November 2004

Monday, November 29, 2004

DynoTech : more HOT F7's and Mach Z's

Recently completed some more dyno tuneups with 05/04/03 F7s. Several have proven to be  what I call "hot" F7s--very low fuel flow and apparently advanced ignition timing. The latest,  most powerful yet (fitted with a 2.5 degree key but otherwise stock) made 149.5 HP, with a drag-stingy 95 lb/hr fuel flow at 43 psi rail pressure! And this was a long hot dyno run. I've got about three of these on a disc. I will try to post a Hot F7 gallery tomorrow including one we tested with a "thing" silencer.

Then hopefully this week we will have Mach Z numbers to post.

Saturday, November 27, 2004


I just finished initial dyno testing of my cousin-in-law Bill Roger's new Fusion. And since I'm measuring airflow CFM to compare to fuel flow lb/hr I have some very good, very promising info that I will post tonight or tomorrow AM!

Sunday Bill and I are going to try some tweeks to see if we can do trail-safe low buck (other than dyno tuning) perkup to the Fusion.

Also today we dyno's a very excellent PSI1200 Genesis top end on a 1000 Tcat. Will try to post that this weekend.

Another significant tuneup was a great SLP ProX 800 dyno tuned yesterday, seems like it's conceivable for upright 800 twins to match the F8's pump gas performance.

Thursday, November 25, 2004

DynoTech : Updates

Of the 10  F7 Firecats dyno tuned so far this month, four have been hotrods, with way more HP than the average stocker. Three with offset keys made 145+ with no fuel tuning (those had stock fuel flow in the mid-high 90 lb/hr range!).  Just observing the variance in F7 HP curves it appears as though not only do we have variation in fuel flow, but ignition timing  as well. Firecats make more HP with advanced timing, but then overrev HP suffers (a box with more ignition retard at high revs would help). So I'm rethinking my standard recommendation that Firecat owners install offset keys before coming to dyno tune to save expensive dyno time. If you are one of the fortunate F7ers that has a good "box" with lean mixture and generous ignition timing, adding more timing with an offest key narrows the HP band (from 7200 Ex valve opening to where advanced timing causes HP to drop).  This may be OK for savvy clutch tuners who can make adjustments to keep engine speed at max HP. But surely relaxed ignition timing allows for much greater overrev HP and ease of clutching. It might be worth spending an extra hour changing the key at the dyno if just fuel tuning leves HP short.

The fourth November F7 "hotrod" we encountered, a brand new 05 sled made 140 HP off the trailer. It had fuel flow that was in the low 100 lb/hr range (maybe 10% less than typical 03/04's), and probably programmed timing that was more generous that the more typical 03/04s that make closer to 130 HP. The owner of the sled opted to leave timing stock, and in this case by just leaning fuel flow a bit he was rewarded with 145 HP with a great, flat HP plateau, over 140 from just after valve opening to beyond 8000. And since the many 03/04s we tuned last season have proven totally reliable at 140-145 HP, obtaining that HP level without adding excessive timing will make this sled easy to clutch for good performance. After I get some non-cat stuff posted I will try to remember to post this latest 145 HP tuneup with that great, broad powerband.

On 11/28 my cousin-in-law is bringing his new Fusion to dyno test. Other dyno testers have reported difficulty with deto sensors being set off by dyno vibrations (remember we had that problem with the 800 Pol in last year's Shootout). Since we've all heard modest dyno numbers so far, I'm anxious to see if it's tuned lazily. If so we may be able to help that some.

Sunday, November 14, 2004

DynoTech : recent revelations...

I talked to Dan and Dale friday--after they saw my 05 F7 post, they grabbed one of their own 05's and put in on their dyno. Their 05 made way less HP the ours, 110+ lb/hr fuel flow. So probably Kaz' 05 was one of those lucky hot ones like we've seen in the past.

