Snowdog 91 Formula

It would be interesting to find out what you discover about it. I'm wondering how in the world that would even work!
Changing a fuel pump and using the existing TBI harness with an Edelbrock chip makes me wonder what in the world they actually did.
It's more curiousity to me than application.
There is no way that would work with my existing system anyhoo.
I'm getting flustered about throwing that #$%#!#$ code 43.
I am most certain that everything is set correctly. I'm just puzzled as hell as to what else I can do. I need to get a burner and start to do what you are doing Jon.
Just wish you were closer to my location. *sigh* Why is everyone out there on the East Coast? Arrrrrrrrrrrrrrgh!!! I'm going crazy!

snflupigus

http://www.turbocity.com/TruckShow/tshow6.html

what ecm is that, ITS BIG, have they added injector drivers ???

RSFreak

I posted this on one of the previous threads regarding this subject. My thought was that you could have two TBs but only have sensors on one of them. You wouldn't need two IACs or TPSs anyway. Just link the throttle blades so that they open just like a dual-quad setup and find a way to fire the injectors on the second TB.

snflupigus

ok, ya. i think there is a consensus on that already.

i still dont know what the big deal would be using two ecms. one with a bare necessity harness the other stock.

AlexJH

I got the 4 samples from Fedex today. So it looks like National is still making them.

racereno

RacerXWS6, Sorry so long to get back but, Thank You for sending that excellent e-mail on our part to Turbo City. We may get squat but maybe it'll raise interest in the external circuit we need, who knows.
AlexJH, kudos for your initiative on this deal. You'll be a saint for idiots like me!
JPrevost, you mentioned having the smarts/knowledge to tune 2 TBIs. I can only agree but if I'm roughly doubling HP (to say 400hp) and keep the injectors sized appropriatly (read not TOO big) will it be doable?

RSFreak

Really? I wasn't getting that.

JPrevost

Check out the other post about dual TBI's and you'll see some of the issues with just hooking up 2 ecms. I think there is an easier way and I'll explain it really quick because it's sleep time.
The ecm injector drivers IC just has a reference signal, you can tap into it with 8 injector drivers if you wanted. So the plan of attack would be to just study a schimatic, find the correct wires and give the ecm it's 12 volt power supply. One wire goes from the reference line to the injector drivers IC on the other ecm and now you've got them working. All you're doing is using the ecm for it's internal power supply and I'm almost positive you wouldn't even need an eprom or any other wires going to it. Just 12 volt supply, ground, injector wires (obviously), and a wire to join the 2 ecms reference line! I don't have the need to do any of this right now but when I do my cam swap you can bet I'll have this all figured out. If all else fails, I'll just build the external injector driver board for whatever the parts cost and call it a day.

Tuning is not as easy as saying twice the hp requires twice the fuel. It's much more complicated than that and actually has little to do with horsepower and more so with torque. Torque is cylinder fill with air and fuel, more in the more torque but as the engine speeds up cylinder filling might not be as effective and you'll end up with more horsepower but less torque, it's really cool. Anyways, if anybody were to go and do this I would highly recommend you get into eprom burning ASAP and not just a couple weeks before initial fire up. Tune a stock motor, then play with parameters and then work on something a little more. Don't just jump into it like me or you'll end up doing a lot of back peddling. Also don't listen to nah-sayers unless THEY have been down that same road and have ACTUAL proof that something wouldn't work. Anything is possible, just sometimes you have to sacrifice quality (in this case gas milage) with function (having enough fuel). That's where I'm at with my small injectors. I have to do some serious sit down and figure out how I want to go about making sure I don't run lean.

racereno

Thanks JP, that's a great explanation and some very good advice. Fortunately I'm really after TQ and am happy to let HP fall where it may. I've got my WinALDL cable made and hope to get the PP2 next month so I'll work at it.

kevm14

I think it has everything to do with HP. 400lb-ft @ 2000rpm takes less fuel than 400lb-ft @ 4000rpm. The difference? Twice the HP. Fuel requirement is very RPM dependent, in fact, it's RPM/torque dependent. What's another way of explaining RPM/torque? HP...
HTH

FRMULA

Yes, no problems whatsoever. I run Holley Projection 4Di with the 900cfm TBI unit.

racereno

....and what is HP? An estimate derived from known TQ through a simple equation. :lala:

Sorry I couldn't help myself, it's been one of those days. You're both right, just lookin' at it from different perspectives which always helps.

tokabi

if your willing to spend the money holley makes an efi controller (with a seperate adapter) that can control dual four barrell tbi's.

limey

As far as splitting two drivers to control four tbi injectors, Bill Howell, use to have an auxillary driver box that he used to drive a holley 900tbi unit with a stock 454SS truck computer, also holley sells an auxillary injector driver kit pn 534-122 that doubles the output from a projection4 controller(four peak and hold drivers) to drive eight peak and hold drivers, so you can use two X 4bbl tbi units. no one said you have to supply 4 inputs, just supply 2 and have it doubled to 4 outputs.

snflupigus

show me a link to that injector driver output deal you are talking about from holley, i cant find it on their site.

