Do larger throttle bodies really work?

[Lefty]

I was just reading the Tech Section on Ranger engines, in particular the 3.0. The author explains how to install a 60mm Escape throttle body.

https://www.therangerstation.com/tech/60mm-3-0l-escape-throttle-body-on-3-0l-ranger-intake.

The article is well written and the directions are pretty clear.

I'm just a little skeptical. There is no mention of performance data. Can we really expect better acceleration or improved mileage? Did the Ford engineers make a mistake? Why did they put a 52 in the Ranger and a 60mm in the Escape?

Have any of you actually done this? How did it work?

 

[4.0blue98]

I really couldn't say I noticed much with a larger throttle body alone. I have swapped in a larger one years ago. I also put a decent CAI and larger Cat back exhaust and then had some custom tunes made. All of it made a big difference but not sure about each one alone.

 

[Lefty]

I have had twin exhaust pipes installed along with a bigger better breathing muffler. I noticed a little bit better acceleration. Perhaps then, that larger throttle body would help.

I will pull a TB next time I go to the boneyard. I would imagine that I will need to pull the larger intake too.

 

[RonD]

A 3 Liter engine can pull in, at most, 3 liters of air every 2 Rotations at wide open throttle(WOT)
So it would just be math as far as enough air flow at WOT

I would think a bigger throttle plate would feel different on the gas pedal, letting in more air sooner based on pedal position

There is a test using a Vacuum gauge, setup so you can see it in the cab, to see if air flow is restricted
Vacuum in the intake/cylinders pulls in the air/fuel mix, so at 0" vacuum no air/fuel mix will flow into the cylinders, this happens when you "float" the valves, i.e. RPMs are high enough so both intake and exhaust valves are open at the same time, so no more vacuum, or power, lol

On a straight, un-Policed road, lol
Run up to higher speed and WOT, should see 1.5" to 2" of vacuum up until valves float
If its higher that 2" then you have air restriction

Bigger throttle body won't hurt anything

 

[4.0blue98]

I haven't read that tech section so not sure if you'll need to swap the intake or not. Mine was an after market made to bolt on. I actually ran a dual cat back with only muffler tips for a while and swear the single Dynomax I have now helped but I have no data...

 

[4.0blue98]

Ahhh, valve float... nature's Rev limiter.

 

[gaz]

@Lefty ,
I can tell you this. When I was stationed in Japan I tested my car with a stock T/B on the dyno and then again on the same dyno with a 3mm tapered hone to a stock T/B with no other improvements/changes...just a tapered hone. IT MADE +3 HP ACROSS THE ENTIRE RPM BAND!!!

Not a huge gain but incredibly useful and it only cost a pack of 120g sanding drums for the Dremel and a sheet of 320g to refinish.

There is such a thing as putting too large of a T/B on, a simple tamper job will work GREAT!

 

[Lefty]

@Lefty ,
I can tell you this. When I was stationed in Japan I tested my car with a stock T/B on the dyno and then again on the same dyno with a 3mm tapered hone to a stock T/B with no other improvements/changes...just a tapered hone. IT MADE +3 HP ACROSS THE ENTIRE RPM BAND!!!

Not a huge gain but incredibly useful and it only cost a pack of 120g sanding drums for the Dremel and a sheet of 320g to refinish.

There is such a thing as putting too large of a T/B on, a simple tamper job will work GREAT!

I'll take 3HP. Thanks

 

[4.0blue98]

@Lefty ,
I can tell you this. When I was stationed in Japan I tested my car with a stock T/B on the dyno and then again on the same dyno with a 3mm tapered hone to a stock T/B with no other improvements/changes...just a tapered hone. IT MADE +3 HP ACROSS THE ENTIRE RPM BAND!!!

Not a huge gain but incredibly useful and it only cost a pack of 120g sanding drums for the Dremel and a sheet of 320g to refinish.

There is such a thing as putting too large of a T/B on, a simple tamper job will work GREAT!

That's pretty good and data too!

 

[Josh B]

I'm confused how if it is offered more airflow to carry more fuel, how does that change the fact it can only support 3L per rev?
So is the air carrying a greater qnty of fuel the answer to that?

 

[RonD]

Engine displacement is the volume of air that any engine can "pump" thru itself every 2 rotations(4-stroke engine)
"1 rev" would only be 1.5 liters on a 3 liter engine
A 4 stroke engine needs 2 revolutions for all 4, 6 or 8 cylinders to have "fired" one time

So a 3 liter engine can pump 3 liters of air thru, and a 5 liter engine 5 liters of air thru, every 2 revolutions

Air/fuel ratio limits the amount of fuel you can add to that air and not flood out the engine
A 5 liter engine has more power than a 3 liter engine because more fuel can be added each 2 rotations, 2 liters more air

You can Force more air into an engine, turbo or super chargers do that
If you force in more air then you can add more fuel and release more energy

But naturally aspirated engines need vacuum to suck air/fuel mix into a cylinder

 

[Curious Hound]

It has been a few years since I looked into that for my 3.0l. If I recall, when I removed the OEM throttle body from the intake, the entrance to the intake plenum was equal to or slightly smaller than the throttlebody throat. So, a bigger throttle body didn't make sense because it was not restricting airflow at WOT.

I generally look for things that are restricting airflow and "fix" those things to make it easier for air to get into the engine.

