Hi,
I am planning to put a turbo on my 85 LB9.
I am only planning to run about 7 psi.
My questions is can I just get some bigger injectors and a FMU and not screw with the computer?
Thanks

 

The stock computer won't recognize the bigger injectors from what I hear, which is why even a simple 305 to 350 swap requires a new prom too. I have no idea what else you'd need for that turbo though.

 

You could use an adjustable fuel press reg also and turn down the fuel pressure to make the injectors "look" smaller when not in boost. Then turn up the FMU to get the fuel you need in boost.

 

So you think it is possible?

 

Anything is possible. It all depends on what you want for time, cost, and reliability.
It sounds like you are trying to do it cheap and simple.
A cheaper & easier solution would be to install a nitrrous fuel solenoid for the extra fuel along with a manifold pressure switch that turns on the solenoid when boost comes in.

 

i dont post here much but theres nothing on the z forums right now. you can do it(vortech on a 350z uses a similar solution) however the major problem you run into is reliability. it could work for a long time however at the same time one knock could destroy your engine. the more you invest the longer it will last(if its also installed correctly.) there are tons of tuning solutions out there and a retune shouldnt be too expensive although its been several years since i owned my 3rd gen now i can tell you as an example though a 350z can be retuned for basic stuff for only 300 bucks. im not familar with third gen prices anymore but dont try and take shortcuts, it usually ends very badly =/

 

The only problem I see with using a fuel solenoid is that I don't see a way to have the fuel delivery progressively increase as the boost increases like an FMU. Or is that not a problem?

 

If the turbo is sized right, it will come on fast and reach 7psi in a hurry so you may not need progressive control. Run it rich at peak torque and let it lean out as RPMs rise, if it wants to lean out.... generally peak torque wants most fuel and after that fueling requirements phase out towards peak HP. Nitrous solenoid for fuel is an interesting idea that COULD work with a Hobbs boost switch, but you will really need to dial in jet size and fuel pressure to get the right amount of fuel on that setup.

I dont think 7psi on a 305 will require much larger injectors than stock but its not a bad idea to swap to new injectors since you will be running higher pressure. Don't want to chance blowing a motor on 20+ year old stock injectors or are they new?

You will need aftermarket ignition system with timing control. Pull 7-10 deg on 7 psi....usually 1 deg per psi works well but be conservative at first. MSD and Mallory have kits with boost referenced timing control. Just need to wire in the module and set the amount you want to pull.

With the FMU controlling fuel and timing controlled by ignition box, I think you will be fine to run boost. My buddy did the same thing with a procharger kit, ran 12 psi on a stock L98 (vette motor with aluminum heads). ran strong but eventually blew up due to aggressive tune I believe.

7psi aint all that much so it should live. Just keep it somewhat rich and low timing.


Oh and being an 85 MAF car, you will need to rig up the MAF in front of the turbo more than likely. I dont think you will want to blow through the MAF but that could work too. I've seen guys do that before on LSx motors and mustangs.

If you could tune the car and swap to a later year MAF system, you could tweak PE mode enrichment vs RPM and the upper MAF tables if you blow through MAF to get fueling. Stock 305 wont max out the stock MAF sensor so you still have probably 50 grams /sec airflow available that you can use to add fuel via MAF tables. If you know what rpm boost is made at WOT, you can tweak PE mode to add fueling per rpm to cover the fueling.

Problem is, how do you control fuel on half throttle or heavy part throttle situations and the turbos are starting to make some boost but your not at WOT so PE mode doesnt come on? Blow through MAF will handle some of that but its likely to max out early. I'm not sure, i never tried that before on a stock motor. Also in those cases a new PROM tune working the low rpm HIGH load timing tables would be necessary because you could hit those with the turbo. Stock tunes are pretty conservative in those areas anyway so it may be ok.