JPrevost

http://www.holley.com/HiOctn/ProdLin...I/534-122.html

snflupigus

somebody needs to reverse engineer that thing!!!!!!!

JPrevost

Did you not see the post where I attached the schimatic for the extra injector drivers? It's the same thing and the circuit I posted is able to support 4 TBI injectors, what else do you need?

WideOpenVTwin

http://www.national.com/ds/LM/LM1949.pdf

Just incase anyone needs the datasheet

snflupigus

i need somebody to build it, prove it works, and then i will think about building one.

AdioSS

On the GM_TBI list, Ken Rolt just recently posted a link to a guy's website that has a 91 Caprice wagon. The dude swapped in a mild 454, but the big deal is the fuel injection system.

He used TWIN TBI!

I invited him to join and he answered several questions about it. Here is part of his reply

> Car: 91 Caprice Wagon (original 305/700r TBI car)
>
> No ETs or Dyno results yet, but comin within the month hopefully.
>
> Car as it stands now has all the creature comforts functioning (i.e.
> A/C, PB, PS. Cruise control worked perfectly until recently when I
> swapped out the 700R for a beefy TH400. Anti-lock brakes worked
> perfect to till I added the huge offset 20's and gear/tranny change).
> The car is driven regularly and gets averages roughly 16-18 mpg
> overall. Emissions are no probelm either. I have never had cats and I
> have always passed nicely.
>
> Engine: GenIV 454 .030 over, Speed Pro mini dome forged pistons,
> Chromoly rings, Comp Cams retrofit Hydraulic roller (.212/.218
> duration at .050, .510/.510 lift and a 114 centerline), Comp Cams
> roller rockers (1.7s), GM 113cc semi-closed chamber heads with peanut
> port intake ports(2.06/1.72 stock valves), GM 3/8ths rods that have
> been shotpeened and beam polished for durability. Long block yields
> approximately 9.5 compression and and 19inches of vacuum at the map
> sensor.
>
> Induction: Offenhauser 2x4 low profile open plenum alum intake, Dual
> 350 truck throttle bodies(Blueprinted and match ported, 4.3
> injectors, 500cfm each), Dual Stage5 Top Gun Nitrous plates(100-
> 300hp). Both TBs have functional idle screws and IAC solenoids. Rear
> TB is the brain of the pair housing the Map sensor vacuum port and
> the TPS sensor.
>
> Ignition: GM Delco '89 454 distributor, MSD coil, MSD 6AL, MSD RPM
> activated switch with micro shift lite, MSD cap and rotor, Taylor
> spiral core wires, Autolite Nitrous spark plugs.
>
> Electrical wiring/sensors: Factory 91 Caprice wiring harness. ECM was
> replaced with a 7747 ECM with Turbo City chip. Only sensors needed
> for this ECM are the Map, TPS,Thermostatic switch and O2 sensor; all
> of which are the stock 91 caprice sensors. I have changed them to the
> 89 454 sensors and no difference was noticed. I used an
> inexpensive "splice" kit that Turbo City offers for the inline IACs.
> However, the IACs are not necessary. I have run with the holes
> plugged. Very little difference. The TBIs react as Carbs instead of
> Injection.
>
> Tranny: TCI Streetfighter TH400 with 2000 stall
>
> Rearend: Stock Wagon housing with the stock 30 spline axles. Auburn
> posi, Richmond 3.42s, Alum girdle cover, welded tubes and boxed stock
> control arms are the upgrades.
>
> Miscellaneous: Hedman mid length direct fit headers, Moroso solid
> motor mounts, March Underdrive pulleys, 4row radiator, TCI tranny
> cooler, 89 454 Suburban accessories and brackets(didnt even have to
> change my A/C or PS lines for the different accessories), Edelbrock
> Victor Series Alum water pump, GM 454 valve covers, LS7 deep pan with
> baffle and Hi volume oil pump, LS7 doubleroller

<snip>

> Im sure Im forgetting some things. The car is very tame and a
> pleasure to drive. It still has that big car Imapala ride that I
> love. I tried desperatly to use as many GM over the counter parts as
> possible. The car was originally created for Power Touring and did
> well at it. All in all the whole swap is cake. ECM swap was pretty
> simple too. I had a few bugs but eventually they were squashed. The
> setup is very dependable, anyone can do it and all the parts can be
> bought from any GM parts supplier.

snflupigus

he never said how he wired the injectors

kdrolt

http://www.geocities.com/dulmoon/Dra...gonMotorsports

snflupigus

thanks, we will be getting some ground breaking info from this guy soon i hope. good looking car hes got. WOW.

Dave_A

Wait, wasn't CFI merely a dual TBI setup with single-barrel TBIs on a less-than-optimal intake manifold design? Couldn't someone adapt the control wiring for this to work with bigger TBIs (and mount them on a better ntake)??

