August 2007

Friday, August 31, 2007

DynoTech : Dyno Schedule for September

9/1 Sat HTG ported F7 carb we've posted on dyno pages since stock, tweaked from 120 to 150 plus so far with single pipe, now trying some new single pipes and D&D twins. D&D F8 twins with can silencer added broad top end hp curve, about 160 for 400 revs on top. Greedy Tony will next add vforce3 reeds and ported carb boots.
9/2 Sun AM HTG 975 06 Fusion hooked up to dyno now, will cal Boondocker Sun but bewildered by high fuel pressure (120psi), if anyone knows if this is normal or not please email or call me. Yup 118psi is 06 fuel pressure setting! My five year old gates EFI fuel lines that redirect sled fuel into dyno fuel flowmeters and back were struggling with this record setting fuel pressure--the old hoses looked more like lawn sprinklers straining against nearly triple the fuel pressure they're accustomed to. About an hour was spent repairing leaks, reclamping fittings etc (on my time). This 06 Fusion was much easier to dyno tune than all the 05's that have come before it. The automotive fuel line connectors on the sled are now totally accessible instead of being buried on 05s, this 06 engine seemed much smoother, and the deto protection never once caused problems [most 05s couldn't be tested here below ex valve opening, since apparently some vibration triggered the knock sensor at low revs]. On this 06 we could do transient tests from 5000 to beyond HP peak with perfect repeatability. Even with non-HTG aftermarket single this engine made close to 180hp at high .60s. HTG Rob says that 175plus should be typical even with HTG Ypipe, stock OEM single pipe and muffler. This 06 Fusion seems to be a totally different, better thing than the dozen or so 05s that have come here before it. This fellow has purschased the sled new at typical Fusion get-it-off-the-floorplan price, added the HTG big bore kit, Boondocker and has a bargain sleeper hotrod.      
9/4 Tuesday Full Power Perf stage 3 Apex turbo tuning for 400 hp (will have new larger dampened driveshaft by then). PM 2008 Yamaha Nitro for baseline testing/ airflow etc prior to Justin finalizing turbo system.cancelled
9/5-9/6 more pro race sled engine testing w/ cameras off.
9/7-9/8 Sean Ray finalizing SkiDoo PS1000 twin for Tim and Brian Tyler.cancelled
9/7 Jess Pych dyno tune D&D F7 Imp Stocker  This one was built by D&D, has the high rpm race pipes exiting on both sides of the sled, made incredible HP at 9000++rpm. Like other firecats, this one required different Boondocker settings to achieve max HP than another sled exactly like this campaigned by D&D. 

week of  9/10 getting ready for Woody's monster scheduled below for 9/17.  New  1.75" OD rubber dampened driveshaft made out of new Jeep front end driveshaft tubing/ spline and custom sled connector with 8-hole lord neoprene connector centered and aligned by a $250 helicopter spherical
bearing (all parts to connect this stuff are made on a lathe and mill, not ordered from any catalog). Also that 120psi 06 Fusion fuel pressure was an eye opener--Ive long ago converted the SF901 oil pressure channel to monitor fuel pressure to deal properly with EFI sleds and bikes. however, the blue SF901 dyno control console (seen on the homepage with Sean Ray at the controls) contains switching devices, computer boards, rheostats, transducers, gauges, ventilation fans, and many other mysterious  tiny things that create lots of  heat from electricity. Unfortunately  the pressure gauge and transducer inside the console that used to measure oil pressure now measure fuel pressure. I suspect that the 1/4" plastic tubing from engine stand to console is filled mostly with air that compresses as oil (and now  gasoline) pressurizes the system during operation. However if there should be a leak in the pressure measuring transducer, the bourdon tube inside the analog gauge, or any of the tubing/ fittings connecting the two,  high pressure (up to 120psi) gasoline could be sprayed inside the hot control console with catastrophic results...and that ventilation opening beneath the console, in front of the operator's testicles makes me cringe when I think about the fireball that might be created by a 120psi fuel leak!
So I've acquired a fuel pressure isolator from McQuillen Racing, which is basically a small cylinder with an oringed piston that contains fuel under pressure. On the opposite side of the piston is a 50/50 mix of h2o and ethylene glycol that will transfer the pressure into the console to the gauge/ transducer. Now, should a leak occur inside the console or control room, a few ounces of coolant will harmlessly be lost before the small isolator cylinder bottoms out, and pressure reading drops to zero. I plan to install this safety device on Monday/ Tuesday before Woody comes with methanol to pressurize my control console with. Methanol flames are invisible, and even scarier to think about. Isolator installed, finished Wednesday lots of work bleeding air out of  system, now only  antifreeze in line to console. Also finished machining/ pressing together new 1.75" rubber shaft, will have welded  friday in time for woody to test on monday...
9/13 Thurs AM ShiDoo Rev600 trail port w/ CS twin pipes & head.Raceport improved stocker w/ 18-1 RKT head, "race" ECU w/ rev limiter removed, maxed out at 140 8800 rpm with jetting fresh C16 needed for compression, no way to roll timing need Jim Cooper to come with laptop to try retarding/ advancing timing, should be 150 plus in this engine maybe would be happier with closer to 16-1. Needs another session with lower compression/ jim Cooper to roll timing to max HP.
Thurs PM.Sunnyside Eric/ Cody Johncox finalizing dyno tune on Jason DiSalvo's Yam 450 flattrack bike on Cycledyne. This one had awful carb calibration, tuned it with  needles/ main jets from 46 to 53 plus DJHP (DynoJetHorsepower which is a happy correction factor designed to match the numbers from a DynoJet roller dyno. More importantly picked up over 20 DJHP in midrange by optimizing A/F ratio. Cody won the last race with the bad calibration, will be fun to see how he fares with the engine dialed in properly.

