Thanks again for your contribution Scott. Hands on experience is certainly the most valuable insight.

 

Dusting off an old thread as I start absorbing as much 951 information as I can. Looking at the balance shaft belt, why is there a need for a balance shaft delete kit? Why not just cut the belt, yank it out of the engine bay, leave the shafts in place and be done with it?

 

Because that leaves 15+ lb of useless metal in the car.

Sam

 

And is it really worth all that hassle for 15 lbs? It would be far simpler to lose 15 lbs of your own body weight and the net advantage will be the same.

 

If you are not going to remove the shafts, why would you want to disable them by removing the belt ?? no gain there. IMHO

Fast951, Boosted951, lejams and Shaheed can attest to how smooth my car is with no balance shafts and lightened internals

 

David's car is VERY smooth, I had to see it to believe it... It idles as good as stock, and on the dyno, I didn't notice any vibration whatsoever... While talking about David's car, I think it's a gorgeous car.. Job well done David...

Did you check the TPS?

 

But there is a gain: horsepower. Those shafts require horsepower to be spun. As a real world tested example: Mitsubishi Eclipse with dual counter-balancers, the same design Porsche bought. A respected performance house strapped a stock Eclipse with the balance shafts functional to a dyno, made a few pulls, shut off the engine, disabled the balance shafts, restarted the engine, several more pulls were made, and there was an average 12 to 15 wheel horsepower increase with the shafts disabled.

 

If disabling the balance shafts gains 12-15 RWHP, then lightning the flywheel, pressure plate and crank should give you 50 RWHP....

(think about how much the balance shafts weigh and their diameter.... compared to the flywheel and pressure plate especially)

 

It's worth that hassle and more for 15lb - when you've spent countless dollars and hours lowering weight everywhere, 15lb is a substantial gain for little cost. If you're not that serious about competition, then no, of course it's not worth it to you.

Sam

 

Whats the equation for figuring out hwo much more HP you get per pound removed? If you remove the shafts on an N/A for example, you save a few HP simply no belt... Then removing the hafts entirely might give you another HP, or close to another. On an N/A, well thats not bad. Then throw in OTHER weight saving things...

 

Anyone have a 944 with the balance shafts installed, access to a dyno, and have a Buck knife handy?

 

Removal of the belt on 944 NA equates to 2-3 hp as tested on a Dyno.

Removing the shafts from the engine does zip for engine power is if they are not turning they are just static weight.

I don't recommend balance shaft removal for even 944 NA's since that 2-3 hp comes at the risk of broken oil pick-up tubes and cracked fuel rails. Both which can cause serious failures. Even on an NA it is not worth the risk. Forget it for a Turbo.

If however you have you crank machined the maybe it is ok. Reasoning is that these shafts are designed to counter balacne the secondary harmonics of the piston & crankshaft. They have been tuned to stock rotating & recripocating mass in the engine. If that mass changed then the tune is proabably off. In that case it may be ok to remove them. Otherwise 2-3 hp not worht risk of a blown -up motor or engine fire.

 

Too much trouble for too little gain.

 

When I purchased my E Club Racer in 1999, the counterbalance shafts had been removed because of a spun bearing problem. Nothing else was changed, and there was barely more vibration at idle, and no noticeable difference at speed. I eventually had to replace the block because of a hairline crack, but the crack seemed to originate at the spun bearing location, suggesting it started at the time of original injury, not secondary to increased vibration. We believe thermal expansion and cooling made the crack more noticeable with time, leading to no oil pressure. So maybe it stays relatively smooth if you only delete the shafts. We kept the shafts in the replqacement block.

 

5hp is the gain/loss, according to Porsche. The weight savings is approx. 23lbs(including everything).