GT500 High-Flow Inlet Elbow And 72mm Throttle Body Install - Elbow Vroom
With A Free-Flowing Inlet, PVT Reaches Its Goal Of 700 RWHP
From the September, 2010 issue of 5.0 Mustang & Super Fords
By Steve Turner
Photography by Steve Turner
At this point, it's a familiar...
At this point, it's a familiar sight to see PVT spinning the rollers. We broke it in on the rollers at Anderson Ford Motorsport with less than 100 miles on the odo. Since then, PVT has made several trips to VMP Tuning in Deltona, Florida, to reach its current power level.
My how times have changed. It used to be that 400 rwhp was a minimum standard for street cred. Then the standard stepped up to 500. Now that power is flowing fast and furious from the factory, the standard for turning heads with your dyno sheets is constantly on the move. To borrow from pop culture, 700 is the new 500 ...
In the case of Project Vapor Trail, my '08 Shelby GT500 project car, we started in the high-400-rwhp range stock, and moved past 500 before the car left the dealer's lot. This was thanks to Ford Racing Performance Parts' TVS supercharger, which Anderson Ford Motorsport installed before we took delivery. Then just a tune and pulley from VMP Tuning had us over 600 rwhp in a hurry. However, I knew there was more power available with huge blowers and full exhaust upgrades.
I just had one goal-to make big power without significantly degrading the car's driveability. Along the way, I decided to retain the stock manifolds, stock fuel pumps, and 93-octane fuel as the gateway to keeping PVT a well-mannered muscle car. I also decided that making 700 rwhp within those limits was an admirable goal.
So, after moving up to an Innovators West 10-percent-overdriven lower pulley, a full Bassani 3-inch exhaust, and a CJ throttle body, the car was sitting in the mid-600-rwhp range. Besides retaining the aforementioned limits, no aggressive internal engine mods were part of the plan. So there weren't many easy bolt-ons left to reach the goal. Fortunately, GT500-guru Justin Starkey of VMP Tuning has developed a new high-flow inlet elbow and twin 72mm throttle body for stock and TVS blowers that promises to reduce inlet restriction, lower blower discharge temps, and increase power.
Could the combination of the VMP twin 72mm throttle body and high-flow inlet give PVT the big push into the 700-rwhp zone? Well, it turns out it can. Check out our install photos and dyno sidebar for all the details. Suffice it to say that PVT reached its goal on all fronts. It makes big power and it still drives great. Mission accomplished.
On the Dyno
The democratization of the chassis dyno was a boon to magazines everywhere, and I have personally enjoyed the ability to test parts. Learning is always fun, and when you are learning about increasing power, it's all the more fun. I headed over to the VMP Dynojet with high hopes of attaining my 700-rwhp goal. It was a cool mid-January day in Florida. The temps in the dyno room ranged from 60 to 65 degrees, and the humidity was a non-existent-for-Florida 25 percent. So the conditions were ideal. It's unlikely the car would do this well in the heat, but it's fun to see what it can do in ideal conditions. Even our baseline number was way up.
Before we opened up the inlet, Justin wanted to ensure that our catalytic converters were not holding us back. Swapping them out for off-road tubes proved that Bassani's high-flow units really do flow well. The slight losses from losing the cats were negligible. Keep in mind we are already running a full Bassani 3-inch system aft of the stock manifolds, so the system was pretty optimized with the cats.
Moving to the free-flowing elbow and twin 72mm throttle body, there was a lot of pressure on this one modification. We also lost the stock rubber inlet tube in favor of the larger Ford GT inlet, which has shown a 5hp gain in some of our prior testing, so totally opening up the inlet with the VMP gear really delivered. The power soared past 700-and even the torque hit 700! That was an impressive gain. The only tuning changes were designed to make the larger throttle body function properly, and the resulting driveability is great. Better yet, the car made this power on Sam's Club 93-octane fuel with the stock fuel pumps!
|CJ Throttle Body/Cats||Off-Road Exhaust|
|VMP Throttle Body/Elbow||CJ/Cats VS. VMP/No Cats|
Remember the days when a 65mm...