Also D&D is planning to bring two sleds to the SW Shootout--a long track F9 (their F8 cyls with larger bore and longer sroke) and a 660 turbo with trail hopup kit. I hope we get to dyno both here, since SnowWeek will publish any Trail Mod dyno sheets we come up with.

Carl McQuillen (585-768-2322) has set up a jig to make it easier to EDM advance keyways in Cat flywheels. The latest on he did a 7 degrees for an F8 carb sled we're dyno tuning tomorrow. He stamps the original keyway with a "0" and in this case the new keyway is stamped "+7". Carl is also the guy who manufactures the Fuel Safe nitrogen blanket system to pressurize drummed race gas, maintaining light ends with  three psi nitrogen. The Fuel Safe also dispenses the fuel like a beer tap. Our drummed race fuel lasts indefinitely this way. Half-full drums of race gas can go "dead" in a short time--light ends go away like CO2 goes away in half-full liters of Pepsi (every time you open the Pepsi bottle to take a swig that "whish" means more carbonation lost). Similarly, every time you crack the bung on your drum of fuel the "whish" you hear and smell means more light ends gone. When enough light ends are lost, fuel does not readily vaporize and detonation can occur with low EGT's and safe-appearing A/F ratios.

Last Saturday we also did our third back to back comparison of big mouth  Firecat airbox inlet vs stock. And for the third time, Bob Swift's SLP twin-piped F8 lost low end and midrange WOT airflow, then added airflow at HP peak when we switched from  big mouth to stock. As I recall we picked up 2 HP at peak due to added CFM with fixed trail-safe fuel flow lb/hr. As a bonus, the slight reduction in midrange airflow was welcomed, since the ECU does not provide adequate low end/ midrange fuel to keep up with the high-flowing twin pipes without jacking fuel pressure to the moon.

I'm planning to take a crack at dyno tuning a Polaris Fusion this week, hopefully Tuesday. Sled will be borrowed from Cooper's Sales and Service.


Friday, November 12, 2004

DynoTech : 2005 F7 EFI shocker and new stuff being tuned...

Today we dyno tuned our first 2005 F7 EFI.
Kaz was bringing his his new sled to tune, figuring on relying on his D&D pac to drop fuel pressure to optimise HP. We had communicated by phone a few times and I suggested as I always do with EFI F7ers: install a 2 or 3 degree key ahead of time (all smart F7 riders need that). It's more economical to do that in your garage than on my dyno at $125/hr. Come here with timing key in place and we'll be done more quickly.
Normally that means a baseline test or two, 10-1 A/F ratio is typical, then reduce top end fuel pressure with a main jet, a D&D pac needle jet, or any other needle valve to do the same thing.
So Kaz brought his new '05 F7, remember he has a 2 degree offset key, and blasted two runs back to back cool and hot, 147 HP!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
Then we installed a Speedwerx single and added  more HP.
Then we choked down the fuel pressure with D&D pac and added even more.
That two degree key  adds a few HP but this is unbelievable. Base fuel  flow lb/hr on this '05 F7 was 99-100 lb/hr. One hour earlier we had a 03/04 F7 on the dyno, 110 lb/hr base fuel flow. Was this another anomoly like Mike "Ziggy" Zigmont's '04 F7? Or is this how the new "05's are tuned by AC?
I've got all the dyno numbers here, SFD files, etc,  if I can stay awake I'll post them tonight. If I can't stay awake I'll try later this weekend. Everyone needs to see this.

I'm dynoing three sleds tomorrow (Bikeman F8, Speedwerx 1000, ZR900 mod) then dynoing two more on Sunday (both SLP ported ProX800's).

Spiders build fancy mosquito-catching webs on my dyno all summer. But in the fall the cool air sets in, and the spiders flee as the hordes of blue, yellow, green, red, black, and orange sleds converge here to dyno tune, having great fun optimizing whatever they have.

