BlackFormula

iTrader: (3)

Ok so i'm considering going TBI or TPI instead of carb. Don't get me wrong, i LOVE LOVE LOVE my carburetor. But thinking of going FI for future power adders and such.
My question is, besides the ECU, Harness, Intake and all related Sensors...
what else do i need?
I have a HEI Vacuum advance Distributor (can i run this on FI???)
i have a in-tank sending unit/fuel pump for tbi
i have a TBI intake and all equipment on it.

what else do i need to do? Can i run my HEI dizzy with vac advance? if so, where should i port the vacuum for the timing advance at WOT???

thanks in advance to anyone for their help! ThirdGen Rocks!

bestracing

Most GM's use a ported vacuum for their vacuum advance which I'm not sure the TBI has that. you would also have to disable the timing advance functions on the ECM as well to keep from setting the CEL/SES light.

You really should use the computer controlled HEI distributor to take advantage of the spark advance control and knock sensor timing retard functions. I prefer the external HEI vs. the Internal HEI

BlackFormula

iTrader: (3)

thanks. I'm hoping to go TPI just because the tpi setup makes great low end power which is where my engine makes all of its power (L Code crate motor), so it's a great match.
i do have a "blaster" type coil on the TBI intake i do have here, and dizzy's are a dime a dozen these days for a SBC. but i like the HEI setup, just not sure if i can use the Vac advance hei on a FI setup?
also not sure if there's anything else i have to do, besides the intank sending uinit, fuel lines, harness, and intake peices with sensors...

bestracing

You will also need the o2 sensor, knock sensor, oil pressure switch for the fuel pump relay, dual cooling fan (recommended) as well.

Now thinking deeper about the Distributor, the ECM needs to know the RPMs of the motor which it gets from the distributor ECM pin B3 Blk/Red wire and B5 Ppl/Wht wire which is the distributor reference pulse in leads. Without these signals there is no reference for when the injectors need to pulse and how fast they need to pulse. SO my answer is without major modification to get this reference signal to the ECM you will need the factory ECM distributor.

Things to consider...

The TPI will not make good power past 4500 rpms.

If your motor already makes great low end power there is no need to add a TPI, they were designed for the 305 which didn't have great low end power until they installed the TPI system.

A good TBI system can make great power using a good dual plane intake. Look at Holley and Edlebrock aftermarket TBI systems. Dual plane intake is good for low end torque as well.

BlackFormula

iTrader: (3)

so id basically be better off going TBI instead of tuned port is what you're saying there right? i like a TBI, but ive always liked tuned port too but my 305 TPI car was a boat anchor really....

anything i can do on OBD1 to "bypass" a couple sensors? i know with obd2 its possible, not sure about obd1...
my crate motor is pre 1979 so i dont know if it even has a place for a knock sensor, and ive got headers on the car so i dont know where id put the O2 either at this point.

I'm still researching and collecting the remaining parts for the swap...

bestracing

In my opinion the TBI would give you much more flexibility over higher RPMs than the TPI. It's like a carb but with better fuel control using injectors. Look at Holley TBI kits for example.

Knock sensor will be installed on the left side of the block in the drain plug location. They didn't do anything special there between the old and new blocks.

I've had a block that had the oil pressure switch down by the oil filter. Some old blocks just had a pressed in plug there and you would have to tap it for a 1/8" NPT fitting. I've seen others have the switch tied in with the oil pressure sending unit behind the intake manifold rear seal.

OBD I can disable some things but it's not as easy as flash programming like on the 94-95 OBD I ECM. Either you have to program and burn your own chips or send your ECM to a place like PCMforless and have them do it for you. I've found a lot of useful information from Hot Rodders installing EFI systems on their Street Rods.

BlackFormula

iTrader: (3)

thanks for your help. yea PCM for less here in charlotte has done a great job for some of my people in our club.
I did notice there's a fitting threaded in next to the oil filter. figured it was for a oils ending unit, but i'm running a mechanical oil pressure gauge now anyways

so, i need the knock sensor, wiring harness, non hei dizzy and some ECU work or a custom Prom...
not too bad i guess. TB has been around a while, i just figured if this motor makes great power on the bottom then TPi might be ideal for it's low end power gains. but perhaps the TB setup could benefit more over a wider range of RPMs <shrug> i have a TBI manifold and all that ready to go whenever i need it, as well as everything i mentioned earlier.


