Re: Fuel atomization: Carb vs. EFI
[Re: Cab_Burge]
#2725363
12/19/19 12:01 PM
12/19/19 12:01 PM
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Joined: Jan 2003
Posts: 8,037 Tulsa OK
Bad340fish
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Tulsa OK
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There's really no debate to be had on which technology atomises better. You've had at least two people who have worked in the industry say the same thing (Mr P Body and myself). Higher pressure gives better atomisation. EFI is ALWAYS higher pressure therefore, leaving the carb or injector, better atomisation, every time, period.
Per my original reply - what you do with it after that is getting a lot of good discussion here, but there's no uncertainty about which device atomises better. I am still in doubt about which system, EFI or a dual quad tunnel ram set up, is better for a all out drag race motor Hence NHRA Pro Stock not going faster now with EFI than they did with dual carbs on a tunnel ram intakes I remember several different mechanical fuel injector companies testing the location of the injectors heights in there all out race set ups for dirt and asphalt track roundy round all out race cars My understanding is that the higher up you can place the injector the more power you can make, downside is they are a little harder to dial in for street driving with the injector way up the intake. It would have been interesting to see what happened with pro stock if the EFI conversion didn't require the loss of the scoops and tunnel rams. Holley makes a 4500 bolt pattern throttle body that is 2500CFM, a pair of those on a tunnel ram would be fun.
68 Barracuda Formula S 340
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Re: Fuel atomization: Carb vs. EFI
[Re: Gavin]
#2725372
12/19/19 12:28 PM
12/19/19 12:28 PM
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Joined: Jul 2004
Posts: 19,318 State of confusion
Thumperdart
I Live Here
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I Live Here
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If EFI is so much better(which I don't believe it is in every case)then why did Pro Stock slow down across the board. Plus there's some well known heads up racers I know that sold there's and went BACK to carbs and picked up LOTS of power......My opinion on the 2 places it shines, 1, on our daily drivers get to work stuff and 2, super high end high power(2000+hp)stuff but in between that carbs shine and I've been part of it personally...........
Last edited by Thumperdart; 12/19/19 12:28 PM.
72 Dart 470 n/a BB stroker street car `THUMPER`...Check me out on FB Dominic Thumper for videos and lots of carb pics......760-900-3895.....
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Re: Fuel atomization: Carb vs. EFI
[Re: Thumperdart]
#2725390
12/19/19 02:22 PM
12/19/19 02:22 PM
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Joined: Jan 2003
Posts: 8,037 Tulsa OK
Bad340fish
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Tulsa OK
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If EFI is so much better(which I don't believe it is in every case)then why did Pro Stock slow down across the board. Plus there's some well known heads up racers I know that sold there's and went BACK to carbs and picked up LOTS of power......My opinion on the 2 places it shines, 1, on our daily drivers get to work stuff and 2, super high end high power(2000+hp)stuff but in between that carbs shine and I've been part of it personally........... Pro stock didn't just swap to EFI, they also got a 10,500 RPM limit, lost the scoop, and run a spec throttle body and intake tube. Not to say that the carb still wouldn't make more power but I feel it would be MUCH closer or equal had they got to keep the tunnel rams.
68 Barracuda Formula S 340
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Re: Fuel atomization: Carb vs. EFI
[Re: Gavin]
#2725441
12/19/19 07:18 PM
12/19/19 07:18 PM
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Joined: Apr 2008
Posts: 117 Aus
hysteric
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Joined: Apr 2008
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Aus
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There's really no debate to be had on which technology atomises better. You've had at least two people who have worked in the industry say the same thing (Mr P Body and myself). Higher pressure gives better atomisation. EFI is ALWAYS higher pressure therefore, leaving the carb or injector, better atomisation, every time, period.
Per my original reply - what you do with it after that is getting a lot of good discussion here, but there's no uncertainty about which device atomises better. But does that mean that it produces a better homogenized mixture?
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Re: Fuel atomization: Carb vs. EFI
[Re: hysteric]
#2725443
12/19/19 07:38 PM
12/19/19 07:38 PM
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Joined: Jan 2003
Posts: 31,082 Oregon
AndyF
I Win
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I Win
Joined: Jan 2003
Posts: 31,082
Oregon
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There's really no debate to be had on which technology atomises better. You've had at least two people who have worked in the industry say the same thing (Mr P Body and myself). Higher pressure gives better atomisation. EFI is ALWAYS higher pressure therefore, leaving the carb or injector, better atomisation, every time, period.
