TB EFI and Carburetor Questions

[Paul G]

Why does a carb make more power than an EFI system? It has been proven on TV many times on the hot rod builder shows. But still they have never explained why.

Same CFM of air, same AFR of fuel, yet carb makes more WOT power. Can it be when the fuel is delivered? EFI can self tune for smooth transition across the RPM and load range. Much more difficult with a carb. So carbs are set up OOTB to run rich, rich is safe for all engines.

 

[c00nhunterjoe]

Haven't driven my FI Tech equipped Plymouth in several months. Went out the other day, never touched the throttle, turned the key to start, fired right up and settled into the programmed idle of 800 rpm.

Bingo. I installed the Holley Sniper EFi with the Holley Hyperspark timing control. 440/512 Indy Max Wedge heads and solid roller. It can sit for months and start right up. Regardless of temperature. Absolutely one of the best things I have ever done to my car.

i have a 950 holley on my 440/ indy max wedge heads, .750/290@ .050 solid roller cam and it sits for months and fires right up regardless of temperature as well.

[John_Kunkel]

And YOU can't see the difference between driving a 2020 Toyota with a "stand up shower option" and an auto NUT scratcher....
and
operating a 50+ year old classic ?

I most assuredly do, and I recognize when modern technology can improve the drivability of a 50 year old classic and I'm not afraid to marry the two.

[Kern Dog]

For me, COST is a consideration. My carbureted cars start and run fine for me in North Central California where it rarely snows.
I don't see the benefits being worth the costs. AS simple as a carburetor is, if I have a fuel issue, a simple filter or carb swap usually fixes the problem. To me, electronics are still a mystery. My late model cars are so reliable, I haven't had to learn much about them other than basic maintenance. Maybe if I had EFI in my classics it would encourage me to understand it.
It really is a matter of cost versus benefits.
That same argument is why I hold off from doing the 5 speed Tremec swap in my car. I'm sure the car will be more fun to drive but is it worth $6500 ?
If the stuff was free, sure.....

[69Chrgr]

And YOU can't see the difference between driving a 2020 Toyota with a "stand up shower option" and an auto NUT scratcher....
and
operating a 50+ year old classic ?

I most assuredly do, and I recognize when modern technology can improve the drivability of a 50 year old classic and I'm not afraid to marry the two.

John Kunkel is spot on again. Maybe some people would rather get rid of the electric starter and go back to points and condenser and brag about how much better they are......

[c00nhunterjoe]

And YOU can't see the difference between driving a 2020 Toyota with a "stand up shower option" and an auto NUT scratcher....
and
operating a 50+ year old classic ?

I most assuredly do, and I recognize when modern technology can improve the drivability of a 50 year old classic and I'm not afraid to marry the two.

John Kunkel is spot on again. Maybe some people would rather get rid of the electric starter and go back to points and condenser and brag about how much better they are......

Anytime you want to line your 512 against my 440, im game.

[XH29N0G]

I got my spare points and condenser on the shelf in case of a solar storm, em blast, or alien invasion.....

I just wanted to know what the evidence was for different power through the curve.  It seems like there may actually be some evidence for that.  It also seems like there may be differences in intake design that make a difference too.

I appreciate the responses I have had so far and am grateful we have not descended into efi vs carb until late in the thread. 

[c00nhunterjoe]

I got my spare points and condenser on the shelf in case of a solar storm, em blast, or alien invasion.....

I just wanted to know what the evidence was for different power through the curve.  It seems like there may actually be some evidence for that.  It also seems like there may be differences in intake design that make a difference too.

I appreciate the responses I have had so far and am grateful we have not descended into efi vs carb until late in the thread. 

Bottom line- if you are an xbox bandit and cant tune a carb- gp injection. Otherwise go carb.

[Rolling_Thunder]

The advantages that I have read about usually revolve around driveability. Cold weather operation, travelling through high elevations, etc.
EFI has a place, no denying that but for a car that is a "toy" in a fair weather environment? It is a big investment for what seems like a small gain, if any.

There it is- traveling through high elevations.... i dont recall my parents or grandparents telling me stories about having to stop for rejets during family road trips in the 50s and 60s....

Unless you were going from say Death Valley, CA to maybe Denver or Aspen it wouldn't really need too much - then again engines of the OE set up were made to run through a variety of conditions and perform well over a spectrum....    WE make it a tuning nightmare when you add some cam here...    a carb there...    as is the story of most cases...    we are our own worst enemies...    if we just left things stock they would be fine....    it's people hunting for every last drip of horsepower that make things more temperamental  (all personal opinions)

[69Chrgr]

And YOU can't see the difference between driving a 2020 Toyota with a "stand up shower option" and an auto NUT scratcher....
and
operating a 50+ year old classic ?