9/17 Woody's Performance big bore stroker Apex dragsled, Supercharged/ Alcohol. this was the first sled weve had here EFI "stand alone" controller for fuel and spark. This was Autotronics system from Australia, installed on Woody's Stage3 MPI centrifugal SC big bore stroker Apex drag sled. Woody hired Enzo to do Methanol mapping at the dyno, but we spent most of our time hunting for missing cylinders, finally traced down to coils being wired out of sequence. After mapping midrange fuel/ spark (easy to do on the dyno), several full throttle runs finally produced 426hp before popping an oring out of cyl #4. I dont think this was deto related, but poor machining of oring grooves in head (cut too large). I will try to post dyno sheets/ more technical info on this interesting setup.

9/19 Steve Bennett from West Virginia and I think his ex-brother in law Boondocker tuning a Mach Z twin / CS pipes, asphalt racers. Steve's pal WVa Jimmy Walker asphalt races a bone stock MZ with Bikeman chambers and CS twin pipes, Boondocker.  Came to dyno with  Billy Howard's  (Jimmy's skidoo dealer) Boondocker map, made 195 at .63.  Jimmy Cooper  dropped in the mid-altitude map into  the ECU,  went to  200 at  .58. Then Jim Cooper bumped timing back and forth with laptop, perfect timing dropped midrange a bit but added peak and broadened HP curve out.

9/20 Bikeman Erich, full day or more F8 trailport/ M1000,  Pol 700 EFI, all for independent verification. Cams may be off, not sure until 9/20. Bikeman trailport F8/ vforce/ D&D Ypipe/ stamped single tuned on local 93 octane, dandily made 178hp/ 119 lb/ft.  The M1000 was impossible to believe. Stock M1000 cyls w/ Vforce reeds, BMP 12.5-1 head, BMP Ypipe, BMP stamped SINGLE pipe, made 240 HP at .50  lb/hphr at 7500!!!  Checked all dyno calibrations, which were spot-on. But I still thought something might be wrong with the dyno--how could a head/ reeds/ single pipe add 70hp to a stock engine? So we pulled the M1000 off the table, and brought in Erich's bone stock Polaris Dragon 700 EFI that he wanted to try a pipe mod on. Amazingly as we should have expected the dyno was perfect, 138hp stock  (and the pipe mod worked dandy). So at 8 pm we put the M1000 back on the dyno. We called Dead 1 Dave Craiglow (good friends with HTG, D&D) to come see this, bring his CDI to compare, and to help "tech" the engine. 240 again, then added a pile of Boondocker numbers, "dropped" HP to about 230 at .60. Dave examined the engine ports, measured stroke. No N2O lines anywhere. I will post full dyno results on all three sleds.
9/21 Tripod Dan doing another dyno tune on his HTG Storm 1000impst cancelled

9/22 Going to Old Forge to meet w/ Geo Taylor and Old Forge dealers to make Shootout plans.

9/23 Maybe going to Holley NY to observe grass drags.

