Advice - Economical fuel delivery for Turbo

[Schmieder]

Planning 4-7 psi boost. 1996 Grand Prix 3100/3400 top swap.

Everything seems simple enough until I get to the fuel delivery issue. I read some people claiming stock injectors w/ stock ECU will work fine.

But my stock injectors are getting replaced anyways due to age and want of newer injectors. I am looking into 36lb injectors.

BUT, I keep hitting walls regarding tuning. I can't swap to OBD1 due to emissions and tranny. Can't budget in Megasquirt yet after all other heavy expenses that come with the turbo project.

And the issue about blowing up the enine when I hit rev limit! UGH!!! The headaches. I believe an after market timing retard could stop spark to prevent that though, not sure of the effects.

Now, I have a few ideas and need advice...

(1) Someone mentioned swapping an ECU from a 1997 Lumina. As it is a tunable OBDII ECU and will fit my harness just right. Is that correct? At that point I could get a cable and utilize freeware tuners.

(2) Use a 6:1 FMU with adjustable FPR and tune using a wideband o2 sensor w/ gauge (have it already)

(3) Run 4 psi on full stock and increase gradually until wideband shows a leaning effect, then drop back a bit.

Stronger Fuel Pump will be put in by shop just after the build. I'm sure I can soft foot the pedal to the shop safely. I really don't want to drop the fuel tank myself.

Is there an economical fuel/spark piggyback controller that will work on my ecu?

Every bit of advice is very much appreciated.


btw, I would have posted in a currrent thread I started but everytime I log into that thread I get logged out and can't log in again. Very strange.

[1988GTU]

I'd use what you have and tune it with dhp. Injectors are all you will probably need with 4psi. ... I have some 28 pound injectors AND 22 pounders that would be of help. PM if interested.

DHP will end up being a cheap, proper alternative.

[Schmieder]

I'd use what you have and tune it with dhp. Injectors are all you will probably need with 4psi. ... I have some 28 pound injectors AND 22 pounders that would be of help. PM if interested.

DHP will end up being a cheap, proper alternative.

Yeah but DHP doesn't support 1996 Grand Prix. From what I read the ECU isn't tunable. Or is this just a liability issue regarding mixed ECU's in 96 models?

those injectors you have may be an option. I'll be in touch if I choose that route.

[1988GTU]

Not from what I read. I suggest digging deeper into that area.

[Schmieder]

Not from what I read. I suggest digging deeper into that area.

Basically your saying I can buy the DHP Tuner and it will work for my ECU?

If that is the case, all is great.

I do want to push 6-7 psi. Probally 6 psi max on a stock engine for now.

So why do people say DHP won't work for 96's? If you don't mind me asking.

[Schmieder]

Ok, so I see I CAN tune the 96 ECU but it has less tables to work with.

Seems like a silly question but, what exactly does 'less tables' mean? Lower resolution to rpm?

If I can tune for new # injectors and turbo install, thats all that matters. Well, except for up'ing or removing the rev limit.

Heck, I've hacked many electronics with linux. I can't see why a vehicle ecu would be any different.

[1988GTU]

There are limits to a 96 pcm, and limits to the 97 pcm. It all depends how far you want to take tuning to the next level. A 96 PCM should be fine with mild boost and a simple engine configuration.

I am not fluent with obd2 tuning like I am with obd2 problem solving, but if I had to guess, it will just lack fields in the programing where you cannot make certain changes as you could with 97 and 98+. Will it hinder your ability to tune a simple boosted motor, more than likely not.

[RedZMonte]

im running a '96 OBDII swap on my car ('95 Z34), DHP tuned, 42.5# injectors 7psi and daily beaten... i have not had any issues with it.. Originally i ran stock injectors and a Vortec 12:1 FMU w/ a Walbro 255LHP HP pump on 5psi w/o issues. the OBDII is the best setup IMHO for the turbo cars, easy to tune, runs/idles/economy/drivability of a stock DOHC just more power. the '96 does have a little limitations from what i understand over the '97 but it is compatible with the 4T60-e so im ok with it.

TimG is running a Splitsec FTC1 on his '95 Z34 w/o problems as well. He is also running 42.5# injectors and 10psi IIRC.

