Have been thinking about joining this board for a while as I have a couple of friends that are on it and talk highly of it.

So...With that all out of the way.

My insomnia has been kicking my butt the last couple of weeks, but a side benefit is... I have a lot if time to think about crazy ideas.

One of which, I would like to throw out here and get some feedback on.

I'm in the process of building a super low budget, back of the track build.

Car will be sub 2400#, gen4 5.3, cheap sloppy stage 2 cam with spring upgrade, rebuilt old truck b/w s475 that has been upgraded with a new b/w 80mm wheel and cover, 2nd gear th400 and a 8.8 3.73 rear end.

I am wanting to use as much of the stuff I already have as possible, which brings me to the "wee bit different" part of this post.

I have several holley carbs, a Holley LS carb intake with fuel inj. bungs and several sets of factory injectors.

Now here is where, the sleep deprivation and way to much time to think kicks in.

My crazy idea is... I want to run a blow thru carb...Along with a set of injectors, both on e85.

The idea is to run the carb with just the basic blow thru set up (think hanger 18) and use the injectors (decapped) to make up any extra fuel requirements on boost, with timing and injectors controlled with the cheapest means possible.

This were I need your input.

I want to control the injectors off of the o2 sensor to make up the fuel needed and be able to control the ign, curve as the boost comes in.

It would be nice to be able to have the ecu also control boost and have data storage.

So what would be the cheapest means to do this ? Micro squirt ? Stock ecu ?... Or ???

I will be honest...This is the area, this old fart is the weakest at.

Seems like most cell phones, computers and ecu's are are a wee bit over my pay grade.

I honestly think that it would be possible to do this. Set the carb up, like it is running 400-500 hp of fuel...And the ecu and injectors taking care of the other 400-500 hp of fuel need under boost.

Depending on what I would need ecu wise, I think I can make this happen for dirt cheap... (I love dirt cheap)

I have searched around google for anyone doing this but have not found anything. But then again I am a old fart and not the best at the whole google search thing.

So...Let my know what you think of this hair brained idea ???

 

I’ll admit it’s the first time I’ve heard of a carb and EFI on the same engine. Sounds like a dirt cheap nightmare. Sell all the carb ****, buy injectors and be done with it. I honestly don’t think it’d ever work worth a damn.

 

You won't need to make up any fuel, a single 750 cfm carb would probably flow enough full for 1500hp, the boost forces way more fuel through with the added pressures in the bowls.

Carb haters will come out, but there is still something special about using a 6014, home built hangar18 style 4150, and a turbo and making obscene power. Dont forget the Prostar 500, that will be the most expensive part of it.

At 2400 lbs you could got 160mph in the quarter very easily with not much money put out. Just remember to do the little things, start off with a main body with both IABs and HSABs, and make sure the point the bowl vent extensions forward into the on coming air in the hat, after that just tune it, its actually super easy to tune them if you do those two things. You can actually get around the power valve trickery with the air bleeds usually if you dont want to mess with the boost referenced stuff...Ive only run low 20s boost in a bt though, not sure past that. Usually its a tip in stumble that you cant get around without brpv but air bleeds can fix that with enough fiddling.

 

I thought they made a set of plates fo rtes Holley specifically for blow through.. NO or a different pawer valve and different bleeds.. Cant remember, lost my way back machine..

 

I think its been done, or something sim. On just a blowthru carb I made over 900 RWHP (540, F2 Procharger).
There was something out there a few years ago, it was a plate that went under a carb, had fuel run to it, and used an 02 sensor. Some kind of box went with it. Might have been MSD. Anyway, you dialed in the carb pretty close, and this added fuel based off the 02 sensor.

 

I found it, was a K & N kit-always wondered if it worked.
https://www.knfilters.com/20-0001-eci-kit-4150

 

Thank you both for responding to this thread.

3 window...Yes... The simple but more expensive way would be to go all fuel injection and be done with it.

Hank Peabody... My original plan was to do just that... Blow thru and a 6014.

But I like to tinker and enjoy thinking outside the box and have to stay really frugal with my spending or I just can't afford to play.

Which is what brought me to the idea of mixing the too.

Full fuel injection would cost a pretty penny and blow thru e85 carb at higher hp levels requires a bit more carb work along with a expensive fuel delivery system.

So laying there at 3am with my mind bouncing around... It came to me to take the best of both systems and try mixing them together.

They way I see it, I have two ways to skin the cat.


#1 Set the carb up as if I was building a 400-500 hp engine, which would require less carb mods and a cheaper fuel system and then use a cheap ecm to adjust the timing and fuel for the stock injectors to make up the fuel needed for the other 400-500 hp which would also not require a expensive fuel system. In this set up I would have the carb controlling the idle, tip in etc. and have the ecu just adjust timing and fuel inj flow under boost.

#2 Which is the one I tend to like better... Is to have the ecu control idle, timing and fuel and block of the idle and tip in circuits on the carb and just use it to make up the extra fuel flow needed.

That simplifies the mods needed on the carb, plus any of the stumble/bog etc.issues.

It would be like running another set of injectors plus you get the added benefit of the extra cooling and atomization as a side bonus.

So...The benefits I see with my "split" system are...

Simpler and cheaper systems needed for each one vs more robust and expensive systems for either of the single system setups.

I already have a carb, stock injectors and fuel rails, intake, separate fuel systems that would work for both the carb and injection.

