September 2013

Monday, September 16, 2013

DynoTech : What we're learning by testing RVP

Now that we have testing equipment I like to test racers' fuel's RVP while we're hooking up the sled/ engine to the dyno. I've caught several samples with no or low RVP, meaning we must have the engine very hot while tuning on the dyno to ensure adequate vaporization. No cool engine tuning can be done with stale fuel, even with excellent vaporizing carbs like properly sized Lectrons. Those "light" or "front" ends of the fuel are critical in ensuring good fuel volatitlity.

Heat and agitation cause the light ends to "boil off", or escape and build pressure in a sealed vessel. During the heating only phase of the RVP test, fresh Sunoco Maximal will build about 3psi in the "bomb". Then, the agitation phase of the RVP tests is removing the bomb from the water bath, inverting it which allows the heated gasoline to gurgle into the vapor chamber. Then, the bomb is inverted again so the fuel gurgles back into the small fuel sample container. This agitation causes more light ends to boil off, and raises the pressure by another 2psi (total 5 psi). If we unscrew the sample chamber from the bomb (it's sealed with an Oring) we get a nice whoosh and about half of the light ends are lost to the atmosphere. Then if we take that same sample, reconnect it to the bomb and test it again the RVP will only register about half--2.5psi or therabouts! Let that 2.5psi escape and reheat and agitate the sample again, and now we're down to 1 to 1.5 psi. I consider that dead, lawnmower gas (dead race gas becomes excellent octane booster for hot trail sleds when mixed with pump gas) It's just like shaking up a part full bottle of Pepsi Cola and releasing the CO2 by cracking the bottle cap. You can only do that a few times before it's flat and undrinkable. 

A RVP test is very much like trailering a partially full sealed can of formerly fresh race gas to a grass race in August in a black trailer. You get to the track, open the can and kawoosh goes most of the good smelling light ends and your fuel is half dead. Because of the buildup of pressure some of the light ends remain dissolved in the fuel. But if you reseal the can and drive home again, if you open the cap you don't get much of a woosh. But what about the fuel that's in the sled's fuel tank? There's no pressure seal there, and I would submit that whatever fuel is in the tank is DOA (dead on arrival).

Typical testing results from sealed 5 gallon "pails" of race gas show RVP about 1psi lower than published by the refiner. I suspect that the lower pressure is the result of the severe agitation of the fuel when the pail is transfilled from a larger container by the dealer. Sunoco tells me that they only sell race fuel to distributors in bulk--railcars and trailers only. They fill no drums or small containers themselves!

What's a racer to do to keep fuel fresh while transporting? First, have no fuel in the sled's tank (or carbs for that matter). And only transport FULL cans or jugs of fuel to minimize headspace that allows the escaping of the light ends. Small drums of race fuel (ie: 30 gallon size) can be used for transportation even for small quantities of fuel as long as 6 psi of nitrogen head pressure (with one of Carl McQuillen's N2 bung systems) is used to prevent loss of light ends and to prevent moisture contamination from humid air and to dispense the fuel while still under pressure. Also, military-style 5 gallon "jerry cans" appear to have the same bung threads as race fuel drums, and could be fitted with a nitrogen system for storage and transporting using a small 20 or 40 cu. ft. N2 cylinder.

When it comes to gassing up your high dollar race sled, those light ends are your friend. The refiners spend huge bucks putting those light ends in the fuel to make it volatile. Handling/ transporting/ storing the fuel in a cavalier manner can cost you horsepower and engines.




DynoTech : Spring/Summer/ Fall dyno schedule

Every year the sled dyno seems to get slower, and here it is (along with MC SuperFlow CycleDyn eddy current roller dyno schedule) for Spring-Fall 2013:

3/16 Jeremy Higgens (MC) Yam YZ450F flattracker (RLJ-Ron Jewell engine)

4/7 Sean Ray (MC) H-D FLH

4/16 David Wells (MC) Suzuki RMZ450 flattracker (RLJ)

4/18 Cory Van Ameron (MC) Honda CR85 flatracker

4/18 Jeremy Van Ameron (MC) Kaw KLX125 flattracker

4/22 David Wells (MC) Suz RMZ450 flattracker back for more HP

4/23 Sean Ray (MC) H-D FXS EFI turbo (he custom builds those)

4/28 Scott Barrett (MC) Honda CRF450 flattracker another high HP RLJ engine, tuning for max HP

4/29 Sean Ray (MC) anther H-D turbo for boost/ fuel/ timing tuning

5/1 Kenny Coolbeth (CT MC Nat'l number 2) Kaw KX450 flattracker RLJ looking for still more HP

