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Fuel Injector vs carburetor


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carjunky
Enthusiast

Apr 11, 2005, 8:42 AM

Post #1 of 9 (62323 views)
Fuel Injector vs carburetor Sign In

When it comes down to pure horsepower which system is the best for generating the most power? Fuel Injector or a Carburetor?


Tom Greenleaf
Ultimate Carjunky / Moderator
Tom Greenleaf profile image

Apr 12, 2005, 1:57 AM

Post #2 of 9 (62312 views)
Re: Fuel Injector vs carburetor Sign In

Interesting query. I think fuel injection took over because of emission control and you don't need the "pump the carb" thing to start a car.

The marine engines still chiefly use carbs and they want all the power they can find and need it!

I think it's mostly driven by cost effectiveness, either could be designed to be effective. At the moment I think carbs still win as they are easier to tweak for optimal power and performance. Other opinions invited, Tom



carjunky
Enthusiast

May 8, 2006, 6:04 AM

Post #3 of 9 (48461 views)
Re: Fuel Injector vs carburetor Sign In

Brian,

Do dragsters use Fuel Injectors or carburetors ? Curious because like tom was saying the marine world is searching for more hp's... And dragsters are in "the same boat" searching for a lot of horsepower as well.


Brian1
User

May 8, 2006, 9:53 PM

Post #4 of 9 (48456 views)
Re: Fuel Injector vs carburetor Sign In

This is an interesting question, I think it could be argued either way!!

Top Fuel Dragsters and Funny Cars use mechanical fuel injection. Most of the fuel is injected through nozzles that are mounted directly into the combustion chamber of the cylinder heads. A small amount of fuel is injected through the supercharger to keep it cool and lubed. The fuel curve is preset before they make their run and it will not compensate for changes in atmospheric conditions like modern electronic fuel injection systems will. This is when a good crew chief is a must!!!!

Yes, I agree you can easily “tune” a carb to make an engine run at it’s optimum potential. However, we all know that an engine that is running either lean or rich isn’t making it’s most power therefore, in modern racing I think fuel injection is becoming more and more common. Warren Johnson, second on the all time win list in professional drag racing, races in the category called “Pro Stock” Warren has been wanting fuel injection allowed for years in Pro Stock. He thinks fuel injection would make more power and be easier to tune. Instead of using “jets” to tune the car he would just use a “laptop” to adjust the fuel ratio.….. Pro Stock currently runs 500 cubic inch, gasoline burning, dual 4 barrel carb V8’s and make about 1700HP. They run about 6.70 seconds in the quarter mile at 206MPH.


In drag racing (and I’m sure in other form of racing also) we use a term called “corrected altitude” which means the altitude the engine “thinks” it’s running at above sea level. Lets say were running at a track that is 1500 feet above sea level, the corrected altitude may be 2800 feet because of the atmospheric condition. Ambient air temp, humidity (water grains) , barometric pressure and actual altitude are some of the factors used in calculating the corrected altitude. I’ve seen conditions on race day change drastically (more than you would think they would or should) In fact, the race track in Joliet Illinois…. Route 66 raceway, very often has what we call “Mine Shaft Conditions” I forget what the actual altitude is but sometimes the “corrected altitude” is WAY below sea level and when that happens….. LOOK OUT!!! There has been MANY national speed and elapsed time records broken and reset at that track because of the mine shaft conditions. When racing in mine shaft conditions, if you don’t “rejet” from the last track where you were running at 2800 feet you could be dangerously LEAN!!! If you were running an electronic fuel injection system you wouldn’t need to worry because it would compensate automatically.


The category my friends race in is a “Super” category. In Super class racing we use a “throttle stop” to slow the cars down to a national index for that class. Our national index is 9.90 seconds but the cars are capable of running in the 8 second range. Because we have more power than needed to run 9.90 we just jet the car “fat” or “rich” so we know it’s safe and not lean and control the speed of the car by adjusting the throttle stop timer. If we need to go slower we put more time in the timer, if we need to go faster we put less time in the timer. We use a “weather station” connected to a computer mounted in the motor home back in the pits that constantly monitors the changing conditions. It automatically computes the changes and how the car will react to those changes and sends a “throttle stop prediction” every 2 minutes to a digital pager that I have on my belt. Just before my friend stages the car I tell him the latest “prediction” and he puts that number into the timer in the car. If everything goes correctly the car should go 9.90 seconds. (there is actually more to it but this was the abbreviated version)

In our class of racing we have more power than we need but in other classes where they need all the power they can get I think fuel injection would definitely be the way to go if allowed in that category.


