When we posed the idea of a modern Chevy versus Ford small-block build-off earlier this year the response we received was overwhelming – it was immediately obvious that this was a head to head battle that needed to come to fruition. And while it took a little longer than we anticipated to get the pair together, we’re now officially ready for show time.
In case you missed our preview of the series earlier this year, let’s get you up to speed.
If we were to pick the two powerplants that have been instrumental in the modern musclecar resurgence, it would have to be Ford’s overhead-cam modular small-block V8, particularly in its most recent 5.0-liter iteration, and GM’s ubiquitous Chevy small-block, which is especially tasty (and yet financially accessible) in LS3 configuration. The concept was to build hopped up versions of both engines while not getting too extreme; something you can install into a daily driver for 50,000+ miles without issue. The block, heads, and intake manifolds needed to be OEM counterparts but from there it was up to us to build it with the best parts for under ten-grand.
Both of these engines make plenty of horsepower and torque right out of the box; with boatloads of these already produced not only for use in cars like the Camaro, Corvette, and Mustang, but also for the full-size pickups and SUVs produced that wear the Bowtie or the Blue Oval as well, these powerplants are quickly becoming engine swap favorites for hot rodders, whether they’re building up an old Falcon or an NB Miata.
And in terms of output, the stock LS3 and Coyote are closely matched rivals – just a handful of ponies separate the pair from the factory. So of course there’s been endless bench racing between the two for years, with speculators proclaiming one engine to inherently outperform the other with only a bolt-on here or an ECU tune there.
With this test series, we’ve decided to put the speculation to rest. But rather than just throw any combination of parts available at these mills, we wanted to take a real-world approach that replicates the kind of build you might take on in your own garage.
The Ground Rules
- $9,999 or less parts budget
- Naturally aspirated
- Stock displacement
- Near 11:1 compression
- Run a production style intake manifold
- Street car friendly – no wild cams
- Hydraulic roller camshafts
- Factory PCMs
- 91 octane and VP unleaded race gas
That budget essentially covers raw materials to put these engines together – additional costs for machining, assembly, external components and other incidentals aren’t going to be included. Both powerplants will be of the all-aluminum variety, and both were put together on the same day at local engine builder L&R Engines. From there we took the pair to Westech Performance for dyno testing – the results of which you’ll be seeing very shortly. In the meantime, let’s take a closer look at our Chevy small-block.
The Bottom End
The foundation of the LS3 build is a bare block from Chevy Performance (PN 12623967, available at Jegs). Chevrolet’s official line is that this block is validated up to 525 hp, but we have little doubt that it’s capable of reliably handling over 800 horsepower with ease. Usage and time at power are ultimately the biggest durability factors for any particular block, and the LS3 is no exception. But under typical high performance street car use, it’s a pretty safe bet that Chevy’s official numbers are conservative.
Of course, it doesn’t hurt to enhance component durability where we can, so we selected a factory LSA crank from Pace Performance (PN 12641691) for the job. While the stock LS3 is a fairly stout piece in its own right, the LSA crank is built from forged steel rather than the nodular iron used with the LS3 crank, plus the LSA crank is actually cheaper than an LS3. Aside from enhanced strength, the LSA crank is also more than ten percent lighter, and finding some rotational mass weight savings is always a nice bonus.
“Keep in mind that there are two different versions of the LSA crank that have been used in production,” says Greg Was of Pace Performance. “The older version with non-polymer-coated main and rod bearings (PN 12603616) was used with the 2009-2011 Cadillac CTS-V motors, while the newer version (PN 12641691 – the one we used here) found its way into some of the 2011 CTS-V engines and all 2012-2015 CTS-Vs, along with all 2012-2015 Camaro ZL1 engines.”
LS3 Bare Block Completion Kit
Chevrolet Performance also offers a kit that brings together all the final components you will need to seal up and complete an LSX or GEN IV production engine.
PN 12575742 includes the following:
- Front Engine Cover (1) PN 809-12633906
- Valley Cover (1) PN 809-12599296
- Head Locator Dowels (4) PN 809-12570326
- Crankshaft Sensor (1) PN 809-12585546
- Crank Sensor Bolt (1) PN 809-11515756
- Timing Chain Dampener (1) PN 809-12588670
Hooked up to those is a set of forged Mahle pistons (PN 197714865) and rings (PN HV385). It’s a stock bore 376 piston with a 12cc dome, but due to the solid dome design, we decked the piston down to 8cc to get the compression closer to our 11:1 criteria (11.03:1) for both engines. When you’re building a high-revving performance engine, the old adage that you get what you pay for applies almost everywhere, but it’s particularly important to heed this advice when it comes to pistons.
“Forged pistons are stronger and more durable than cast pistons, which is the case for most stock applications,” notes Craig Lancaster of Mahle Motorsports. “Because of the increased strength of a forged piston, it can withstand the high loads and pressures of motorsports and other extreme duty applications. Cast pistons generally have a high silicon content which, although it allows one to run piston to wall clearance tight due to the low thermal expansion rate, also makes it vulnerable to damage when detonation occurs. With a forged piston, we have options and can use one of two alloys depending upon the application, 4032 or 2618.”
