Do larger throttle bodies really work?

[Curious Hound]

So then if I pull a throttle body, I need to pull the air intake tube as the intake plenum. And try to mate that with the wires that lead back to the Ranger computer?

I was talking about the actual intake behind the throttle body, the part bolted to the engine.

Although, on my 93, I felt like the plastic plenum from filter box to throttle body was restrictive. I rebuilt all that with aluminum tubing and silicone couplers from eBay.

 

[don4331]

Apologies, to Mr. Oak's resident AI, but valve float is not when: RPMs are high enough so both intake and exhaust valves are open at the same time...

Both the exhaust and intake valves are open at the same time every set of cycles. It was one of the things the early engineers learned - because of the inertia of all the items involved, an engine won't have the theoretical ideal of 180 degree cam timing but significantly more.

The stock 3.0 cam specs:
Valve Lift (Intake / Exhaust) .416" / .416"
(Intake/Exhaust) 282* / 288*
0.050" Duration (Intake / Exhaust) 198* / 198* (0.050" is used as a common reference in the industry as some cams have really long durations to get to the 0.050" valve; truly meaningful air flow doesn't start until valve is off the seat a reasonable amount, the industry settled on 0.050" as that value)
Lobe Separation Angle 110 / 118 (the lobe separation valve allows us to determine how much before/after BDC/TDC the valves are open) <sort of like offset vs backspacing on rims.>

We know from TDC to BDC or vice versus is 180 degrees. If Lobe Separation Angle was 90 degrees, we would know valves started and completed lifting equally before and after TDC () = 180/2. But for our Ranger's 3.0, the Lobe Separation Angle is 110 degrees. Letting Excel calculate the appropriate formulas comes up with:

Intake valve​

start to open: 31* BTDC (before top dead center)​

is open .050": 11* ATDC (after top dead center)​

closes to .050": 29* ABDC (after bottom dead center)​

finishes closing: 71* ABDC (after bottom dead center)​

Exhaust valve​

start to open: 26* BBDC (before bottom dead center)​

is open .050": 19* ABDC (after bottom dead center)​

closes to .050": 37* ATDC (after top dead center)​

finishes closing: 82* ATDC (before bottom dead center)​

​

So, both valves are open on a 3.0 for 113* (Intake 31* BTDC + Exhaust 82* ATDC) and 26* at meaning full 0.050" lift (Exhaust 37* ATDC - Intake 11* ATDC)

Valve float occurs when the springs aren't strong enough to pull the valve closed on the valve seat in the time allowed, so instead of the fresh charge staying in the cylinder it goes out the exhaust/back into intake depending on which valve is floating.

Usually the intake floats 1st as the valve is larger = heavier = harder to get closed in time​

Floating the exhaust is bad as it allows unburned fuel over the valve head/seat - which being every hot ignites it - effectively torch them i.e. burnt valve/valve seat.​

So, engineers tend to design engine to allow intakes to float 1st.​

​

So when @Lefty (OP) is considering changing his TB, he needs to consider what is happening with the airflow in the intake. Messing with the inertia of the airflow mass can have opposite effect to intended.

 

[Lefty]

I was talking about the actual intake behind the throttle body, the part bolted to the engine.

Although, on my 93, I felt like the plastic plenum from filter box to throttle body was restrictive. I rebuilt all that with aluminum tubing and silicone couplers from eBay.

I would tend to agree. Maybe I should try to pull that part from the junkyard too. And now that you mention it. Maybe I should purchase a TB spacer.

 

[Lefty]

Thus far I am inclined to believe @4.0blue98 and @gaz who both suggest that they got a quicker truck in the real world, i.e. that they got improved acceleration. I also tend to believe that my own ranger which already has a slightly improved exhaust will help to make this difference more noticeable.

I do agree that a larger throttle body may not work as well when pulling a heavy load up an incline.

Every change has its pros and cons. I'm still all ears.

 

[4.0blue98]

Lots of good info here. Thanks to everyone!

Like I said before, I really couldn't say any one of my mods really made a obviously noticeable difference. Maybe the last exhaust swap was? The cumulative effects were noticeable but the tunes I have changed shift points and a whole lot of things. If I drop to stock and then go back to the torque tune the change is VERY noticeable. My engine is tired at 214k. Never did anything internally to it as I figured I'd blow it up by now and swap in a V8...

 

[Lefty]

Lots of good info here. Thanks to everyone!

Like I said before, I really couldn't say any one of my mods really made a obviously noticeable difference. Maybe the last exhaust swap was? The cumulative effects were noticeable but the tunes I have changed shift points and a whole lot of things. If I drop to stock and then go back to the torque tune the change is VERY noticeable. My engine is tired at 214k. Never did anything internally to it as I figured I'd blow it up by now and swap in a V8...

Funny. I have sort of hoped mine would blow up. But I've got only 150,000 on mine. It runs nice and tight too.

 

[don4331]

Thus far I am inclined to believe @4.0blue98 and @gaz who both suggest that they got a quicker truck in the real world, i.e. that they got improved acceleration. I also tend to believe that my own ranger which already has a slightly improved exhaust will help to make this difference more noticeable.

I do agree that a larger throttle body may not work as well when pulling a heavy load up an incline.

Every change has its pros and cons. I'm still all ears.

You're missing my point and I take exception to @gaz numbers because they defy physics.

Horsepower is a function of torque and rpm i.e. you can't have horsepower without both torque and rpm. Formula is torque (ft lbs) * rpms / 5252 = horsepower.

