D&D Powersports’ Arctic Cat 800 “Riot Kit” On November 18, 2015 Dale Roes and Scott “Scooter” Moser brought this new, but well broken in 2016 (19 hours of D&D dyno time only) to DTR for Third Party Dyno Evaluation of their “Riot Kit”, and to share technical details with DTR website members. As indicated by the ECU memory, 19 hours of engine run time was spent on the D&D dyno to optimize the new 2016 “LTS Riot head” [lower than stock compression ratio] design along with the creation of an incredibly quiet but lightweight silencer. Scooter and Dale also created a milder version of porting that added significant airflow and HP on top end, with no sacrifice in midrange HP like we often experience with radically modified port timing. 19 hours at, say, two minutes run time per dyno test = 570 dyno tests. That’s true R&D! The new design LTS cylinder head is a stock head, remachined to reduce compression ratio lower than stock. It has a more hemi-like combustion chamber shape that is happy with the twin plug design. And lastly, the squish band is fairly narrow, but with a fashionably tight .029” clearance to piston dome at TDC! To appreciate what this tight squish clearance does for this engine’s performance, scroll down on this website’s members’ pages to 3/4/2015 and reread Kevin Cameron’s fine article “Turbulence Needed”. Kevin suggests that .027” clearance is “ideal”. And the 2015 Etec 800 “Iron Dog” model is said to have .032” squish clearance. So perhaps Dale “split the difference”. After you read KC’s explanation of the value of minimal squish clearance, be sure to read his explanation that follows of the value of similarly tight, turbulent “shrinkwrapped” (the outer surface of the part mirrors the inside surfaces) coolant passages in cylinders and heads. Low velocity coolant flow of large volume billet “bathtub” heads may show lower coolant temperature as it leaves the engine—meaning that if gross coolant flow is constant, it’s surely removing less heat from the combustion chambers—just what you don’t want! It’s tough to beat the heat transfer capabilities of stock, high coolant velocity, tightly shrinkwrapped heads like the Arctic Cat 800 has. The 7 lb. D&D XPR silencer is truly silent, and makes more HP than the stock muffler—deto free up to 1200+ pipe Center Section temp. On our dB meter it was just over one dB louder than stock at peak revs, and very likely could nearly match stock dB if it was wrapped with sound deadening material like the stock muffler has. And at part throttle cruising RPM, it sounds as quiet as stock. I apologize for referring to it as a “can” in the test data, which is a typical lightweight loud straight-though glass-packed tube with a perforated core. The XPR silencer is properly baffled, requiring offset inlet and outlet tubes. The XPR silencer will remind old car hotrodders like me, of the quiet but high flowing, excellent sounding GM Corvair baffled turbo mufflers back in the 1960’s and 70’s that we used, with no HP penalty, to replace our noise-ticket generating, ear-bleeding Cherry Bomb glasspacks! On this day, Dale and Scooter brought the new ZR8000 fitted with the $570 Riot Kit (2 degree timing key, D&D Y pipe, exchange LTS head, clutch spring and arms, and six Bullseye filtered air duct ventilators), $279 XPR silencer, $429 single pipe, and $400 Riot ported cylinders (done only by Dale or his brother). We used a DynoJet PCV to add

