Setting Up an EFI System

[Bill Blue]

Jarrid, I'm now satisfied the Fish just will not cut it. It leans out in the 2000 rpm range, even when running very rich overall. It was in interesting experiment and the car is running fairly well, but 2000 rpm is not the place for a street engine to be soft. Time to move on.

The set up.

Even thought the bottom end of the Pinto engine is good for 7500 rpm or more, the inherent valve train limitations and cam I've selected limit it to 6000.

The cam works good down low. Even with the lean out, I'm seeing 2-3 psi in the low 2000's. With good fueling, I'll probably see the full 7 psi by 2500.

The turbo does not have a wastegate and probably never will. It is an old Rajay. It sets on top of the manifold so I don't have the room to raise it and the manifold has no provision for a wastegate. In the original kit, boost was controlled by the small stock (1 3/4") exhaust system and an intake restrictor. I am using 2 1/2" downpipe, 2" exhaust and no intake restriction.

Boost is controlled by a modified radiator filler and radiator cap. This relieves excess pressure and works to hold boost to 8 psi. I know all this is stone age, but for a multitude of reasons, that is pretty much how its going to be. I think some intake restriction might help lower intake temperatures and will look into it as the project progresses.

The turbo is an over the top setup and due to the air conditioning and vertical space restrictions, I see little possibility for an intercooler. So this is not going to be a street monster 2.0.

With all this in mind, while looking for a spare intake manifold, I think a good place for me to start is the throttle plate. The Ranger 2.3 Duratec unit is 2 3/8" dia and has 3 wires going to it. At his time, that's all I know about it. Do you think this would be usable? If not, what should I get? Should it be setup on the intake manifold or turbo inlet?

Bill

 

[Jim E]

Bill,
Is there a modern or fairly easy to get and cheap turbo that will bolt in place of the turbo in your set up? if for instance the thing somehow manages to break itself.

 

[RootesRacer]

The throttle body you suggest, sounds fine, the 3 wires are to the TPS sensor which is required.

The throttle body MIGHT also have a 2, 3 or 4 wire idle bypass solenoid (IAC), this would be good to gave for closed loop idle control.


Eooooh on the boost control, that scheme will make the air intake very hot when it comes to play. You could probably jury rig a similar setup that dumps the exhaust around the turbo when exhaust pressure hits a limit, this would halt further build of boost and I wouldnt say Eooooh to it. It also wouldnt overwork the compressor side with subsequent rise in intake air temp.

I think an intercooler would be ideal, but at your target boost, perhaps a nicely setup ECU controlled water injection would keep the temps in check and keep detonation at bay. With programmable ignition, you can tune out possible detonation, but of course you are leaving power on the table due to lost charge density.

 

[Bill Blue]

Bill,
Is there a modern or fairly easy to get and cheap turbo that will bolt in place of the turbo in your set up? if for instance the thing somehow manages to break itself.

Jim, I don't know anything about the modern turbos and not much about this one. It mounts using three bolts on 3.5" bolt center, I don't have any spare vertical space and that's about all I know. Also, from what I have been able to learn about the Rajays, they seem to have an almost unlimited lifetime.

Jarrid, are you talking about welding a bung into the cast iron manifold and bypassing to the downpipe or atmosphere? Sort of am exhaust pressure controlled wastegate? Any ideas where I can get some info on this? Also, where do i get a radiator cap that can withstand exhaust temperature? (just pushing your leg).

The IAC is manifold mounted and looks to be awkward to use with this setup, especially if the throttle body is mounted on the manifold. If the TB is mounted on the turbo intake, it could probably be made to work. Would be very easy to use downstream of the turbo.

Water injection? I have most of the stuff on hand to do that.

Bill

 

[RootesRacer]

Yes, what I am talking about is an external wastegate.
It would have to hold up to the temperatures, but there is little difference
in dumping exhaust manifold pressure to control boost versus dumping intake manifold, they track linearly.

The intake method is usually known as a dump valve, and allows dumping of boost during a throttle closure, which if not done, can kill a turbo compressor due to shockwaves that develop. Ive also seen the turbine/compressor mounting bolts loosen up do to the shockwave, and the engine eating the bolt, or metal shavings from the compressor when it touches its housing.

I recommend the external wastegate, AND the dump valve to keep the turbo alive.

