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custom efi?

ryan22re

ryan22re

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id really like to have a discussion on the pros and cons of several different types of efi. i would like to eliminate any system right off the bat that uses a mass airflow sensor. i would also like to eliminate tbi. not that i have anything against it. id also like to eliminate any system that has a price tag over $1000 or so. id really like to be able to buy the system in stages, make alot of my own parts, and use readily available sensors.

ive been thinking about buying a tpi computer and harness and then modifying it to suit my needs. but i would really like a system that could be changed on the fly. is that possible with tpi?

ive been reading about megasquirt, which is basically a computer that you build for pretty cheap, and is pretty easy to set up. ive heard of guys using it, but i am unsure about its reliability. http://www.bgsoflex.com/megasquirt.html if you want to read about it.

what else am i missing? do you know of any user friendly efi systems that can be built on the cheap?
 
For your cost limitations, I'm not certain you can do it to be honest.

Now you'll need to clarify, are you talking all the extraneous stuff like wiring, relays, fuel line, pumps, etc., or $1000 for the injectors, base, plenum, sensors, and computer, the rest being necessities? Because if including those, you'd need to get your hands on a LOT of free parts to be under $1000 IMO.

I have yet to hear of any real downside of Megasquirt in regards to reliability. The only real downside I see is still lack of timing control. I thought V2 was supposed to solve that, but it appears V2.2 is just a step in that (eventual) direction.

If you start veering away from something "complete" like TPI, you end up spending money on stuff that adds up VERY fast...throttle bodies, injector rails, injectors, etc. If using stock stuff, the separate components of TPI are fairly cheap, compared to say aftermarket fuel rails, wiring harness, etc.

For cost vs. gains, I don't think an Lx motor swap can be beat. Yes it will be expensive, but it will also be worth it. Not that you were talking $3000 swaps or anything, but newer motor, superior performance bone stock is hard to overlook when the inferior earlier injection will probably cost you $1000 in parts alone, plus all your time.

Check out moates.net for on the fly TPI stuff.
 
i really really like the new motors. i just dont want to spend that much cash. i was thinking that it could be done for cheap, maybe not a grand, but to spread it out over a while collecting parts while i build my engine, would be a little easier to take than just dropping $2500-3000 on a complete efi system.

so the megasquirt doesnt do the timing control that well?

what about custom tuning a tpi? could it be made to work on an intake other than a tpi?
 
Megasquirt doesn't handle timing at ALL, guess you are stuck with vacuum/centrifugal.

Look at the superram, miniram, and others that I've forgotten about to see what can be done with "stock" TPI. Limitation of the system was mainly the runner length, (high end power was hurt) plenty of designs have shortened the runners. But again, those are expensive pieces, then look at fuel rail prices. Custom is expensive, I haven't seen anything that gets around that fact regarding injection.
 
dyeager535 said:
Look at the superram, miniram, and others that I've forgotten about to see what can be done with "stock" TPI.
Click to expand...

those intakes would quickly break the bank.

im asking, how much can tpi be modified? im not worried about intakes or fuel rails. that is the easy part. what i am asking is what are the limits of tuning a tpi computer? what can it handle before i run into problems?
 
Well the limits I guess are on what you expect or want to do with it. There are plenty of people racing the setup, but that's where I was headed with the custom intakes and what not...if you want to make large numbers, you will have to spend large $$. :) But will it run an electric fan setup...yes. Can you eliminate things like EGR, AIR, EVAP, and do it pretty easily with PROM burning, yes.

If you are talking about say, buy TPI setup complete, throw it on truck motor, can it be tuned to work especially if I want a cam or head change later, the answer is undoubtedly yes. As with any injection, you get real wild with the vacuum signal it will be harder to tune, but it sounds like you aren't necessarily intent on making huge power?
 
well i think that what i am planning to do would have a vacuum signal that would be very different from what tpi is used to. would most likely be a hyd roller cammed 383 with vortec heads and some kind of tunnel ram and two throttle bodies or a single plane and one tb.

i know that might be a lot to ask of tpi, so thats why i am asking.
 
You are talking about a 383 on a system that chokes 350's, yes I can see where you are going. It's essentially the hardware limitation, but too crazy of a cam and you will run into problems with driveability. A lot of that can be tuned out with work, again it's "how much" you are dealing with.

I've got a hydraulic roller cam and Vortec heads (obviously, my sig) but I stayed very mild on the cam when I rushed on buying parts instead of planning/thinking about tuning. It works without any in depth PROM tuning so far, but it needs tuning work anyways. Now I'd probably go with a more aggressive cam, and found some better heads to work with, as it does fade fairly quickly as RPM's climb. Great low end, believe me, but I could have traded that for some upper end. Not sure what you have planned for a cam, but that is something to consider.

Single plane and one throttle body will probably get you there the cheapest, but again, throw in fuel rails, the right size injectors, and the plumbing, the $1000 is easily out the window I'm sure. Someones taken a stock TPI throttle body and mounted it essentially to a metal box to save on throttle body expense. Ugly, but it probably works.

Vortecs are going to be your intake manifold nightmare for injection. I'm sure you are already seeing that. Aftermarket heads (AFR, World, etc) are going to make intake selection a lot larger. See what others have done with 383's and TPI over on thirdgen.org, but that long runner setup side by side with a more efficient intake arrangement on an engine that size, is going to look stupid.
 
yeah those darn vortec heads. i got a set for $100 used, and i really dont want to spend more cash on aftermarket heads. im thinking of modifying a vortec intake for fuel injection or a non vortec intake for fuel injection and for the vortec heads.

prob gonna pick a cam around 260-270 degrees duration with around .500 lift. try to stay on the low side of that. keep the rpm limit around 5500-6000.
 
i just checked over on thirdgen and those guys say that megasquirt will control a tpi/tbi dizzy.

hmmm....
 
I read that bgsoflex page, it says under the 2.2 info that it does not yet control timing. If it does, great, nothing wrong with that! :)

I don't think there are many, if any intakes for "regular" heads that can be modified (anywhere near cost effectively) for the Vortecs. The ports on the Vortecs are way too high, to try and port match you end up cutting all the way through the intake at the top. Seen at least one intake butchered like that.

One other option came to mind last night, what about a Ramjet/Marine takeoff unit? I know that kind of stuff pops up fairly often, and I'm certain there is a guy over on thirdgen that has modified a Ramjet setup to run with an O2 sensor. I've seen some crazy prices on Marine takeoff stuff that is brand new, and I have a feeling the Ramjet stuff might be the ticket for a 383, IF you can find it cheap enough.
 
the new megasquirt2 with pcb v3 DOES control iac valves and hei ditributors.
megasquirt1 did not, although you can upgrade.
the homepage is extremely informative. http://www.megasquirt.info/
i was so impressed i just ordered one tp experiment with.
 
ryan, i just reread your first post, and the megasquirt2 does have a map sensor included, which you don't want.
 
He didn't want MAF, so the MAP they talk about is what he'd want.

I see the timing stuff there now, I agree, with timing being a possibility, it makes even more sense.
 
reread and misread, sorry!
i'll share my results on the build and see if i get megasquirt2 to work. i should be getting it next week, and then i'll have to solder the whole mess together first.
 
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