9/26 Tripod Dan 1000IS, water in mag cylinder.

9/27 Full Power Justin w/ two Apex Stage 3 turbos, Nitro stocker for baseline before turbo.

email from subscriber 9/19
i have had the opportunity to view some of your dyno runs online and was wondering if you might be able to define the following abbreviations:
-LAMAF1 [air/fuel ratio determined by lm1 wideband o2 sensor]
-A/AF-B [mechanical A/F ratio, using two fuel flowmeters--for bypass EFI  quicker reacting than lm1]
-Air 1+2 airflow CFM through engine
-FulA-B fuel flow lb/hr, two turbines used for efi systems with return systems
-Fuel B turbine A - turbine B for EFI sleds with no return
-BSFC B brake specific fuel consumption lb of fuel per horsepower per hour
-ManPrs boost inches of mercury, 2in hg = 1 psi
-VolEff how many CFM compared with cubic ft displacement of engine x RPM
-Time-S duration of test
-TsTim2 duration of test
lots of detailed info on dyno terminology is in archives-it's useful to spend time looking at those. Thanks for your interest, too many are happy just to see HP and that's it. Jim C

Friday, August 03, 2007

DynoTech : Lightest possible sled weight vs max possible HP

Rich Daly (owner of DynoPort/ Bender Racing) brought his notoriously quick Pro Stock 1000 SkiDoo triple for a tuneup here.  Besides being a savvy pipe designer and thrashaholic, Rich has spent a great deal of creativity including time and $ building as light an asphalt sled as possible. The greatest possible HP and the lightest possible weight = best potential for low ETs and high MPH.  Rich was interested in maximizing his HP here, possibly assessing differences in pipe center section temps vs peak HP RPM.

He brought just the engine to be tested on my dyno engine plate. The plate is about a square foot of 3/8" thick aluminum, swiss-cheese drilled  to accommodate the dozens of different crankcase engine mount bolt patterns encountered over the years.  The plate is supported by six cylindrical stanchions, each of which bolt solidly to the steel table. Six stock early Yamaha Phazer rubber motor mounts connect the plate to the six stanchions and allow for ample movement and absorption of engine vibration.  The rubber mounted engine plate combined with the rubber-dampened drive shaft between crank and dyno brake  provide  a safe, smooth running environment for even the nastiest big twin or stroker multis.

But this pleasant rubber dampened operating environment is probably foreign to a vibrating triple stroker like Rich has! The engine is normally solid mounted into his ultra-light drag chassis, which probably provides a certain amount of flex and vibration absorption itself, but every chassis is a bit different. That's why I prefer dyno testing engines exactly as they are to be used--mounted either solidly or in rubber of various stiffness. That way if the carbs are unhappy with a particular frequency of vibration they are subjected to in the sled, fuel flow problems show up immediately. The dyno fuel flowmeters show dramatically how the carbs can shut off, run dry then surge back again as revs climb. We've often cured those problems with larger needle and seats, higher fuel pressure, adding weight to the carbs, softer carb boots, or better yet softer motor mounts that some racers dislike. But soft mounts (if that's what it takes) are way better than carbs whose float bowl levels rise and fall like Maine ocean tides, and fuel that gets aerated into the consistency of a vanilla milkshake. In that situation, you get at worst shutoff before the finish line and unexplainable seizures, or at best extreme difficulty maintaining maximum horsepower jetting.

That's why I suggested to Rich that he bring the whole sled, but he indicated that the chassis was out somewhere being lightened(!). So we bolted his stroker triple to my normally forgiving dyno engine plate.

While we were setting up the engine Rich explained his engine's unorthodox cooling system--bare combustion chamber domes with no covers, bolted to cylinders that are filled with stagnant water which is cooled between rounds. That saves the weight of a water pump, cylinder head covers, and the coolant that normally surrounds the combustion chamber domes. Plus no need for heavy radiators or heat exchangers. But this seemed like a step backwards--"free air" cylinder heads with no fins? And what about combustion chamber heat being allowed to climb with no coolant? I know from too many first hand experiences that boiling water above the combustion chamber creates steam pockets which = instant detonation. But pressurized steam is hot, fairly dense stuff, and surely must not be as bad as still air around  Rich's smooth bare combustion chamber domes!?

Rich also expressed his admiration for the CrankShop pipe stampings he was using, explaining that the shape and body length was ideal, giving him a broad HP curve, and giving credit to Larry Audette. Why recreate the wheel? Sure he could have copied them out of cones or had his own stampings made, but it's refreshing to see that there can be honor among the few who create good things like this. That's one of the reasons why Rich has so many pals.

