TB EFI and Carburetor Questions

[XH29N0G]

Working on them is fun.  No doubt about it.

[Paul G]

I have a 505 stroker in my 73 Charger with an older Edelbrock E Street TB EFI system. The engine is built to have 10.5 to compression. Trick Flow heads and a mild cam, 540 lift, 240 duration. It runs very well at 32° of timing.

I decided to play around with E85 blends in an effort to chase more power with more timing and stave off detonation. E85 can have up to 108 octane. Read up on it. Blending in E85 with pump 91 octane can yield a higher octane level. The down side is lower BTU content, which means you must supply more fuel to the engine. An E30 blend is very common. It can raise the octane level to around 95 or so.

It is so easy to add more fuel with EFI. Just change AFR targets via the hand held controller. Get it dialed in and save the tune in the ECU. Going back and forth between tunes as you switch fuels takes seconds.

Now try to do that with a carb. 

[flyinlow]

Do you blend the e85 in a can and then pour into the car?

[Challenger340]

We see it all the time because we typically run the Engines in on a Carb before switching over to EFI...... and yes we've tuned/power run the Carb first before switching over to EFI.
Generally speaking....
we see between 15-20 hp up to 25 hp and same Ft/Lb Torque losses going to a Holley Sniper System on a 500hp 500ft/lb BB Mopar from a well tuned 750 cfm downleg booster Holley Dyno Carb(which is small for those Engines).
and yes....
we've spent time with the Holley Sniper's trying to tune back UP to where we were with the 750 Dyno Carb..... we must be doing it wrong as we never get there.

[Challenger340]

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.

So What ?
I can do that with my bone stock untouched/unrebuilt 440 in my '69 R/T SE using the original AVS Carb ?
Only difference is I have to pump the pedal a couple of times to set the Choke...... and if it's been sitting a few months then Crank it 10 seconds beforehand to get the fuel back up to the Carb ?
Fires right away..... runs on the Choke .... after a few minutes kick it down to the stepped Idle..... and that's WITH the factory single point ignition !

[Paul G]

Do you blend the e85 in a can and then pour into the car?

To do it the right way, you need an alcohol test kit, Amazon $25. Get an app for your phone that calculates how much E85 to mix with whatever octane pump gas you have. Blend it in the fuel tank.

[c00nhunterjoe]

I have a 505 stroker in my 73 Charger with an older Edelbrock E Street TB EFI system. The engine is built to have 10.5 to compression. Trick Flow heads and a mild cam, 540 lift, 240 duration. It runs very well at 32° of timing.

I decided to play around with E85 blends in an effort to chase more power with more timing and stave off detonation. E85 can have up to 108 octane. Read up on it. Blending in E85 with pump 91 octane can yield a higher octane level. The down side is lower BTU content, which means you must supply more fuel to the engine. An E30 blend is very common. It can raise the octane level to around 95 or so.

It is so easy to add more fuel with EFI. Just change AFR targets via the hand held controller. Get it dialed in and save the tune in the ECU. Going back and forth between tunes as you switch fuels takes seconds.

Now try to do that with a carb. 

I can change jets in my carb in a few minutes as well. But i dont need to so i dont. If you think your 10:1 motor needs 108 octane, then thats another story. Like you said, the ethanol fuels require alot more fuel to achieve the same power. So what? Tune it once, tune it right. I never got the "lets keep changing tunes" gig. When ethanol blended fuels became the norm in my area, i went up 2 jet sizes and it was perfect. That was the 1st time that carb was opened in 10 years.

[Mike DC]

I can change jets in my carb in a few minutes as well. But i dont need to so i dont. If you think your 10:1 motor needs 108 octane, then thats another story. Like you said, the ethanol fuels require alot more fuel to achieve the same power. So what? Tune it once, tune it right. I never got the "lets keep changing tunes" gig. When ethanol blended fuels became the norm in my area, i went up 2 jet sizes and it was perfect. That was the 1st time that carb was opened in 10 years.

Going on road trips is an issue.  Varying gasoline sources. 

[c00nhunterjoe]

Ive been on tri state road trips and dont have an issue with fuel. Ethanol blended is pretty much nationwide now. Its harder to find ethanol free fuel.

[XH29N0G]

Challenger 340,  Thank you for that information.  I don't doubt it, but I wonder why a system that should be able to control fuel amounts on a finer level wouldn't be able to work as well.  I had thought it was mostly the different intakes, but I am assuming all is the same with your set up other than the TBI and carburetor.  I would assume the air delivery is about the same or favors the TBI.  It makes me wonder about atomization or something else, but I might be barking up the wrong tree.  Any thoughts will be appreciated because I am learning a lot from this discussion.