Cast pistons generally have a high silicon content which, although it allows one to run piston to wall clearance tight due to the low thermal expansion rate, also makes it vulnerable to damage when detonation occurs. – Craig Lancaster, Mahle Engine Components
In order to bring the LS3 as close as possible to the near 11:1 compression ratio we’re looking for from both engines, the pistons were cut down to drop the compression ratio slightly. We ended up with a compression ratio of 11.3:1 after all was said and done, which puts the compression of the LS3 engine .2 points higher than the Coyote’s. But, like the Coyote’s 1.84ci displacement increase (due to a slight overbore versus factory spec), its effect on performance will be negligible.
Altogether, the LS3’s bottom end combination gives us a rock solid foundation to build power on while not blowing through the budget (or the block) to get there.
With the bottom end of the engine suitably beefed up for increased performance over stock, we’re looking to the top half of the equation to see where we can make some significant performance gains.
Comp Cams pieces were selected for the lion’s share of the valvetrain components, including our camshaft of choice (PN 54-469-11) and a matched set of springs for the increased lift and d. We went with this particular cam due to its increase duration and lift specs over the stock stick, which in turn should provide a broader power band with more more mid-range torque and a higher top end, albeit at a slight cost to torque on the low end.
- Duration: 231 intake / 247 exhaust at .050″
- Lift: .617 intake / .624 exhaust
- Lobe Separation: 113 degrees
And if you’re swapping out the stock cam, ideally you’re going to want to upgrade the valvetrain as well to make sure all the components are beefed up for the job, so it made sense to match up the new camshaft with valvetrain components also sourced from Comp Cams.
With the switch from the stock camshaft to the Comp piece, we knew we’d need valvetrain components that are more robust in order to reliably handle the increased lift and duration. Comp’s valve springs (PN 26926TS-KIT) are designed to do just that — handle more lift and increased spring pressure. The dual springs are constructed from Comp’s Super Clean wire and are nearly as light as titanium; with improved harmonics versus the stock springs, they’ll also last a lot longer. Tool steel retainers are included with this kit.
Comp’s Pro Magnum lifters (PN 875-16) are also specifically designed to perform at higher engine speeds. When an engine is equipped with a hydraulic roller camshaft – like our LS3 is — high RPM performance is limited by the improper positioning of the internal piston, as the lifter inevitably “pumps up.” This improper location can result in broken valves and therefore lead to lost power or even engine failure, and these reduced-travel lifters offer a distinct advantage over standard high performance hydraulic lifters in that regard.
We also used the Comp Cams trunion upgrade kit (PN 13702-KIT) to convert the stock LS rocker arms into captured roller trunions. These are also designed for high-RPM applications, and like the other valvetrain components they allow the rocker arm to handle the increased lift provided by the new camshaft.
Rounding out the valvetrain package are Comp Cams’ Hi-Tech pushrods (PN 7955-16). Constructed using high-quality premium steel alloy for bolstered strength and durability, these pushrods are far more rigid that the stock pieces and are robust enough to handle the increased valve spring pressures that result from the more aggressive cam profile we’re using.
Initially we’d planned on using unported LS3 heads from Chevy Performance, but once we discovered that only $200 separated these cylinder heads from Chevy Performance’s factory CNC-ported LS3 variants, we opted for the latter. For that relatively paltry sum, the ported LS3 heads offer a number of advantages over the LS3 as cast pieces, with the number one obvious reason – increasing airflow while decreasing turbulence to the cylinder.
“The CNC porting is done to these cylinder heads to improve high RPM power,” explains Rocko Parker of Chevrolet Performance. “The heads typically make a little less power than the non-CNC heads on the low end of the power band, based on what we have tested. But on the upper end of the rev range they make more power, so they are best suited for an engine where high power and high RPM are desired.”
And if we’re going to outfit the engine with the internals it needs to make more power, we’re going to have to provide it with an increased supply of air and fuel in order to do so. On the fuel front, we’ve bolted up a set of F.A.S.T. LSX high-flow billet fuel rails (PN 146027-KIT) and while we’d initially planned to pair that up with a set of F.A.S.T.’s 65 lb-hr fuel injectors (PN 30657-8), we were running out of budget, so we opted to go with the stock pieces.
To help get the bigger bang we’re looking for, we installed a set of FAST ignition coils (PN 30256-8). These provide a hotter spark than the stock pieces and are ideal for a mid-level, naturally aspirated engine like ours, though they’ll work with builds using up to 15-20 pounds of boost and up to about 1,500 horsepower.
Putting It All Together
If there’s an overarching theme to our LS3 build, it might be one of streetable usability first and maximum output second. We’re certainly interested in making this LS3 really sing, but considering the fact that one engine will not “win” based on sheer peak output alone (along with the price cap we’re using on this head to head build) when it came time to select components, reliably building power across the rev range was the highest priority.
It also future-proofs the engine to some degree, allowing for some flexibility in terms of future part swaps and the possibility to moving to forced induction at some point if we want to do so at a later date. It never hurts to give yourself some options down the road.
In the meantime, however, what we’re interested in is how the LS3 stacks up against the Coyote 5.0 using a similar budget. With 1.2-liters of additional displacement, the Chevy might have its work cut out for it on the power-per-cubic-inch front, but it also might negate that with additional low-end torque.
And while these two engines make similar power in stock configuration, how they go about doing so is very different, with Chevy’s old school pushrod design still proving its worth, while over the past two decades Ford’s DOHC design has been honed into a formidable platform for Blue Oval performance.
But which one will prevail in this head to head build-off? The dyno sessions will speak volumes – keep your eyes peeled for the information from those, it’ll be coming your way shortly.