Conversion from Carb to EFI

[mylesm260]

Re: Conversion from Carb to EFI

Ummm, sorry, not even close.

If modern 4 cycle engines, the Exhaust Gas Recirculation (EGR) valve allows small amounts of exhaust gas to mix with the intake charge prior to entering the combustion chamber.

There is no effect on combustion chamber size what so ever. The only way EGR could affect dynamic compression is by the sole fact that allowing E.G. to enter the intake path heats the AF mix and makes it less dense, but actually cools the combustion temp.

*sigh*

EGR effects dynamic combustion chamber sizes. Sorry, it's a fact. It may not effect the "physical" size of the combustion chamber, but it does effect the "logical" size of the combustion chamber.


Okay,
A quick Diesel VS gas comparison for you.


Diesel engines' have no throttle body. Their engines can breath very very freely. they control their power output and rpms based on fueling.

Gas engines DO have throttle bodies. When the piston goes down, it creates incredible vacuum to draw the air and fuel into the combustion chamber. When the engine is not at wide open throttle, the throttle plate restricts this intake. The result is the piston is fighting the throttle body.


This "chocking" of the engine and having the piston trying to force air into the combustion chamber creates a massive inefficiency (diesel engines use a small fraction of fuel at idle compared to gas engines.)


To try and counter this wasted "vacuum energy" engine designers invented EGR. Exhaust is essentially an inert gas that can fill the combustion chamber without requiring a massive vacuum and a massive amount of fuel.

And yes, controlling EGR is in addition to controlling fuel and spark, but it's not rocket science, I could wtrite the code for it in two seconds.

IF engine load < X (say 20%) than EGR = on
IF engine load > X (say 20%) than EGR = off

 

[ryendube]

Re: Conversion from Carb to EFI

*sigh*

EGR effects dynamic combustion chamber sizes. Sorry, it's a fact. It may not effect the "physical" size of the combustion chamber, but it does effect the "logical" size of the combustion chamber.


Okay,
A quick Diesel VS gas comparison for you.


Diesel engines' have no throttle body. Their engines can breath very very freely. they control their power output and rpms based on fueling.

Gas engines DO have throttle bodies. When the piston goes down, it creates incredible vacuum to draw the air and fuel into the combustion chamber. When the engine is not at wide open throttle, the throttle plate restricts this intake. The result is the piston is fighting the throttle body.


This "chocking" of the engine and having the piston trying to force air into the combustion chamber creates a massive inefficiency (diesel engines use a small fraction of fuel at idle compared to gas engines.)


To try and counter this wasted "vacuum energy" engine designers invented EGR. Exhaust is essentially an inert gas that can fill the combustion chamber without requiring a massive vacuum and a massive amount of fuel.

And yes, controlling EGR is in addition to controlling fuel and spark, but it's not rocket science, I could wtrite the code for it in two seconds.

IF engine load < X (say 20%) than EGR = on
IF engine load > X (say 20%) than EGR = off

well iguess you do understand a lil more .. im not hacking

but your simple code is backwards and missing a line

IF engine load < X (say 20%) than EGR = off
IF engine load > X (say 20%) than EGR = on
IF engine load > Y (say 80%) than EGR = off


dont want it on at idle, cause unstable combustion and dont want it on at full load because of reduced charge density.

wow have strayed so far off this threads topic. anyways heres a link you may find usefull in comparing marine/truck aplication

http://www.bucksengines.com/Data/24.pdf

 

[Handegard]

Re: Conversion from Carb to EFI

EGR has no other function than emissions control, period.

Pre-burnt exhaust gasses are inert as far as combustion goes. Some EFI systems will command the EGR valve open to "dilute" the mixture going in in a effort to reduce combustion temperatures when knocking occurs.

2.2L N/A Ford Probe 89-92 Uses EGR like any other car. The turbo version is setup to use it when knocking occurs. EGR is wildly mis-understood to be "one of them th'ar emission things to be removed" but it provides other benefits and uses.

 

[mylesm260]

Re: Conversion from Carb to EFI

http://www.bucksengines.com/Data/24.pdf

Hey, I was just looking at the engine specs in that PDF..

It says both the marine and truck 4.3's are using Sequential Central port injection in 2001?!?

Is that true? is you're marine motor central-point? Like the trucks?

All the 4.3 EFI marine manifolds I've seen have been multi-point.

IF that's the case, then it's likely the same manifold as truck, and that makes dumping truck efi into a boat that much better.


Like I was saying, I'm using 100% truck EFI, including the trucks central point "poppit" valve injection.

 

[ryendube]

Re: Conversion from Carb to EFI

I have not seen one that is SCPI, but then again I havent seen that many period. I wouldnt use that setup if I had a choice its problematic and only benefits is fuel economy. Intake seal is known to fail, intake known to crack, and coolant dribbles right into the pan mixing with oil rotting your crank bearings. poppit hose are known to dry out and crack, they are expensive lil guys I think about 90$ and you dont do just one. hey im a fan of the engineering behind it the whole injector to poppit increases atomization of the fuel etc etc but real world its a pain.

 

[mylesm260]

Re: Conversion from Carb to EFI

I'm using it because I'm cheap, and that's what was on this motor when I bought it (from a wrecker, 2001 awd asto van)

until I read you're pdf, I thought all the marines were multi-point.

I'm aware of all the issues with this system, however I plan to pull this motor and marineize an LY6 this winter, so it's only gota last me a few more months

 

[ryendube]

Re: Conversion from Carb to EFI

I'm using it because I'm cheap, and that's what was on this motor when I bought it (from a wrecker, 2001 awd asto van)

until I read you're pdf, I thought all the marines were multi-point.