Also there is a new Fusion sitting at Cooper Sales and Service waiting for me to have two days to test and tune. Maybe next week. Plus the new MachZ's hare on their way, we need to dyno one of those before the Old Forge Shootout.

Thursday, November 11, 2004


SnowWeek/ SnowGoer has partnered with DynoTech, George Taylor, Big Moose Yamaha/ Arctic Cat, Old Forge Powersports Skidoo, and White Lake Polaris to make the Adirondack Shootout better than ever.

Because of SnowWeek's participation, we expect a good turnout of "Trail Mod" sleds from aftermarket companies. Each sled will receive 1/2 page with photo in SnowWeek magazine.



Between the box-stock and “dealer prep” runs we will offer aftermarket companies the opportunity to showcase specific trial modifications (engine, components, etc) to stock sleds as run in the shootout.

Each sled will receive ˝ page in SnowWeek including photo, with text describing the performance upgrades on each sled.  The great benefit of the SnowWeek partnership is immediate publicity (December). There is also expected similar publicity in SnowGoer, later in the season.

 Optional: dyno tune at DynoTech (before or after the Shootout)—those dyno results will be published in SnowWeek and on line DynoTechResearch after SnowWeek.

 In the past, there has been lax enforcement of trail mod “rules”. In deference to our aftermarket partners this will change this year. We want TRAIL MOD SLEDS. All sleds will be weighed and “teched” by Pete Webb and Sean Ray. Displacement, compression, etc will be noted. Perhaps sleds that don’t fit the “trail mod” classification can be run in exhibition, separate from Trail Mod.


 Pump gas, 93 octane supplied by DynoTech will be used. Gas in sleds will be pumped out, three gallons of the 93 octane pump gas will be put into each sled.

 Each sled will be weighed, and if weight is less than the stockers at the shootout, a list of components/ cost will be supplied that created the weight savings.

 Suspension travel must be reasonable, 50% travel should be acceptable.

 Whatever stock track comes on the sled will be used. Trail carbides will be used (no more than used on the stock sleds) and not carbide tipped ice picks like Big Bob used several years ago (that precipitated the “Big Bob Rule Stretcher Award).

 The SnowWeek crew will organize a short trail ride before the aftermarket sleds are run—maybe a two-three mile trial ride (the Woodgate Shootout track hooks up to the trail system), possibly allowing SnowWeek guys to switch off and ride all the aftermarket sleds so each can be assessed and its trail manners reported on.

 So far we have commitments from Bender, DynoPort, D&D, Hooper, Crankshop, Excell Motorsports.   We are looking forward to more participants this year. In the past, AmSnow required aftermarket participants to be display advertisers in AmSnow. SNOWWEEK IS WAIVING THAT REQUIREMENT.

 Any aftermarket business that has an interest in showcasing their performance products on December 10, and would like to discuss details please call Jim Czekala (585-993-2777) or George Taylor (910-269-1018).

Saturday, November 06, 2004

DynoTech : Dyno Vibes

Today I spent an hour on the phone with  7K Dyno Bill Davis (fully instrumented engine dyno @ 7000' altitude in Marysvale Utah).  Bill and his partner Donavan are now preparing to create a sled chassis-holding fixture like mine that will allow  testing without removing the engine from the chassis. This will be a fantastically good thing for high altitude riders who seek optimum performance without having to jerk the engine/ ignition/ fuel system from the chassis'. They've dyno tested many hundreds of sled engines, 1000's of dyno tests on their engine fixtures. But now the complexity of the new breed of EFI sleds with hoses and wires and computers mounted everywhere means it's time for Bill and Donavan to begin dyno testing with engines in their chassis'.

The gist of our conversation today was how to create a  long enough  dyno drive shaft to allow for motor mount flex as well as dealing with the most evil torsional vibrations emanating from long stroke (and even longer stroke "stroker")  big bore twins that are in vogue today.