I hope I didn’t ramble too long about racing,
Brian.

Roadside One LLC
24 Hour Roadside Assistance - Twin Cities South Metro Area.
Lockouts - Jump Starts - Tire Changes - Fuel Delivery
www.roadsideone.com

(This post was edited by Brian1 on May 8, 2006, 10:00 PM)


Tom Greenleaf
Ultimate Carjunky / Moderator
Tom Greenleaf profile image

May 10, 2006, 9:03 AM

Post #5 of 9 (48448 views)
Re: Fuel Injector vs carburetor Sign In

Good one Brian1. The marine industry is going fuel injection and I'm out of that now but even new boats/yachts were still using carbs and points long after cars changed?? Don't know why.

The last yacht I worked on had twin 454 single quads at about 360 HP each and still couldn't reach more than 18 knots at a whopping half mile to the gallon if you pushed it hard!!!! At an average cruise is could do .75!!!! Spent several vacations on that boat and among four people the fuel was NOT the largest expense at the time.

Fuel injection belongs in yachts. From a fly bridge you can't hear the engines when you start them very well and can easily just rev them out of control - not good. Takes a sharp eye on the gauges to see what's happening.

__________________________________________

Just fun - saw about a 200 foot yacht pass us headed for Nantucket at probably 60MPH!!!!

_____________________

Trivia with boats:

How far can a large cruise ship go on a gallon of fuel? Scroll down
















About 11 Inches!!!! -- I think we can stop complaining about our carsSmile T



Brian1
User

May 10, 2006, 2:56 PM

Post #6 of 9 (48443 views)
Re: Fuel Injector vs carburetor Sign In

Man I’m glad I’m not paying for the gas in those big boats, especially at 0.5 miles per gallon!!! I’m not sure how it works where you live but here in Minnesota, if you buy gas for your boat at a marina it’s usually about $1.50 to $2.00 per gallon more than at a regular gas station for cars!!!

Good point about not being able to hear the engine(s), I never thought about it that way. With the outrageous cost of big boats/yachts I would think even IF fuel injection doesn’t make more HP and/or doesn’t get better mileage they should have FI just for the better drivability factor alone.

Brian.

Roadside One LLC
24 Hour Roadside Assistance - Twin Cities South Metro Area.
Lockouts - Jump Starts - Tire Changes - Fuel Delivery
www.roadsideone.com


carjunky
Enthusiast

May 11, 2006, 6:24 AM

Post #7 of 9 (48436 views)
Re: Fuel Injector vs carburetor Sign In

Here in New Jersey, Gas is the same price difference - about $1.00 more at the marina's compared to the service stations... so some of my friends with smaller boats make many trips by car to fill up the tanks.. lol


Tom Greenleaf
Ultimate Carjunky / Moderator
Tom Greenleaf profile image

May 11, 2006, 8:29 AM

Post #8 of 9 (48431 views)
Re: Fuel Injector vs carburetor Sign In

Yup - always paid more at marinas than gas on land. In New England it's a short season and they have to maintain the place for fuel all year round so I kind of forgive them. I used to bring gas (which marinas didn't allow) but just did it. Almost pointless when you need hundreds of gallons so just smile, pull out the credit card and make a MartiniSmile Why do you think the yachting club drinks?? Hey - have to add that if you are driving/helmsperson of a boat you should be without alcohol or anything else until you are moored or docked. Here and I think the USA can own your boat or yacht until things are settled at YOUR expense until settled.

Hey - we may get known as YachtJunky.com if we keep this up.

---------------------------

Smile and the whole world smiles with you - carry on - T



grand_sea
User

Jun 18, 2006, 8:02 PM

Post #9 of 9 (48340 views)
post icon Re: Fuel Injector vs carburetor Sign In

Hey this is great, I've learned more about cars and boats on this site in the last month then I think I've learned from any other site on the web!!

Don't worry, Tom an engine is an engine doesn't matter what it powers!


Thanks to everyone Involved with this site staying afloat!!!
R.G.
south central Minnesota






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