So, to have the same 3 hp improvement at 1200 rpm as at 2400 rpm, @gaz modification would have had to increase torque by 6 ft lbs. and to have the same 3 hp increase at 4800 rpm, it would have had to increase torque at 1200 by 12 ft lbs. And a larger TB with proper blending should be making more torque at higher rpms = increased peak torque. So @gaz should have been asking his dyno operator what gives.

And I'm very suspect of the placebo effect - you did all this work to you truck so darn it, it better run better.

The larger throttle body works better when pulling a heavy load up an incline (assuming you are letting the engine rev) as it should be decreasing intake resistance. Decreased resistance = increased power. Increased power requires ability to shed that head - that why the F-150s/Super-Duty have such bluff front ends - they need serious amounts of radiators/intercooler/condensers. But that comes at a cost - my example was the ability to cool the exhaust valves i.e. why heavy trucks go to sodium filled exhaust valves.

 

[pjtoledo]

just to further confound the issue , let's do some math.

the curtain, which is the area available under an open valve to let "air" into the cylinder is the basic determining factor for how much air gets in.
(pre-tuning of runners etc). think of the curtain as a virtual cylinder from the valve head down to the seat.
so, a 40mm intake valve lifted .418"/10.63244mm
pie * 40mm = circumference 125.66 mm, multiplied by lift * 10.63224 = about 1336mm squared, or 13.36 square centimeters to let air into the cylinder.

the area of a 52 mm throttle body is pie R squared, pie * (52/2) squared or about 2123 mm squared, or 21.23 square centimeters.
subtract the area of the throttler shaft, 8mm * 52mm, for 416mm/4.16 cm squared yields about 17.07 square centimeters to let air into the intake.

going by math alone it seems the throttle body is capable of supplying more than the valve demands, again, not considering port & runner tuning.

BUT WAIT ! There's more!
the throttle is constantly supplying air without interruption for each complete revolution of the crank.

with a V6, the valves are only demanding air for 3 of the 4 crank cycles per revolution, so from the start if all things were equal the throttle could over-supply the valves.


how's that for stirring the 'ol pot??

 

[pjtoledo]

FWIW, I am quite familiar with port & runner tuning. obviously makes a huge difference in performance/efficiency.
the intake manifold on my Taurus SHO has long, 15" runners for up to 3500, then the secondary plates (not throttle) open the hi rpm runners which are only 5".
they feed from opposite surge tanks for optimum results.

EDIT: that's a 3.0L engine that revs to 7400 with a 65mm throttle body.

 

[cbxer55]

I have a 60 mm throttle body on my 98 3.0. My friend Rick, who does transmissions, after installing a shift kit and 4.1 gears in it, said it is a "strong running V-6".

I also replaced the dual circular throttle body on my Lightning with an Accufab, which is a YUGE oval throttle body.

The Mod section at LightningRodder.com says that a larger throttle body provides a much more noticeable boost in off-idle acceleration. That's what I noticed on both. Nice thing is, at least according to the article in LightningRodder, no tuning is necessary for a throttle body change. It doesn't hurt anything to do it, but you don't have to.

Btw, the Accufab throttle body is polished inside and out. And in both instances, I enlarged the opening at the front of the intake manifold to match the larger TB. Using rotary files and a Dremel tool.

 

[Lefty]

You're missing my point and it take exception to @gaz numbers because they defy physics.

Horsepower is a function of torque and rpm i.e. you can't have horsepower without both torque and rpm. Formula is torque (ft lbs) * rpms / 5252 = horsepower.

So, to have the same 3 hp improvement at 1200 rpm as at 2400 rpm, @gaz modification would have had to increase torque by 6 ft lbs. and to have the same 3 hp increase at 4800 rpm, it would have had to increase torque at 1200 by 12 ft lbs. And a larger TB with proper blending should be making more torque at higher rpms = increased peak torque. So @gaz should have been asking his dyno operator what gives.

And I'm very suspect of the placebo effect - you did all this work to you truck so darn it, it better run better.

The larger throttle body works better when pulling a heavy load up an incline (assuming you are letting the engine rev) as it should be decreasing intake resistance. Decreased resistance = increased power. Increased power requires ability to shed that head - that why the F-150s/Super-Duty have such bluff front ends - they need serious amounts of radiators/intercooler/condensers. But that comes at a cost - my example was the ability to cool the exhaust valves i.e. why heavy trucks go to sodium filled exhaust valves.

@gaz may be wrong about the numbers. But he may not be reporting under the influence of a placebo effect. After all, the engineers at Ford must have believed that the 6omm throttle body would provide enhanced performance for the Taurus and the Mercury. Why wouldn't the same TB provide enhanced performance in the 3.0 Ranger?

 

[cbxer55]

It's right up the alley of the old days, when we put larger carburetors on our hot rods.

 

[superj]

They still do that here. They pull fuel injection and put a carb that is way to big so your eyes are watering when you are behind them at a light

 

[4.0blue98]

 

[Ramcharger90]

Years and years ago I had a 98 ranger with the 3.0 and 5 speed I did the 3.8 mustang throttle body and a cold air intake factory manifolds but a new exhaust. It was a little bit better on economy and acceleration atleast it seemed that way, nothing to right home about. I put an 8.8 in it after the 7.5 blew apart which must have had a better gear set in it that's when I definitely noticed a change. Also I remember a guy around the same time did a Franken ranger with the 3.0 it maybe on here or it was on the old YouTube I'll look but who knows if it's still out there. I remember the truck was black and was about the same year as a 98.