler, Vig 3200 LU converter and 009 (43#) injectors. The previous owner has ran a best of 11.27 with this combo and the car ran 11.30's-11.40's all day long. I'm not sure how he got away with this for so long.

It's obvious that I am out of injector. I'm debating whether to go with 50#, 55, or 60s. Thoughts?

 

[bison]

If you dont plan on making much more power any of what you posted will work. Your too lean otherwise. You could turn up the fuel pressure to richen it of the pump is up to it.

 

[toomanymodz]

If you dont plan on making much more power any of what you posted will work. Your too lean otherwise. You could turn up the fuel pressure to richen it of the pump is up to it.

Wellllllll, eventually I'd like to swap out the PTE-51 for a more 'modern' turbo. Perhaps a 6262 BB :biggrin:

According to the time slips I got with the car, it would trap anywhere from 116 to 118 MPH. I'd like to get it up to around 122 eventually, but I'd rather not run much more than around 22 or 23 lbs of boost.

I've ordered a new race helmet from Summit and plan to take it to the track soon. I want to work out any gremlins first. Zero knock is a good thing.

A friend of mine just bought some fully CNC'd Champion irons. They look awesome. I may buy a pair later this year.

 

[Boost231]

depends on what you final goal is with the car. i would get the 60's. if you get alky you can take the 60's pretty far.

o and turn the boost down. you wasnt 0 knock. at 23psi .5 deg can hurt the motor real fast let alone 2.5

 

[bmackinnon]

Mototron 60's are the most modern design... idle smooth as glass at low pulsewidths.... and should be plenty... go with them... and since you'll need a new chip, turbotweak FTW....:wink:

 

[toomanymodz]

Sounds good. I've ordered some 60s and will order a TT chip next. I'm running a stock MAF with no screens. Doesn't the TT require one screen?

 

[bison]

Sounds good. I've ordered some 60s and will order a TT chip next. I'm running a stock MAF with no screens. Doesn't the TT require one screen?

You will have to tell him no screens. Be sure to get another chip burned when you get the bigger turbo and want more mph.

 

[87GN_70GS]

43#/60# x 102% = 73%

With the 60's, you should be down in the 73% dc range, which will give you plenty of safety margin and room for future growth.

 

[toomanymodz]

You will have to tell him no screens. Be sure to get another chip burned when you get the bigger turbo and want more mph.

This sentence is from his website:
"If you have a stock MAF, make sure it has at least 1 screen in it (stock MAF's had 2 screens). NO screenless MAF's, it really screws up the calibration."

I sent Eric an email to see if I can go screenless anyways. I really don't want to have to buy a new MAF. I wonder if there is a way to put a screen back in there.

 

[bison]

This sentence is from his website:
"If you have a stock MAF, make sure it has at least 1 screen in it (stock MAF's had 2 screens). NO screenless MAF's, it really screws up the calibration."

I sent Eric an email to see if I can go screenless anyways. I really don't want to have to buy a new MAF. I wonder if there is a way to put a screen back in there.

There are guys on here running screenless stock MAF's. Id only expect it to be a problem at low engine speeds where the air is more turbulent at the meter. Maybe a simple open loop calibration. Email Eric. Fwiw i run a screen in mine and have made a lot of power with the screen in it over the years. I always wanted to test 1 screen vs. no screen

 

[toomanymodz]

I finally heard from Eric. He strongly recommends that I run one screen. He cannot guarantee that the chip will run right without a MAF screen.

So, can I add a screen to my stock MAF, or is screen removal a permanent thing that cannot be reversed. If so, I'll have to buy another MAF.

 

[Boost231]

you can put the screen back in. you just need the screen and the plastic circle clip

 

[toomanymodz]

you can put the screen back in. you just need the screen and the plastic circle clip

That is certainly good news. The big challenge will be to find someone who wants to sell just the MAF screen and clip. I have PayPal :biggrin:

 

[Clark6]

I finally heard from Eric. He strongly recommends that I run one screen. He cannot guarantee that the chip will run right without a MAF screen.

So, can I add a screen to my stock MAF, or is screen removal a permanent thing that cannot be reversed. If so, I'll have to buy another MAF.

Just get a maf translater and run the LT1 3" maf. I bought one a while back off ebay for like $45. I have a harness adpater if you need it for the Lt1 ($10 shipped).
Or , I now have the translater with a z06 MAF.

Either way you go , its better than stock in my opinion.

 

[toomanymodz]

A fellow turbobuick member has graciously stepped up and donated me a MAF screen and clip. My 60 lb injectors arrived today and I've ordered the TurboTweak 6.0 chip from Eric. This is all coming together nicely.