Frequently Asked Questions

Explore answers to the most frequently asked questions about tuning and performance enhancements for your vehicle.

Questions Specific to 3.7L Engines

What are the best engine bolt-on type mods for the NA Ford V6?

It Depends on what you are building.

If your goal is to increase power over the whole RPM band, and to improve throttle response; here’s what our research has shown to be the best mods. These mods are listed in general order from greatest impact to least:

1. Well-ported lower and a bigger throttle body.
These are listed together because they work well together. 
This was the first mod done on our test car, and nothing else made such a dramatic difference (The car is FBO and NA now).
About the larger Throttle Body:
The stock ECU responds really well to the extra air, especially at lower RPMs:  You’ll notice the biggest change from 1,500 to 3,500RPMs.  We used a Ford 80mm Throttle Body and Viser’s adapter.
2. Sleeker intake hose and a drop filter.
This is usually the first mod done by most; and those who have done it know it doesn’t provide much of a gain.
Bottom line; the stock intake box is great!  The intake hose could become a restriction if everything else has been upgraded, and a high flow filter is generally a good idea.
3. Headers.
We won’t start a war over long tube v. shorties.
Long tubes seem to be the best; shorties sound good and are easier to install.
4. High-flow CATs.
If you’re driving on the road, we recommend staying legal and keeping your CATs on the car. 🐱
They restrict the exhaust more than a straight pipe though.
5. Bigger injectors.
This is a controversial suggestion, though it shouldn’t be.  Here’s the short of it:
a. The 3.7 comes with 29lb injectors, which is plenty for the stock engine and another 20-30 HP beyond that.
b. If you modded the 3.7 well, you can use extra fuel capacity in the high rpm range.
c. You’ll need a tune if you get bigger injectors.
We used Ford 52lb injectors.  This is overkill for an NA 3.7, but they work great with a tune.  35lb injectors are plenty for the NA FBO 3.7.   
6. Tune aka Software upgrade.
This Mod could be listed 1st, but we’re listing it here for 2 reasons:
a. A tune is not required with the other bolt-on mods, except an injector upgrade and a fuel change.
b. Waiting to get a tune saves money and time. 
7. Change your fuel
A tune is required for this change, which is why it’s listed toward the end.  A fuel change helps the most for boosted cars, though it helps a little for NA cars.
8. Drop weight.
Make your car lighter, and performance will improve.
a. Don’t compromise safety by cutting away the frame, etc,. Proceed with caution, as with all these suggestions.
Lowering Rotational Mass is most helpful:
Aluminum driveshaft
Forged wheels
Two-piece rotors
Lightweight flywheel – must be matched with the right clutch.
There’s lots more to be said about each category above.  These are just highlights.
If you could only add one engine mod to the 3.7, what would it be?

It would be tough to choose between these 3 engine mods – any one of them would add noticeable power:
1.  Long Tubes and High Flow Cats.  The customized Long Tubes was the last bolt-on added to our test car, and it made a difference in sound and in performance.
2.  Tune.  If you add nothing else, a good tune is a must.  It’ll wake the car up and make you fall in love with it all over again.
3.  80mm Throttle Body with Viser’s adapter.   Based on our experience, this was an excellent mod.   The adapter and throttle body was added after the Ported lower, and it added a ton of power from 1,200 RPM thru 4,000, and it added power and capacity at the top end.
If the tune had been done 1st, I believe the bigger throttle body would not have made as big a difference, especially in the mid range.

Will larger injectors improve Horsepower?

No.  Not by themselves.
If you modify your engine well, your power potential could outgrow your OEM injectors – for example:
If you port the lower intake properly, and get a larger throttle body; larger injectors will help above the 4,000rpm range.
To reiterate:
-Larger injectors will only help if additional capacity is needed.  
-Bigger Injectors won’t help with acceleration or throttle response at lower RPMs.
-A tune will be required if you install larger injectors.

I have a lower intake that was ported by someone else. Will I get a power increase from your adapter and an 80mm throttle body?

Probably.  No promises.
Most shops port their intakes in a way that primarily benefits boosted cars.  We  focus on NA builds.  Our ports are designed to optimize performance for engines that are not boosted.