He also was using huge (52mm I think) Crankshop carbs and a stock ignition which on his dyno made max HP at stock timing setting. So no need to mess with timing, just max out HP with fuel flow and assess its effect on pipe temp and subsequent HP peak RPM.

Initial dyno runs were shortened by poor fuel flow, allowing the middle carb to run lean and allow that cylinder to drop. We fitted a dyno pressure transducer to the carb fuel lines, and found that the stock SkiDoo fuel pump was defective, delivering only the pound and a half fed to it by the dyno fuel system. So Rich had a spare, hooked that up and 4 psi of fuel pressure made the engine happy.  But even though fuel flow was fairly constant it remained very low at about 100 lb/hr, way too low for the 250 hp we were making at the time.

So thinking that even with the rubber mounted engine plate carb vibration might be the culprit, we decided to add some mass to the already fairly hefty CS carbs. Rich tiewrapped/ duct taped my five pound two and a half ft long nickel plated pinchbar to the three carbs. Instantly we picked up 30 lb/hr constant fuel flow from 8500 to 10,000RPM! We also picked up 15HP.  Now Rich was able to begin jetting down. Even though BSFC was still high, without measuring airflow to get us an accurate A/F ratio reading we must lean out cautiously since wildly ported engines can have excessive short-circuiting of mixture, creating high BSFC at max power. Plus we had the added variable of the hot aircooled domes instead of cold liquid cooled domes.

So Rich checked plugs, jetted down a few sizes and me made 150 lb/ft and 270 plus HP with a broad powerband from 9000-9800 RPM.

Now looking for max max HP, Rich removed the air cooled combustion chambers to have a real good look at the piston domes. Nearly a one-half inch wide "wash" band was there, like you might see on a safely tuned trail engine. "Wash" in this case was the shiny residue from oil that remained on the cool piston surfaces (oil is an excellent temp indicator).

Rather than jet down some more, Rich left the carbs safely fat and installed a set of stinger restrictors to increase backpressure.

Thinking we were safely fueled, the next dyno run with tighter stingers rewarded us with misfire at 9000. Subsequent investigation revealed a DTR first--broken mag and center cylinder spark plug insulators on the top side! Fortunately, the insulators were not damaged inside the combustion chambers which could have dropped ceramic chips into the cylinders.

Could the bare combustion chamber domes, unsupported by sturdy head coolant covers, have deflected enough under the hammering of deto to break the plugs? Estimating the plug outside mass at 2 oz, and figuring it must take 30 pounds of force to snap the insulators, that equates to 240 Gs if that's what caused the plugs to break!

So stepping back, we removed the stingers, jetted down  10 lb/hr and  the HP stayed constant. We had maxed out on Rich's race gas, with what the dyno showed as trail-safe BSFC.

Back to weight vs HP; I'm surmising that after helping dyno tune maybe a thousand  full mod engines like this,  if it had good cold water coolant around the combustion chambers we could make more power with less fuel!  Here, with Rich's "free-air" finless chambers,  extra vaporizing fuel is needed to keep chamber temps low enough to stave off deto. That extra fuel makes no HP, just cools the compressed charge and takes up space in the combustion chamber.

So I'm guessing that if Rich added coolant to his chambers, that is cold coolant, he would make maybe 8 more HP with .10 or .15 lb/hphr lower BSFC. That might mean adding 25 lb of pump, coolant, heat exchangers etc. After Rich does the math, I'm betting that those odd bare chambers will remain. Plus now he has $5 [spark plug] deto sensors on each cylinder, so he can "jet" accordingly.

Wednesday, August 01, 2007

DynoTech : DynoJet RWHP is too optimistic

When I bought my SuperFlow Cycledyn eddy current roller bike dyno about 10 years ago, they told me to expect lower HP numbers than what I was used to on my DynoJet roller that I had just sold to a friend. SuperFlow technician Brent Williamson told me that DynoJet overestimated the mass value of their drum, leading to overstated HP. That can be easily proven by dyno testing a bike, steady state using the SuperFlow eddy current absorber and strain gauge to read torque/HP in steps, which takes the inertia on the roller and absorber out of the picture. Since a steady-state step test and acceleration only test on the SuperFlow roller dyno match so closely, we have to assume their argument is accurate.

