Ford vs. Chevrolet has been a rivalry that has existed for literal generations. The rivalry really kicked off after WWII and has been raging since. Obviously, it has continued on into modern times, as evidenced by the LS vs. Coyote series we’ve shown you in the past. However, the modern-day versions of Ford and Chevy’s small blocks are apples and oranges in relation to each other. But, that hasn’t always been the case.
One of the most unique points in history was the mid-1980s, with the Camaro and Mustang heavily competing against one another. Both vehicles were powered by engines of similar displacement, with the Fox Body Mustang sporting a “5.0L H.O.” engine and the Camaro a “305 TPI” engine.
With such similar displacements and power ratings (The Chevrolet had 215 horsepower at the brochure, while the Ford had 225 in 1987) they were obvious competitors. When you start digging a little deeper, you see that while similar in total displacement, the two powerplants achieved it through different means.
While the Blue Oval combination used the tried and true 4.00-inch bore and 3.00-inch stroke that had been in the small-block Ford since 1967 the Bowtie did it a little differently. To retain the familiar 350’s 3.48-inch stroke, the bore was reduced to 3.736 inches.
Richard Holdener had the idea to roll back the clock and compare these two powerplants against one another in modern times. After testing a brand new Chevrolet 305 TPI on Westech’s dyno, in both stock and modified naturally aspirated configurations, he added a supercharger for giggles.
Wanting to revisit the rivalry of the ‘80s, Holdener decided to do the same tests with a 5.0L Ford. However, there are some slight differences, as he points out in the video. Primarily, that the Ford engine came out of a junkyard, and the small-block Chevy was a brand new, fresh engine.
Brothers From Another Mother
“A lot of guys think the differences in bore and stroke are a big difference between the two engines,” says Holdener. “Just because one has a smaller bore and bigger stroke, doesn’t mean that the power curve will change, necessarily. We’ve done lots and lots of testing on the effects of bore and stroke. The big thing that determines what is going to make power is displacement.”
“If you have two combinations that have exactly the same cylinder head, exactly the same camshaft, intake, headers, and all that, and only changed bore and stroke, but kept the displacement the same, the power output will be all but identical,” Holdener says.
Now, before you say anything, there is a “but” in there. “That can change if we go up in power output, and up in RPM, and start requiring more head flow,” explains Holdener. Once you need more-than-stock flow from the cylinder head, a bigger bore starts to become an advantage. “With a bigger bore, you can put bigger valves into a bigger head, and get more flow and make more power. That’s one of the limitations of the 305 Chevy.”
That small bore also plays into cylinder head availability. As Holdener points out, while the small-block Chevrolet is usually the poster-child for the aftermarket, and the small-block Ford is usually selection-limited in comparison, for the small-bore 305, the roles are reversed, with very few cylinder head choices available, and the SBF having a much wider selection, comparatively.
Stock Vs. Stock
For this test, the two engines being fielded are as close as possible to each other in each test to try and generate comparable data. For the Ford side, Holdener started with an unknown-mileage E7-headed 5.0 H.O. engine from the junkyard. First, it was run on the dyno with no accessories, long tube headers, optimized timing, and open throttle body. That generated 261 horsepower at 5,100 RPM and 321 lb-ft at 3,400 rpm.
With the same setup — long tubes, no accessories, optimized timing — the LB9 305 TPI made 267 horsepower at 4,700 rpm, and 333 lb-ft at 3,700 rpm.
“The Chevy made a little more power than the Ford through the mid-range, and maybe that’s because it’s brand new, and the Ford isn’t, so maybe it’s a little stronger,” says Holdener, although the Ford did squeeze out 800-more RPM than the 305.
Modified Naturally Aspirated
For the Ford, Holdener installed a Trick Flow camshaft, measuring .540 inch of lift at the intake, .560 inch exhaust, with 224 degrees, intake, 232 degrees, exhaust duration at .050 inch of lift, and a 112-degree lobe separation angle. “That cam has always worked well for me. It’s a good all-around cam,” says Holdener.
For the cylinder heads, the 170cc intake runner 11R cylinder heads were chosen. In addition to the improved valve angle, the heads feature 2.02-inch intake valves and 1.60-inch exhaust valves. “They are basically the CNC version of the Twisted Wedge head Trick Flow is known for,” Holdener says. “It’s a really good head, and I really like it. They work really well.” The Trick Flow kit came with a long-runner Street Heat intake manifold and was combined with a 70mm Accufab throttle body.
“At this power level, the 70mm throttle opening is probably a little restrictive,” Holdener surmises. That combination netted 408 horsepower at 6,200 RPM and 397 lb-ft at 4,400 rpm — a significant boost for a basic head, cam, intake swap. Not to mention being able to turn the combination to 6,500 rpm.
On the Chevrolet side, a Comp Cams XR276 hydraulic roller camshaft was used. It features .570 inch of lift on the intake, and .565 inch on the exhaust, with 218 degrees of intake duration, and 224 degrees of exhaust duration, at .050 inch lift, and a 113-degree lobe separation angle.
Replacing the factory iron heads are a set of Trick Flow Super 23 cylinder heads with 175cc intake runners and small 56cc combustion chambers filled with 1.94-inch intake valves and 1.50-inch exhaust valves. “These are probably the best heads you can get for these small-bore engines, in my opinion,” Holdener says.
Keeping the 305 true to its tuned-port nature, a Holley Stealth Ram intake. “This is probably the best TPI intake out there. It’s basically a tunnel ram with a box on it and a tuned port dual-52mm-blade throttle body, so you can get more air in,” says Holdener
With all of those parts, the 305 TPI picked up over 100 horsepower, posting final modified naturally aspirated numbers of 372 horsepower at 5,900 rpm and 353 lb-ft at 5,000 rpm.
“That 11R head allowed the small-block Ford combination to make a good bit more power than the 305 Chevy,” explains Holdener. “The Trick Flow Super 23 heads on the 305 were as-cast, but I think the Chevy is just limited by its bore size and the head you can put on it.”
Obviously, adding a supercharger is going to significantly increase power, although, more than 200 horsepower on the 5.0L is a little more significant than expected. At a peak boost of only 10.0psi through an air-to-water intercooler, the TorqStorm-equipped small-block Ford made 638 horsepower at 6,400 rpm and 545 lb-ft of torque at 5,600 rpm.
Using the same TorqStorm supercharger on the Chevy 305 along with the same air-to-water intercooler, at 10.2 psi of peak boost, there was a larger relative gain from the naturally aspirated test, picking up 240 horsepower. That gave the 305 a final number of 612 horsepower at 6,000 rpm, and 546 lb-ft of torque at 5,500 rpm.
“[The Ford] made a little bit more power than the Chevy with the same blower and similar modifications, but I think we’re splitting hairs here. That’s probably from the fact that we had a better cylinder head choice and a little more camshaft in the Ford,” Holdener concludes. “I think we could get more power out of the 305 with a little more camshaft, and some porting on the Super 23 heads.”
What does all this prove? Engines don’t really know what is stamped on the valve cover and are simply air pumps. Similar displacement with similar components will make similar horsepower, whether it came from Detroit or Dearborn.