Clevor Engine Intake Manifold Upgrade - Box Score
Upgrading our Clevor Engine Build with a Trick Flow Short-Runner Upper Intake
From the July, 2012 issue of 5.0 Mustang & Super Fords
By KJ Jones
Photography by KJ Jones
We're always talking about next-level performance for late-model Mustangs. Handling and engine-performance are the main points of focus, and typically, our mantra is the more, the better. This never- ending quest for performance has us always on the lookout for new products or methods of increasing-and-improving performance for '89-'13 Ponies.
In 2011, commissioning Coast High Performance to build a fuel-injected, 408ci Windsor with Trick Flow's new PowerPort 225cc Cleveland cylinder heads and R Series intake manifold (a Clevor engine) was one of the ideas we followed through on. Since that project's first report ("Hot In Cleveland," July '11), Greg Montoya nailed the hammer to the mat in our hard charge to learn more about the potential of this unique combination.
On this particular leg of the continued effort, we want to see the impact--negative or positive--of a simple intake- manifold swap on this Pony's unique bullet. This idea came about after Tech Editor KJ Jones and Gregg Changet at Trick Flow--although pleased with the Clevor's initial chassis-dyno results (432 hp/428 lb-ft without nitrous)--thought there was "a lot more power where that came from." We thought the Box R upper plenum intake manifold would be the best place to find it.
As we've explained in past reports, Trick Flow's Cleveland-style heads offer bigger valves, canted valve angles, large intake/slightly raised (0.100-inch) exhaust ports, and closed chambers. That makes them comparable to the Ford Aussie 2V and 4V heads of the '70s--heavy breathers that proved to be great performers on stroked engines.
Horse Sense: The dragstrip segment of this test, while successful, left us just on the edge of crossing one of the major performance plateaus for any regularly driven street/strip Mustang--the 10-second zone. Post-track investigation showed us that the clutch in Greg Montoya's '89 GT was thoroughly fragged, and it more than likely had been since our first runs on the chassis dyno. We're noting all this to reinforce how important it is to seat a new clutch before hammering a 'Stang on the chassis dyno or track. A new Centerforce Dyad will be backing up the 408 Clevor engine by the time you read this.
While Trick Flow's R-Series...
While Trick Flow's R-Series upper plenum definitely served our 408 Clevor well, we believe it actually limited the engine's potential. With the focus of this project being to see how installing the box version of the R manifold will influence the project bullet, removing the original upper is the only real labor involved with this effort. The lower intake (PN TFS-516L0115) is constant for both uppers.
Standing the plenums side-by-side,...
Standing the plenums side-by-side, their runner differences are quickly discerned. Basically, the Box R intake gives intake air the proverbial straight shot (only 3 inches) into the ports of the cylinder heads. Like its standard R-Series counterpart, the replacement plenum also features a 90mm throttle-body flange.
Here is a close look at the...
Here is a close look at the interior layout of the Trick Flow Box R plenum, from the top and bottom sides. Notice the even spacing of the runners, and how the entry into each port is slightly ported to reduce turbulence. We dig the fact that this upper has a removable lid, which will make additional porting simple (if Greg cares to go there), and the O-ring that keeps high-pressure air inside the box. On the discharge end of the runners, the staggered rectangle spacing is apparent.
Since air exits through a...
Since air exits through a staggered runner arrangement on both R upper intakes, there's no need to replace the lower. However, a 1-inch billet spacer is required for linking the Box with the lower manifold.
Unlike the R Series upper,...
Unlike the R Series upper, fasteners for securing the Box R do not pass through any of its runners. The spacer makes this possible, as it first bolts to the upper plenum, which then is secured to the lower intake with studs.
Here is another example of...
Here is another example of the Box R's perfectly straight, 3-inch runner design (total runner length is 10.3 inches once the upper is attached to the lower manifold). While this setup is theoretically produced for racing (it's far from being 50-state/CARB-legal) and the higher end of an engine's rpm band, we believe reasonable driveability can be achieved in Greg's Mustang through its Anderson Ford Motorsports PMS engine-management system.
When you think about our Clevor's original induction setup, it's easy to understand how the long runners of the engine's Trick Flow R Series upper manifold actually decrease intake-air's (drawn through Anderson Ford Motorsports' 4-inch Power Pipe, Abbaco's 97mm DBX mass air sensor and a 90mm throttle body) velocity and efficiency, before passing into and through the large openings in the heads.
Replacing the standard R-Series upper-intake manifold with Trick Flow's famed Box R topper (PN TFS-51500008; $395.99) is a move that we're excited about. It should increase air volume in the manifold and shorten the distance that it actually has to travel. We strongly believed it would take the Clevor's naturally aspirated performance to a level that's more in line with the horsepower and torque values we all optimistically forecasted at the outset of the project.
Like many of you, Greg's a more-than-capable do-it-yourselfer and has handled all of the bolt-on assignments for Project Leave It to Clevor since the effort really hit full stride in our Sep. '11 issue ("Turning Tricks"). So with that said, check out the photos and captions highlighting the upper manifold exchange, and the compelling data that is a result of hitting both the dyno and the dragstrip immediately after the operation was completed.