But my argument to Brett was [at that time] there were probably 10,000 DynoJet dynos and one Superflow Cycledyne (mine would be number three). So whatever numbers DynoJet has been offering tuners and magazines are unfortunately "the standard". So I had to spend the first few years dyno tuning bikes on the Cycledyn, trying to explain why my HP numbers were "lower" than what they made on so and so's DynoJet roller dyno. The last software upgrade I got from SuperFlow a few years ago now has a "happier" "DJHP" channel so our dyno sheets can show whatever  the bike owner wants. The DJHP number is about 10% higher than Superflow's SAEHP. Good move. Sean Ray used  the new HP channel to make 138 DJHP while tuning boost and EFI fuel here on his Garrett turbocharged but otherwise stock 88 CI Softail Custom. A few weeks ago, he took it to a DynoJet dyno shootout at Stan's H-D here in Batavia and made 138 there, as well (plus runs low 11's and 120+).

Now with Justin Fuller coming to dyno his R1 turbo on my 901 shaft dyno we have more good data to compare HP at various locations on the bike. When he used my Cycledyne a few weeks ago, he made 200DJHP (182 SAEHP, SuperFlow's wheel number on the same run) at 5.5psi boost and 12.5/1 A/F ratio. And it made 195 DJHP (177 SAEHP) at a more conservative 11.5/1.

Yesterday, with my 901 engine dyno connected directly to the R1 transmission output shaft, with the same boost setting and  fuel very slightly richer (10.7/1) the bike made 189 SAE HP. That is exactly accurate, strictly torque vs RPM plus exact correction for baro, temp and humidity-- no fudging for tire slip/ drum mass estimation.

That 189 actual output shaft SAEHP, according to out two SuperFlow dynos, is reduced by 6% from chain loss and tire friction to 177 SAEHP at the rear wheel (tire). That makes sense. But there's no way the HP increases from 189 SAE HP at the output shaft sprocket to 195 at the tire (DJHP). 

So when Justin turned up the boost on his R1 to 9psi, his output shaft true SAEHP was 230, which would equal rear wheel 216 SAE HP (SuperFlow) or 239 DJHP.

I'm hoping this isn't too confusing, and is just meant to be informative. Mark Dobeck's invention and subsequent proliferation of the DynoJet roller dyno is surely worthy of a Nobel Peace Prize. 20 years ago, BDJ (Before DynoJet), there were few options for motorcycle performance people to get meaningful dyno numbers. Jerry Branch had (and still has) a SuperFlow engine dyno that connects to the rear axle of the bike. There was another one in CA that Cycle Magazine used to use that had an eddy current absorber, but not much instrumentation. Then there was my place in WNY. I was lucky to have racers like Colin Edwards' have their bikes tested/ tuned here with Kevin Cameron as consultant. Colin's team would travel here from Colorado with truckloads of TZ250's and related stuff to obtain the meaningful information they needed.

But now every bike performance aficionado surely has a DynoJet or SuperFlow (or other brand like Huff or Land and Sea) roller dyno within 30 miles to test and tune with, thanks to Mark Dobeck's vision.

Regardless of pure accuracy, any dyno can be a useful tool, if it's repeatable and you make HP progress going from A to B (or Z). Most magazines use DynoJet rear wheel numbers to publish stock bike's performance, so there's nothing wrong with comparing modded bikes with different but stock bikes on the same brand of dyno.

Just be aware that every HP is not necessarily created equally.



DynoTech : Just got boned buying 93 oct for an R1 turbo bike

Justin Fuller came yesterday with his R1 bike turbo kit prototype to do additional dyno tuning, and compare a different Garrett ball bearing turbo design with hopefully a bit less turbine inlet backpressure.

He had been here a few weeks ago using my rear wheel roller dyno for preliminary tuning, on 93 octane we made 195 DJWHP (DynoJetWheelHP) at 11,500 at 5.5psi boost and 11.5/1 A/F ratio. Leaning down to 12.5/1 added 5 HP to 200 DJWHP even, the number Justin was shooting for for pump gas advertising purposes. Some time during extensive road testing, Justin experienced some plug speckling (detonation) at high speed, top gear after over three miles at WOT(!!!), maybe 180mph plus?

