Loewenherz Racing

#3 - Deciphering Previous Rocket 3 Records

Here is a shot of two record holding Rocket 3s.  Finding good pictures of the bikes is not terribly easy, however, I know both bikes are using the Carpenter Racing "Brute" exhaust.  These pipes are of course pulse tuned with a long megaphone attached after the collector, they make power, a known fact.

Pic 1: Jason DiSalvo setting a world record speed of 174.276 mph in 2012.  As you can clearly see, the bike is largely stock externally.  The adjustments externally include, lowering the bike ~1" in the front and an unknown amount in the rear, removal of fork protectors, narrow handle bars, and a tiny front fender.  This earned them an M-AF class record.

Pic 2:Here we have Jeremy Ragle's Rocket 3, somewhat more modified, which, currently holds the records for M-AG, M-AF, and MPS-AF.  He has earned himself a nice list of accomplishments indeed!  You can see quite a bit more customization has been done to his Rocket 3, removal of a lot of components, relocated rider peg location, narrow bars, single front disc brake, and the general "strip down" of all extraneous things not required on a Rocket 3 for performance to save weight.

Both bikes run the same Carpenter Scoop intake, and both bikes run Metzler 880s.  I have no further info available on internal engine modifications, but I have a pretty good idea of what's been done to both Rocket 3s.

A known formula, that is proven to work, will by nature land you right in the ball-park of those who created to formula.  Follow the known, end up with the known.  I am using the same basis and doing everything differently.  The two riders above on their bikes probably end up weighing close to the same, Jason is a small jockey, Jeremy is a bit larger than Jason.





From what I am able to compute, air density and power go down between 13 and 19 percent at the salt compared to sea level.  Making the assumption that the bikes run the 265 package from carpenter, and known both bikes set M-AF records using race fuel to achieve the advertised 265whp, we can extrapolate a few things.  IF that intake scoop is well sealed, based on testing I've researched they are probably making something like 40 millibar over ambient air pressure at 170MPH, so their max power will be something like 230whp compared to sea level where it would be something like 273whp at speed, and 265whp on the dyno.

Lets review power vs RPM vs speed and learn a few things.

Left: Calculation of speed vs RPM using a Metzler 880.  You can see, both bikes fell between 6,800-7,000 RPM at their terminal speeds IF they used 5th gear.  If they made the pass in 4th gear using a 9,000 RPM redline instead of 8,000 RPM (and I have every reason to suspect they used 9,000) they'd have been between 8,100-8,400 RPM.

At 8,100-8,400 they're in the overrun portion of the power band, so, slightly past peak power but still making very good power.

In the above dyno of a Carpenter 265 bike, the red (5th gear) and blue (4th gear) dashed line indicates where on the plot the initial Jason DiSalvo record would have been set.  By extrapolating the overrun area, the 4th gear line would have been at ~250whp and 5th gear line would have been 238whp.  Lets now factor in altitude at Bonneville and see where the power would likely have been.

5th: (238whp * 1.03 (ramair intake setup))*0.85(altitude correction) = 208whp
4th: (250whp * 1.03 (ramair intake setup))*0.85(altitude correction) = 218whp

So, a 10 whp difference.  All this to find out, WHERE DOES THIS PUT ME?!  Lets find out:

At first look, it would appear I'm missing peak power, but not all is clear here.  The 174mph mark for me with the 255 tire will come up with 235 whp on the plot in 5th gear, however, there's more than meets the eye.  This dyno in 92 octane no spec fuel, and it's with my air filter in place.  Having tested my air filter, I know I gain 4% peak torque without it and 2.8% peak power, and we're shockingly close to peak torque at 174mph, actually 187lb-ft at 6,600 RPM so lets doe the same math, without my air filter as above:

Without Filter at 6,600 = ((187lbft *1.04)*6,600)/5252 = 244.3whp

Bridgestone, 6,600 RPM @ 174mph:
5th: (244whp * 1.03 (ramair intake setup))*0.85(altitude correction) = 213.6whp
Metzler, 6,900 RPM @ 174mph:
(250whp * 1.03 (ramair intake setup))*0.85(altitude correction) = 218whp

So using a Metzler 880, and my torque curve which differs from the Carpenter Brute equipped bikes, I can match their power level in 5th that they need 4th for, turning the motor slower and still climbing up the power instead of gradually falling off in the overrun area.

This leaves out the factor of fuel.  The gas class "spec" MUL/C fuel is 3.5% oxygenated and holds the potential for increased power in my motor!  At peak, the extra 3% + removing the air filter and gaining 2.8% for it, puts me at 274whp potentially at sea level without any ramair effect included, so, about 10hp ahead of the standard Carpenter 265 bike.

If I gained 3% using MUL/C, a very likely possibility knowing these motors respond well to oxygenated fuel:
(257.5whp* 1.03)*0.85 = 225whp

I will have the potential to go faster than the Carpenter bike did in 2012 if the salt quality is similar.  What I've not considered that may turn out to be key, is the Avon tire, it has a sharper profile and softer compound than the Metzler 880 and may provide superior traction on the salt.

Late Edit:
Comparing some apples to apples below we can see the difference my changes have made to the curve.  The blue line is my estimate based on using MR12 which is 6% oxygenated since that is what was used on the original dyno shown on this sheet.

The important comparison for me, is BLUE vs TAN.  This shows and significant increase in area under the curve despite peak power being very similar.

Black vs Tan is apples to apples, same dyno, same tire, same head and cams, same exhaust, same intake.  The only difference is 92 octane vs MR12 and 13:1 vs 11.5:1 static compression.