ZR8000 MUFFLER TEST PHASE 2

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1 ZR8000 MUFFLER TEST PHASE 2 SLP (ceramic coated), MBRP (stainless), BMP PL, BMP trail, SPEEDWERX The Kaczor bothers Darren and Jim came back to test the rest of the aftermarket mufflers this time using Jim s brand new 2014 ZR8000 for our test mule. Our plan was to test all the mufflers with the engine bone stock then install the D&D Riot kit on the engine. Today, like we did during the first session, Darren monitored my laptop with the Arctic Cat diagnostic software to observe coolant temp and signs of detonation and resulting timing retard. We would monitor sound levels with a digital sound level meter sitting on the dyno control console next to the shatterproof window between the control room and engine room. This would give us an A to B comparison of the aftermarket mufflers compared to the stock muffler. After fitting Jim s new sled with all of the dyno instrumentation we fired it up and did the first test with the hood/ pod in place. Then we removed the hood/ pod and installed the dyno pipe pressure/ temp fitting in place of the factory temperature probe. Disconnecting the factory probe from the wiring harness causes the ECU to default to 1030f where maximum timing is delivered. We duct taped the dyno airflow meter into the rectangular opening in the front of the airbox. The HP was the same as with the hood/ pod in place. STOCK MUFFLER, 20 lb 6 oz,, db, WOT 82 db

2 SPEEDWERX MUFFLER, 9 lb 7 oz, db, WOT 86 db MBRP MUFFLER, 6 lb 13 oz, db, WOT 86 db

3 SLP MUFFLER, 8 lb 11 oz, db, WOT 88 db BMP TRAIL MUFFLER, 6 lb 11 oz, db, WOT 87 db

4 BMP POWDER LITE MUFFLER, 5 lb 0 oz, db, WOT 92 db

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6 After comparing the mufflers on the bone stock ZR8000, Jim and Darren installed the 2 degree offset timing key, higher flowing Y pipe, LCR head (tighter squish clearance, lower compression ratio), and adjustable muffler included in the D&D Riot kit. We made best power with the adjustable outlet in the tightest position. How can we make more HP with less compression? The Cat deto protection is very sensitive one or two light clicks on the dyno or in the field will result in timing being retarded, protecting the engine and reducing HP. D&D s LCR head s reduced compression head allows for advanced timing to bring back the peak cylinder pressure at the correct time ATC without deto. And remember whatever air/fuel mixture is packed into an oversize squish band under compression will burn eventually, but too late to add to HP. Tightening the squish band squeezes more of that wasted mixture at high velocity into the combustion chamber allowing it to burn at the correct time, adding to HP. And, the increased velocity has the added benefit of increasing turbulence in the combustion chamber, which is said to cause the A/F mixture to burn more quickly which can reduce the time necessary to create maximum combustion chamber pressure. It s the same effect as increasing ignition timing, but without the penalty of adding burn time to heat the combustion chamber surfaces. So with the D&D Riot kit the combo of the tighter squish band and 2 degree key may have the net effect on peak combustion chamber pressure as, say, a 3.5 degree key, but with less heat being absorbed by the combustion chamber surfaces which can = less chance of deto. Balancing compression ratio, squish design and clearance, and ignition timing to create maximum torque on a given octane can result in optimal performance. D&D RIOT KIT WITH STOCK PIPE

7 Next Jim and Darren installed their D&D single pipe on the Riot kitted engine. They had to add fuel with their new Boondocker fuel controller, which now has more precise steps adds and subtracts fuel based upon % of fuel flow which is the ideal way to tune EFI very much like the DynoJet Power Commanders do. Then, they installed the full Jaws exhaust system Y pipe with larger outlet and donut, single pipe and muffler. After creating good fuel maps for both systems, the full Jaws setup matched the D&D full system HP within a few tenths of a HP, but Jaws backpressure was lower. Jim installed the Speedwerx muffler on the Jaws pipe, and backpressure increased along with HP. The Jaws/ Speedwerx combo had a slight high RPM HP advantage but the D&D had better midrange torque and HP as the Riot graph comparing stock, D&D, and Jaws/ Speedwerx combo indicates. Jim and Darren plan to run their identical ZR8000s with Riot kits one will have the D&D full exhaust with better midrange TQ and HP, and the other will have the higher RPM Jaws Ypipe and single pipe and Speedwerx muffler with the stock muffler insulation fitted to it to fool the SS (Schutzstaffel) Trail Police who like to lift hoods even on quiet sleds and write $200 tickets for non OEM muffler. RIOT KIT WITH D&D SINGLE PIPE

8 RIOT KIT WITH JAWS Y PIPE, PIPE AND SPEEDWERX MUFFLER Here s a graph of the HP of the three exhaust systems, with much finer resolution showing the exact shape of each curve. Sometimes recording 1,000 data points in a 10 second test provides a more meaningful picture of an engine s HP curve.

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