Bent push rods, both intake and exhaust, were alarmingly frequent on the early high horsepower Intec Singles. Although corrected now, the main cause of the failures is caused by a weak block that flexed under high PTO loads. The problems occurred more frequently as the horsepower increased. For instance, there are no issues with engines of 15 horsepower and less. As the horsepower increased to the 17.5 point, the problem began yet Briggs, under pressure from OEM's, continued to increase the horsepower on the same block up to 21 horsepower. Those engines were failing at very low hours, especially when using a high load implement such as a snow blower or the large 54" decks in heavy grass. Mind you, these engines failed at loads that a 12 hp engine would handle fine. However, horsepower sells and the OEM's placed pressure on Briggs for high horsepower at the lowest cost. The Intec block original design was for a maximum of 17.5 horsepower at which the flexing of .010 between the lower and upper crankshaft main bearings as the PTO load increased. At the time, Briggs felt that the .010 intermittent flex would rarely be present in "average" homeowner residential machines used to mow because the engine is rarely under full load. As the demand for higher horsepower increased and competition from the new Kohler Courage engines achieving 21 hp, Briggs modified the block by adding stiffeners in the area were the cylinder and crankcase joined to offset the flexing caused by the higher compression/higher displacement compression loads stressed that area of the block. They also increased torsional strength of the crankcase after excessive failures of rod bearings caused by the crankshaft flexing in the block so badly that it placed the connecting rod out of line with the rod causing bearing contact with the crank journal. They reputation of the single cylinder Intec as well as consumer and OEM confidence began falling. Briggs was quick to respond with a redesigned block to prevent much of the flex and failures dropped dramatically, that was in 2008. However, engine life was still unexpectedly low on the 19+ hp engines. If an engine reached 250 hours, Briggs felt that it was acceptable as the average homeowner used the machines about 40 hours per season. Finally, Briggs stepped up to the plate, redesigned the whole engine, and named it the Intec XRD. It uses a combination of splash/pressure lubrication, the repositioned the push rods and moved them further from the bore for higher strength, a stronger block, Teflon sleeve bearings, thicker cylinder liner, larger cooling capacity, a stelite exhaust valve, larger push rods and a substantially stiffer block. This has solved the extensive failures and doubled the average life hours to 500. The early Intec twin had some push rod issues but Briggs corrected the problem and it is a decent 500-hour engine. Mind you, they are not in the same league as the outstanding Vanguard.
The consumer perception that they need a 24 hp engine in a lawn tractor is a result of brutal marketing competition. To differentiate, OEM's would use a higher stated hp engine as a selling point against competitors. It is completely a misconception that the lawn mower with a 24 hp engine is better than the one with 16 hp. Neither of the machines will encounter a load high enough to consume that much power. Heck, a midsize Kubota or John Deere is using 18 hp engines to power a 3k lb. machine with 4wd, a bucket loader, backhoe, 72 inch field mowers and have more than enough power. If you have ever been to a garden tractor-pulling contest, 90 percent of them are using a single cylinder Kohler between 10 and 14 hp. Back in the 70's and 80's, a 14 hp tractor was considered a high-powered machine. They were powering 4-foot snow blowers, tillers, dozer blades, turn plows and they had plenty of power. I am a collector and own 30 tractors. I would bet a year’s salary that a 70's era WheelHorse with a 12 hp engine would pull these new 20+ horsepower machine backwards as if they were a tinker toy. Power delivery is what is important. You can put a 30 hp engine in a garden tractor and it will do no more work than it can apply to the ground or implement.