Which is faster carb or Fuel injection?

[Stock726]

Originally Posted by Lee Valentine

Joe, on Bryan's 305 the carbureted combo made 20 more horsepower than the F.I. and made power at a higher rpm. The F.I. combo makes more torque and has a flatter torque curve. run at the same weight the carb is faster.

Hot Rod mag did a comparison test about a year or so ago using an FI LS1. They swapped on the Edelbrock LS1 4-barrel manifold/carb and made more peak HP in every test. The torque curve was a lot peakier however. Of course the EFI system is infintely more tunable, so there's that... The results really surprised me, I thought the FI would be more efficient by design?

[Kegracing]

Some really interesting results and good things that make you think here... which is why I replied to this post to start with.
I will have to try to find the Hot Rod article. Same type of apples to apples that Michael is talking about. My question, is the throttle body truely the same cfm as the carb?
Just hard to understand how on same cfm of air flow, the carb would make more HP, with the tuning ability of the FI cylinder to cylinder. NOT arguing, just trying to understand.
But then again, I have raced for years, and racing in the summer in TX... Never been very smart!

Ken

[keith ohanesian]

Lee you guys ran one 10 years ago. It's light and can be FAST.

[Mike Taylor 3601]

I don't have the best comparision,but I'll throw it out there.
Dynoed 350 chevrolet w holley fuel injection can't recall name,had 950 throttle body w/injectors above throttle body,that is why I don't like this comparision,because injectors mounted in intake runners are advantage,I feel make EFI worthwhile, because of indvidual cyl. tunability, intake not effecting fuel flow,etc
Also this injection was limited on tuning,if I recall correctly had idle,mid and wot adjustments.
So with this being said I feel like you could call this system a electronic carb.

They dynoed almost identical, w/ the efi or carb,but he never could get efi to run on the track.
Mike Taylor 3601

[Signman]

Every engine is nothing more than an air pump. Some better than others. It does not know or care how fuel is delivered. (In a perfect world)

When AFR and spark timing within the combustion chamber are optimal the engine will make max power. The burn is more important than the method of delivery.

[B Parker]

Ok Joe next question. Which is faster a real good metric 200 or a real good Pro Trans 350. Who's done that test before?

[Signman]

Originally Posted by B Parker

Ok Joe next question. Which is faster a real good metric 200 or a real good Pro Trans 350. Who's done that test before?

I'll Bite:
Would think the ET may be about the same but the Pro Trans will live behind engines where an M200 will not.

[Bench Racer]

Does anyone know what cfm a 48mmGM throttlebody flows? I would guess maybe 580cfm but this is a wild guess. I cant see how it would be close to a Q-jet's cfm. Just thinking out of the box but I would think the performance advantage of the efi would be a imediate throttle response with improved low rpm torque, with the carb making more total top end power while giving up some on the bottom end. The larger LS-1 or the drag pack efi I think would be superior to a carb in all rpm ranges. Just my $0.02. Don Jackson.

[Tom keedle]

well, seeing how a throttle body (port fuel setup) flows ONLY air and not a fuel/air mix, I can see a less cfm TB flow as much air as a Q-jet....just my opinion...


is a carb flowed "wet"?

[art leong]

Originally Posted by Bench Racer

Does anyone know what cfm a 48mmGM throttlebody flows? I would guess maybe 580cfm but this is a wild guess. I cant see how it would be close to a Q-jet's cfm. Just thinking out of the box but I would think the performance advantage of the efi would be a imediate throttle response with improved low rpm torque, with the carb making more total top end power while giving up some on the bottom end. The larger LS-1 or the drag pack efi I think would be superior to a carb in all rpm ranges. Just my $0.02. Don Jackson.

Don. The smaller throttlebody only flows air not a mixture.
I had a real hard time grasping throttlebody do's and dont's. I might not be right now. But the way I under stand it (simplified) the throttlebody is basicly feeding one cylinder (at max) at a time.
I had a 65mm throttlebody (probably over sized) on my 4 cylinder Neon and a box manifold feeding all 4 cylinders. I switched to 4 Individual Throttlebodies each one directly feeding a cylinder. Each throttlebody is 52mm. It took a long time to sink into my brain that this setup wasn't way to big. But it finally sunk in that the motor was only feeding one cylinder at a time (100%) and one throttlebody over each hole needed to be big enough to feed that cylinder.