some fuel for the higher flowing D&D single pipe, but stock fueling appears more than adequate for the Riot kit with stock pipe, even with Riot ported cylinders. The stock ECU appears to safely enrichen fuel flow in winter air. To be sure of the adequacy of fuel flow, having a $200 wideband A/F gauge like Innovate is very useful. When I bought this SuperFlow dyno 28 years ago, a wideband A/F meter cost $4000. Now the Innovate dyno wideband that feeds info to the dyno computer costs 1/10th of that. With the LTS head and the Cat 800’s excellent cooling, 12.5/1 to 13/1 is usually fine for reasonable full throttle runs on 91-93 octane gasoline. Long, multi-mile WOT runs in poor conditions might require added fuel. In that case, a PCV or some other fuel controller is an inexpensive add-on. So on this day, we would dyno test the Riot Kit components in the inverse order of typical installation. We use lots of graphs which are especially good when comparing components—we are often drawn to just the peak HP or torque data in printed numbers, but seeing the graphic comparisons gives us a better idea of overall performance. Midrange HP is critical for optimal performance on the trail, and graphs show that best. So here is a combo of printed dyno data and graphs, beginning with the highest HP (178) combo and winding up bone stock (153). Here’s the ZR8000 with all Riot kit options, including full D&D exhaust. We began testing with the stock pod in place (the 178 HP test was pod-on), but left it off after seeing dyno heat (intake only, not measured by ECU or dyno) was growing, skewing our numbers slightly. We would refit the pod at the end of the test as we reverted to stock tune, so we could show the A-B effectiveness of admitting outside air into the airbox with the Bullseyes. For each combination, we ran at least two back-to-back 250 RPM/ sec acceleration tests. Dale monitored coolant, pipe Center Section temp, and timing pulled as the result of any clicks of deto. T-Stat was left in place, and D&D’s own external dyno cooling system would maintain typical trail coolant temps. Each first test would end at 110F+, and the second test would end at 120F+. Pipe CS temps would end at 1000-1200F (max timing occurs at @900F+). Note that as the coolant temp exceeds 120F, fuel flow is increased by the ECU. With the full Riot kit, the engine made 175-178HP with some fuel added with a PCV. The HP appears to drop quickly past the HP peak in the 100RPM data increments that’s “smoothed out” by the SuperFlow software, but I included the actual raw corrected data that’s recorded 100 times per second so you can see what happens between the 100RPM increments. In the raw corrected data, the 178 HP test resulted from a hot 1200F+ CS temperature. FULL RIOT KIT, RIOT PORTING, FULL D&D EXHAUST, FUEL ADDED WITH PCV EngSpd STPPwr STPTrq BSFA_B FulA_B AirInT FulPrA STPCorRPM CHp Clb-ft lb/hph lbs/hr degF psig Factor

7000 125.5 94.2 0.642 76.9 55.2 43.5 1.0427100 127.2 94.1 0.654 79.4 55.2 43.4 1.042

7200 132.5 96.6 0.682 86.2 55.3 43.2 1.0427300 137.1 98.6 0.675 88.2 55.3 43.2 1.0427400 142.8 101.3 0.664 90.5 55.3 43.2 1.0427500 147.5 103.3 0.652 91.7 55.3 43.1 1.0427600 153.9 106.4 0.638 93.8 55.3 43.1 1.0427700 159.0 108.4 0.628 95.2 55.4 43.1 1.0427800 166.0 111.8 0.610 96.6 55.4 43.1 1.0427900 170.2 113.2 0.595 96.7 55.4 43.1 1.0428000 173.5 113.9 0.587 97.1 55.5 43.1 1.0428100 175.7 113.9 0.586 98.2 55.5 43.1 1.0428200 155.3 99.5 0.674 99.7 55.6 43.0 1.043

GRAPH OF 175HP TEST COMPARED TO HOTTER PIPE 178HP TEST, RAW CORRECTED DATA RECORDED 100x/ SECOND DURING AND AFTER TEST, HP TOP OF GRAPH, FUEL FLOW LB/HR BOTTOM OF GRAPH

FULL RIOT KIT, RIOT PORTING, D&D YPIPE, STOCK PIPE & D&D XPR SILENCER EngSpd STPPwr STPTrq BSFA_B FulA_B AirInT FulPrA STPCorRPM CHp Clb-ft lb/hph lbs/hr degF psig Factor

7000 127.9 96.0 0.616 74.6 60.9 43.2 1.057100 130.1 96.3 0.632 77.9 61.0 43.2 1.057200 134.0 97.8 0.648 82.2 60.9 43.1 1.057300 136.8 98.4 0.661 85.6 60.9 43.0 1.057400 139.2 98.8 0.667 87.9 60.9 42.9 1.057500 142.6 99.8 0.668 90.1 60.9 42.9 1.057600 146.8 101.4 0.665 92.4 61.0 42.9 1.057700 150.7 102.8 0.659 94.0 60.9 42.9 1.057800 155.3 104.6 0.648 95.3 60.9 42.8 1.057900 160.1 106.4 0.632 95.7 60.9 42.8 1.058000 163.7 107.5 0.618 95.7 60.9 42.9 1.058100 167.1 108.4 0.604 95.5 60.9 42.8 1.058200 170.1 108.9 0.590 95.0 60.9 42.8 1.058300 171.7 108.7 0.577 93.7 60.9 42.8 1.058400 172.2 107.7 0.562 91.6 60.9 42.9 1.058500 171.4 105.9 0.553 89.5 60.9 43.0 1.058600 169.6 103.6 0.550 88.2 60.9 43.0 1.05

