^^ This is a good idea
and @Davedacarpainter 4.9x's in the 1/8th is 7.7x's in the 1/4And it will still make a beer run after any event if need be! :beer emoji:
Well nearly any event:
Supercharged 1994 3.8
- Thread starter Christian Cornwell
- Start date
Well nearly any event:
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So i just got off the phone with a guy that used to build motors for Carol Shelby and he helped me answer a lot of my questions and i thought id share. Although i found the answers to a lot of my questions i do have some new ones. He told me that there is a good chance that my 14lb injectors will support the power and added boost of the 10psi pulley due to the low rpm the engine turns. The way that he told me to calculate whether they will work or not is to find out how many gallons per hour the fuel pump is. This is where my first new question arises.
Does anyone know what the gallon per hour rate of the piggyback pump included with the vortech kit is? I remember seeing this somewhere but cant seem to find it again.
He told me that you need about a half pound of gas for every horsepower. Based on the previous statement that the 8-12lbs is around 350hp the figure is 175lbs of fuel pressure. Im wondering if the combined fuel pumps can support that. He had given me a way to test it but since i remember hearing the figure before i thought id see if someone would know it before i go make a mess with gas. Ill give Vortech a call and see if they know the figure. Hopefully i can save myself fromm having to buy the new injectors.
Does anyone know what the gallon per hour rate of the piggyback pump included with the vortech kit is? I remember seeing this somewhere but cant seem to find it again.
He told me that you need about a half pound of gas for every horsepower. Based on the previous statement that the 8-12lbs is around 350hp the figure is 175lbs of fuel pressure. Im wondering if the combined fuel pumps can support that. He had given me a way to test it but since i remember hearing the figure before i thought id see if someone would know it before i go make a mess with gas. Ill give Vortech a call and see if they know the figure. Hopefully i can save myself fromm having to buy the new injectors.
Update to this post that i posted 2 minutes ago...
I called Vortech and they told me that their piggyback pump is 155 liters per hour. Converting this to gallons this comes out to around 41gallons. With one gallon of gas weighing about 6 pounds this comes out to the pump having 246lbs of fuel pressure? Can someone tell me if this is right. I believe that the math that i did should produce the correct result but honestly just don't have enough knowledge on the topic.
No... None of that is right. You're confusing volume, flow rate, and pounds per square inch.
That being said, spose you could find some 19 lb injectors off a wrecked GT in junk yard for super cheap just to play it safe? I still think 14's are going to be stretched mighty thin based off prior reading over the years.
I'll be keeping an eye out for new injectors. If I could find a cheap set of 19s I would but I think I'll just keep an eye out for some 24lb
The chart is a little confusing due to the fact that the kit advertises more horsepower than the chart says my injectors can handle and the kit doesn't require new injectors. With the added fuel pressure on the rail due to the fmu included with the kit, it seems like they might be okay. The guy that I spoke with on the phone whose built a million motors was telling me that it usually isn't your injectors flow rate that can't keep up it's usually the pulse rate. He said that they had a 750hp motor running on 24lb injectors due to the fact it only turned 7000 rpm. With my little v6 only revving to 5grand I'm sure the injectors shouldn't have a problem keeping up the pulse rate.
The problem is those boxes add more retard..........Might not be the best choice for you if clarity is what you're looking for.
Just thinkin out loud here....
The issue with turning the fuel pressure up is this.... it will put strain on the pump. None of us use an fmu anymore, we use injectors sized for the application at 43.5 psi and utilize a rising rate fuel pressure regulator....
When an fmu is used it make the injector act larger by cramming a tonne of fuel pressure into them. As fuel pressure rises the injector "size" does as well.. ie. (The amount of fuel moving thru the injector.)
This leads to other issue however, what happens when the fuel pump gets hot? Or the injectors themselves get damaged from too much pressure? It's simple a lean condition... then the motor goes... boom.
The flow rate relies upon the pulse width and injector size to deliver fuel. When you start elevating pressures to fuel injectors, you run the risk of sticking that injector into either the full open or full closed position. Neither is desirable.
As pressure increases, fuel volume decreases until you hit the limit of the pump, lines, or rails. Everything in that system is being pushed pass specification and this increases the chances for failure. As an added benefit, you also create an awkward injector spray pattern.
Does it work though? Yep... It does.
On a side note: I'm not buying 750 hp on 24lb injectors at any rpm. It may have been a motor capable of producing 750 hp but it did not produce it with 24 lb injectors, not even at 90 psi. without supplemental fuel.
This statement doesn't make a lot of sense so I'm trying to decipher:
Why would your V6 only turn 5000 rpm? Is something wrong with it?
Pulse rate does not determine whether the motor has adequate fuel. Pulse rate is how quickly the injector must cycle to maintain AFR with engine demand, fuel volume, pressure, and injector size. You don't get to pick the pulse rate and it is not the limiting factor of an injector.
A fuel system is just that: A system
You don't get to pick on a single attribute of a single component to determine whether it is adequate to meet power demands. You could put any injector of any size you like into a car with an 88 lb/hr fuel pump and be able to support LESS HP than you did with 19 lb/hr injectors.
Perhaps the term you are looking for is "Duty Cycle" and that varies with volume and pressure capabilities of the rest of the fuel supply system.
One last note: FMUs and in-line pumps are BOTH dicey. They are band-aids that introduce additional failure points.
I think at this point I'm just going to go with a bigger fuel pump in the tank, bigger injectors and eliminate the piggyback and fmu. Sounds like that's the safest bet.
That's just where the older v6s red line. If I'm remembering correct the rev limiter is set at 5200. Seems like being down two cylinders from the v8 it should rev a lot higher but it doesn't.
Glad to read this. I think you will be glad you did. Less clutter, and less chance of failure. Thinking 24 lb/hr injectors, and a 190 l/hr pump in the tank? I dont think there is much of price difference in fuel pumps, so I would say while you are in there, go for a 225 l/hr pump incase you ever decide to get radical in the future (ie stroker, etc).
If it were me making the decision only knowing what is printed in this thread, I would choose 30# or 36# injectors.
Here's why:
Supercharger + injector swap of any kind = dyno-tune or more equipment.
Since the tune is required anyway, why not run an injector that will not need any additional "help". Leave the stock fuel pressure regulator right where it is. Change the in-tank pump, run a proper sized injector that will put you at 85% duty cycle at Wide Open Throttle, and get a tune.
Don't skip the tune. Don't think you can get away with railing on it even one time until it's tuned.
Here's why:
Supercharger + injector swap of any kind = dyno-tune or more equipment.
Since the tune is required anyway, why not run an injector that will not need any additional "help". Leave the stock fuel pressure regulator right where it is. Change the in-tank pump, run a proper sized injector that will put you at 85% duty cycle at Wide Open Throttle, and get a tune.
Don't skip the tune. Don't think you can get away with railing on it even one time until it's tuned.
You're doing a lot of cool things with your car. Sounds like fun. It's been said that there's hate for the V6's. I haven't seen that. I like mine. It's my first. I see it as a daily driver, that gets you where you want to go, when you want to go. It's not a race car, despite what mine looks like. Plus, it's a Mustang.
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