I most assuredly do, and I recognize when modern technology can improve the drivability of a 50 year old classic and I'm not afraid to marry the two.

John Kunkel is spot on again. Maybe some people would rather get rid of the electric starter and go back to points and condenser and brag about how much better they are......

Anytime you want to line your 512 against my 440, im game.
Sure you are.....

[John_Kunkel]

Bottom line- if you are an xbox bandit and cant tune a carb- gp injection. Otherwise go carb.

Curious, when you "tune a carb" how do you know when it's "just right"? Ear? Time slip? Butt meter? AFR meter? Dyno?

[XH29N0G]

John

I think that depends. The carb that I have has the different circuits.  For the main circuit, I started with the AFR because it let me see the mixture. I assume what I was doing with the Jets and bleeds and things like that was probably what his automatically done with the fuel injection.   Then finally, and  more recently, I started timing the acceleration so that I could get data that way and adjust the mixture in a way that would optimize it. The AFR just gives me a number and I know they're supposed to be an optimal one, but it appears that my car accelerates quickest with something slightly different than the setting I came to when looking at it just by afr and reading what was on the internet.

This is what everyone told me, but it took me a long time to learn that.

What I won't have is an ability to change it with changing conditions unless I am willing to map that out with the disassembly and changing of Jets and bleeds.

I'm by no means an expert, but I put that down because I think it probably falls in the middle of what people do. I'll be interested to see if there are any other things that people do.

But I do know is that when I started playing around using acceleration things picked up considerably.

And I learned how small things like keeping all variables in the test constant like level of gas tank or taking that into consideration can make differences.

I'm dictating this so I hope there aren't any really stupid typos, but I'll come back and clean it up later.

I also imagine that if you took the same approach, using acceleration with the fuel curve on an EFI that you could optimize it as well.

For idol and transition, that again is based on what runs best with the baseline that is set by things like vacuum and looking at the AFR.

I'll leave idol for idle.

[c00nhunterjoe]

Bottom line- if you are an xbox bandit and cant tune a carb- gp injection. Otherwise go carb.

Curious, when you "tune a carb" how do you know when it's "just right"? Ear? Time slip? Butt meter? AFR meter? Dyno?

Are those not all the methods used by the efi?

[John_Kunkel]

While you're bending over the fender draining bowls, changing jets/bleeds, I'm....

https://www.youtube.com/watch?v=XrQT6dJwS2Q

[c00nhunterjoe]

While you're bending over the fender draining bowls, changing jets/bleeds, I'm....

https://www.youtube.com/watch?v=XrQT6dJwS2Q

Dont see the point? Still not rocket science to do either one and you still have nuts bolts wire and fuel to deal with installing it.

[XH29N0G]

I am curious as someone who has not worked with EFI and trying to learn about it.  How difficult is it to map out AFR during acceleration?  I am assuming it is pretty straightforward to choose and change.

It would be nice with a carburetor to be able to do that, but I actually enjoy the tinkering part and the thinking between tests about what I should try next. 

[68CoronetRT]

I am curious as someone who has not worked with EFI and trying to learn about it.  How difficult is it to map out AFR during acceleration?  I am assuming it is pretty straightforward to choose and change.

It would be nice with a carburetor to be able to do that, but I actually enjoy the tinkering part and the thinking between tests about what I should try next. 

Mapping out a table from scratch is a big task and takes hours and hours to tune properly. Usually you sit on a dyno all day and just keep making changes. Thats just on the surface, to even get to the running engine point is a task of its own. Injector timing, pulse widths, sensors working together, tip in, accel enrichment, timing decay, off throttle enrichment etc etc.. the list goes on and on.

The beauty of the EFI units now a days is you set a target AFR at idle, cruise and WOT and the computer will auto correct the table forever and ever. Eventually you can just turn the learning off and it should be good to go. I had to do this once when my O2 died and the computer just dumped fuel to try and save the engine because the computer thought it was leaned out so bad. I now carry the tools to change the o2 on the side of the road and a spare o2 just in case.

