Blazeracer

iTrader: (2)

I know most of you guys run EFI, but just for ***** and giggles, I'm blowing old school with a carb. In the N/A drag racing world, cars will just delete the power valve and square up all four corners, then jet accordingly. Before I drill a hole through my carb body for a BRPV, has anyone ever done this on a blow through? I'm running about 22psi and the QFT power valve does not get the job done. I could put a crutch setup on it, but part throttle is pretty much needless. My motor runs two speeds, idle and WOT. On a drag car, no power valve is pretty much standard. I'm getting the bung for my wideband welded on today so next time out I'll have numbers to tune with. Running E85 in a jet boat.

Soooo, has anyone ever done this? Blow through turbo with no power valve.

Blazeracer

iTrader: (2)

Right now my carb has 84's and 96's. I wanna plug the power valve and run 96's in all four.

Blown06

iTrader: (32)

Give it a shot. Carb tuning is becoming a lost art, especially on sites like this. I would be the majority of the members here have never even held a carb. lol

forcd ind

iTrader: (7)

Pretty much on the blow thrus I always ran a boost ref PV-the problems with running with out one was keeping the plugs clean at idle-not sure how that works out with E85
Even back in my old super stock days I always ran PV's while guys were plugging them-some would drill holes in the pri throttle plates to trick the engine into thinking it was lean at idle so they could try and keep the plugs clean on the starting line
Try it and see, some of the guys ran PV's front and rear
I know when Kevin (CSU carbs) would build me a carb with a boost ref PV the jetting wasn't huge, but it would flow some serious fuel
Funny, when I switched to FI, a guy was helping me, and I was trying to relate certain issues to how a carb was tuned, the guy says I have never worked on a carb, so I cant relate, lol-gotta love the new world order, lol

Forcefed86

iTrader: (4)

A lot of good carb/boost info here.

http://www.theturboforums.com/forums...Tech-Questions


Pretty common if you don’t need lean cruise to block the PV with Alcohol based fuels. They don’t foul the plugs near as bad either so running fat at idle isn’t as much of a problem.

You can also run your PV externally if you don’t want to drill holes in your carb. A meth injection jet on top of the carb hat and WOT solenoid (similar to a nitrous kit) will do the same thing as a BRPV. It’s also easier to tune IMO. You can “T” in right off your regulator as well so it will be boost referenced.

rkreigh

why remove it? it only operates under vacuum. under boost it's not an issue other than protecting it from blow out.

as a drag race only mod it's fine.

Blazeracer

iTrader: (2)

Because under boost the non boost referenced power valve gets slammed shut over 10psi from the backside and you go blow-torch lean.

rkreigh

well my understanding of PV is wrong then. I thought they opened only under vacuum not boost??

so it sounds like the "transition" of vacuum to boost causes a lean out condition.

I didn't think the PV would cover that ???