Things that I will need... E85 o2 sensor, carb hat and some form of ecu to handle the injectors, timing and if possible both boost plus data storage. (I can buy both of those separate if needed)

So...Breaking it all down, what I am in most need of... Is help in figuring out what type of ecu would be the most cost effective to use ?

Stock with HP tuners/EFI live, Micro squirt or ???

One other thing to take into account... Is to remember that I am a old fart so the simpler the better.
( I do enjoy learning new things....Just not something on par with quantum physics to begin with first...Think baby steps...) LOL

Again...Thanks to those who replied.

Thinking about it....This may have been better posted in the fuel, ecu etc. section.

 

Thanks for the link...I'll have to check it out.

 

Wow...Checked it out...Pricey little bugger.

 

Ok I'll play..
First thing if your running the carb get a Alcohol conversion kit, it will prevent many evils, gets rid of all the alcohol sensitive gaskets and bits. I assume Holley still sells them.. (Dirt track parts...)
I would run a full EFI pump, and just have 2 regulators, one to the injection and 1 to the carb to get that pressure down.. (If your going to just run 1 fuel source. )

 

pdxmotorhead... Thanks for the reply.

Yes...I already have the e85 goodies for the carb.

As far as the fuel pumps... I agree with you. It will be a small front mount fuel cell and I think I will try just running the walbro 525 pump for both. (May have to get a different low pressure regulator) but I think at max power it might be on the edge.

It should be able to supply the low pressure side with more fuel than if it was all high pressure. The pump is supposed to maxed out at around 600-700hp on e85 depending on the boost level.

We will just have to see.

The more I think about this dual fuel system...The more I like it and think it's possible

I would still love to get some input on ecu's and what would be the most cost effective system to use.

Keep the ideas coming.

 

If you're absolutely set on doing it......Setup the EFI system to run normally but run the power to the injectors off a boost switch. The system will think its running like normal because of the fueling from the carb, and then when you get into boost the injectors will receive power from the switch closing and start operating as normal which would add the additional fuel.

 

Holy crap I had no idea that K&N thing existed and I did blow through stuff ALOT in the early 2000s haha. Thats pretty cool but I still say a single carb even on e85 will make enough power very simply and easily (800whp is not a big deal) to go 160 at your weight. Im all for outside the box but your idea sounds like a hassle but Im lazy. I did a twin charge setup recently and while it worked great and was fun to put together in the end I was like what was the point exactly, but I do still like the idea. Just make sure you're committed. MS2 would be the ecu to go with.

If $800 is pricey for the K&N (I agree) you better cost it all out, even the cheap fuel injection winds up costing, price a single plane manifold with injectors, not cheap just for that!

Im all for blow through though, its super satisfying to get a car working like it came from the factory, and its not that hard, but does take some fiddling for a month or two.

I like your out of the box thinking though because I also build so bizarro **** (awd vw bug tvs2650 ls3 for instance)

 

The minute you add EFI to the plan, you need to add the $$$ to make EFI work (high press pump, filters, lines, reg, injectors, etc.) which translates, just run EFI or just run blow through.

 

Thanks for all the new responses and I understand that it would be easier to go either full blow thru carb or full EFI.

But to go that way would require spending more money to get them to support the 800-1000 hp I am looking for.

Like I posted earlier.

On the carb side...

I have a Holley LS single plain carb intake with injector bungs.

Several holley carbs plus nitrophyl floats etc. to make it blow thru.

Fuel pump and boost referenced regulator etc that will support 500-600 hp on e85

On the efi side...

I have several sets of stock gm de-capped injectors and fuel rails etc.

Stock 2001 gm 3500 truck ecu etc.

Fuel pump and regulator etc that will support 500-650 max hp on e85.

It will use a front mount fuel tank.

Parts that I need to make them work together.

Carb hat.

E85 o2 sensor.

Aftermarket ecu of some type or the stock ecu with HP or EFI Live. (Whatever is most cost effective.)

By combining the two... I save a bunch of money that I would have to spend to upgrade either one by themselves.

Things like.

Upgraded fuel pumps

Bigger injectors.

More expensive carb mods etc.

This is going to be strictly a back of the track no prep car.

No street driving etc.

I am thinking the best way to run it would be.

Let the ecu take care of the idle, timing, afr etc. and add a tps to the carb for the ecu.

Then block the idle and tip in circuits on the carb and use only the accelerator pump, main jets and power valve as extra fuel enrichment with the ecu adjusting the afr.

Basically the carb would become the throttle body and extra fuel enrichment.

Which saves me from having to buy a throttle body and larger injectors etc.

The two driving forces with all of this is...

First to save me money, and to play around with something outside the norm.

Which brings me back around to my original question.

What would be the cheapest ecu to make it all work.

Have one vote for MS2 which is one of the ones I have been looking at.

Any other ideas ?



.

 

I wonder if you could add a cut-off solenoid to the carb, plumb the carb with 92 pump out of the stock fuel tank, and have the MS running injection only, from a E100 tank.
Then when boost hits the mark you want the EFI turns on and at setpoint the MS2 shuts the gas off to the carb, you'd need a timing controller for the distributor..

That way as a daily the engine would run on pump and the EFI would only take over when the car is in angry squirrel mode..

Sorry all may friends wives claim I am an enabler.. "I hold the beer" LOL