I don't know that much, but the idea popped into my head while reading this...

snflupigus

still only 2 injector drivers, and i think they still have one iac. sorry man. doesnt help much

rsc350

I have a question! Why could you not just take the output to the injectors from the ecm and build a board to split it in two and double it, we did things like that in my electronics class, it is not that hard. I could be wrong on this I supose but it is my major and I didn't sleep too much in that class lol.

snflupigus

um, dude. did you even read the post?? or maybe all that stuff was on another thread. could be. anyway, been talked about before.

Dave_A

Hmm...

This guy (http://www.newcovenant.com/firebird/) seems to be trying to rebuild a L03 to use (in his words 'heavily modified') CFI and a pair of V6 truck TBIs (2bbl each) in place of the CFI TBIs.

Maybe someone should ask him how he intends to drive them (if you believe what he's trying to do... It seems that he (at least claims on his site) to be actually building what he's describing... It could be another 'goingfaster.com', but then again...

Just my 2c...

mikeb1

I emailed him and he said he was using a a 1227747 ecm out of a 91 chevy pickup and he was wiring the injectors in series as sometimes they wont fire if wired in parallel (his words ?) and he's doing the chip programing himself. hope this helps , mikeb1

mikeb1

sorry he said he was wiring the injectors in pairs in series

tristate

Several years ago when Turbo City still produced their dual tbi systems I talked with one of the workers that had the system installed on his truck a 1990. He said that it was a stock engine, the TBI's were mounted on a tunnel ram. It was very cold natured, engine had to warm up before going down the road. It used one IAC and TPS sensor. It used all GM compontents, they used 2.8 injectors, 4.3/5.0/5.7 TBI's, the wiring harness was Turbo City's own design. He said the computer was modified , not sure but I am thinking he said they had to put in 2 drivers. I think he said the injectors were wired seperately. I remember him saying that it required a custom chip, I believe it was to run all 4 injectors and to cut down the fuel supply. I bought a TPI instead. I am sorry for that as everybody one, but nobody has dual TBI's.

snflupigus

wow. old thread reborn... I love it when that happens.

kdrolt

Here's some related threads on the topic. The MEFI is GM. The enclosed links may not work so I'll update them if I can find the new URLs.:

https://www.thirdgen.org/techbb2/sho...highlight=MEFI

https://www.thirdgen.org/techbb2/sho...highlight=MEFI

HillbillyJeeper

Forgive me if this has been discused. Ive read some old threads. But me and my dad have been discussing the idea of dual TBI's. And thinking about th old tri-power carb setups, where only one carb had idle controls, and they where set up progressive. Our thought was to use a stock tuned computer to control one TBI, with idle and all, And run the second TBI strickly mechanical. Set it up so the second one does nothing untill after like 3/4 throttle, when you need more air and fuel, and fire the injectors constant off a switch. When you reach 3/4 throttle or whatever, the second TBI opens and the injectors fire. I know there would be no way to control the mixture, aside from injector size. But it would give you the extra air and fuel flow you need in the upper RPM range. What would the issues be with doing it this way, aside from the lack of mixture control?

BMmonteSS

Lack of mixture control.....thats way too big of a problem to ignore. You could probably hydro lock an engine with 6 50 lb injectors all flowing at once, let alone get it to make any kind of power. In order to get the ecm to control the amount of fuel the extra TB's would supply you need an injector driver board (do a search) that uses the stock drivers as a signal and fires the additional at the same time as the main injectors. Progressive opeing of the additonal TB's would be a nightmare to tune. None of this has a hope in the world of making it out of the driveway without lots of DIY chip tuning, and even then it would be very hard to do.

How much power are you wanting to make? A BB TB with higher than stock FP will support over 400HP.

Ronny

iTrader: (1)

HillBilly: as you are possibly aware the crossfire is dual TB. 2 single TB's sitting on a plate. your choice of manifold, bore size, injector size, and ECU. be creative.

wolfmanken

ok look i got a '79 camaro with a 383, tunnel ram and an injection system out of a 92 pickup.
Iam running dual tbi's run in series so 2 injectors are running off each drive(it works fine trust me)
Biggest problem i found is way too much fuel delivery, so either i need the chip programmed or iam gonna try a inline fuel pressure regulatot and drop fuel pressure from 15psi down to 10 or so and see what happens.
And the other problem is it idles around 525RPM which sounds great but stalls when u snap the throttle.
Anyhow i know i can work the bugs out its just gonna take some time, i'll post again when i make more progress

liquidh8

would be nice to see it worked out.

TierAngst

Lets not forget that the new EBL system is setup to control dual tbi's

liquidh8

I have the ebl, I guess driving the second set of injectors is the big obstical yet to be overcome.

357mag

July and Sep 2004 Car Craft has a couple features on a 67 Camaro running two Holley 4bbl TBIs using one Commander 950 controller and one set of sensors.

Tim sends