 

I thought you were intending on use the FMU and timing control so you didn't have to tune the PROM. Keep in mind that 1985 ECM is an odd ball. I don't know of anyone that tunes them. Most swap them out for the 1986-89 ECM so they can tune. If you do the swap then go with the bigger injectors without the FMU and do the tune in the ECM.
Without a tuned ECM and larger injectors then you may get by with some 24 or 30#/hr without tuning for the non-boost part.
The FMU is quick and dirty and so is the fuel solenoid. The solenoid would be tuned for peak boost and be on the rich side below that level. Either setup will work.

I have a stock 305ci with boost and 7 PSI doesn't feel like much of an improvement. It seems decent at 10 PSI so I am looking at it from that point of view where you will want more boost once you dial in 7 PSI. The FMU will max out the fuel pump because as fuel PSI increases then flow decrease from the pump. A stock pump is only good for 400HP at stock pressure and you will be at 310 HP with 7 PSI. The FMU pressure will reduces the 400HP pump limit much lower. Is it good enough for 310HP is the question. The solenoid doesn't create the problem as bad.

 

I really like this approach for a cheap way of doing this. At one point I did the math to figure out pressures for some of the more common injectors and FMU rates, but I don't remember what I decided would work well.

This is probably the fastest and cheapest way to do it, and I don't see why it wouldn't work well, especially on a MAF car. Get a hobbs switch set to about 3psi, let the MAF take care of fuel to that point and at that point you should be making enough more power to spin the turbo up fast and trigger the solenoid.

FWIW, BBS turbo used this setup on his own car, and posted quite a bit of impressive street video of the car.

With either approach I would probably do some programming to get it perfect, but both should be workable without it.

heh, I'm running 83pph injectors in my turbo 305 project, but that's just how I roll

 

83pph PFI injectors as in 8 of them in a 305ci? Sounds like a handful. What ECM are you running? I know the MS ECM had some tweaks to try and get the low-Z to turn off faster instead of leaking through a zener diode.
I have been playing with the 95 truck ECM ('427) so that I can eventually do bank fire around idle and low rpm and go to bank fire at higher rpm so I run big injectors. I don't know why the MS ECM hasn't adopted this yet. That is how one should roll with big injectors.........SEFI or bank fire/batch fire mix.

I hope you have a big cam in that sucker to waste fuel at idle.

 

What, is that a big injector for a 305?


Yep, 8 of the bosch version of the more common low Z seimens injectors:

They're actually 83pph @ 3.5bar, I'm probably going to run them at a little under 3 where they should be around 75pph. I may jack that up some more if I decide to try some E85 (the only local station that has it is on the way to the track). They're fast and high Z.

This weekend I hope to put my MS back in... I've been running the '165 in the car after getting the MS running a while back. I'm still waiting for my injector harness adapters to get here (idiot has misshipped them 2x now)

Not as big as I wanted, was planning on an 280 XFI roller, but the 224/224/114 (XE lobes) that i had in the basement was close enough that I didn't feel that the $300 for the other cam is worth it. I may change my mind once i get some track time.

 

Ok I think i got everything figured out here except the ignition. What are some of the ways you can get the timing to retard only with boost?
And whats everyones opinion on those ebay stainless steel turbo headers?
Thanks Guys!

 

a bunch of ignition boxes can do it, the traditional answer is an MSD 6BTM...

I don't think that anyone has actually gotten some of the ebay headers to work in a third gen without cutting them up and modifying them.

 

Which ebay headers? the single or twin headers? The single headers require cutting at least on the crossover to get it to fit right. That is on any engine, not just the thirdgen. Some have gotten the driver's side header to clear the steering rod, and some cut & weld to get it to fit. You will need to run a short spark plug to clear the pipe on the pass side.
For $250 or less it is a start of a turbo system and quicker than fabbing from scratch, but plan on cutting & welding.

The twin setup requires you to fab a merge pipe.

 

Ya the twin turbo headers. They are like 135 bucks so Im a little skeptical.

 

which twin headers ? the foward facing ones, or the ones that go up over the valve covers

the best bet is to buy a pair of shorty block hugger style headers flip them upside down and make ur merge pipe from those

 

I have Edelbrock TES headers right now. But what headers are the most easy to work with? The ones that face forward or the ones that go over the valve covers?