Carbs make more power than FI?

[gmc406]

Some forums have a voting option when you start the thread. I wish this one did. I know many of you have been around long enough to remember the “ Why are carbs being used if EFI is some much better?” thread. It would be interesting to see how things have changed in opinion from then till now. I know this topic will come up again in a couple more years. Be neat to see if there’s a difference in opinion then too.

[Ron E]

Carbs seem to still have a very slight advantage to EFI in arenas like comp. I.E. where the converter stall is less than 1000 RPM below HP peak RPM. A super narrow range. Everywhere else that I'm aware of EFI is just better.
Anybody remember going outside to start your car on those 20° mornings and having to stay with it until it stabilized. Now, just hit the starter, go back inside and everything's good. I love that.

[hoffman900]

Carbs seem to still have a very slight advantage to EFI in arenas like comp. I.E. where the converter stall is less than 1000 RPM below HP peak RPM. A super narrow range. Everywhere else that I'm aware of EFI is just better.
Anybody remember going outside to start your car on those 20° mornings and having to stay with it until it stabilized. Now, just hit the starter, go back inside and everything's good. I love that.

Carburetors are only better on a wet plenum. How about a tunnel ram manifold with high pressure shower injectors pointing down the runner from the roof? My guess is you can shrink the plenum size slightly which will aid in shift recovery. That’s just a hunch though.

[Truckedup]

Most of the talk here about possible carburetor advantage is about drag racing OHV engines with port limitations due to basic design....The fuel injection advantage seems to be more clear cut with modern 4 valve engines ....

[WeingartnerRacing]

Here is the real advantage. A good Carb and ignition $2500. Efi $5000-6000 to go the same or maybe.05 faster. Why, so many other parts to gain more for less. Then when an efi car can’t fire because of some sensor the carb keep it simple stupid principle wins again.

[treyrags]

Side bar on Comp Eliminator. How are they not hinged on the indexes when you're penalized for going faster than the index at certain increments? I'm well aware of a few of the top guys being part of Pro Stock teams, which serves to reinforce my point. They've got the carburetors extremely developed but their fuel injection experience is that with an inadequate system.

These "penalties" don't slow them down, it makes them work harder to go faster. So I guess even though Comp is not restricted to the "inadequate" system Pro Stock has, all these guys just have their head in the sand?

[dfarr67]

You can't make blanket statements about EFI versus carb unless you compare apples to apples comparisons on the same spec engine in a vehicle racing.

Dyno only comparisons don't take into account the tuning while running capability of an EFI system versus a pre-tuned and adjusted carb.

Implementing EFI in classes of racing with rules that make users modify existing intake manifold carb intake systems you are not going to have optimim results.

EFI will replace carbs in almost all forms of racing except as George Klass said, "I am not going to put it on my lawn mower!"

Cub Cadet and Troy-Bilt are some of the EFI mowers available now. Kawasaki engines too.

My Ski Doo 600ACE is direct injected with (I think) 11:1, ran OK on 87, better on 90 octane. Does wonders for performance and economy- but sure makes the sport more expensive.

[andyf]

Here is the real advantage. A good Carb and ignition $2500. Efi $5000-6000 to go the same or maybe.05 faster. Why, so many other parts to gain more for less. Then when an efi car can’t fire because of some sensor the carb keep it simple stupid principle wins again.

This comparison may or may not be true, it all depends on what you are comparing. On a higher end bracket car it is basically a push. On a lower end car the carb will be cheaper. The higher end stuff usually has extras that add money such as timing retard, two step, nitrous controls, data logging, etc. All of that can be replaced with a Holley HP or Dominator system. So if you are starting from scratch it is less expensive to use EFI.

I know this since I'm building an EFI controlled car from scratch right now. The EFI system is expensive but I don't need to buy a distributor, ignition box, big MSD coil, data logger, nitrous control system, start retard, high speed retard, carb and jet kit, gauges and a gauge panel, etc. Not to mention, I don't need to mount or wire all of that stuff. So according to my spreadsheet it is cheaper to build with EFI from the start.

[andyf]

You can't make blanket statements about EFI versus carb unless you compare apples to apples comparisons on the same spec engine in a vehicle racing.

Dyno only comparisons don't take into account the tuning while running capability of an EFI system versus a pre-tuned and adjusted carb.

Implementing EFI in classes of racing with rules that make users modify existing intake manifold carb intake systems you are not going to have optimim results.

EFI will replace carbs in almost all forms of racing except as George Klass said, "I am not going to put it on my lawn mower!"

Cub Cadet and Troy-Bilt are some of the EFI mowers available now. Kawasaki engines too.

My Ski Doo 600ACE is direct injected with (I think) 11:1, ran OK on 87, better on 90 octane. Does wonders for performance and economy- but sure makes the sport more expensive.

Yeah I'd want EFI on a snowmobile too! Carbs and sub-freezing weather are not a great mix. Not to mention a lot of high g stuff if you start taking jumps or riding steep hills.

[David Redszus]

Over the years we have seen a number of fueling options.
1. An engine designed for carbs using carbs.
2. An engine designed for carbs using some form of fuel injection.
3. An engine designed for fuel injection using fuel injection.
4. An engine designed for fuel injection using carbs.

Option #3 will win every time, all other things being equal; which they seldom are.

Just as all carbs are not the same, neither are all fuel injection systems.

