I have been writing a technical treatise on drag racing fuel systems (for carbureted full-fendered vehicles with a fuel tank in the rear).
Would like to get some inputs from this group:
A) How many of you use a by-pass type fuel log (one that uses a by-pass line from the front of the car back to the fuel tank?
B) How much fuel pressure do you run (number at staging is preferrable for my purposes)
C) How much Hp does your engine produce? (based on track data - 1/4 mile trap speed preferred)
D) What is your current 60' time and the 330' time?
D) Did you have your engine dyno tested? IF so, what was the CBHp at peak?
Would prefer brief responses with data and little rhetoric.:thumbsup:
Thanks in advance.
Regards to All that like this kind of stuff,:hurray:
IG
A) My by-pass is at the rear of the car not the front.
B) 32#s bottom of regulator 5.75#s out to carb
C) 146.24 @ 3340#s according to the weiss calc is 815
D) 1.42 (spining) 3.828
E) 821
My car is a turbo charged with a blowthrough carb. I use a bypass regulator mounted at the carb.
My base pressure at the carb is 7 3/4 psi. At launch I have 10 psi of boost which gives 12psi above the carb where the regulator is referenced so I have 19 3/4 psi of fuel pressure going to the carb. During the run I will have as much as 38 psi of fuel pressure going to the carb.
Based on weight and trap speed i have roughly 1,080 hp (3,545 lb and 157.71mph)
A) Product Engineering 450gph pump along with their "hi-flo bypass" setup. The pump uses a high pressure bypass directly from the pump to fuel cell, and the "hi-flo bypass" setup uses bypass lines on both the high and low side of the regulator (mounted near carb).
B) Typically 6.5lbs (although I've tried lower and higher)
C) My 440 ran 147.36@3450lbs & the 496 ran 142.29@3580. By the formula I use, the 440 "showed" 861hp at 700ft-DA (Kestral) and the 496 "showed" 805hp at 286ft-DA(Kestral)/615ft-DA(Performaire).
D) 440= 1.271-3.664 Both best 60' & 330 on same pass.
496=1.283-3.745 Each occuring on a different pass with different gearing.
E) 440=871chp on a SF902.....496=773chp on a SF901. Something to keep in mind here is the 440 was tested on the dyno in the same configuration as it was run in the car (same carb, headers, v-pump), the 496 was tested with a 4150 carb and no v-pump. As run in the car, it's best #'s came from a 4500 carb & v-pump (~9") while running headers that are less optimal as compared to the headers used on the dyno. Just speculating a bit, IMO the v-pump & carb would pump-up the dyno #'s,while the headers would drop the #'s a bit. As run in the car, I would not be surprised to see it make ~800+.
A) No bypass, im running 2 holley blacks into a Y then to a dead head regulator
B) 7ish
C) 10.40 @ 126.26, 3680# 593.17 flywheel HP based off trap speed according to Wallace
D) 1.346, 4.142 foot brake
E) 662 @ 6200 by VortecPro
Im in the process of upgrading to a magnafuel system, I ran the exact same ET and MPH with a 1.40 60' than i did with a 1.34. Maybe im just throwing money around but i would think with that much difference in the 60' it would show something different at the top end.
My car not in everyone's here's league so may not be relevant , but I do run a bypass regulator between mech pump and carb My mech fuel pump requires a reg ...... 600 Hp dyno'd typical et 11.13 @123.30mph 1.56 60 ' launch fp 7.5 steady to stripe
best 60' 1.39 10.88 @ 1.22.10
If Ok have a question
when running a bypass regulator how critical is the bypass jet size and or the return line size ? I run a 1/4 pee line back to tank and removed the suggested .070 bypass jet to eliminate vapour lock issues ........ but being told to run the jet not without ?? with 1/4 line cant see it being an issue ......seems to run fine am I missing something?
Brian, looks like two different tracks, could be a discrepancy in the 60' lights, I've had that happen to me. How many times have you hit the 1.34 number?
Brian, looks like two different tracks, could be a discrepancy in the 60' lights, I've had that happen to me. How many times have you hit the 1.34 number?
It was at 2 different tracks and almost 2 1/2 months apart. At the time the 1.40/10.40 @126 was the best it ran and that was before the DS and carb swap. I ran a 1.35 on my follow-up pass from the 1.34.
did you get a chance to run again at the track that gave you the 1.40 after the changes? I know 6 hun is a lot but I've seen as much a 3 or 4 from track to track so before you start doing anything to the car I would validate it by running again at the first track.... if the rest of the incrementals (330, 660, 1000) were the same I would suspect it was just the 60' light...that said 2000' difference in DA is a lot too...that should be worth 8 hun at least, maybe even a tenth in the 1/4. Look at your incrementals for both passes and see how they compare...