Per my original reply - what you do with it after that is getting a lot of good discussion here, but there's no uncertainty about which device atomises better. But does that mean that it produces a better homogenized mixture? Exactly. When I look down the throttle bores of a Sniper it drools big drops of fuel into the intake manifold just like a carb does. The injectors in a Sniper do not spray fuel into the intake which is what most people seem to be assuming.
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Re: Fuel atomization: Carb vs. EFI
[Re: AndyF]
#2725447
12/19/19 07:50 PM
12/19/19 07:50 PM
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Joined: Apr 2008
Posts: 117 Aus
hysteric
member
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member
Joined: Apr 2008
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Aus
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Can anyone please explain how a carb atomizes fuel better than fuel injection.
For the sake of my question both the carb and fuel injection are tuned properly. I don't think anyone on this thread knows the answer to that question. That is a very complicated technical question and nobody would be able to prove it one way or the other without a lab full of equipment. A carb works opposite of injection so the behavior is totally different. In a carb the low pressure area in the venturi sucks the fuel out of the bowl. The pressure differential in a carb is only 5 or 6 psi while an injector operates around 50 psi. The metering block in a carb adds air bubbles to the fuel which helps. There is no air bubble system in an injector. If someone really wants to know the answer to this question they would need to talk to an injector engineer at Bosch. My guess is that they know how to measure it and and could explain it. My understanding is that a 5 gas analyzer would tell you how the fractions are being converted. What happens to the flame front when the mixture isn't ideally homogenized? Just because you atomize fuel doesn't mean the mixture is ideal at the time of ignition. I'm no expert but maybe the question of atomization is just one part of the puzzle. Maybe a thorough reading of Ricardo's work might shed some light on the matter
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Re: Fuel atomization: Carb vs. EFI
[Re: AndyF]
#2725448
12/19/19 07:54 PM
12/19/19 07:54 PM
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Joined: Apr 2008
Posts: 117 Aus
hysteric
member
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member
Joined: Apr 2008
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Aus
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There's really no debate to be had on which technology atomises better. You've had at least two people who have worked in the industry say the same thing (Mr P Body and myself). Higher pressure gives better atomisation. EFI is ALWAYS higher pressure therefore, leaving the carb or injector, better atomisation, every time, period.
Per my original reply - what you do with it after that is getting a lot of good discussion here, but there's no uncertainty about which device atomises better. But does that mean that it produces a better homogenized mixture? Exactly. When I look down the throttle bores of a Sniper it drools big drops of fuel into the intake manifold just like a carb does. The injectors in a Sniper do not spray fuel into the intake which is what most people seem to be assuming. Would be interesting to make a clear manifold and actually see the differences in fuel delivery between a Holley a Carter TQ/Rochestor Qjet and a Sniper.
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Re: Fuel atomization: Carb vs. EFI
[Re: AndyF]
#2725453
12/19/19 08:05 PM
12/19/19 08:05 PM
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Joined: Aug 2011
Posts: 2,872 Pattison Texas
CSK
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Pattison Texas
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I still have some tuning to do, because self tuning EFI is more of a selling point & not a true reality, but the EFI HILBORN 8 Stack I have on my Street Strip car is AWESOME, Individual runners, so the low vacuum, drivabilty issues from a large duration cam are gone, cam is a hyd roller 255, 258 @ .050 & it idles like a stock 440 & drives just as smooth. a carb on a common plenum intake CANNOT do what this EFI set up does, also I can change runner length to tune for power @ different RPM's, as I said earlier I can run much leaner without lean misfires, that tells me better fuel atomization & Obviously better fuel distribution than my ported Indy SP intake. Will keep Y'all updated on my progress at the track.
Last edited by csk; 12/19/19 08:11 PM.