[pocket-rocket]

im running a '96 OBDII swap on my car ('95 Z34), DHP tuned, 42.5# injectors 7psi and daily beaten...

That's too funny, lol, I like it.

Schmieder, I'm glad you are doing your homework to do it right and not throwing together some hack job that will only blow up in your face and leave you out tons of $$$ and disappointed

[Schmieder]

So lets see if I have it right.

I can get bigger injectors. Stock 17-19#'s to 36#'s

But to make them work properly I need a higher fuel psi in the rails. Of course the ECU will open the injectors and pulse as programmed which will end up rich but won't the O2 sensor over ride and reduce injector pulse?

So then the 36# injectors will work just fine with a higher fuel psi, achieved with an AFPR?

At this point would I need to also install an FMU to yet increase psi even more to accomodate @ 6PSI boost? Or will the larger injectors running under higher psi be enough to supply a correct amount of fuel? Or is this a job better suited for an Adjustable Rising Rate Fuel Pressure Regulator? lol, theres a mouth full, ARRFPR!

Assuming the O2 sensor is the master of the injectors pulse, the O2/ECU will handle the fuel demands of 6 psi boost as long as the injectors can flow enough and there is sufficient pressure in the rails?

Feel free to just lay it out. I understand my boost levels of 4-7 psi can have good fuel management w/o the tuning. I know tuning is preferred but atm it is not an option. Down the road I can do my homework concerning Megasquirt, piggyback or standalone. But that is another time.

So for a 3100 with a 3400 top swap, a basic 3400 block under 6-7 psi boost. 36lb injectors, what fuel management devices/set-up would be best? AFPR, FMU, ARRFPR, boost triggered HP Inline Fuel Pump?



Yeah, I'm a german so my pride would be bruised deeply if I blew up the block, NOT AN OPTION! lol.

The Fuel Management issue is the last step in planning. Once I get thsi down right and solid, I will begin the general purchasing stage.

As far as welding up the system, piece-o-cake. I have that artistic, geometrical eye. You know, the kind of eye good a pool, sculpting and 36/24/36 gazing! All I have is a Lincoln Mig Gasless but is very adjustable and will work great. Not the prettiest welds but are very, very strong. I plan on using my port n' polish kit to clean up the welds anyways.

In a few days I will get some pics up. The before the project pics. Then some along the way and then the finish and maybe a little movie if my buddy will let me use his camcorder. I love watching youtube turbos, it inspires me even greater to perfect this project.

[1988GTU]

With 10 or less psi you should not need anymore than 28lb inj. You will NOT need a rrfpr or any other regulator for that matter than the stock 3x00 one.

All you need is a 2 bar map sensor, #28inj or even less, tuning, and a wideband for better accuracy in tuning.

[RedZMonte]

Larger injectors will require tuning in the ECU.. reason being is when your not under boost the ecu will command the injectors to open and close according to the injector size the ecu is programmed for (Stock 19#) the O2 can only tell the ecu to trim so much fuel... it will run rich with larger injectors untuned.

The RRFPR/Vortec FMU will only increase fuel pressure based upon how much boost it reads... Ex... 12:1 refers to 12psi fuel pressure to 1psi boost... basicly the injectors open and close the same as stock but the higher fuel pressure forces more fuel threw. Honestly the best way to achive the correct fuel ratio is to have:
1: Good Fuel Supply (H.O. Fuel pump) keeps constant pressure
2: correct injectors (not maxing them out like a FMU does)
3: proper tune. Being a '96 i would find a DHP FS and tune it right off the bat.
4: Stock 1:1 fuel pressure

The GM OBDII ECU is a fully programable ecu, that is why the DHP software is so awsome, you have a OE base tune on your computer now that is adjusted slightly (injector size, little fuel, little timing) and your not having to start from scratch and tune the idle partial throttle, WOT, decelleration ect.. Unless your going to make a FULL Drag car standalone is not needed or suggested.

Cheap and easy initial setup: (I ran this setup for ~1-2years again daily beaten)
1: Walbro 255LHP HighPressure pump
2: 12:1 FMU
3: 5psi

It will still be reliable and inexpencive. obviously you want to make sure everything else is up to par... New fuel filter, good plugs/wires, basicly proper maintenence.

