I installed a Paxton sn92 on my wifes 91 z28 350 tpi car the blower was sent to paradise wheels for a rebuild and upgrade...I installed an AEM air fuel gauge idle is fine go into boost in goes lean...I already have a high flow 255 lph fuel pump installed,I have south bay fuel injection adjustable fuel pressure regulator I have it set to 52-55 psi I wanted it rich well its not the car has 22 lb injectors..how can I get more fuel to make the car rich under boost?....I have paxtons direction no mention of an FMU it does say reduce timing which I did...so any help would be great thanks.....

 

I would say those injectors are way too small. Depending on future mods/boost level I would toss some 36's or 42's on it. 36's should be good for around 550fwhp.

Jay

 

Didn't these kits bolt up to stock 350's tho?...I just don't know how to get the car to raise fuel pressure under boost...do they make FMU's for this?...not looking for 500 hp car is staying basically stock...except for the blower.

 

You could try and pick up a FMU unit if you want to go that root. I never used one myself but you're going to need something to control your fuel cause the stock setup won't do it. Other good option would be picking up a EBL setup and tuning your own car.

 

I have run FMU's on mustangs so I have an idea how to...Were can I get one for the L98 Camaro tho?...I mean I can buy a vortech one new how or were do I get the lines to hook it up And how do I run the lines?....

 

I'm sure there are some used ones out there from all the procharger setups sold, think anyone of them would work for you. The one that came with my kit had some rubber lines you hooked up, can't be to hard.

 

Ok i will see if i can locate one...rubber lines?...im guessing this gets tied into the return lines thought these cars had all hard lines from the rail to the lines going to the tank?...do you just tie into it? i hope there isnt any cutting involed...lol.

 

there's rubber lines going from the front of the fuel rails to the hard lines on the front inner fender/frame rail, you can pumb it in there (easiest to just mount it to the driver's side strut tower).

I know I have one sitting around, but I'm not sure what fittings I have for it (FMU's aren't vehicle specific, but figuring out some way to plumb it into the system might be, unless you're willing to cut the stock rubber line and just clamp it in- it would work but wouldn't be the safest way).

If it was my car I'd get much larger injectors and lower the fuel pressure (the pump will flow more with a lower pressure, giving you more head room, and more room to adjust for boost) and then reprogram the ecm to match the injectors.

 

Thanks for the info...stupid question would you be willing to sell the FMU...and this just ties into the return portion of the fuel line right???.basically cuts off the return and uses the extra fuel. I know its not the best way but it does work no?...My wife has had this car for 20 yrs she wants period correct stuff...i know years back they used FMU's i do have a AEM air fuel gauge so i can at least set a good air fuel ratio by changing discs i think...i wonder, could i lower fuel pressure with the FMU too so it will ramp up from the FMU in boost?....Believe me i would rather do a tune but i do what she wants...LOL....

 

Even wanting period correct, the easiest and best route would be to get larger injectors, hell you could even paint them to match the 22lbers, and reprogram the prom. No one will ever see the prom and at a quick glance you will never even know the injectors were swapped out.

 

who can reprogram the prom for me?

 

You can if you spend a little money on the equipment.

https://www.thirdgen.org/forums/tpi/...-hardware.html

There is more than enough information (and people that are doing it themselves) on this site to be able to get to exactly what you are looking for. My buddy reprogrammed my car one evening and it was the best thing I had done to date and I was only rolling around with a factory 305TPI.

 

That looks good but way past my skills...I might try an FMU and do it that way I was looking at the old cartech FMU which is now B.E.G.I fmu I have a wideband in the car so if I can get it close it will at least be safe until I can get a tune or find someone who can tune it for me...I know its not the best and old way of doing it but it seemed to work back in the day no?

 

If you have a wide band you could get it close with fmu yes-however you may well still need to increase injector size and reprogram the inj size. At least change as needed per wideband the pe % change f/a ratio vs rpm table to dial it in and that should get you to where it's safe for wot.

 

What pe% ? f/a ratio vs rpm table?...some of this is new to me...

 

If you're starting to mod it, time to start reading up at diy-prom......
Most folk here(me included) got the bug to start modifying our engines. Then went the route of paying for a prom tune; sometimes at a shop or mail order or tried both. After enough frustration-and everytime time you throw on a new set of heads etc, you need to retune....you'll want to finally just diy.
It may seem intimidating at first, however if you can tune a car with a carb and wgts/vac dist. then you can tune with the ecm.
Start reading on diy prom-endless knowlege and help there.
oh yea-pe is power enrich(added fuel for wot) the table is where you adjust the fuel air ratio vs rpm. With an fmu and adjust that table you can run it safely.
Then you're ready for afr heads....cam....etc etc!

 

ok I got ya...this is no other mods will be done to this car except for the blower...so maybe the old school FMU will work ok...now for the 89 iroc we have with a cam that will need a tune...lol...

 

36s or 42s on a stock L98?

I'm running 42's on my 600+ HP 412...

-- Joe

 

These are bosch-3's im guessing 22 lb injectors on a stock 350 tpi with a mufflex 4 inch cat back,air foil,TB bi pass, and the Paxton sn92 upgraded with the better impeller so around 6-8 psi tops...I would think I could use an FMU and be ok no?....it maybe is making 350hp tops... Oh yeah it also has a 255lph walbrofuel pump and a south bay fuel injection AFPR...

 

Get an adjustable fmu-use the wide band and go carefully......

 

I was looking into the B.E.G.I fmu its fully Adjustable its the old vortech style seems pretty decent.And yes I would keep an eye on the A/Fs for sure...