Thanks everyone. 

The swapping jets things.  I can do that pretty quickly, but not as quickly as putting a number into a computer.  And if I switched to E85, I would need to buy another set.  I also don't know how I might need to change IFR, bleeds, and emulsion, but I'm guessing that too.  I'll wait for a bit to post, but if people want to discuss dogleg vs annular, I would also love to learn.  I switched to annular because it seemed easier to tune for a smooth AF, but it did require a little bit of playing with emulsion and air bleeds to keep it flat at high end.  It certainly feels responsive at the low end, but I do not know what I am giving up up top.  Or if I am.  Again, looking to learn. 

I really like the patience, detail and information I get from all of you.  Thanks.

[70 sublime]

OK I hope I am not the only one

What the heck does dogleg and annular mean ?

[XH29N0G]

Written that way (or maybe google searched that way) might give some interesting results.  

Dogleg is a booster (the thing the gas comes out of when it goes into the air stream in the carburetor) that bends down and into the venturi (hole in the carburetor).
Annular is a type of booster that has a bunch of little holes and is a bigger diameter (which means it will block air) but it also tends to introduce gas more easily (at lower flow rates) than dogleg boosters.
A straight booster sticks out straight.  

There is an explanation at: https://www.musclecardiy.com/performance/holley-carburetor-booster-science-guide/
and some pictures pinched from the web, below

[cdr]

Challenger 340,  Thank you for that information.  I don't doubt it, but I wonder why a system that should be able to control fuel amounts on a finer level wouldn't be able to work as well.  I had thought it was mostly the different intakes, but I am assuming all is the same with your set up other than the TBI and carburetor.  I would assume the air delivery is about the same or favors the TBI.  It makes me wonder about atomization or something else, but I might be barking up the wrong tree.  Any thoughts will be appreciated because I am learning a lot from this discussion.

Thanks everyone.  

The swapping jets things.  I can do that pretty quickly, but not as quickly as putting a number into a computer.  And if I switched to E85, I would need to buy another set.  I also don't know how I might need to change IFR, bleeds, and emulsion, but I'm guessing that too.  I'll wait for a bit to post, but if people want to discuss dogleg vs annular, I would also love to learn.  I switched to annular because it seemed easier to tune for a smooth AF, but it did require a little bit of playing with emulsion and air bleeds to keep it flat at high end.  It certainly feels responsive at the low end, but I do not know what I am giving up up top.  Or if I am.  Again, looking to learn.  

I really like the patience, detail and information I get from all of you.  Thanks.

The problem with the TBI EFI compared to a Carb IS,,,, on the intake stroke with a CARB, the air is drawn in across the venturi & boosters & fuel is drawn in with that air ,and you have a accurate AFR, the TBI just sprays fuel when ever,and you have raw fuel sitting in the bottom of the intake, the intake charge being drawn into the cylinder is part pure air & some air & fuel mixture,  the O2 sensor   reads an AVERAGE of all the cylinders, some are lean, some are richer, the fuel is NOT timed with the air intake on a TBI, a CARB is MUCH more balanced in the AFR area when air comes in so does fuel, I hope I explained it so that it makes sense , I have a hard time putting things into words.  Think of this, with TBI the piston is going down drawing in air & the fuel is being turned on & off the whole time the piston is going down. a carb it is constant, air AND fuel

[cdr]

For those that dont know, I obviously am not against EFI, my point was learn about HOW to use it & set it up. This is my STREET car, Hilborn Holley EFI, 14 mpg. it has 8 separate Throttle blades , 8 injectors.  tune each cyl

[XH29N0G]

Thank you.  That makes a lot of sense.  I also really like the look and I gather performance of your Hilborn system.

[Challenger340]

For the difference is power Carb to TBI think 2 things:
* Air Density as it relates to temperature..... things get denser as they cool.... or are FORCED to cool
and
* "Change of state"..... as it relates to solids/liquids/gases


NOT a perfect descriptive regarding change of state, but good enough for the concept here ?
but as we go from a block of ICE..... ADD HEAT to melt into WATER...... ADD HEAT to turn the water into steam

Same goes for when the liquid fuel is pulled across a Venturi in a Carb and FORCED to "atomize"(not a gas but still much smaller/finer particles suspended in the airflow).... nonetheless, it must PULL HEAT out of the surrounding ambient Air Flow to do so resulting in a cooler/denser A/F charge
and,
that is the advantage Carbs have to power over TBI systems which do not possess the same cooler/densing effect of the A/F charge as the Carb Venturi

[John_Kunkel]

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.