This is just my thoughts on it but everyone has their own opinions on the subject.. I Just know what has been successfull for me and cars i have helped turbo (look at the turbo vette pics in my profile). My car buddies have turboed and blown up everything under the sun lol...they have lots of knowledge from trial and error (its cheaper to learn when someone else makes the mistakes)... LOL maybe thats why my shyt hasnt blown up

S

[Schmieder]

With 10 or less psi you should not need anymore than 28lb inj. You will NOT need a rrfpr or any other regulator for that matter than the stock 3x00 one.

All you need is a 2 bar map sensor, #28inj or even less, tuning, and a wideband for better accuracy in tuning.

Ok, so 28# injectors. check!

Now, lets discuss my options if tuning is not possible atm. I know, it is not the best setup idea, but I read it can be done effectively, safely enough since my boost levels will be low.

Using a wideband O2 gauge, fuel pressure gauge (electric on dash) I should be able to effectively increase fuel flow by mearly increasing fuel pressure a few steps at a time. Pinching the return line after the FP gauge and FPR should give me the max potential of the pump. Then using the wideband O2 gauge I can see when I hit max fuel flow when she begins to lean at wot/rpm.

Or am I making this fuel delivery issue to complicated? Is it as simpe as gently increasing fuel pressure to meet the airflow demands?

Remember, I am trying to accomplish good fuel delivery w/o tuning yet. My goal is to eventually drop in megasquirt ecu, probably piggyback due to tranny. Unless MS has a tranny controller out. Then I will have ALL the tuning ability I need.

Thanks for your input! I know, tuning is the way to go but it is not possible yet.


Oh, edit for a few more questions if you don't mind.

Can I use a check valve on the stock MAP sensor to simulate n/a conditions on the ecu? Instead of getting a 2-bar and tuning the ecu to read the new map sensor?

How about using a check valve for other vacuum lines such as brake booster, accessory and tranny vacuum line? I would imagine these sensors/devices weren't designed to read boost. All they really need is a normal vacuum at idle, strong vacuum in deceleration and no vacuum at WOT. Is this correct?

[1988GTU]

Don't avoid PCM0 (DHP) tuning. That is one area you will want to spend most in.

You are making this fuel delivery issue too complicated. Tuning for the 28's will result in more proper fuel and no hacking at the fuel lines or twisting knobs or smashing bricks and shaking magical eight balls will be required.

[Schmieder]

Cheap and easy initial setup: (I ran this setup for ~1-2years again daily beaten)
1: Walbro 255LHP HighPressure pump
2: 12:1 FMU
3: 5psi

It will still be reliable and inexpencive. obviously you want to make sure everything else is up to par... New fuel filter, good plugs/wires, basicly proper maintenence.

Thanks, that is the set up I was looking to confirm for initial running. Like I posted a moment ago, I will be investigating and learning the Megasquirt systems soon. But I want to take my time with the MS. As in build it myself and design a coonection series that would mate up to stock wires/connectors for easy swapping MS to Stock ecu. I might even try to fashion a master switch that would determine which ecu to run. Flip the switch and back to stock and visa-versa.

New fuel filter, lol, a story there. The old one was rusted on I had to cut the line out. Two vice grips locked ultra tight and I eventually stripped the bolts atleast 1/8" in. Now I have steel braided AN6 lines running from the filter to the engine bay. Took a little rigging but is sturdy as anything.

As far as the Walbro pump is concerned, will one designed for the 97 grand prix work for my 96? I can't find a walbro 255 that is rated for my vehicle.

so far maint.. new fuel/oil filters, new spark cables/plugs, new coil packs, new water pump, new radiator, new TPS, well cleaned MAF, new PCV valve, new battery, all grounds cleaned and applied dielectric to all electrical connections, oil flush w/ seafoam, coolant system flush/back flush (before new rad), mild porting of the heads and intake mani's, ported the TB. I think I did the TB really good. I cut out the top bar, reduced the bottom bar by about 1/3, tear-dropped the blade, sunk the screws into the blade and leveled the threads on the other side. According to my mapping, it has open area mathematically equivilant to a 58mm TB.

The heads were a little harder but I kept it simple. All I did was smooth the short side radius in the pocket, flush the ledge under the valve seat, gasket match and reduce casting flaws. Oh and I polished the combustion chamber. Neat stuff one can do with air tools.