Having idle control is definitely a good idea, particularly if you need to drive the car under widely varying temperatures. You can add the IAC anywhere onto the common plenum part of the intake, being on the throttle body is not mandatory. Feeding it with clean air however is.

Dont DQ the idea of getting rid of the distributor, I think I can make the economics work out.

 

[Bill Blue]

In the meantime, where is the best place to mount the TB? That is something I can get started on pretty quickly.

Bill

 

[RootesRacer]

In the meantime, where is the best place to mount the TB? That is something I can get started on pretty quickly.

Bill

Put it wherever it makes sense, obviously it needs to be mounted on the intake, and its placement should be such that all ports get a fair share of the airflow.
That is if you mount the throttle too close to one port runner, the inertia of the air may render that port weaker in flow than the other farther ports.

Larger plenum design prevents this.

Forgive if this is obvious, but plumb the turbo so its outlet goes to the throttle, when then feeds the intake.

Running a throttle upstream of the turbo can cause turbo oil issues, as well as the throttle having only one bar across it can limit throttle airflow, whereas having 1.5 to 2.5 bars of pressure across the throttle will make the throttle seem larger, without causing throttle sensitivity at light power levels.

Also make sure others have used that throttle body for turbo applications since a large diameter throttle, small shafts and thin plates can make for boost related damage and throttle sticking.

On a similar note, make sure your intake valve springs are strong enough to close the valves at max boost. You'd be surprised how often someone forgets to go heavier on turbo engines and have the intake valves float under boost at moderate RPM.

 

[Bill Blue]

Put it wherever it makes sense, obviously it needs to be mounted on the intake, and its placement should be such that all ports get a fair share of the airflow.
That is if you mount the throttle too close to one port runner, the inertia of the air may render that port weaker in flow than the other farther ports.

Larger plenum design prevents this.

Forgive if this is obvious, but plumb the turbo so its outlet goes to the throttle, when then feeds the intake.

Running a throttle upstream of the turbo can cause turbo oil issues, as well as the throttle having only one bar across it can limit throttle airflow, whereas having 1.5 to 2.5 bars of pressure across the throttle will make the throttle seem larger, without causing throttle sensitivity at light power levels.

Also make sure others have used that throttle body for turbo applications since a large diameter throttle, small shafts and thin plates can make for boost related damage and throttle sticking.

On a similar note, make sure your intake valve springs are strong enough to close the valves at max boost. You'd be surprised how often someone forgets to go heavier on turbo engines and have the intake valves float under boost at moderate RPM.

Jarrid, I figured the manifold was the preferred choice, but decided I'd make sure before engineering the fit. Unless you advise otherwise, the TB will be mounted on the carburetor mounting boss. The layout of this system points the turbo to the intake, no problem there.

Turbo kits are offered for the Focus 2.3, boosted to 12 psi and stock TB. Guess it should hold up to 7.

Valve springs are almost at the max recommended for this engine. The intake valves are going to have to fend for themselves.

Bill

 

[Bill Blue]

Jarrid, have most of the small parts gathered up and am starting to look at design. First obvious problem is injector location. Seems they are always placed on the topside of the intake. The Pinto manifold is small and the area between the carb base and block is pretty cramped. Looks like it would be best to place them on the bottom of the manifold. Accessibility issues aside, is a bad idea?

When locating the injectors, what are the important criteria?

Bill
By the way, finally got the carb to perform half way decently, but still have major issues. I think I have been spoiled by EFI.

 

[RootesRacer]

Jarrid, have most of the small parts gathered up and am starting to look at design. First obvious problem is injector location. Seems they are always placed on the topside of the intake. The Pinto manifold is small and the area between the carb base and block is pretty cramped. Looks like it would be best to place them on the bottom of the manifold. Accessibility issues aside, is a bad idea?

When locating the injectors, what are the important criteria?

Bill
By the way, finally got the carb to perform half way decently, but still have major issues. I think I have been spoiled by EFI.

The main reason that injectors point down is becuase there are o-rings on the ends to seal into the intake ports and you wouldnt want fuel to puddle on them. I'd try to find any other way than to point them up from the bottom, just asking for trouble IMO.

Ideally you want a straight shot to the valves, you dont want the injectors spraying the port sides since that will cause fallout.

You could possibly use 4 motorcycle ITBs (they have injector bungs and fuel rail integrated) and mount them to a plate, this is commonly done since motorcycle ITBs are cheap from totaled bikes.