As far as the amount of fuel is concerned. There is an optimal air/fuel ratio. The pcm is going to use data such as mass airflow and intake air temperature to calculate how much fuel to use to maintain the proper ratio. So, if the engine pulls 3 liters of air, the pcm is going to fire the injectors to give the proper amount of fuel for that much air. Any more than that and it's running rich and wasting fuel, not becoming more powerful.

 

[Lefty]

It has been a few years since I looked into that for my 3.0l. If I recall, when I removed the OEM throttle body from the intake, the entrance to the intake plenum was equal to or slightly smaller than the throttlebody throat. So, a bigger throttle body didn't make sense because it was not restricting airflow at WOT.

I generally look for things that are restricting airflow and "fix" those things to make it easier for air to get into the engine.

As far as the amount of fuel is concerned. There is an optimal air/fuel ratio. The pcm is going to use data such as mass airflow and intake air temperature to calculate how much fuel to use to maintain the proper ratio. So, if the engine pulls 3 liters of air, the pcm is going to fire the injectors to give the proper amount of fuel for that much air. Any more than that and it's running rich and wasting fuel, not becoming more powerful.

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?

 

[superj]

Not on a ranger, bu on my jeep 4.0s i6 and my bmw 2.5 and 2.7 i6s, i have used larger bore tb with great success but i went eith stuff people had already tested out and knew worked.

There is a guy who makes any size overbore theottle body you want for jeep engines. He is a retired machinist and has built many jeeps and had all the measurements for flow and stuff on the 2.5, 4.0, and 4.2, plus if you had a stroked engine, which soze worked best for anything from a 4.5 to a 5.0i6. His throttle bodies on all three jeeps i put them on made the engines feel totally different and one, it made such an improvement that i ended up not doing gears in the diffs.

That one, my 87 cherokee, got better gas mileage and more power. The other two 4.0i6 engines felt different but didnt gain a noticeable improvement in gas mileage. I never dyno'd any so i cannot say if the got more power, either. But they felt more fun.

On the bmw i6s i got more power and improved gas mileage. I gained power above 3500 rpms and my mileage went up 1-2mpg by using stuff from an 3.5 i6 on my baby 6s.

I read about the tb mod you want to do and thought about it but apparently forgot it too because i never pulled the parts i needed.


Normally sinxe you are getting more air with less pedal, the engine will feel "touchy" or "jumpy" lower in the rpm range and feel quicker higher in the range. If the tb is to big, driveability suffers.

If the intake has a restriction because the hole where the tb bolts is to small, grind that to fit the tb first. Then you will probably feel way more of a difference and can then decide to get the bigger throttle body. Grinding any factory restrictions will make a huge improvement, as noted above.

I smoothed the factory carb on my 79 gmc stepside back when i owned one. It was a quadrajet but smoothing the throat of ridges and weird angles made it flow alot better. I think stock it was 325cfm and doing that made it flow up around 350cfm. Its been about 20 years so i could be off on the flow numbers though.

 

[don4331]

I was just reading the Tech Section on Ranger engines, in particular the 3.0. The author explains how to install a 60mm Escape throttle body.

https://www.therangerstation.com/tech/60mm-3-0l-escape-throttle-body-on-3-0l-ranger-intake.

The article is well written and the directions are pretty clear.

I'm just a little skeptical. There is no mention of performance data. Can we really expect better acceleration or improved mileage? Did the Ford engineers make a mistake? Why did they put a 52 in the Ranger and a 60mm in the Escape?

Have any of you actually done this? How did it work?

Ford put a larger throttle body on the 3.0 Duratec found in the Escape than the 3.0 Vulcan in the Ranger because it rev'd higher/made more power.

3.0 Duratec 240 hp @ 6,550 rpm (4 valve/cylinder, DOHC)​

3.0 Vulcan 140 hp @ 4,800 rpm (2 valve/cylinder, OHV)​

​

The Duratec is basically reving 1/3 faster than the Vulcan, so the throttle body needs to flow 1/3 more. 60mm throttle body is more/less 1/3 greater in area than the 52mm. (The little extra power the Duratec makes proportionately is due to aluminium heads allowing higher compression)

Anything less than 5% is within error of the dynamometer. (Changes in temperature/humidity/air pressure make more difference).

If the tb is too big, driveability suffers. <- great statement

With the cam/heads/intake/etc set up to make best power at ~5k rpms, the intake valves need to open before top dead center (TDC) and close after bottom dead center (BDC) as the valves and the air in the intake manifold have inertia.​

However, at just 1,500 rpm (e.g. cruise), opening the valve(s) before TDC/leaving open after BDC results in air being pushed out of the cylinder i.e. less than 100% filling.​

A smaller throttle body ensures there is flow in the correct direct through the throttle body and into intake keeping the cylinder closer to full.​

​

So, the engineers at Ford compromised the throttle body between better response a "normal" rpm over maximum power. Some of the factory 'imperfections' are designed to be there to create turbulence - which helps prevent detonation (turbulence ensures proper mixing of air & fuel).

Now, the hot rodders, replace the compromised throttle body with a maximized one and get better top end numbers. But give up power down low/driveability. They also set air fuel ratios closer to ideal (even a little lean of ideal) which again is great for a single dyno pull (or 1/4 mile) but burns exhaust components on a long climb pulling a trailer in your truck.

Note: Maximum power at wide open throttle on a dynamometer does not translate into usable power at part throttle on the street.

Engineering is taking the theoretical from the scientists and translating it with the desired compromises into what the end user wants. Ford's engineers compromised on what the average user* wanted; might not be what the enthusiast wants...

Average user includes the government regulators.