my idea is that with well flow matched injectors, and a 4bbl tbi unit you could keep velocity up while still flowing a good amnt of air to all cylinders. this would make for great throttle response good economy and great idle charcteristics no?

not to mention being really cool looking. my idea would be to rig somehow tpi.skinny style injectors into some sort of fuel unit, and mount/rig/engineer it to mount over a 4bbl high cfm tb.

so, some genious please point out to me why this has obviously or not popularly or to my knowledge been done, but even more obviously or rather probably been thought of before and not advertised.

thanks. night.

 

if you're not talking about this I dunno what the hell you are

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-Tas
'89 Formula WS-6
[soon to be Torch Red with black hood and headlights =) ]

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nope im talking about a manifold that has both a north to south and east to west divider in it. so that the front left bore goes to the front left bank/2cyl in the manifold. and so on and so on. and tbi injected not port.

 

lm thinking its because of vacuum. With dual plane there is always one cylinder wanting air. In a quadplane that wouldnt be the case. lt would only get one cylinder per crank RPM. vs Two. The valves would be closed 3/4 of the time. So there wouldnt be able to be any consistent flow. Once again, in a dual there is always a valve open to continue the flow, in a quad there would be no way.

Just my thoughts.
Clayton

 

what if you didnt neet vacuum. or do you so that the heads can pull air.

 

Vacuum pulls the incoming air through the fuel. You need a consistant flow to make carboration work right.

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not carb, tbi.

 

I follow your thinking on this, Snf. What you'd want to do though is to divide the runners so they are 180 degrees apart (in firing order.) I don't think there would be much of an advantage to this design though. Dual-plane manifolds are mainly made to increase low-end torque on a carb'd system. They'll also help TBI systems keep the vacuum up, but obviously limit top end because at some point, you're pulling air from only one barrel for four cylinders and it just isn't enough.

I have some crazy ideas for manifolds too, if you want me to I can let them rip. Most people think I'm nuts though.

Ken

 

CARB and TBI do the same thing. And both need vacuum.

 

Keith, carb requires vacuum for a different reason; TBI is less sensitive to vacuum than a carb is since it doesn't directly influence the amount of fuel. A carb requires vacuum directly to pull the fuel out; TBI uses the vacuum to partially determine the pulse width of the injector, which is already spraying pressurized fuel.

Carb and TBI are the same however in the sense that they inject fuel at the same point, as opposed to TPI or MPFI that injects fuel just ahead of the cylinder head.

Also, TBI can be tuned to respond to the lower vacuum, as where a carb this task is usually much more difficult (if even possible.)

Ken

 

Well, what I was saying is that both mix air and gas. Air being pulled through the fuel being sprayed helps it to mix, yeah I would agree a carborator is more dependent on vacuum.

[This message has been edited by Keith5 (edited January 25, 2001).]

 

Vacuum is used on all vehicles to pull air into the cylinders. W/O pressure differential nothing happens anywhere. Fluids (air and fuel or just air) move from high to low pressure. Its a fact. So therefore, if your quad intake doesnt have a constant vacuum, there will be no consistant airflow, and no airflow means the car becomes a pretty and expensive yard ornament.

Clayton

PS although the idea of 180% quad intake is an idea w/ possible merit.

 

Sorry, Keith. You're right.

Has anyone seen the Offenhauser Dual-Port manifold before?

Ken

[This message has been edited by Ken73 (edited January 24, 2001).]

 

now that is interesting!. hmmm

ive been thinking, you are right about the engine then only being able to pull air from one cylinder, but one 1.5 inch bore could feed 2 cylinders fine couldnt it. vacuum could be held up maybe by keeping the intake low, so that vacuum wouldnt necessarily be needed to be kept in the intake, but if you had the tb really close to the intake valves on the heads, then vacuum would be fast, but not constant. fast would suck the air no prob???

i dont know. i think its interesting to think of such thinks, and ken, ive been called nuts so many times with some of my ideas its not even funny. i think i am. but i want to someday try all of them. including. 2 turbo charged 3cyl metro motors in a little car. these are the things i think of. you could have one in the front and one in the back. how about a tripower 502 with 3 tbi's on it.

see, im nuts.

 

On the subject of vacuum and carb to head distance;

Snflupigus, you bring up an interesting (to me) point about the distance of the carb to the head. On snowmobiles, there is one carb per cylinder, and the are all isolated. (no connecting plenum). The goal is to get the carb as close to the cylinder as possible so the carb gets a stronger signal. (velocity/vacuum) If you install a longer carb boot,(runner)the carb has a hard time delivering fuel because the vacuum signal becomes "slugish" with the extra volume. A car generally relies on a smooth, constant vacuum to draw fuel at a constant rate, not a suck-suck-suck-suck-suck, like a snowmo.

So if you did use a quad plane manifold, with a carb, you could still get a good, but instantanious signal by moving the venturi closer to the head. But I think for TBI this system would not work well because where would you pick up your MAP signal? Which ever of the four planes your MAP was hooked up to would have a wildly fluctuating signal that I think would be hard to tune around, and would not work at all with a stock chip. But what if you had four vacuum lines hooked to all four planes, and made them converge to a "junction block" with a miniture plenum, and then one vacuum line from there to the MAP sensor. I don't think the vacuum lines could possibly flow enough so the four sides could "see" each other,(they would remain independant) but the MAP would recieve a signal from all for sides and the "miniplenum" would smooth any pulsations. What do you think?

BTW, Hi Ken.

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Hi, Tom.

How about this; have you ever seen a simple reed valve? (i.e. for an aquarium air pump, to keep water out of the pump?) Imagine four reed valves at the "miniplenum" so the vacuum would stay (somewhat) constant, yet still have seperate plenums for each barrel.

Now, suppose you're going to use a 4bbl TBI unit - how do you fire the injectors? (With what ECM?) The '7747 fires all of them at once, no? You'd want to fire the injector in sequence with either of the two cylinders that currently have their intake valve open. (MPFI?)

Ken

 

hmmm, so you would need a sort of sequencial fuel injection like the ls1. Yes, then i like the reed valve idea, and the vacuum block to have the map hooked to. i think this could be done, it would be very interesting, but i dont know if cost benifit analysis would yeild an answer to do it, or not to. i may look into this idea more when i get time.