1968 Charger COLD A/C Hilborn EFI 512ci 9.7 compression, Stealth heads, 4.10 gear A518 ODtrans 4100lb,10.93 full street car trim 2020 T/A 392 Stock 11.79 @ 114.5
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Re: Fuel atomization: Carb vs. EFI
[Re: Bad340fish]
#2725460
12/19/19 08:24 PM
12/19/19 08:24 PM
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Joined: Sep 2014
Posts: 4,457 Washington
madscientist
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Washington
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If EFI is so much better(which I don't believe it is in every case)then why did Pro Stock slow down across the board. Plus there's some well known heads up racers I know that sold there's and went BACK to carbs and picked up LOTS of power......My opinion on the 2 places it shines, 1, on our daily drivers get to work stuff and 2, super high end high power(2000+hp)stuff but in between that carbs shine and I've been part of it personally........... Pro stock didn't just swap to EFI, they also got a 10,500 RPM limit, lost the scoop, and run a spec throttle body and intake tube. Not to say that the carb still wouldn't make more power but I feel it would be MUCH closer or equal had they got to keep the tunnel rams. The RPM limit didn't hurt the GM architecture. The hood scoop was on of the MOST cried about pieces of a Pro Stock car ever. WJ sniveled about them for years and claimed a huge gain in MPH if the big "mail box" was gone from the car. EFI retarded Pro Stock in more than one way.
Just because you think it won't make it true. Horsepower is KING. To dispute this is stupid. C. Alston
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Re: Fuel atomization: Carb vs. EFI
[Re: hysteric]
#2725530
12/20/19 02:05 AM
12/20/19 02:05 AM
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Joined: May 2003
Posts: 6,570 Downtown Roebuck Ont
Twostick
Still wishing...
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Still wishing...
Joined: May 2003
Posts: 6,570
Downtown Roebuck Ont
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There's really no debate to be had on which technology atomises better. You've had at least two people who have worked in the industry say the same thing (Mr P Body and myself). Higher pressure gives better atomisation. EFI is ALWAYS higher pressure therefore, leaving the carb or injector, better atomisation, every time, period.
Per my original reply - what you do with it after that is getting a lot of good discussion here, but there's no uncertainty about which device atomises better. But does that mean that it produces a better homogenized mixture? Exactly. When I look down the throttle bores of a Sniper it drools big drops of fuel into the intake manifold just like a carb does. The injectors in a Sniper do not spray fuel into the intake which is what most people seem to be assuming. Would be interesting to make a clear manifold and actually see the differences in fuel delivery between a Holley a Carter TQ/Rochestor Qjet and a Sniper. A buddy of mine in the R&D biz did that years ago. First thing he learned was that fuel staying in suspension in a wet manifold is basically a myth. There is a cloud of it directly under the carburetor and then 90% of it goes directly to the floor of the intake manifold. Kevin
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Re: Fuel atomization: Carb vs. EFI
[Re: BradH]
#2725552
12/20/19 09:01 AM
12/20/19 09:01 AM
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Joined: Jan 2005
Posts: 2,540 Milwaukee WI
TRENDZ
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Milwaukee WI
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I never heard of direct injection above the valve. Direct injection has always been in-cylinder nozzles at extremely high pressures. Port injection, as used on sprint car engines generally have the nozzles entering the port from the exhaust side of the head, straight into the bowl. Other than the clarification, I think you/ he is spot-on. The higher the rpm range, the farther away from the intake valve the injector should be. F1 engines live life way above 10,000 rpm. They have had injectors at great distances for years.
"use it 'till it breaks, replace as needed"
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Re: Fuel atomization: Carb vs. EFI
[Re: TRENDZ]
#2725566
12/20/19 09:45 AM
12/20/19 09:45 AM
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Joined: Jan 2003
Posts: 15,439 Val-haul-ass... eventually
BradH
Taking time off to work on my car
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Taking time off to work on my car
Joined: Jan 2003
Posts: 15,439
Val-haul-ass... eventually
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Port injection, as used on sprint car engines generally have the nozzles entering the port from the exhaust side of the head, straight into the bowl. Yes, that's what I mean; I'm not familiar with all the correct terminology.
Last edited by BradH; 12/20/19 09:55 AM.
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Re: Fuel atomization: Carb vs. EFI
[Re: Bad340fish]
#2725723
12/20/19 08:38 PM
12/20/19 08:38 PM
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Joined: Jul 2004
Posts: 19,318 State of confusion
Thumperdart
I Live Here
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I Live Here
Joined: Jul 2004
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State of confusion
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I remember they changed a few things but most interviews I saw it seemed the drivers/tuners preferred carbs and a forward scoop plus I'm sure singing the HEMI'S way up is missed as well...........I saw the spec sheet on Erica Enders carbs and it was quite eye opening..........
72 Dart 470 n/a BB stroker street car `THUMPER`...Check me out on FB Dominic Thumper for videos and lots of carb pics......760-900-3895.....
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