3rd gen rocks, lots of knowledge here!

92camarorv6

so guess the 1985 corvette was a 305 tpi.....dop....

BlackFormula

iTrader: (3)

i mean, corvette had a great 350 TPI. the problem was more of, the engines they were using after 1980 were designed for high end power where the TPI unit is designed to maximize low end power.

but, TBI might be better for something like say....Top Mount Roots style supercharger and nitrous?

bestracing

Not a non-HEI, you need an ECM controlled distributor which would be either an internal or external HEI to get the correct ignition pulse for the injector timing unless you use something aftermarket to get the correct crank signal to the ECM. I had forgot that the Dizzy provided that for the early EFI systems. The later systems are now using the crank position trigger which is much more accurate.

BlackFormula

iTrader: (3)

i was thinking just grab the ecu, harness, dizzy out of the same car in a scrap yard and go from there.

I don't think my TBI ecu will work for the tpi will it? i would imagine the prom would be programmed different for the injectors

InfernalVortex

iTrader: (4)

TBI as a system has far more potential but there's just no aftermarket support for the stock GM TBI setup. You'll have to spend so much money on an aftermarket one that can actually support serious power that you may as well just buy a miniram or a FIRST or a stealth ram or something.

Im open to changing my mind if anyone can show me a Camaro making more than 300hp with a stock TBI. Im not sure Ive even heard of one making 300 yet... but robertfrank may be close. I would love to be proven wrong but it just seems like you're swimming against the tide trying to make those things support power, which is shame. The horsepower-choked-injection TPI is SO limited unless you spend TONS of money and then you can only get so far with it. Just aftermarket runners, which arent really all that big at all, will cost you as much as a stealth ram.

Maybe look into that new Crossfire injection intake... the Renegade I think?

Also, the TBI and TPI are both batchfire. The TPI fires one bank all at the same time, then it fires the other bank all at the same time, just like the TBI. The TPI computer is a lot better though, but a lot better is relative. Modern EFI's leave em in the dust.

You quickly get into the area of "hell I may as well just buy an LS1" when you start talking about EFI swaps. LS1's come stock with great EFI. Hell even the LT1 comes stock with a excellent EFI system that puts TPI to shame. You can get a whole LT1 pullout with computer for less than $1k. With a big cam and a few valvetrain upgrades you can then make 400hp. Its unbelievable what you can do with those things on a budget.

BlackFormula

iTrader: (3)

i feel ya man. but i cant afford LS1, i just dropped a brand new crate motor, fresh paint, new interior, and a ton of other stuff in it.

Really just trying to get away from carb for right now anyways, i've been doing more highway driving and long trips than i used to.
I already have the sending unit, a TPI intake manifold with the throttle body, injectors, sensors and all that is on its way this weekend, and i have the knock sensor and can easily pick up a o2 sensor and hopefully a wiring harness, and i dont think my TBI ecu is gonna work so i gotta find one of those.
these parts are ok used or scrap yard that i still need, i dont need all this stuff brand new so i'm still building on a budget.
the only unanswered question i have right now is about the Tbi/TPI ecu. i'm 99% certain that the tbi ecu wont work for TPI, but i could be wrong too i might just have to switch the prom out? i'm not sure on that....i don't know much about computers right now when it comes to interchange.

InfernalVortex

iTrader: (4)

Get a 7747 ECM with a setup close to yours. They're much better than the TBI ones.

I would probably try to use that TPI setup and make a single-plane EFI setup out of it.

Z28ricer

iTrader: (2)

Get a decent manifold: stealthram, ramjet, or miniram, or converted LT1

eficonnection 24x setup

then be happy.

BlackFormula

iTrader: (3)

well i'm bartering to get the tpi parts i still need, so it wouldnt make any sense for me to spend a ton of money on an intake just yet. having carb issues, so at this point im just dying to get on FI so i can control the engine management better

Z28ricer

iTrader: (2)

Theres virtually nothing from an OEM tpi setup that will be useful to you, if your crate engine is making any decent power.