Thanks for the participation with your answers thus far.:thumbsup:
There have been a couple of questions in the stack that I will comment on after a bit more time has passed. Sorry, but the specific answers will have to wait in order to keep focused on gathering data as outlined in my original thread beginning. Thanks for your patience, though.
My major interest in getting some data from folks is to come to some sensible conclusions based on data.
Please add to the data stack if you are not too shy to add to this simple thread.
My best so far is close to the example that 40 posted accept that I was .05 slower in the 60 foot.
1.364
3.913
6.100 @111.8
9.636 @137.7
magnafuel 300 pump with return bypass direct from pump back to tank
stock tank sumped
-10 from tank to pump -8 to aeromotive deadhead regulator
5.75 to 6psi
I run a Mallory bypass regulator at the front of the car.
Out to the carb is a -10 with a Y then -8 to each carb bowl.
Line to and from the regulator is -10.
Pump is a Comp 140.
Fuel filter is a spin on diesel filter (looks like an oil filter)
Fuel pressure is 7.5 psi, never moves.
700 hp on the engine dyno.
Best mph @ 3600 lbs is 133.6
60ft is around 1.37
Sumped tank, quickstar 300, bypass from pump (rear of tank) to front of tank, -10 to regulator @ carb, 6.25 lbs to float bowls with "t" from bowl inlets to top shot system.
1.37 60' 4.00 330' 6.26 660' @ 108.40
Not necessarily true, but what do I know. I'm just a poor bracket racer. My car trips with the body instead of the front tires....results in a slower 60ft with identical e.t.'s
Appreciate your comments but not sure what you are stating.
The quote you listed is not mine and poor bracket racer or not, the physics of the vehicle know nothing of anything other than the forces applied to the vehicle and the 60% to 70% of the driver's mass which is water. All the liquids therein respond to acceleration.
This chart table data was previously posted on another thread that is just a small part of the technical treatise I have been writing on Drag Racing Fuel Systems.
Tomorrow I will try and wind up this thread with some more data as partial repayment for those few of you that have participated here.
In the meantime perhaps you can peruse the data and decide if this data is of interest or not. Do you know how much time it takes to deplete the fuel bowls on your carburetor? Do you know how long it takes to fill the bowls while you might be accelerating? Perhaps you should know those things and more. IF maximum performance is indeed your objective.:thumbsup:
Howdy Folks that might be interested in this kind of stuff,
There have been inputs of note shared from 12 different vehicle combinations and that is roughly less than 1% of those that viewed the listings. I would hazard a guess that really means roughly 99% of the folks out there are more than pleased with what they know or don't know about the requirements of a drag racing fuel delivery system.:thumbsup:
Some final thought provoking data for those of you that might be interested::boring:
IF you are using a Holley four barrel carburetor that uses center pivot floats (.066gal capacity), the carburetor will supply enough fuel for 600Hp (.799 gal/min requirement for track power) to last approximately 3.965 seconds without replenishing. That number allows for about 80% consumption so the main jets stay wet so the time is somewhat variable on both level consumend and the power produced.
SO, it really does depend on how well the fuel delivery system can replenish the fuel consumption requirement:yes:
An assumption of “if the car runs andit 60 foots hard, then the system is adequate” is far from the truth.
Kindly remember some very sensible basics - IF you have an engine that is capable of producing 700Hp and you either knowingly or unknowingly supply it with only enough fuel to produce 600Hp, guess what - You have a 600Hp racecar! Better ETs win more races and harder acceleration across the full length of the racetrack will be the best package for providing the best ET.
By the way, the tentative title to my writings on fuel delivery systems is:
A Sensible Analysis of Drag Racing Fuel Systems for Racecars (Carburetors, Gasoline, and Fenders)
Again, thanks much to those that participated in this little cross-stitching thread. :beers:
As time permits, I would like to take all the inputs and produce a general analysis of the vehicle data presented by participants that might work for all.
One thing that doesn't get talked about much is the size of the needle and seat.
I suppose it would be fairly easy to time how long it takes the fuel system to fill the bowls from empty.
I'd be interested to see what your data and conclusions say about each of the cars fuel systems who posted? I wouldn't take it personal.
FWIW, my engine made 700 on the dyno, and it seems according to the calculator, that in the car, it's quite close. That said, the fuel pump my dyno guy uses is a Holley Blue.
Thanks for the interesting work.
Ron
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