I suggested to Justin that NA engines converted to turbochargers on pump gas are best used for acceleration in short bursts, and anyone who wants to do bonneville-style top end blasts should spend $20 for better gas to protect their $5000 engines. But Justin being a perfectionist was interested in seeing what we could get away with by switching to a Garrett ball bearing turbo with less backpressure. So he sceduled additional dyno time for yesterday.

This time we took the extra effort to dyno the R1turbo on my SF901 dyno. This required creating a custom shaft adaptor out of the R1 output shaft (please don't call it a "countershaft") sprocket. Measuring the torque and HP at the output shaft is perfectly accurate; the computerized absorber servo controls engine speed, and eliminates some guessing that accompanies drum acceleration due to mass value estimation and tire slip. With shaft connection, the dyno measures exact output shaft information, then computes engine RPM via the primary and transmission gear ratio. Also my 901 is more completely instrumented than my Cycledyn roller (that will change shortly). With the 901 engine dyno Justin could monitor fuel pressure, boost, exhaust backpressure, and get actual mechanical measurement of fuel flow with one meter measuring fuel from pump to rail, then another meter subtracting the fuel that gets bypassed back to tank. A fuel line nightmare, but very effective. The 4" air turbine measures CFM, and converts that airflow to pounds of air per hour, and A/F ratio.

Justin brought the bike just as it ran on the Cycledyn at 195djhp with 11.5/1 A/F ratio to obtain a new baseline measuring, without any loss from chain and tire. He wanted fresh pump gas to test with and I sent him around the corner to a gas station that usually sells you 93 when you try to buy it. Being a single hose multi-grade pump, the first of the three gallons of 93 that Justin bought was pumped into his truck, the next two were saved for testing (there surely is a quart or two of 87 in the mixing chamber/ pump/ hose that hits your vehicle before the good stuff gets there. Whenever you see a motorcyclist cruising around slowly looking at gas pumps before he stops at one to fill up, he's surely trying to find a pump that just delivered high test, meaning he's more likely to get 100% of whatever is in the "high octane" tank in the ground.

With two gallons of his newly bought gas and the engine well warmed up it peaked at 171 SAE HP at the output shaft peaking at only 10,300 RPM then dropping like a rock. Exerything mechanically looked good, fuel pressure, boost etc were fine.  Leaning the fuel down to 12/1 caused HP to drop even more! Remember last time we dyno'd the bike we picked up 5 DJHP by leaning to 12.5/1. 

Then Justin connected his custom deto sensor to the engine block, and he detected severe detonation just as the HP dropped on our real time HP graph on the computer screen.

Justin then enrichened his fuel flow to 10.5-10.8/1 and the subsequent dyno numbers carried HP all the way to 11.800 rpm where it made 198 SAE output shaft HP! The quiet but deadly sound of deto had subsided, and HP returned as the result of cooling combustion chamber temps with extra fuel. I was miffed that I hadn't thought of that, and Justin assured me that even with my moderate age-induced dementia I would have thought to enrichen mixture, eventually. This change was so dramatic, I need to try to post a Jpeg graph on this weblog.

So Justin sucked all of that mystery gas out of the tank, and refilled it with fresh 106 octane leaded gas. Then turning up the boost to 9psi, the engine was happy making 230 SAE output shaft HP at 10.8/1 A/F ratio, .60 lb/hphr BSFC. Justin tried leaning the fuel back down to 11.5/1 and the engine picked up enough HP to haze the clutch (stock plates w/ stiffer springs) so dyno info from that point on was useless. So those of you who might have heard Justin and I talking about 300HP, it was the engine slipping and grabbing the clutch, causing torque and HP spikes that mometarily fooled us.

Based upon Justin's RX1 and Apex sled turbo numbers, 300-400 HP is surely doable with lots of octane.

But for now, I believe Justin has had an eye-opening experience with "high test" pump gas. If he is to sell these kits for pump gas, he must tune each kit to 10.5/1 on boost. Car and Driver Magazine just reported that of something like 1500 samples of high test pump gas purchased in Michigan then tested for octane, more than 10% were low octane. Also maybe 10 years ago Dateline NBC did a private assessment of gas grade cheating by gas stations in CA, where they found one in eight substandard, with the worst testing out at 75 octane! That's too much of a gamble knowing that 8- 10% of fillups can destroy an engine tuned for max HP on high test gas, if deto sensing and protection is absent.

I complained to the Bureau of Weights and Measures about this bad gas purchase, and the director is going to that gas station, same pump, and take a sample today to be tested next week. I'll be anxious to hear the test results when they are finished.