FULL RIOT KIT, RIOT PORTING, D&D YPIPE, STOCK PIPE, STOCK MUFFLER EngSpd STPPwr STPTrq BSFA_B FulA_B AirInT FulPrA STPCorRPM CHp Clb-ft lb/hph lbs/hr degF psig Factor

7100 132.9 98.3 0.601 75.6 59.9 43.1 1.0497200 135.9 99.1 0.637 82.0 59.9 43.0 1.0497300 138.0 99.3 0.641 83.7 59.9 43.0 1.0497400 140.1 99.4 0.652 86.5 59.9 42.9 1.0497500 143.5 100.5 0.657 89.3 59.9 42.9 1.0497600 147.4 101.9 0.655 91.4 59.9 42.8 1.0497700 152.2 103.8 0.646 93.2 60.0 42.8 1.0497800 158.0 106.4 0.632 94.5 60.1 42.8 1.0497900 162.1 107.8 0.618 94.9 60.1 42.8 1.0498000 166.3 109.2 0.604 95.1 60.1 42.8 1.0498100 169.4 109.8 0.596 95.6 60.1 42.8 1.049

8200 170.7 109.3 0.590 95.4 60.1 42.8 1.0498300 170.6 108.0 0.579 93.5 60.1 42.8 1.0498400 168.0 105.1 0.570 90.6 60.1 42.9 1.0498500 162.5 100.4 0.575 88.4 60.1 42.9 1.0498600 144.2 88.1 0.638 86.9 60.1 43.0 1.049

GRAPH OF RIOT KIT, RIOT PORTING, D&D YPIPE, WITH VARIOUS EXHAUST

FULL RIOT KIT, STOCK CYLINDERS, D&D YPIPE, STOCK PIPE, XPR SILENCER EngSpd STPPwr STPTrq BSFA_B FulA_B AirInT FulPrA STPCorRPM CHp Clb-ft lb/hph lbs/hr degF psig Factor

7100 131.6 97.3 0.621 77.0 62.0 43.1 1.0537200 133.7 97.5 0.631 79.5 62.0 43.0 1.0537300 136.8 98.4 0.648 83.6 62.0 42.9 1.0537400 141.1 100.1 0.648 86.2 62.0 42.9 1.0537500 144.2 101.0 0.645 87.7 62.1 42.9 1.0537600 147.3 101.8 0.642 89.1 62.1 42.9 1.053

7700 150.9 102.9 0.640 91.0 62.2 42.8 1.0537800 154.8 104.3 0.639 93.2 62.4 42.8 1.0547900 159.2 105.9 0.632 94.7 62.5 42.7 1.0548000 162.6 106.8 0.624 95.7 62.5 42.8 1.0548100 164.7 106.8 0.619 96.0 62.5 42.8 1.0548200 165.2 105.8 0.613 95.3 62.5 42.8 1.0548300 162.6 102.9 0.610 93.3 62.5 42.9 1.0548400 157.5 98.5 0.613 90.9 62.4 42.9 1.054

GRAPH OF RIOT KIT, RIOT PORTED CYLINDERS COMPARED TO STOCK CYLINDERS, STOCK PIPE, XPR SILENCER note that there is no loss in midrange HP with Riot porting…

FULL RIOT KIT, STOCK CYLINDERS, D&D YPIPE, STOCK PIPE, STOCK MUFFLER EngSpd STPPwr STPTrq BSFA_B FulA_B AirInT FulPrA STPCorRPM CHp Clb-ft lb/hph lbs/hr degF psig Factor