Should I upgrade to 3" Exhaust or is 2.5 enough?
Good question, since there’s a ton of aftermarket exhaust systems being sold out there.
The dual 2.5″ pipes are more than enough for the 3.7 V6.  The stock dual exhaust system (past the cats) is really well designed:
Our test car still has stock exhaust pipes, resonator, and mufflers.
We also still have the stock intake air box (with an AFE drop filter and an AirAid tube).
Aftermarket Cat-back exhausts (for the 3.7) won’t add power.
They can change the sound though.
    
If you’re looking for a boost in performance, there are better places to spend money:
-Long tubes
-High flow Cats
-Ported Lower
-Bigger Throttle body
-A good tune
-Gears
What makes Viser Performance Intakes unique?
We focus on the needs of an NA build (Naturally Aspirated). Both the shapes and the surface texture of our bolt-on mods are designed to maximize airflow, velocity; and to mitigate oscillation in the intake:
Our port design vastly improves low and mid-range power, as well as high end power, when combined with a throttle body upgrade.
Our Throttle Body Adapter is specially surfaced to move air thru the transition with almost no resistance.
 
These two products will make your race car much faster than it’s supposed to be, they’ll make your street car much more drivable, and they’ll even improve your gas mileage, if you can keep your gas pedal off the floor.

General Questions

What engine mods would you suggest for an NA 4.0?
Here are some ‘simple’ and effective bolt-ons for the 4.0:
–Viser’s Spacer with blades – This helps with throttle response as well as torque, and it does it by straightening the air.   The prototype tested very well, so we’re excited about this bolt-on!   Dyno results are coming soon, and we’re looking forward to seeing those results!
–Long tube headers – Long tubes are known to add power, especially for NA builds.   Shorties are great for Boosted builds, and they sound great! 
-High flow cats and dual exhaust, when a single exhaust just won’t do!
-BBK 70mm Throttle Body – Feedback on the larger throttle body has been overwhelmingly positive.  We don’t have personal experience with this bolt-on, but I don’t have any reservations about recommending it.
-Cold Air Intake.   The 2005-2010 intake is good but not great.  The after-market intakes can actually provide a little power boost!  This is not true of the 3.7.  The stock box on the 3.7 Mustang is great!
–A good tune:   A dyno tune would be best, IMO.   There aren’t many remote tuners out there, but some have good reputations with the 4.0.  I’m not familiar enough with any of them to make a recommendation though.

-Drop weight, especially rotational mass – forged wheels, aluminum drive shaft, aluminum flywheel, 2-piece rotors, rear seat delete, etc..

Make these mods, and you’ll have a powerful 4.0!

Good luck with your build? 4.0s are fun!

If you want to go to the next level with a 4.0, you’d want to talk with a good race mechanic about porting the heads, building a custom intake, changing the cams, rods, and pistons, etc…
   
I love unusual builds, especially NA builds.
Good luck!
What inspired you to start this little company? Why Ford V6 intake upgrades?
Our founder (Tony) owns and races an S197 V6 Mustang.  After doing tons of research, he designed and installed some bolt-on mods for the intake, and they performed much better than expected!
so he decided to share them.
There’s little more to it than that.  He wanted to share what he knows to be the best NA bolt-on available to the Ford V6.
Why Ford?
Tony is 6’4” 240. The Mustang is one of few American Made rear wheel drive cars he can fit in.  That made Mustang an easy choice.
Plus they are great cars!
What are the benefits of a high-flow catalytic converter?

High-flow “cats” attempt to maintain emissions standards while improving airflow.  If your car is driven on public roads, high-flow cats may keep your car legal.  
   
The cats on our test car were clogged, after 100,000 miles, so any new cats would have been an improvement.   High flow cats may be that much better.

What is the impact of changing fuel type on performance?

Switching to a higher octane fuel can enhance performance, but a tune is often required to fully realize the benefits, especially if you switch to E85 fuel.
A fuel change seems to benefit boosted cars more than NA cars.  
After weighing the pluses and minuses, we decided to run 93 octane gas in our test car.

How does dropping weight affect my car's speed?

Reducing vehicle weight improves acceleration, handling, and fuel efficiency, making your car faster and more agile.  
It’s a terrific performance mod!

Will a lightweight flywheel improve my car's performance?

A lightweight flywheel reduces rotational mass, allowing for quicker acceleration.

Weight-loss is a great modification, especially a reduction in rotational mass.