Ok so as far as i understand, the main ways to enrich the carb under boost is to either

A. Tune the jets/accelerator pump to provide adequet fuel/air ratio under wide open throttle and have it suffer at cruising speed

B. Route a vaccum line thats connected to the pressurized side of the turbo to help the carb understand boost (unclear on details here as its hard for me to find good tech online that i can apply to my motor)

The car is a daily driver so i dont want it running rich all the time, or burning holes in my pistons when if it goes to lean..

My theory is to use a fuel enrichment controller in conjuction with a fuel injector mounted right before/inside the carb, MAP sensor, and an oxy sensor..

So what im really trying to get at is.. has anyone heard of anyone using fuel injection to supplement a turbo'd blow through carburetor before?

Thanks,

Aaron

I would surf over to http://theturboforums.com/

You're looking for carburetor tech info not slant six specific info.

Evidently AFB/Edelbrock carbs are working well under pressure with little more that Thermoquad floats grafted onto the AFB float arms and some tuning. There used to be a twin turbo Thunderbird that used a fuel injector and a pressure switch for enrichment. Guys on this board are using methanol injection for enrichment and cooling.

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Joshua

Some of the turbo-mopar 4 banger guys have added a 5th injector to supplement the stock fuel injection system. I've never heard of adding a fuel injector to supplement a blow thru application.

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11.02 @ 120.56
http://www.youtube.com/watch?v=EAxRmoDgsdY
Chassis dyno
http://www.youtube.com/watch?v=wd6hFGzLJMc

I'm no where near getting my turbo motor finished, but I'm trying something I saw outlined in a book. I'm using a Holley 390 with all linkages between primaries and secondaries removed. I put a fitting into the vacuum diaphram and put the spring on the other side. This will be connected to the pressure side of the turbo. This allows the secondaries to open as boost pressure increases. In theory this will richen the system referenced to boost.
Another piece of the puzzle is a pneumatic switch that will vent the diaphram when the throttle is released. So that the engine wouldn't continue to run just on the secondaries.
Like I said, it's not close to running yet, but it's an idea. I'm still collecting all the parts.

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David Belau
1966 Dodge Dart GT IRS SOLD
1967 Plymouth Barracuda
http://dartslantsix.wordpress.com/

your right,you need to be carefull on your boost opening the secondarys idea.You must also have some way to "shut it off"when you let off on the primaries. Otherwise,even letting off the gas' the boost could keep the secondaries open,leaving you with a dangerous problem.Look, I've run blow-thru carbs with an extra electronic controlled "enrichment device"of my own invention for 5 years.And with aftermarket fuel injection systems becoming cheaper,and with more options,and more versitilety,just buy the wheel that wasn't availible 5 years ago,instead of re-inventing it. Your life will be much simpler

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V8?? We don't need no stink'n V8!!

bigslant6fan,

To which method of enrichment that is available today are you referring? I will be putting mine under pressure soon and was considering jetting the carb up a little, then using two NOS fuel solenoids and a pair of fogger nozzles hooked up to two hobbs switches. This would net me a slightly fat mixture under normal drivings conditions, right on under full throttle and would flip back and forth between a little rich and a little lean depending on how much boost.

It would be pretty easy and since I already have most of this junk, it's affordable too. But if there's something that works better and would fit the budget I'd be interested.

BTW, did I buy a pair of wheels from you last year? I would have been there in a Jeep.

I was suggesting a stand alone aftermarket fuel injection setup.You will be better off in the long run.Yes, I run a carb,yes I got the air-fuel ratio close enough that I didn't burn up a motor(yet),but it took a long way to get here.Sort of like a rehabilated drug addict telling you your better off NOT to do drugs. If you go to mason-dixon race I'd be glad to talk to you.

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V8?? We don't need no stink'n V8!!

Cool, I'll be at the Saturday race.

Using nothing but hobbs switches will not work,and heres why;Lets say your boost threshold is 2,000 RPMs,and your redline is 5,000.At 1,900 no boost,and at 2,100 FULL boost,your idea just turned completely on in 1/4-1/2 a second.At 2,100 your washing the rings,and at 5,000 she's getting getting piston melting lean.If you MUST try this idea,maybe use the pressure switch to start the first stage,and connect one (or several) RPM switches in series to increase fuel at higher speeds.It may get you by,but is far from ideal.The key to maximum power,and not ruining your engine is the correct AFR at all times.

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V8?? We don't need no stink'n V8!!

Instead of making another post and adding to the pages we have Ill just revive this one.

tank->high psi pump (hobbs switch to relay control)-> AFPR-> injector nozzle. with afpr seeing the boost the same as the afpr for your fuel would be. this would be adjustable for your beginning turn on and amount and then as boost rises so does the psi at the injector.
or something like an aeromotive 13202 with 4 ports. one in, one return, one to the carb (main), and then the 4th to an injector nozzle that has a valve activated by hobbs switch with to keep from coming on with the normal fuel. so then it would be afpr (4th port)->electric valve (controlled by pressure switch), then injector nozzle. this would keep from seperate tank for meth etc to run out, less parts and so forth. makes sense in my head from an electrical stand but no exp with rising rates etc on injectors.
Seems too simple and that im missing something but just a thought. For those with a bit more exp in this, what am i missing?

Pohlman

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225, Offenhauser, Holley 350, A833OD, 3:55, GM HEI,99 Durango starter
BOOSTED! WH1C, BIG FMIC, 10#
Operation Noble Eagle 03-05
Operation Iraqi Freedom 05-07
Operation Enduring Freedom 12- 13

Doing a bit more research into this, it seems to make more sense the more and mroe i read. (all numbers for talking points) If you get the carb set up to run nice all the way around at 10# and then decide to turn up the boost (known to happen with boost) then instead of tearing the carb all apart etc to adjust as you turn up the boost one could go with water/meth or e85 injection to help with the afr.
Now, let get to the fun part. When one runs efi and wants to get more fuel but not buy injectors, then they usually just increase the fuel pressure, which then puts more fuel through the injector. why couldnt one do the same with the meth injection to fine tune it.
using some quick searches, AEM has a recirculating pump for 150 psi, and a single injector with 3 nozzles. (.0155,.0315,.0630) or 130cc, 315cc, and 550cc. Now that is all based at 150psi rates. why couldnt one run from the pump to the adjustable fuel pressure regulator and then supply it with a boost ref to control the psi a little more and fine tune the output at the injector?
so in rough numbers, starting with 315cc nozzle and say 100psi for (just found my first problem in thought ) ...that would mean lower output but only a rise rate of 1:1 on most afprs so it would only rise to 105psi if only raising boost to 15#....nevermind, ill leave it as is here so that if the next person thinks this would work they will see the problem.... back to being bored in Kyrgyzstan...

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225, Offenhauser, Holley 350, A833OD, 3:55, GM HEI,99 Durango starter
BOOSTED! WH1C, BIG FMIC, 10#
Operation Noble Eagle 03-05
Operation Iraqi Freedom 05-07
Operation Enduring Freedom 12- 13