Remember the days when a 65mm throttle body was the big upgrade for a 5.0? Some of you are probably too young, but it's true-a single 65 was big back in the day. These days it seems you can't get big enough. This is the latest power combo from VMP, a dual 72mm throttle body and high-flow inlet elbow (PN 72ELBOWBLK; $799; $39 upgrade for polished TB; $75 upgrade for polished elbow; $100 to add motor and TPS). If you are only shooting for 650 or lower, you can go with the same package with the VMP dual 67mm throttle body (PN 67ELBOWBLK; $769).
If you've been following the...
If you've been following the progression of PVT, you know we already upgraded PVT's post-manifold exhaust system with a full 3-inch system (PN BAS-5407R5) from Bassani. We initially opted for the catalytic version and the quiet mufflers. Knowing that we were about to optimize the inlet side of PVT, Justin wanted to ensure we maximized the exhaust too. Removing the cats has proven a good power builder on stock-exhaust GT500s, but in our case, the Bassani high-flow cats proved excellent. The difference between running them and not running them was negligible.
On the left is the stock inlet...
On the left is the stock inlet elbow, which is shared by stock and TVS supercharger applications. On the right is VMP's new D-shaped high-flow inlet elbow. Using hand-modified prototypes and computational fluid dynamics, Justin came up with a new elbow that mounts in the stock location and looks stock, but reduces inlet restriction.
There is a slight catch, of...
There is a slight catch, of course. To get the most out of your VMP high-flow inlet elbow, it's necessary to port-match your supercharger. If you aren't fully confident in your mechanical abilities, you might want to call on a professional to do the work. Ideally, you want to unbolt the supercharger, remove its rotor pack, perform the port match, clean the blower case thoroughly; then reinstall the rotor pack. So it's not a pure bolt-on, but the results are well worth the effort. This is what your blower inlet should look like after the port-matching.
This is only the second time...
This is only the second time the FRPP TVS has dropped down onto PVT's 5.4. The first time the blower was stock. Now it features an optimized inlet and the previously installed VMP stock-look 2.65-inch pulley. In this configuration, the TVS packages and performs so well, it's an excellent option for street-going GT500s with stock hoods, stock motor mounts, and strut-tower braces.
You can either swap the motor...
You can either swap the motor from your stock throttle body on the VMP Dual 72, or opt to pay a $100 premium to get the motor and TPS preinstalled. It's an easy swap, and VMP provides instructions, so don't let that deter you.
The VMP high-flow inlet elbow...
The VMP high-flow inlet elbow is a direct swap for the stock elbow. It even accepts the stock throttle body O-ring for a leak-free, hassle-free seal. Besides its higher flow, the VMP inlet also features a slotted lower-forward mounting hole to ease installation on cars with aftermarket fuel rails and 80-lb/hr injectors like PVT.
To match PVT's polished FRPP...
To match PVT's polished FRPP CJ 123mm mass air housing, we opted for the polished version of the VMP dual 72mm throttle body. It is a beauty, and at this point, an easy bolt-on. Now you can run VMP's smaller dual 67mm unit with a stock elbow, but the high-flow inlet elbow is required for the dual 72mm unit. Of course, adding such a big throttle body requires some tuning. "When a larger-than-stock throttle body is installed on any electronic throttle control vehicle, the drive-by-wire tables should be recalibrated," Justin explained. "Proper recalibration of the tables is necessary to prevent the dreaded wrench light or failsafe mode."
To make sure the stock rubber...
To make sure the stock rubber inlet tube doesn't hold back the performance of the VMP throttle body and elbow, we also added the larger inlet elbow from the Ford GT. We played around with this on PVT during a previous visit, and it showed a 5hp gain with the stock elbow and VMP dual 66mm throttle body, so factor that in if you are sticking with the stock rubber inlet.
While we had the blower off,...
While we had the blower off, it was a good time to add Fore Precision Works matching fuel rail spacer for the taller injectors, like our 80-pounders. They fit fine on the passenger side, but proved a bit too tall for the driver side, where they are largely hidden anyway.