We started using timed port fuel injection sprayed at 450-500 psi, over 45 years ago.
No carb could come close with regard to performance. However, the best carbs at the time
(Webers) could be easily adjusted while the injection system was much more difficult to tune.
But once properly tuned it was no contest. Every factory prepared race car of the era switched to FI.

But not all FI systems are equal in performance. Part of the problem is system design and part is
due to installation error.

Today, we still have low pressure EFI systems that are often improperly mapped, coupled to an ineffective
induction system and questionable ignition mapping. A throttle body system with injectors can't really be
considered close to state of the art.

Injectors that squirt like a fire hose, rather than spray a fine fog are sub-optimal. Mixture quality
is just as important as mixture quantity. Fuel evaporative cooling that chills the inlet manifold
rather than increasing inlet air density is also sub-optimal.

In short, buzz words do not reflect the true performance potential of either type system.
Simply bolting on new hardware does not ensure improved performance. Like every other system
on a race car, it must be carefully, and sometimes painfully, optimized.

[groberts101]

If we're talking about pure average power from start to finish?.. I don't even remotely comprehend why anyone would argue the merits of carbs over injection. The design and physical limitations with EFI are far fewer than any carb'd setup would ever allow.

Where I think the disconnect is happening here, well.. besides people inherently liking to draw lines in the sand and stand with arms, is that we don't see fully optimized and absolutely idealized EFI systems simply because, first off.. HOW THE HELL DO YOU FIT IT ALL UNDER A HOOD? Even open wheeled cars have to consider engine packaging and drag created from the engine packages whether they be front or rear engine configurations.

Then from there we should consider and look at the available mfgr'ing processes and technological capabilities as they relate to overall unit cost and future maintenance potential. What would happen to everyday injectionsystems if they moved towards variable size and length induction system with 16 or more ultra high pressure injectors? Could that configuration beat a tunnel rammed carb setup?

Also IMO, it would be downright silly to underestimate and ignore the fact that almost ANY race car can be made to go quicker/faster but tossing aside a spent or broken engine after only 1 run isn't even feasible for anyone other than NASA, and even they have bean counters who force decisions on the engineers. Does that mean the parts they use are inferior to ones which could make more power? Yes AND no.. since it's all related to what we expect to gain from the money spent to accomplish it. I just said it in another thread here.. the juice ain't worth the squeeze.

[Steve.k]

Cub Cadet and Troy-Bilt are some of the EFI mowers available now. Kawasaki engines too.

My Ski Doo 600ACE is direct injected with (I think) 11:1, ran OK on 87, better on 90 octane. Does wonders for performance and economy- but sure makes the sport more expensive.

Yeah I'd want EFI on a snowmobile too! Carbs and sub-freezing weather are not a great mix. Not to mention a lot of high g stuff if you start taking jumps or riding steep hills.

The new series etec skidoo direct injection two strokes make better milage than comparible 4 strokes. They had a bit of a issue getting the right injector made that would stratafie the charge in the short distance between closing of exh port and tdc.And your right it makes a huge difference in mountain riding where we are.I didvhear at one time what the max hp limit was for injectors but it slips my mind. Some guys getting close to 200hp on high 800cc. The carbs can still pull a little more hp at this point.

[WeingartnerRacing]

Here is the real advantage. A good Carb and ignition $2500. Efi $5000-6000 to go the same or maybe.05 faster. Why, so many other parts to gain more for less. Then when an efi car can’t fire because of some sensor the carb keep it simple stupid principle wins again.

This comparison may or may not be true, it all depends on what you are comparing. On a higher end bracket car it is basically a push. On a lower end car the carb will be cheaper. The higher end stuff usually has extras that add money such as timing retard, two step, nitrous controls, data logging, etc. All of that can be replaced with a Holley HP or Dominator system. So if you are starting from scratch it is less expensive to use EFI.

I know this since I'm building an EFI controlled car from scratch right now. The EFI system is expensive but I don't need to buy a distributor, ignition box, big MSD coil, data logger, nitrous control system, start retard, high speed retard, carb and jet kit, gauges and a gauge panel, etc. Not to mention, I don't need to mount or wire all of that stuff. So according to my spreadsheet it is cheaper to build with EFI from the start.

Not from my math at all the grid set up with custom carb $2500 efi same set up $5000-6000 and you still have to buy the ridiculously over priced accufab throttle bodies.

[dfarr67]

My Ski Doo 600ACE is direct injected with (I think) 11:1, ran OK on 87, better on 90 octane. Does wonders for performance and economy- but sure makes the sport more expensive.

Yeah I'd want EFI on a snowmobile too! Carbs and sub-freezing weather are not a great mix. Not to mention a lot of high g stuff if you start taking jumps or riding steep hills.

The new series etec skidoo direct injection two strokes make better milage than comparible 4 strokes. They had a bit of a issue getting the right injector made that would stratafie the charge in the short distance between closing of exh port and tdc.And your right it makes a huge difference in mountain riding where we are.I didvhear at one time what the max hp limit was for injectors but it slips my mind. Some guys getting close to 200hp on high 800cc. The carbs can still pull a little more hp at this point.

Etec 600cc is 120hp, ACE 600cc is 60hp- very quiet, apparently last (40k miles claimed), the two strakes I think last around 7k miles.

[Steve.k]

Yes thats about right. Mine is 800 etec bored to 872. Dave trygstad builds the kits in Minnesota. The new 900ace turbo up to 150 hp now.