7100 133.1 98.5 0.612 76.6 62.9 43.1 1.0557200 135.2 98.6 0.629 80.0 62.9 43.0 1.0557300 138.4 99.6 0.647 84.3 62.9 43.0 1.0557400 141.5 100.4 0.648 86.2 62.9 43.0 1.055

7500 144.9 101.5 0.653 89.1 63.0 42.9 1.0557600 148.8 102.8 0.655 91.6 63.0 42.9 1.0557700 153.7 104.8 0.654 94.4 63.3 42.8 1.0567800 157.6 106.1 0.646 95.7 63.6 42.8 1.0567900 160.4 106.7 0.637 96.0 63.8 42.8 1.0568000 162.4 106.6 0.629 96.0 63.7 42.8 1.0568100 162.5 105.4 0.628 95.9 63.6 42.8 1.0568200 159.5 102.1 0.637 95.4 63.6 42.8 1.0568300 145.2 91.9 0.691 94.2 63.5 42.9 1.056

GRAPH OF RIOT KIT, RIOT PORTED CYLINDERS COMPARED TO STOCK CYLINDERS, D&D YPIPE, STOCK PIPE, STOCK MUFFLER once again note the excellent midrange HP with Riot porting…

============================================================ RIOT HEAD, STOCK CYLINDERS, STOCK YPIPE (instead of D&D), STOCK SINGLE PIPE, STOCK MUFFLER..no graph of stock ypipe vs D&D ypipe (test 32) EngSpd STPPwr STPTrq BSFA_B FulA_B AirInT FulPrA STPCor

RPM CHp Clb-ft lb/hph lbs/hr degF psig Factor7000 127.7 95.8 0.624 75 62.6 43.1 1.0557100 128.8 95.3 0.636 77 62.6 43.1 1.0557200 130.8 95.4 0.65 80.0 62.6 43.0 1.0557300 133.9 96.3 0.661 83.3 62.6 42.9 1.0557400 138.4 98.3 0.662 86.2 62.6 42.9 1.0557500 141.9 99.4 0.657 87.7 62.6 43.0 1.0557600 144.7 100.0 0.657 89.4 62.5 42.9 1.0557700 147.9 100.9 0.658 91.5 62.5 42.8 1.0557800 151.4 102.0 0.653 93.0 62.5 42.8 1.0557900 156.2 103.8 0.644 94.6 62.5 42.8 1.0558000 159.4 104.6 0.637 95.4 62.6 42.8 1.0558100 160.7 104.2 0.636 96.1 62.6 42.8 1.0558200 159.0 101.8 0.639 95.5 62.6 42.8 1.0558300 153.3 97.0 0.646 93.0 62.6 42.8 1.0558400 142.0 88.8 0.677 90.2 62.7 42.9 1.055

GRAPH OF LTS HEAD, 2 DEGREE KEY, D&D YPIPE VS STOCK YPIPE, note 2 HP increase at peak, but 6 HP midrange increase…

Here, Scooter removed the LTS Riot head and installed the stock head. Now the engine is completely stock, except the 2 degree offset flywheel key. STOCK HEAD, ALL STOCK EXHAUST W/ 2 DEG KEY, EngSpd STPPwr STPTrq BSFA_B FulA_B AirInT FulPrA STPCorRPM CHp Clb-ft lb/hph lbs/hr degF psig Factor

7000 126.3 94.8 0.623 74.1 62.0 43.2 1.0557100 127.9 94.6 0.641 77.0 62.0 43.2 1.0557200 129.8 94.7 0.667 81.4 62.0 43.0 1.0557300 132.4 95.2 0.679 84.5 62.1 43.0 1.0557400 135.2 96.0 0.679 86.3 62.1 43.0 1.0557500 137.7 96.5 0.677 87.6 62.1 42.9 1.0557600 140.3 96.9 0.681 89.8 62.1 42.9 1.0557700 143.4 97.8 0.685 92.4 62.1 42.8 1.0557800 147.6 99.4 0.679 94.2 62.1 42.8 1.0557900 151.4 100.6 0.667 94.8 62.1 42.8 1.0558000 154.4 101.4 0.657 95.3 62.1 42.8 1.0558100 156.6 101.5 0.649 95.5 62.1 42.8 1.0558200 157.0 100.5 0.643 94.8 62.1 42.8 1.0558300 154.6 97.8 0.642 93.3 62.1 42.9 1.0558400 149.0 93.2 0.650 90.9 62.1 42.9 1.055

