help-

[adamsvega]

how can i increase fuel enrichment with boost on a blow through carb -the more i go over this in my mind the worse it gets
..if the jeting is square and i reverse the powervalve spring then psi sould it not let fuel in as boost builds ??/

[SmallBlockNova]

Why not call somebody who specializes in blow through carbs, like C&S, CSU, Steve Morris. etc.

[BlownchevyII]

BRPV

[wazslow]

theturboforums.com and go to the carb section. There is a TON of info in there...

[HonkIfPartsFallOff]

Alot of times the nature of the beast is that you have to much fuel enrichment as boost builds. The emulsion circuit is often times cut to just the kill bleed and the top e-hole, and the HSAB is also very small or blocked off all together to delay the whole process. BRPV's are really a way to fine tune. It allows you to take fuel away while trying to build boost. Adam just rember a 750 cfm carb thinks it's alot bigger when all that cfm is being crammed through it.

Then take into account the difference in pressure above and below the carb, coupled with that pressure difference acting on the fuel in the bowls. If you want the exact therory, i can't give it to you. I know they work damn good when properly built.

TheTurboforums.com and http://www.TuneYourEngine.com is the place to go to get some advanced reading, but alot of the mods are proprietary so your only going to get some much info.... Much like the Force, you have to beleive it's with you.....

[Gameracing]

Just an idea, if you change the boosters, ie; move them down into the venturi, they would be more sensitive to the flow of air around them, and pass more fuel .

[HonkIfPartsFallOff]

most builders do that when they add the aerosol boosters to their blow through carbs.

[adamsvega]

like this??????

this is what we had for 2bbl rule dirt cars and ofset adaptors on single plane for claimer rules

[HonkIfPartsFallOff]

No, i have no idea what that is....

Like this:

[adamsvega]

heres my therory on blow through carbs and part throttle drivablity . the booster signal is only a psi differential not a "vacume suck "
. so the higher air velocity through the carbs venturi still pulls major fuel even threw the almost closed throttle plates . a normal carb will atomize well and the boosters do a ok job in even ditribution . but the extra volume of air will require less throttle opening for a given rpm use and likly will draw most of the fuel to the front and back cyl.'s do to the throttle plate angle ramping it from the booster . when you lessen the given throttle angle for the load with preasurized air you will agravate this transition part of the fuel curve . at wide open throttle all bets are off and all should work even matched as long as you get your high speed bleed ,emulsion bleed and jet right. this is why i think that carb shops will use a anular booster in these applications to keep as much fuel flowing past the high side of the throttle angle . it would be like trying to use a 1150 dominator set up for dual carbs on a 302 w/ single plane . it will idle and run at wide open but trying to tune it will give ya a anurism !!!! heres the catch 22
if a carb sized for your actual air volume say 16 psi no inter cooler is going to net you about double your cubes of air injested then size wise a 350 would want 1200 cfm . the comprimise is how much air volume you have at part throttle v.s. a n/a motor that size . ...... that is why most peple cop out of a carb on a turbo /super charged car that must have street manners and let the fuel maps handle the load/volume delivery .

the trick is to be able to build a carb that has the cfm req. to not be a restiction and be able to evenly atomize fuel into all parts of the manifold at high psi low throttle angles .. a dog leg or straight booster is to low and a anular booster is a major flow restriction .
it seems that looking at wet flow inside a carb we need to lower the venturi and or raise the booster . still keeping the signal strenth to draw fuel . this will put us into a land not alot will travel .... ............ i would bet that a huge dominator carb with hogged out bores would serve well with a high triple booster like a q-jet and possibly a venturi draft tube for high speed enrichment .
dont get into a huff the q-jet was a extreamly efficient carb at distribution on part throttle and wide open. just tunning the caverness vacume secondarys was on a case by case bassis . ...
i think this is why some carb shops use the previous pictured high mounted draft tubes for their max cfm carbs .it still get a signal but will keep the fuel evenly spread on part throttle...
what do ya think did i hit it or miss ,????
ive been known to out think myself sometimes and be way off base

[Gameracing]

try running a boost referenced line to the regulator to raise fuel pressure under boost, overwhelming the needles and seats and pouring it in !!

[HonkIfPartsFallOff]

try running a boost referenced line to the regulator to raise fuel pressure under boost, overwhelming the needles and seats and pouring it in !!

Have to do that with a blow through carb. The bowls see more pressure than the manifold does. Regulator should be ref'd to the hat pressure not manifold pressure. Aeromotive makes the perfect regulator for the application.

[wazslow]

try running a boost referenced line to the regulator to raise fuel pressure under boost, overwhelming the needles and seats and pouring it in !!

Have to do that with a blow through carb. The bowls see more pressure than the manifold does. Regulator should be ref'd to the hat pressure not manifold pressure. Aeromotive makes the perfect regulator for the application.

Aeromotive 13202 is the best one for that application.

[Turbo chevelle]

Aeromotive 13202 is the best one for that application.

Thats what I've herd.
Thats what I will be using for my BT setup!
10AN feed and return.

http://www.jegs.com/i/Aeromotive/027/13202/10002/-1