I'm aware of all the issues with this system, however I plan to pull this motor and marineize an LY6 this winter, so it's only gota last me a few more months

i hear ya. I thought cause i had read a it a hundred times and have been told by marine mechanics that they used a different cam, according to GM they dont.

 

[mylesm260]

Re: Conversion from Carb to EFI

Well, my understanding of the cams is this.

the 180 HP trucks/vans (2 wheel drive) cam is different than the 200 HP (4 wheel / all wheel drive) trucks/vans


I believe the 200 HP truck cam is the same, if not very very similar to the marine cam.

 

[ryendube]

Re: Conversion from Carb to EFI

Well, my understanding of the cams is this.

the 180 HP trucks/vans (2 wheel drive) cam is different than the 200 HP (4 wheel / all wheel drive) trucks/vans


I believe the 200 HP truck cam is the same, if not very very similar to the marine cam.

that pdf shows the cam specs.

 

[mylesm260]

Re: Conversion from Carb to EFI

Wow,

That pdf just proves something that I've been arguing in this forum for over a year now......


that's very usefull information, thank you.

 

[lime4x4]

Re: Conversion from Carb to EFI

I can't find it right now. But there was a website that showed u how to drill and install an o2 sensor for marine application (wet exhaust manifolds). Basically all u did was a drill a 5/8" whole in the bottom of the manifold right under an exhaust runner pretty close to where it bolts onto the head.Then tap it the correct thread pitch. If i come across the website i'll post it

 

[lime4x4]

Re: Conversion from Carb to EFI

this isn't the website but it does offer a kit. Read the second paragraph very interesting

http://www.martincoadvertising.com/...-for-marine-water-jacketed-exhaust-manifolds/

 

[lime4x4]

Re: Conversion from Carb to EFI

here is the link for the pdf for the holley efi install. It's towards the bottom

www.sportcompactonly.com/manuals/Brand/Earls/199R10226.pdf

 

[mylesm260]

Re: Conversion from Carb to EFI

"The availability of a working oxygen sensor allows installation of automotive type EFI systems, which provide superior idle, low speed and cruise speed operation and fuel economy. Some existing marine EFI systems can also be converted to closed loop operation with new ECM calibrations."

Nifty!

Notice how they don't mention increased performance?

The fuel savings would pay for itself.

Only problem I see with that is this:

If a heated o2 sensor gets wet, it's toast, instantly, furthermore, there's going to be salt-water mist.. I do not believe an "automotive grade" o2 sensor will last very long in a riser.

Indmar boasts about their special o2 sensors that are marine worthy....

Hey, if it IS possible, that means I could megasquirt my LY6, and run a wide-band o2 sensor.

 

[ryendube]

Re: Conversion from Carb to EFI

Wow,

That pdf just proves something that I've been arguing in this forum for over a year now......


that's very usefull information, thank you.

some set ups can cause reversion on wet systems, only thing i would worry about

 

[Handegard]

Re: Conversion from Carb to EFI

I found this thread because I'm thinking about using Megasquirt for my boat

I have a Volvo 4 cylinder. I was disapointed when I found some automotive fuel injection stuff, and found out it was the old school fuel distributor style, and not EFI...

Looks like my next boat will be a Ford 5.0. I'll use megasquirt on that in a heartbeat if I can get marine o2 sensors...

 

[mylesm260]

Re: Conversion from Carb to EFI

Ya, I was going to megasquirt my setup when I started, but ran into the o2 sensor roadblock.

Tuning a map based system (megasquirt) is basically impossible without some kind of feedback.

I was also toying with the idea of doing a maf megasquirt setup, but I figured for all the @#$#ing around, I might as well just leave the factory GM truck ECU in there.

IF you're thinking about a motor swap, maybe we could all get together and start a thread and plan out an Ly6 marineization...

The bellhousing and coupler are going to be a direct bolt up to the existing mercruiser v8's.

Only sticky point is manifolds, but indmar and PCM both make manifolds for them.

400 HP, aluminum, variable valve timing....

 

[RayTCraft]

Re: Conversion from Carb to EFI

WOW
I sure didn't expect all this response but I want to thank all of you for your input. From reading through eveyone's reponses and after considering all that has been said I'm inclined to make 1 out of 2. I'm going to just clean out the Blazer block and rebuild from there using my existing pistons, crank, cam, heads, intake and carb. My engine is a 1990 vortec (roller cam setup). The truck the block is coming from is actually a 1994 4.3L (OOPs, my mistake ). I have been told by a guy at an engine machine shop here that they are fully compatible. Does that jive with what you guys know?

 

[bruceb58]

Re: Conversion from Carb to EFI

Vortec Cylinder heads did not hit the 4.3 engine until 1996. The engines may have been called Vortec but that was a name only. You need a 1996 engine or later.

The balance shaft motors started in 1992. They have a different intake manifold than earlier models.

 

[ryendube]

Re: Conversion from Carb to EFI

Easiest way to tell regardless of what has been done to the motor what has been swapped. Look at how the intake threads to the heads. Old style is angled, new style is straight. straight is Vortec.



Question to the engine nuts ive been discussing with. What about Efilive or HPtuner, CATS now jet spectral etc I know of some open source programmers aswell. Ive been leaning towards buying one of these instead of aftermarket ecm. as far as ive read up on them you can edit all tables with some and even eliminate/add I/O. I have only experience with an older untis and the holley system, last time i built an EFI the technology wasnt on the up and up.

as far as Ive read EFIlive seems to be the top, but Ive like what ive read about the CATS system (JET spectral). Any first hand experience?