Despite using a thin-wall...
Despite using a thin-wall wrench to secure nuts on each manifold stud, Greg found it necessary to grind the tool down a bit (left) for better leverage and swing in the tight space.
Greg lowers the TFS Box R...
Greg lowers the TFS Box R upper plenum onto the lower intake manifold. Once the intake is bolted down and the throttle body, linkage, and vacuum connections are made, the Clevor-powered 'Stang is ready for the chassis dyno. Again, this swap process is as simple as they get.
While the Box R application...
While the Box R application calls for using the aforementioned 1-inch billet spacer, we must note that it increases the overall height of the manifold quite a bit and could warrant a hood swap (to at least a 4-inch cowl). With Greg's interest being to maintain a 3.25-inch cowl-hood profile, a beautifully machined 3/8-inch spacer is used in place of the 1-inch piece.
The Box R upper plenum certainly...
The Box R upper plenum certainly does away with the traditional Fox 5.0 appearance that the 408 Clevor had when we started this project, but we dig the no-nonsense, racier look.
You might recall that Greg...
You might recall that Greg installed a 3.25-inch cowl hood from Boss Inc, to accommodate the Trick Flow R Series upper.
With the Box R plenum being...
With the Box R plenum being a bit longer (front-to-back), a 5x5-inch (tall) opening was made at the back of the hood's lower panel, to accommodate that extra length, and 3/8-inch spacers are used on both hood hinges, to ensure there's enough height clearance.
Shortly after the dyno test, we took advantage of a private test session at Auto Club Dragway that featured several project cars and motorcycles from Source Interlink Media's SoCal-based performance mags. Despite 85 degree temperature, density altitude that reportedly was close to 4,000 feet, and a clutch that was not doing well at all (see Horse Sense), Project Leave It to Clevor put down solid low-11-second runs across the 1,320.
While Greg's run notes are included in the caption for each timeslip, we must add that the GT carried a full fuel tank and tipped the scales at 3,500 pounds with Greg in the seat. Perhaps if we had removed the spare tire, jack, and full nitrous bottle (which we weren't using), approximately 50 pounds would have been gone and "official" 10-second e.t.'s could be claimed.
Run 1 (11.14/124.63 mph)
Run 2 (11.06/124.51 mph)
Run 3 (11.02 124.72 mph)
Run 1 (11.14/124.63 mph)...
Run 1 (11.14/124.63 mph) Drag radials @ 15.5 psi Two-step at 5,000 rpm (bog at launch) Shift light at 6,300 rpm Run 2 (11.06/124.51 mph) Drag radials at 15 psi Two-step at 5,200 rpm (left good) Shift light at 6,350 rpm Run 3 (11.02 124.72 mph) Drag radials 14.5 psi Two-step at 5,200 rpm (left good) Shift light at 6,400 rpm
Run 2 (11.06/124.51 mph)...
Run 2 (11.06/124.51 mph) Drag radials at 15 psi Two-step at 5,200 rpm (left good) Shift light at 6,350 rpm
Run 3 (11.02 124.72 mph)...
Run 3 (11.02 124.72 mph) Drag radials 14.5 psi Two-step at 5,200 rpm (left good) Shift light at 6,400 rpm
Post-swap activities include...
Post-swap activities include a stop at B&D Racing in Van Nuys, California, where Brian Schapiro put Greg's Pony through a few hard runs on the chassis dyno.
To say the dyno results from our intake swap are anything less than amazing would be the biggest understatement of the year. Project Leave It to Clevor picked up a solid 60 hp at the feet by simply removing Trick Flow's R Series EFI upper-intake plenum and replacing it with a Box R unit.
Of course, some tuning was necessary for achieving the mark, so we called on B&D Racing's Brian Schapiro for assistance in that area. Brian's nearly 20 years of experience with Anderson Ford Motorsports' PMS engine-management system has been huge for this project, as calibrations for naturally aspirated and nitrous-oxide performance have been spot-on every time. (For this effort, Brian only slightly modified his original WOT/dyno calibration for the Clevor, which resulted in the engine making just shy of 500 rear-wheel horses using Rockett Brand 100-octane fuel).
Conventional thought would lead one to think that taking away so much runner length (nearly 6 inches) would knock down rear-wheel torque by several lb-ft. As the data shows, this notion is totally dispelled for the Clevor engine.
Like the increased horsepower, torque with the new manifold is impressive. The peak hits 400 rpm in front of the torque generated with the R-Series plenum. Of course, with 3.73 gears and spool socked into the 8.8 rear of Greg's '89, we're pretty sure the tire-frying will be fairly instant through three gears whenever Greg nails the throttle on traction-limited pavement.
Here is the dyno graph that depicts the savage, naturally aspirated horsepower and torque that our project 408 Clevor is throwing at the rear tires of Greg Montoya's '89 GT. If you refer back to our report on the combination's initial dyno test ("Big-Steam Dream," Oct. '11; available at www.50mustangandsuperfords.com) and note the differences in the chart that accompanies this graph, you'll see that the switch to Trick Flow's Box R upper-intake plenum clearly made a big difference across the entire dyno run.