So What ?
I can do that with my bone stock untouched/unrebuilt 440 in my '69 R/T SE using the original AVS Carb ?
Only difference is I have to pump the pedal a couple of times to set the Choke...... and if it's been sitting a few months then Crank it 10 seconds beforehand to get the fuel back up to the Carb ?
Fires right away..... runs on the Choke .... after a few minutes kick it down to the stepped Idle..... and that's WITH the factory single point ignition !

And you don't see the difference from what I posted? Pump pedal? Crank 10 seconds? Kick off fast idle? Can you say diehard? Joe, you have a brother in arms.

[69Chrgr]

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.

[XH29N0G]

Challenger 340 I like the explanation. Gives me something to think about see if I can understand better

I certainly know that when I start the car, the carburetor cools down so much that it starts to condense water vapor on it and then after a while it heats up with the engine

Never thought about trying to calculate how much cooling that would be and whether that might be different from the situation with the TBI

Thanks

[cdr]

A Throttle Body EFI has very similar cooling to the fuel charge as a carb, it is a wet flow set up.   

[Challenger340]

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.

So What ?
I can do that with my bone stock untouched/unrebuilt 440 in my '69 R/T SE using the original AVS Carb ?
Only difference is I have to pump the pedal a couple of times to set the Choke...... and if it's been sitting a few months then Crank it 10 seconds beforehand to get the fuel back up to the Carb ?
Fires right away..... runs on the Choke .... after a few minutes kick it down to the stepped Idle..... and that's WITH the factory single point ignition !

And you don't see the difference from what I posted? Pump pedal? Crank 10 seconds? Kick off fast idle? Can you say diehard? Joe, you have a brother in arms.

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 ?

Hey John.... just say'in....
Ya better stick to your /Honda/Toyoti's if pumping a pedal a few times or Cranking for 10 seconds after sitting for many months is too hard for you to figure out ? or are you too lazy ?

[Challenger340]

Challenger 340 I like the explanation. Gives me something to think about see if I can understand better

I certainly know that when I start the car, the carburetor cools down so much that it starts to condense water vapor on it and then after a while it heats up with the engine

Never thought about trying to calculate how much cooling that would be and whether that might be different from the situation with the TBI

Thanks

Think "takes HEAT AWAY" as the fuel/liquid is FORCED to atomize across the pressure differential(venturi) creating a cooler/denser A/F charge

Same as when liquid propane for example.... is de-pressurized/released into ambient air pressure and must "change state" from a liquid to a Gas in the lower NON-pressurized environment..... it PULLS HEAT from the surrounding environment to do so.... manifested as we see in 'frost' around the point of escape.

[Challenger340]

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.

Ever had it dump it's program for no reason ?

[XH29N0G]

It would seem that the heat of vaporization should be approximately the same.  

What I think being argued is that there is something else related to the sucking the gas out (some sort of adiabatic cooling ??) that would be different than injecting it into the system.  I do not know if this would make a difference and am trying to understand.  If someone knows and can explain that would be much appreciated. Otherwise I will keep digging.  It is an interesting idea.  

It also makes me wonder about the level of saturation of air by each process.  


PS.  I want a stand up shower option and nut scratcher in my next car   .  

But after my car sat for a few months, all I did was to remove my aircleaner, pour gas through my little funnel into the vents on the fuel bowls, replace air cleaner pump 2 x, turn the key and VOY-LA running engine...then feather throttle because I do not have a choke..and then VOY-LA engine that will run on its own....  

Now there is an elegance and satisfaction in having something that will work without power input once the engine is running and warmed up.....

OK, maybe I am just happy to be done with the day and on to the beer...

I love my carburetor and I am sure I would love EFI if I had it.  My goal was simply to ask whether there was evidence to suggest a difference in power and torque between the systems and why it might be....  I have really enjoyed the discussion and it really has made me think a lot and taught me a few things.

[Paul G]

In my opinion, EFI is just better on the street. Easier start up, easier warm up, easier to dial in, adjust's itself for changing weather conditions. No more winter tune, and fiddle F around, then do it again in the summer. No hammer tapping the float bowl with EFI.

Downside is the EFI cost vs. carb, the install because of the high pressure fuel system that is required, and the electronics. Map sensor goes out, TPS goes out, fuel pump fails, call AAA. Sensors are an easy fix on the road, if you can troubleshoot. No "check engine light" with retrofit EFI.    

I dont think I will buy another carb anytime soon. Actually, anyone want to buy a used Thermoquad that bogs, your pick of leaky finicky Holley's, how about a shitty Edelbrock.