Sunday, October 31, 2004
THIS COMING WEEK...Monday doing a 99 XCR800, Stock vs
DynoPort pipes, Vforce reeds, shim kit to raise cylinders, modified heads to compensate and then some...
Wednesday we have a SkiDoo600 with a 734 big bore...
Friday we'll be tuning another D&D F8 top end with a Bikeman modded stock pipe and maybe a new version of a D&D big bore single....
THIS IS BUGGING ME: some guy posted on the web, whining about not wanting to pay $20 for DTR because he heard that all we say here is aftermarket stuff doesn't work?! So he has a stock F7 with 132 HP that I can put on our dyno and tune with timing and fuel only to close to 150 HP. A bone stock 700 pump gas twin with 150 HP!! Did Arctic Cat/ Suzuki leave anything on the table? Does a factory stock 700 twin capable of 150 HP have bad reeds? Is the stock F7 single pipe low on HP? Did Arctic Cat goof on the best possible airbox intake? Give us all a break. The 03 snowPro intake was huge like the high $ billet aftermarket intake horns, but 04 and later airboxes have the smaller high velocity intakes like the F7s-- could the smaller intake inlets make more HP at peak revs due to airbox sound wave tuning? Or should you poke a bunch of holes in your well-tuned airbox for "bullboys" and let a bunch of HP robbing hot air into your intake??
Last Friday I had a guy from Maine tune his F7 dragracer w/ 500' factory drag ECU. He came with a large diameter 03 snowpro intake, switched to a stock F7 intake and he increased top end airflow CFM with the smaller stock F7 air intake. With that stock airbox horn in place he tuned to 151 HP.
So this whining guy with the 132 HP F7 can pay big bucks for big reeds, big air horn, aftermarket pipe, big loud can and still may have 132 HP. Or he can read our stuff, figure out the facts, and have great fun if he can find an instrumented dyno to tweak upon. The whining guy has all the parts in his bone stock sled to make 150HP. All it takes is tuning to get him there, or (wisely) partway there. My own tinking is based upon the many sleds tuned here ONLY with fuel reduction and timing increases, those 132 HP F7s are perfectly reliable for intelligent people at 140-145 HP. And those 145 horse guys have stock reeds, stock pipes, stock airboxes, and stock mufflers.
Wednesday, October 27, 2004
Last week I had an F6 travel 1300 miles (one way) from New Brunswick to tune a Firecat, probably a new distance record. The owner requested anonymity, so all you NE Canada guys can do is look for an extra pair of hose clamps on the hose from the fuel pump to the injector rail on a newly extra-quick F6.
Next week, we're dynoing a 600 SkiDoo twin with a 732 Big Bore. Hoping that this will be positive, information that we can share.
Also next week we're doing a popular XCR800 tuneup--DynoPort triple pipes, cylinder shim to increase port timing, various combustion chambers, reeds, etc.
I'm surrounded by Polaris Fusions sitting in dealers' warehouses--no one is knocking at the door here yet but if no one shows up I will try to borrow one from Cooper Sales/ Service next week. I had heard that Polaris was going to allow their dealers tuning access to Fusion ECU's, but are now understandably rethinking that. The Fusions have deto protection so there's seemingly no need for Polaris to tune fatly, but if they are we will try to figure a way to override the fatness and get big HP like we do with the Firecats.
No 1000cc SkiDoo twins available just yet. I'm hoping that we will have an independant sample prior to the SnowWeek/ DynoTech/ Adirondack Shootout in Woodgate on Dec 10. Also where AmSnow required aftermarket trail mod particpants to be display advertisers in their mag, Snowweek/ Snowgoer will not require that. Anyone who has REAL trail mod packages to sell/ show off, you are welcome. Thi year it is really trail mod, no pro stock dragracers, stock tracks, trail carbides, (our) pump gas, engines teched (bere/ stroke/ compression etc). Maybe an organized trail ride for the trail mods before putting them on the track at half-time?
One contentious issue is aftermarket sale of fuel pressure dropping devices for Firecats. Because of the WIDE variation in stock F7 fuel flow these things must be dialed in on instrumented dynos to be safe.I have dyno tuned many dozens of Firecats--stock fuel flow varies more than 10%!! So if you take one of the [lucky like Ziggy] properly tuned stockers and lean it out by blindly reducing fuel pressure it will probably be toast, just like Ziggy would have been on the dyno if observant dyno people hadn't caught it.
Friday, October 22, 2004
The Blue Marble guys just shipped me a couple of cases of oil for me to test. I've followed BM oil streams around the internet, and you DTR subscribers know our batting average for dyno testing fancy oils/ oil additives/ treatments etc.....00zero.
This time Sam DynoMan (he has a track dyno testing service) who is a local Blue Marble distibutor brought a low mileage bone stock Polaris 600 twin, with polaris oil for baseline dyno testing. His plan was to baseline on our SuperFlow engine dyno, treat his engine however they do it by soaking cylinders and parts etc, run it for a while, track dyno it and if results were positive, bring it back for an "after" test.
After we baselined the engine at about 115 HP (very typical) I checked compression and squish, wrote my initials on the CDI, and Sam took the sled home for treatment/ further evaluation and dyno testing on his DynoJet track dyno. A week later Sam called me, ready for another "pull" on my dyno. Bring it on.
This time, with Blue Marble oil as the only change (***) the engine made 117 HP on the average of two hot engine tests. Compared to the baseline test, fuel flow lb/hr was identical (= no jetting chages), airflow CFM was identical (= no airbox mods or porting). And since the HP peak occurred a hundred revs HIGHER than baseline probably no ignition timing was advanced. Very interesting.
What could be done to fool us? We're measuring fuel flow and airflow and we can expect increased torque and shifting of midrange HP and HP peak RPM to lower RPM with added timing and compression. In this case the midrange torque was identical and HP peak was a hundred revs higher! Since friction drag increases as the square of engine RPM, could lowered friction be helping us? About the only thing someone wanting to cheat our system would be to add HP increasing additives to the gas (ie: propylene oxide). But usually that stuff is noxious smelling, especially since propylene oxide is used commercially to sterilize fruit flies in fruit storage buildings (just what I want to sniff during testing). I don't think DynoMan Sam was cheating, but I have to test this for myself.
My plan is to take John T. Cowie's Polaris 600 twin that Sean Ray used in DTR (shimmed up cylinder, cut head, etc etc) and do that same Blue Marble oil treatment procedure ourselves. Very Soon.