G-Force Engine Development: NC450V Gen 5.1 (Early 2007)

Billet Crankshafts
Although the original plan was to go with SP Crankshafts here in the USA, they ended up sitting on our parts for over 3 months without doing a thing. It took a very nasty letter to the owner to get any action, and what he did was pass us on to a local crankshaft company, Marine Crankshafts, he thought was capable enough to do the job. Mike Lohmeyer and I drove down there last November to discuss the job in person. They seemed extremely confident they could do the job, including the cam drive gear.

We agreed they would complete the crankshafts by January 1st, 2007. We didn't see the cranks until March, with less than a week to the first race. As Lohmeyer was assembling his engine, he was almost done when he noticed we had a problem with the cam drive gear on the crank. It was ground incorrectly and caused a very ratchety-notchy binding.

We played with it for some time and found the only solution was to shim the gear towers off the crank gear to get rid of the notchiness. Unfortunately, the only shims I had available at the time were .020" thick shims. This did the trick, but introduce some extreme gear back-lash into the gear train. We weren't happy, but had no choice. We hoped to not have to run the motor for more than a race or two like this while they came up with another solution for us.

Pistons:
This motor had a lot of firsts. It was also our chance to try out the newly designed CP pistons. Because of our troubles with our previous supplier, we again chose to use a reputable USA piston supplier that came highly recommended by many top engine builders.

CP allowed us to work closely with them on the CAD model before we ever went to production, which prevented us from having any major complications. The final product was a piston that was much lighter than our original custom piston with much more flexibility in bore size, compression height (wrist pin location) and compression ratios. Not to mention, they were more asthetically pleasing as well..

General Motor Configuration
We chose to run the pistons against the stock cast-iron liner as we had good results with that in the Gen 3 motor, and the costs were less. We also chose to run the Carrillo Steel "H" beam rods, mainly because we already had some spare sets, so the cost was again a factor. We would have preferred the Ti rods, but weren't ready to spend another $4,000.00 on rods just yet.

The motor ran well. It didn't produce the HP numbers we were hoping for, but we suspected the extra cam gear back-lash was losing us some power (continuously variable cam timing- not in our control) as well as the fact that we chose to run stock VFR carbs with an airbox, air filter. We also had the cams closer to stock settings with the first trial of this motor. We hadn't even begun to play with it yet as we ran out of time from the late crank issues. We just needed to throw the motor together and get to the track at this point.

Sad to say, although it ran well and Lohmeyer was able to use the power to destroy the 450cc Superbike class in the first couple of races, and got him battling with the front of Formula-IV a few times, the motor suffered a catastrophic failure. At the time of the failure, we were certain the crank had broken, or some other mishap related to some new part. However, we were shocked - and sickened - to discover it was the transmission that failed, and took out the rest of the motor.

We couldn't believe the carnage that such a small piece of gear could cause. But, we searched the entire motor with a fine tooth comb, and magnifier (litterally) to see what else could have caused the damage. The gear stood out in the debris of the oil pan as the only part of the rear of the engine compartment that made it in the pan. It was just too odd and out of place to have just been coincidence. The odds were one in a million. This was just simply "bad luck".

I was so in doubt I went back and confirmed it with FEA - unfortunately, after the motor had destructed. The results matched nearly the exact shape of the gear piece that broke off. This assured me the gear did snap under power, not from something hitting it. This was the first stock transmission failure we have experienced with this motor. We did have similar failures after we undercut some sets of gears, but figured the undercutting process weakened the dogs. We never expected this, but you know what they say, "it's always the next weakest link to fail"......

This is as far as the new Gen 5 production has come. We are still gathering the pieces to rebuild another Gen 5 motor for Lohmeyer. Elrod and Sampognaro have had to put their parts aside as we are still waiting for the gear issues to be resolved with the billet cranks, and we are waiting to see about the cryogenically treated RVF transmission parts as well.

With the faiure of this motor AND the "MULE", we are currently trying to gather enough spares to get a motor for Lohmeyer to salvage the 450cc Championship for 2007. Unfortunately, even though Lohmeyer has had some great finishes in Formula-IV, there will be almost no chance for a Top-Three finish in that class this season.

SPECIFICATIONS (Gen 5.1):