5.0 Mustang & Super FordsHow To Engine
FRPP 392 Crate Engine With Xtreme Energy Roller Camshafts
Making power with FRPP's 392 crate Windsor and three mechanical-roller Comp cams
When it comes to flexing big horsepower biceps and rippling expanses of torque, setting aside the compact 302 for the fullsize 351W is a major step up in both power production and long-term engine durability. Now, with the recent advent of Ford Racing Performance Parts' $6,295 Windsor-based 392-inch stroker, we've come to enjoy 430 Mustang-friendly horsepower direct from the FRPP catalog. Good for low 11s at the strip or deeply satisfying oomph off the road circuit corners, the 392 crate engine's 351W architecture is an easy-enough bolt-in to late-model Mustangs.
Previous testing has shown Ford's 392 is actually good for a healthy 456 hp and 469 lb-ft of torque on our usual Westech Performance Group's 901 SuperFlow dyno test bench. These figures are considerably higher than FRPP's ratings of 430 hp and 450 lb-ft of torque, a situation we've come to expect with Ford engines, thanks to their relatively conservative power-rating strategy. We should also point out the 392 package is available as a short-block ($2,995) or even just a reciprocating assembly ($1,495) if that better suits your needs. The recipro-cating assembly is designed to work with '93 or later 351 blocks with their one-piece crank seals.
Happy as we were after dyno'ing the 392 in its stock form, we started considering what the big-inch, single-plane intake Windsor could show us with a little more cam.
Getting together with John Baechtel at Westech, we went through the Comp Cams catalog-Westech has an arrangement with Comp that makes testing Comp gear almost too easy-to see what sort of camming we could try in the FRPP test engine. We wanted a range of cams that were nicely spaced in lift and duration, and that would make good power in the 392.
What we came up with was the Xtreme Energy line of mechanical roller camshafts. The 392 is delivered from Ford with a healthy Comp hydraulic roller, and the Xtreme Energy lineup begins with a mechanical-roller grind that mimics the juice stick. So, as a bonus, we could see if similar hydraulic and mechanical cams offered any power gains relative to each other.
The chart on p. 42 outlines the stock hydraulic roller and the full five-cam Xtreme Energy lineup. In the interest of time, we ran the small, medium, and large of the Xtreme Energy cams; the two italicized cams were not tested, but extrapolating their performance is easily done.
From the chart it's clear the lower mechanical rollers are definitely streetable units, calling for just 9.0:1 compression and lower-stall converters. The XR280R cam looked to us where any sort of daily-driver status would absolutely require large doses of youthful enthusiasm, and the XR292R is definitely a radical piece. Comp says it features a Pro Street sort of idle and requires a 3,500-rpm stall converter and a good intake and exhaust to show its stuff. We had all of that, minus the compression, so we made a note to give the 292 a bit of leeway when analyzing the results.
More Power, of Course
Aside from having to fish a set of mechanical lifters out of the ether at the last minute (thank you, Ford Performance Solutions!), our test went without incident. We installed the 392 just as it arrived from Ford-our test engine was a demo model that was delivered from Ford wearing a 750 Holley carburetor and FRPP ignition wires-to baseline the stock combination. We were happy to see it register within 1.5 hp of what it baselined a couple of months ago for another test.
We then moved to the three mechanical-roller cams and their lifters, starting with the middle grind, the XR280R. We noted an inch of vacuum at the power peak, and so substituted a larger carburetor to reduce the restric-tion. Westech didn't have an appropriately sized Holley, but did have an 850 Demon, a carburetor we've seen help in the past with better power and lower fuel consumption. Of course, we then had two variables in our test-a cam and a carburetor-so we ran all three of the mechanical rollers with both carburetors. Our procedure was to stabilize the oil and water temperatures at fairly high limits, then make three power pulls. The pulls were then averaged to arrive at the official power and torque figures. The carbs were swapped and the procedure repeated.
We'll let the charts tell the full story, but will point out that the improvements in power are fairly incremental until you get to the largest cam, the 292.
|Averages by Carburetor|
|Cam||750 Holley||850 Demon|
|Cam PN||Lift Grind No.||Valve Lift||Duration @ 0.050||Lobe Separation Angle||Notes|
|35-769-8||XR268R||0.589/0.602||236/236||110||9.0 comp/2,000 rpm stall|
|35-770-8||XR274R||0.602/0.608||236/242||110||2,500 stall, rough idle|
|35-771-8||XR280R||0.608/0.614||242/248||110||10.0 comp/3.73 gear|
|35-772-8||XR286R||0.614/0.621||248/254||110||3,000 rpm stall|
|35-773-8||XR292R||0.621/0.627||254/260||110||11:1 or better comp, 3,500 rpm stall, good int.|
|Note: Valve lift is computed with a 1.60 rocker. |
*Ford lists its 392 cam with 108/116 degrees of lobe separation, which is 112 degrees when the cam is installed 4 degrees retarded. The cam we removed from our 392 test engine was marked as a Comp XE282HR, which specifications we've listed here.
|Xtreme Dyno Results|
|Baseline||268 Cam*||XR 280 Cam*||292R cam*|
* run with 750 Holley
Ford Racing's 392 crate engine ran stronger than rated in our first tests, and continued to muscle out the power during our camshaft comparo. With no changes to the basic engine short of the cam and rocker arms, the 392 belted out a thumping 483 hp this time around.