GRAPH OF LTS RIOT HEAD VS STOCK HEAD, FULL STOCK EXHAUST, 2 DEGREE KEY note that the lower compression LTS head acts like higher compression and/ or advanced timing, perhaps due to high turbulence from optimal squish clearance and less air/ fuel mixture being squeezed into squish crevices [which burns too late to contribute to HP]. During testing, we added 2 more degrees of timing advance with the PCV with both heads resulting in slight HP loss, but no deto with the LTS head, but when we tried that with the stock head we had clicks of deto resulting in the ECU pulling 3.5 degrees of timing.

Finally, Scooter removed the 2 degree key and installed a straight stock key. Now it was back to the expected 153HP. This particular test was typical, hot pipe and 115F coolant temp. 2016 ZR8000, back to stock… EngSpd STPPwr STPTrq BSFA_B FulA_B AirInT FulPrA STPCorRPM CHp Clb-ft lb/hph lbs/hr degF psig Factor

7000 124.7 93.6 0.64 74.9 62.7 43.1 1.0577100 125.9 93.1 0.654 77.3 62.7 43.1 1.0577200 127.9 93.3 0.678 81.4 62.7 43.0 1.0577300 130.8 94.1 0.688 84.4 62.7 42.9 1.0577400 133.5 94.8 0.686 85.9 62.8 42.9 1.057

7500 135.5 94.9 0.685 87.0 62.8 42.9 1.0577600 137.9 95.3 0.686 88.7 62.8 42.9 1.0577700 140.9 96.1 0.682 90.1 62.8 42.8 1.0577800 144.2 97.1 0.673 90.9 62.8 42.8 1.0577900 147.0 97.7 0.660 90.9 62.8 42.9 1.0578000 149.5 98.1 0.647 90.7 62.8 42.8 1.0578100 151.6 98.3 0.642 91.3 62.8 42.8 1.0588200 152.6 97.8 0.648 92.7 62.9 42.8 1.0588300 151.3 95.7 0.651 92.3 62.9 42.8 1.0588400 147.4 92.2 0.659 90.9 62.9 42.8 1.0588500 136.7 84.5 0.695 88.8 63.0 42.8 1.0588600 126.2 77.0 0.747 88.0 63.0 42.9 1.058

Here’s a graphic comparison of the Riot ported, Riot kitted stock exhaust ZR8000 (@$970 package including clutching) compared to the same sled—great increases in midrange and top end HP, and that great overrev HP is still there.

Finally, Dale and Scooter wanted to show the effectiveness of using their “Bullseye” filtered air inlets in the hood air duct just upstream of the airbox. The stock air duct runs close to the stock pipe, picking up power-robbing heat. We know that we lose about 1% actual, observed (not corrected) HP for every 10 degrees F increase in intake temperature. On the ZR8000 this situation is aggravated some by the fact that the sled’s intake air temp probe is on the inlet side of the air duct—meaning that as air temp rises from being preheated by underhood heat, the ECU thinks it’s still cold causing further enrichment of mixture. If we insert the dyno air temp probe in the airbox, the dyno would recognize the higher temperature and the Corrected HP would be unchanged. But observed HP is what propels the sled (in February, flatlanders often ride in air density that results in their actual HP being higher than corrected HP!), so we recorded and compared the stock ZR8000 on the dyno, pod on, with and without the supplemental outside air intake afforded by the Bullseyes that come with the Riot kit. This test was at @60F dyno air temp, with air blown at the hood. Sled owners can test their own intake temps by fitting a remote open element temp probe in their airboxes. Cold air makes HP!

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Here are pics of the new LTS Riot combustion chamber and the quiet XPR silencer (the XPR silencer includes an inlet restrictor for high altitude operation).