My testing consists of making a small timing adjustment and a WOT target adjustment, thats it. Love being able to do all of that on the fly at any speed with the click of a few buttons. But there was a lot of tinkering to get the car to fire up cold vs hot, high idle cold vs hot, pull timing based on IAT's, idle timing, cruise timing, WOT timing, off throttle fueling so it didnt die when you snapped off the throttle. All these little things add up and just takes time and tinkering with. You go one direction and see if it helps, if not you back track and go the other way, in small steps. It's actually a lot of fun!

[cdr]

I am curious as someone who has not worked with EFI and trying to learn about it.  How difficult is it to map out AFR during acceleration?  I am assuming it is pretty straightforward to choose and change.

It would be nice with a carburetor to be able to do that, but I actually enjoy the tinkering part and the thinking between tests about what I should try next. 

Mapping out a table from scratch is a big task and takes hours and hours to tune properly. Usually you sit on a dyno all day and just keep making changes. Thats just on the surface, to even get to the running engine point is a task of its own. Injector timing, pulse widths, sensors working together, tip in, accel enrichment, timing decay, off throttle enrichment etc etc.. the list goes on and on.

The beauty of the EFI units now a days is you set a target AFR at idle, cruise and WOT and the computer will auto correct the table forever and ever. Eventually you can just turn the learning off and it should be good to go. I had to do this once when my O2 died and the computer just dumped fuel to try and save the engine because the computer thought it was leaned out so bad. I now carry the tools to change the o2 on the side of the road and a spare o2 just in case.

My testing consists of making a small timing adjustment and a WOT target adjustment, thats it. Love being able to do all of that on the fly at any speed with the click of a few buttons. But there was a lot of tinkering to get the car to fire up cold vs hot, high idle cold vs hot, pull timing based on IAT's, idle timing, cruise timing, WOT timing, off throttle fueling so it didnt die when you snapped off the throttle. All these little things add up and just takes time and tinkering with. You go one direction and see if it helps, if not you back track and go the other way, in small steps. It's actually a lot of fun!

all this & having  Data log capability makes all this MUCH easier to accomplish

[XH29N0G]

It sounds like it works for the main things and there are other levels of detail to keep us interested and occupied and can be done. But the principles would be the same.  Adjust for the best time and the smoothest operation.

Maybe someday for me. 

Thanks

[cdr]

It sounds like it works for the main things and there are other levels of detail to keep us interested and occupied and can be done. But the principles would be the same.  Adjust for the best time and the smoothest operation.

Maybe someday for me. 

Thanks

Every time I drive my car I tinker with the tune, its just part of it for me.

[John_Kunkel]

Mapping out a table from scratch is a big task and takes hours and hours to tune properly. Usually you sit on a dyno all day and just keep making changes.

Or you blip the throttle, go back, sniff the tailpipe and call it good like most carburetor "tuners". 

[cdr]

Mapping out a table from scratch is a big task and takes hours and hours to tune properly. Usually you sit on a dyno all day and just keep making changes.

Or you blip the throttle, go back, sniff the tailpipe and call it good like most carburetor "tuners".  

I did not say this, it says it is a quote from me,

My car is EFI, has left & right NTK wide bands, individual cyl tuning. why you are slamming me I have no idea

[XH29N0G]

Csr

I think we all know that you put a lot of thought into what you're doing, and I really appreciate the input.

I like the idea of blipping the throttle and smelling the exhaust, but I'm not that good.

The idea of tuning a carb from one snif reminds me of trying to teach undergraduates in Canada on the topic of mineralogy when the economic downturn happened in the 1990s.  They were all from industry and exploration. they'd pick up the rocks hold them to the side of their head and list off all the minerals that were in them.  Then they'd tell me it was a trick that they learned from the field where they could use the conductivity of heat into their forehead to identify which minerals were in The Rock and whether there was gold in it.  

They knew more about mineralogy than I did. So we made a deal.  I helped them with all the chemical stuff and the stuff related to computations.  They taught me things about mineralogy that I didn't know.

[Kern Dog]

Mapping out a table from scratch is a big task and takes hours and hours to tune properly. Usually you sit on a dyno all day and just keep making changes.

Or you blip the throttle, go back, sniff the tailpipe and call it good like most carburetor "tuners".  

I did not say this, it says it is a quote from me,

My car is EFI, has left & right NTK wide bands, individual cyl tuning. why you are slamming me I have no idea

Look above. John edited down a quote by 68CoronetR/T and pulled HIS words.

[John_Kunkel]

Yeah, error in snipping. Sorry cdr and it wasn't a slam, calibrate your humor detector.