Tim Bender and Sean Ray have been dyno tuning their Polaris/ Ieam Industries 800 twin snowcross engines here. Without getting into specifics about engine output one of these 100 and something lb/ft evil vibrating twin engines recently snapped a [prototype very stiff] dyno driveshaft weld, and twisted out of phase a press-fit joint that required 15 tons (measured on my hydraulic press) to assemble. Aproximately 500 lb/ft of torque was aplied to try to reindex the shaft to no avail. How could this be? Huge torque spikes are created by some of these monster twins when they reach their resonant frequencies (that engine speed where the PTO and mag ends are "ringing", going back and forth in different directions!). The monstrous torque spikes created by these vibrations can be as destuctive as 1000 lb/ft impact guns, twisting themselves out of phase and/ or turning steel dyno driveshaft components into red dust. That heavy mag flywheel winds up, then unloads at just the wrong time, acting like a sledgehammer on the crankshaft itself and anything attached to the crank PTO taper. Those torsional vibrations are the cause of Big Twins prematurely wearing out drive clutch moving parts. Since we do mostly "sweep" testing from low to high RPM, it is very likely that we will encounter, somewhere, the critical speed(s) of any crankshaft. Even if that encounter is brief, torsional vibes can wreak havoc on dyno shafts and the engines themselves.

How can we protect our $100K dyno systems, and equally importantly, our customers' valuable engines from these torsional vibrations and the resultant violent torque spikes? If we use a solid driveshaft capable of handling the torque of. say, a 6-71 Detroit Diesel, driveshat and dyno  longevity will be excellent. But those impact-gun torque spikes from the Big Twins will have nowhere to go, and can easily turn on themselves (literally) and turn the crankshaft out of phase. I've done that here in the past, protecting my stuff with solid shafts at the expense of the potentially offending engines. No one wins or learns anything from that sort of standoff.

So how do we deal with this? Simply, lots of rubber dampening media between the engine and dyno absorption unit. The more the merrier, and those destructive torque spikes are converted into hot rubber that cools when the torque spikes subside. There is some engineering that goes into determining the proper stiffeness of the rubber couplings to absorb the torque spikes. In my case it has been 16 years of farmer engineering which determined that sweet spot of torsional dampening media--if it's too supple for the peak torsionals the rubber will wind up like black licorice chewing gum on the ceiling and shaft parts will fly. If the rubber's too stiff, engine components may suffer.

Today, after 1000's of variously evil engines, we've come close to learning how to deal properly with each situation. There is lots of rubber dampening media in our shaft system, we pay attention to heat levels in the rubber couplers between runs. With the experience gleaned here from the holes in our ceiling, Bill and Donavan can hit the ground running and high altitude "in chassis" dyno tuners there can be comfortable knowing that their expensive engines will be pampered while valuable information is  learned.

A dynomometer with a properly dampened dyno driveshaft is absolutley easier on the engine than a drive clutch, since there is zero side load on the crankshaft PTO!

Every mod engine deserves to be dyno tuned. Bill and Donavan have found that what works here close to sea level is totally different at 7000ft. I need to find a way to include them more ofter in DTR, so they can share their valuable (for mountain riders) technical info. More valuable High Altitude stuff to come after they get their chassis fixture/ driveshaft system complete.

Monday, November 01, 2004

DynoTech : wanted F7 for free dyno tuning 11/19--

I've got a good pal Don Schroeder in Alberta who wants to fly down to NY with his F8 cylinders/ pistons, F7 ECU, injectors  to dyno tune here on Friday 11/19. But he needs a donor sled/ engine to fit his parts to for testing. The deal would be: free dyno time to dial in your F7 EFI to 140+ HP (or F8 to 150+ HP)  (value $250-400). Then remove your cylinders, install Don's Pistons/ cylinders injectors ECU etc and dial him in, probably and extra five-six hours, reinstall your pistons/ cylinders and you're done Phone 585-993-2777 or. Email me if interested.