7730 for use on a geo 3cyl..... READ

[merlot566jka]

lmao, so I have been gone a while and gave my 3500 fiero to americasfuture2k. long story, save that for another thread...

anyways, i just got a 3cyl geo metro. it has 55hp. i paid $500. it gets 4Xmpg.


lets turbo it.

its tbi, I want to use a 7730 ecm, still running on batch fire. It is a distributor car, dont know if the distributor is pure mechanical....its a 94, so maybe not.
I will plumb the intake for 3 injectors, use a rail out of something. the main concern right now is not the hard parts...its if the ecm can do it...

using batch fire, and only 1 bank of injectors (one driver circuit) do you think it would work? the firing order is 1 3 2. max rpm of like 6k. its a 1.0. I know other things will need to be tuned, but I am looking at bare bone basics of ' can the 7730 ecm be installed on a 3cyl engine and it actually run?)

i know they make a turbo sprint and firefly, but I cant find one so I am going to make my own 3cyl turbo.

[robertisaar]

depends: if the dizzy works like the V8 ones do, you should be able to change the cylinder constant to 3 and run 8F...

but 8F is meant for DIS setups, so it could work, but you'll be playing with LOTS of stuff to get it running...

i'd use both injector drivers though. have six smaller injectors instead of three larger ones... better idle that way. gonna be tough finding some small enough though.

planning on running it at normal fuel pressure for TBI or at MPFI pressure?

[SappySE107]

What is the crank trigger setup?

[merlot566jka]

mpfi pressure
where on earth am i going to find injectors that small?!? wonder what that would require...??

if a 2.8 used 17lb
a 2l may use 13lb
a 1.0l like 9lb??????

what did the 1.8 sohc from a cavy or a 2.0 turbo sunbird use?

[merlot566jka]

currently, none, but would be a sinch to work one out....maybe....

3 cyl instead of 6. so if the crank trigger on the v6 has 7 notches, then.... ah crap. either i half the counting the notches or have the 7730 think that 1, 2, 3 is 1 3 2, and 4, 5, 6 is 1 3 2. but that would divide rpms in half, or double depending on which end you look at. then both banks would be utilized, but what about spark.. i could use the dis, but the wasted spark and confused trigger events may be disastrous!

is it possible to change things inside the program so that the count is only to 3 notches and resets on the 4th notch? basically turning the ecm from v6 to 3cyl operation. maybe keep both banks, but have one fire above 3000rpms...

um damnit.

megasquirt?

[bszopi]

The 7730 was used from the factory on 4-cyl through 8-cyl engines, so the crank triggering should be able to be altered in the program.

[Superdave]

Yep, you should be able to make it run the 3 cyl.

I'd study the differences between the MPFI 4 cyl bins and the MPFI V6 bins. You might be able to figure out your spark reference angle and max/min advance settings from those. 7x trigger should work.

For injectors, i'd use an adjustable FPR and drop the pressure way down.

[SofaKingWeToddDid]

lol put two of those 3 bangers together and make a v6!!

[IsaacHayes]

One in the front, one in the rear! OLE!

[robertisaar]

One in the front, one in the rear! OLE!

we had a guy on w-body do that with a cutty supreme...

3100 in front and some kind of 3.8 in the back... weighed like 4200lbs and pulls 14s?

[WrathOfSocrus]

How informative . . . .


Anyway, this is something to think about with the ignition - The 7x signal is sent to the computer and it sends a 3x signal to the ICM. Because of the way the waste spark system works, it fires 2 cylinders at a time hence the 3 coil packs. They fire 1, 2, 3. I have no clue about the timing and advance needs but it should be able to handle the 3 cylinder firing since it is just firing 3 cylinder pairs.

Do you know if the computer is flash only or a removable PROM? I think I read somewhere that some of the 94-95 vehicles like TBI S-10's still had a removable OBD1 PROM (please correct me if I am wrong, I read it a while back on an S-10 forum). Perhaps on another tuning or Geo forum they might already have the ignition information you need.

[robertisaar]

TBI S10s were PROM setups, no flash

i discovered this after labeling and organizing 588 BIN files...

[Superdave]

How informative . . . .


Anyway, this is something to think about with the ignition - The 7x signal is sent to the computer and it sends a 3x signal to the ICM. Because of the way the waste spark system works, it fires 2 cylinders at a time hence the 3 coil packs. They fire 1, 2, 3. I have no clue about the timing and advance needs but it should be able to handle the 3 cylinder firing since it is just firing 3 cylinder pairs.

Do you know if the computer is flash only or a removable PROM? I think I read somewhere that some of the 94-95 vehicles like TBI S-10's still had a removable OBD1 PROM (please correct me if I am wrong, I read it a while back on an S-10 forum). Perhaps on another tuning or Geo forum they might already have the ignition information you need.

The 7x signal is sent directly to the ICM, the ICM sends a RPM signal back to the ECM. The ECM uses that signal to calculate what the spark advance should be, then it sends that to the ICM.

"Time between ref pulses" is the ALDL output that you can use to calculate RPM, The signal is sent in though D8 and D9 on a '7730.

[SofaKingWeToddDid]

lol i think i saw pics of that setup a while back. but i only saw pictures of the engine talking to 3100mpfi and he sent me links over. we were talking about converting a W to RWD. and that was one of the examples of 'awd' he pointed out to me.

did you guys ever see the conversion kits available? they come with a 5.0 V8... of some sorts.

[pocket-rocket]

lol i think i saw pics of that setup a while back. but i only saw pictures of the engine talking to 3100mpfi and he sent me links over. we were talking about converting a W to RWD. and that was one of the examples of 'awd' he pointed out to me.

There was the "Push me pull me" Citation. Hotrod magazine doesn't have it in their archives anymore though It had 2 2.8? engines in it. One in front, one in back.

did you guys ever see the conversion kits available? they come with a 5.0 V8... of some sorts.

http://www.angelfire.com/stars/mycaddy/asg.htm