5/4 Sean Ray (MC) H-D turbo FLH testing different exhaust config

5/5 Jerry Wells (MC) Honda CRF 450 flattracker RLJ engine

5/5 Dave Waters (MC) KTM 950 flattracker tuning

5/14 Al Rowcliffe (MC) Honda CRF250

5/22 Tristen Avery (VA, MC) Honda CRF450 RLJ engine

5/23 Cody Johncox (MC) H-D 750 flattracker tuning carbs for restrictors

5/23 Jim Davis (MC) Yam YZ125 flatteracker

5/23 Mike Luczak (MC) Honda CRF250 flattracker

5/24 "Angus" (MC) Honda CRF450 flattracker trying to find missing HP 

5/25 Tim Nurton, Hentges mod 600 Polaris twin

5/25 Sean Ray (MC) H-D FLH turbo trying one more exhaust system

5/25 Unknown (MC) Kaw Z1000 street bike PCV tuning

5/27 Hank Holden (MC) Kaw ZX10R streetbike, header, no EXUP, PCV tune

5/29 Sean Ray (MC) that same FLH turbo, one more exhaust mod (trying to find elusive boosted HP on the bagger)

5/30 Me (MC) tuning my turbo Victory V92C (serial number 0038) with PC3

6/8 Derek Dicastro (MC) H-D FatBob 96" PCV tune

6/9 Tristen Avery (VA MC) Honda CRF450 flattracker back for more RLJ HP

6/9 Brian Neuman (MC) Honda CRF450 flattracker RLJ engine, carbureted

6/12 Mike Luczak (MC) Honda CRF250 flattracker once more

6/12 Mike Luczak (MC) Yam YZ125 flattracker

6/17 Angus (MC) Honda CRF450 flattracker, 20 HP is still missing!

6/19 Clark Angarano (MC) ZX10R stocker with Guhl Motors reflashed ECU that holds the throttle blades open to the rev limiter 180+ HP!

6/19 Danny Angarano (MC) stock Triumph 675 speed triple

6/20 Greedy Kenny Coolbeth (MC CT) back with another Kaw KX450 RLJ engine

6/20 Gene Hurin, HTG Polaris 1000 triple Imp Stock pipe testing

6/21 Frankie Amalphie, Yam SX700 asphalt racer with Race Logic template porting (worked great)

6/27 Cody Johncox (MC) H-D 750 flattracker, RLJ engine mods

6/28 Mike Zacher (MC) Honda CRF450 RLJ flattracker

6/30 Sean Ray (MC) testing the same FLH this time with no turbo to make sure engine was fine, and it was almost a powerful as it was with 10psi boost???

6/30 Tim & Brian Tyler, Pol 800 twin PS

6/30 Jason Owen, Arctic Cat 800 twin carbureted PS (over 200 HP)

7/4 Dave Waters (MC) KTM 990 flattracker

7/14 Mike Luczak (MC) Honda CRF450 flattracker

7/14 Mike Luczak (MC) Yam YZ125 flattracker

7/27-29 Pro private engine testing DynoCams off

7/29 Justin FPP Fuller, SkiDoo 4tek turbo with H2O/ methanol injection and pump gas

8/1 Chris Wells (MC) RD400 Cafe Racer for carb/ timing tuning (doubled his HP)--Chris also has a TZ750 in parts in his garage...I made him promise to bring it here for tuning!

8/1 Joe Iannello (MC) Suzuki 1400 Intruder for carb tuning--some dealer had butchered the carburetion and I spent 5 hours changing pilot and main jets (stock it has one Mikuni and one Keihin carb!). Now it's perfect. I gotta quit bragging--I dislike working on carbs.

8/2 power hungry Gene Hurin back again with HTG Pol 1000 Imp Stock

8/7 Tim & Brian Tyler, Hentges mod 600 for PS grass drags

8/8 Paul Moore, Quad dragster with 1200 PWC mod engine/ methanol fuel for carb/ timing tuning

8/10 Can't remember his name, (MC) H-D 117" twin cam PCV tune

8/22 Justin Jones (MC) Honda CRF450 flattracker engine newly modded by RLJ,

8/23 Andy Stiles, Hentges 600 mod IQR sled for improved stock grass drags

8/25 Chris Metz (MC) Aprillia 1000 streetbike, mod exhaust, PCV tune

8/26 Cody Johncox (MC) H-D XR750 flattracker one more time

8/28 Tripod Dan Cross, HTG 1130 outlaw drag sled, maxing out HP with timing/ fuel tweaking

9/7 Jess Hellwig, Cat 800 stroker PS from Pro Stock, Inc

9/13 Jeff Stinson, Cat 700 Imp/ PS with Jaws High RPM pipes, water in one hole

9/13 Ken Aldrich, Cat 800 stock drag sled

9/19 Jason Owen, PS800 Cat twin

9/20 Tripod Dan, XCR800 improved stock

9/24 John DeAngelo Cat XF1200 Boondocker turbo

9/24 Dave Wells MC, Ron Jewell modded Honda CRF450 flattracker

9/25 FullPowerPerf Justin, VMax4 800 prostock

9/28 Bill Tranter RKTek SkiDoo 827 tune deto-free on 87octane

9/29 Jim Sigg (pal of Jay Owen) MC--HD 103 bagger

10/10 Pete Beasely MC--Victory 106ci bagger

10/16 Don Zuzze 03 F7 stocker, fuel pressure tune for grass drags

10/17 Paul "sponge" Spry, F8 improver Boondocker tune for grass drags

10/17 James Chittenden ZRT600 hotrod