How Do You Figure A Fuel System?

If You Have A Fuel Pump And Hat Lines Port Lines Nozzles Etc. How Do You Figure What The Engine Wants. As Far As A Base Line I Realize That You Need Engine Spec Blower Rpm Etc. But To Set Up A Basic Starting Point From Scratch What Do You Use As A Reference. How Do You Know Lets Say A 502 Chevy With A 8/71hh Good Heads You Have The Cam Specs And Know All The Info About The Engine. What Formula Would One Use To Figure Out How Many Gallons Of Fuel It Would Need At What Rpm And How Do You Know That,what Size Nozzles To Use In The Hat And Port Nozzles. What Jet To Start With And Poppet Pressure I Think You Get The Idea What I'm Asking. Now Dont Think I'm Going To Use This Info To Start Setting Up Fuel Systems (no Way) I Just Had Mine Set Up And With All The Info I Had To Supply I Was Just Curious Of How It Is All Put Together And Figured Out. A Computer Program Maybe You Now What They Say Curious Mind Want To Know? It Just Seems There Is So Many Different Combos Where I Dont Think Someone Would Go Well I Have A Buddy That Runs This So Lets Try It Im Not Asking For Tuning Secrets Just How To Figure Where Do You Start? Thanks Jamie

 

your best bet is....get all your stuff flowed or call tom conway and have him do it. it will save you alot of headache's and a hole lot of money..trust me

 

Thanks Dave, I Just Had Mine Set Up By Jim Oddy I'm Just Trying To Figure Out How Its Done. I Know Flow Bench Blah Blah Blah But How Do You Figure How Much Fuel The Engine Needs For The Combo That You Have If You Just Send Them A Bunch Of Parts ( I'm Thinking To Much) Thanks

 

Jim Oddy has more than likely built and dyno tested more blown chevy engines than anyone . I am sure he keeps records of every combo he has tuned or built for his customers as do the other fuel system tuners . Your manifold , heads , comp ratio , camshaft , cubic inch ,mag size, blower type and size and O.D. ratio all play into this not to mention a few other variables like fuel pump size , hat only nozzles , or port and hat nozzles , the list just goes on . Bottom line is experience . You can buy the latest fuel system software but it doesn't do you much good without a strong baseline tune up . The magic formula does not exist, to many variables and to many combos or we ALL would have bought it . You have probably bought a safe tune up to get your feet wet and to help you learn about tuning your own engine and learning what your combo wants . I would suggest writting down all of your info from Oddy such as all nozzle sizes and locations , timing recomendations , BV leak down , poppet settings , jet sizes and locations and so on so you refer back to them if you sway away from them .

 

I would have to say you are in Manic mode, take another Prozak and let it go till you run your car down the strip at least 4 times, then call Bruce the next day and ask away. [/QUOTE]
sorry, i had all my phone numbers disconected . jamie, do you realize what your asking?...... there are a certain few individuals who know exactly how to figure a fuel system out correctly. you could probably count them on your fingers. do you think they are willing to post their ideas and formulas on this or any site and do it for FREE!. some of these guys make a very good living by selling the fuel systems that we buy. and some of them get paid pretty well to go to the races and tune the cars that have their fuel systems.

 

I Realize That Bruce, I'm Just Asking Is There A Formula They Use Such As A Computer I'm Not Asking What The Formula Is. Im Just Trying To Figure Out How Do They Know What A Engine Needs Like You Said Before Bruce There Are A 100 Different Combos Out There. And I'm Sure They Dont Know Each Persons Set Up.EVERTHING ON EACH ENGINE IS DIFFERENT, I'm Just Asking What Determines What You Need To Figure This Out I'm Not Asking For Secrets. Basics Only, Ok 526 Cid Engine 14/71 Blower How Do You Know If It Needs 20 Gals Or If It Only Needs 12 Gals I Dont Understand How They Get A Base Line If The Engine Is Not Running You Cant Read Plugs So How Would You Know If Its Going To Be Safe, Real Lean Or So Rich It Wont Even Start, I Could Put A 20gal Pump On And Some Random Jets And Nozzles Etc I Would Not Know If It Would Even Start Thats All Im Asking. How Do You Know What A Bbc Wants Vs A Venny With A Screw Blower Or A Sbc Like I Said I'm No Asking For Any Secrets! MAYBE I'M NOT ASKING THE QUESTION IN THE CORRECT WAY. JAMIE

 

i understand what you are asking jamie, but it is still the same thing. there is NO computer program to come up with the initial set up. if there was it would be cheaper to buy the program than pay somebody 3000 dollars for the initial set up. there ARE programs to show you how to adjust for air conditions AFTER you get a system and make a run. you can then store the run with notes . if the run was a fat lazy run , it WON'T tell you how much to lean it. that is still up to you or the guy you are paying to tune it. if there was a program to magicly come up with the basic nozzel area for every kind of engine combonation possible it would be worth a ton of money. in this sport knowledge and experience cost a whole lot more than software.

 

Dude, the fuel gurues, get paid to do what they do,they know what they know from expariance, like a doctor knows how to do a heart transplant, I have been racing blown alky cars for 30 years and i don`t know how to figger it out( what your asking) you can ask the question 40 differant ways and if you get an answer you can bet your a$$ that its not right. so stop asking and pay your dues like everyone else, its the only way to learn, unless your one of them bench racers that want to know evry thing in terory but realy dont know $hit.

 

Tom Conway..............nead To Sat Anymore? World Champ How Many Times? Div. Winner How Many Times? It's Worth The Ticket

 

Thank you for making my point, do you think that if you asked a heart sergon how to replace a heart that ,#1 he would tell you? ,#2 that even if he did you would know how? all im trying to say is in this game you learn from doing things, nobodys going to tell you what it took 20 or 30 years to learn, ( except me.) even though you wont belive me, cus i did it all the time i raced,any body ask me something i would tell them the truth the way i did it, and they would not belive me . because everybody dose things differant, and you will figger it out your own way .i rest my case, now go home and get your shoeshine box!

 

Eli, I Owe You A Apology I Do Believe you, I'm Just Having A Bad Day And I Just Went Off Running My Mouth Or Should I Say Fingers , Jamie

 

No apology needed, We probably got the same condition, and i understand where your coming from, if im right, im 20 years. BP,hears some good advice, never stop taking your meds.

 

Yes There Is You Guys Are Tring To Help Me , So Again Apologize (meds Are A Good Thing) Jamie

 

The simple answer to the question is.....
The fuel needed is calculated from the expected power output. There are othe variables, but for a Blown Alcohol engine - that covers most of them. Putting a number to how much fuel required for a given H.P. comes from experience and observation of others combinations.

 

Too many racers think that a fuel system is a magical,voodo,thing. Guys like Tom Conway and Les Davenport know through hundreds of runs of their own and other racers,that a certain size engine,with certain atmospheric conditions,a certain blower boost,needs a certain amount of fuel.
When a racer gets a system flowed,it is determined what size nozzles,and jets are required to obtain a certain gallon per minute flow at certain rpm's.Knowing how much GPM at certain RPM's is where the Masters make their money.