Guest Mike Posted October 31, 2006 Share Posted October 31, 2006 I searched but found nothing specifically addressing this. Has anyone done done a real-world comparison of a car with completely stock drive shaft, half shafts, flywheel, wheels, tires, etc., while everything else remains equal... as opposed to all light-weight components? I'd like to see some dyno tests and 1/4 mile times and how the decreased rotational mass affects performance. Quote Link to comment Share on other sites More sharing options...
JMortensen Posted October 31, 2006 Share Posted October 31, 2006 There are so many variables there that I don't think you're going to get a "test result" for this question. I've driven the same Z with a stock flywheel and a 12 lb flywheel. Makes a HUGE difference. I've also driven one with a 10 lb flywheel. You can actually feel the difference in the 12 lb to the 10 lb flywheel pretty easily. I traded my friend some 25 lb Carrol Shelby wheels, 15x7 for her ZX 6 spoke wheels which are 14 lbs. She got home and called me to tell me that the car didn't seem as fast and didn't brake as well. Anecdotal I know, but I think that's the kind of info you're going to get on this one. Quote Link to comment Share on other sites More sharing options...
Guest Mike Posted October 31, 2006 Share Posted October 31, 2006 JON... Yes, this is exactly what I'm looking for. I prefer dyno and quarter mile results but anectdotal is good too. I'm very tempted, once my car is properly setup, to do this very test. If changing just one component makes a significant difference, then surely changing them all will yield a subtly amazing result. Your thoughts? Quote Link to comment Share on other sites More sharing options...
JMortensen Posted October 31, 2006 Share Posted October 31, 2006 I agree 100%. Quote Link to comment Share on other sites More sharing options...
Guest Mike Posted October 31, 2006 Share Posted October 31, 2006 It's a few weeks away but I'll post my results. If what I'm hearing is true, reducing rotational mass yields more HP/$ than engine mods once you reach a certain point on the engine. Quote Link to comment Share on other sites More sharing options...
OlderThanMe Posted November 1, 2006 Share Posted November 1, 2006 I went from 14x6.5 eagle wheels to 15x8 steel diamonds and gained a few pounds but increased tire size to a 225/60R15, 26" tall tire and noticed a little bit more sluggish response in acceleration but my "S12-8" Toyota brakes that do a much better job at stopping the car than the stock calipers. Quote Link to comment Share on other sites More sharing options...
Guest Mike Posted November 2, 2006 Share Posted November 2, 2006 I had a '71 Firebird with a mid/mild 400. When I went to wider tires with the same overall height, I had better traction at take-off but I noticed lesser acceleration once I quit spinning. I attributed it to more friction since the weight was nearly the same. Quote Link to comment Share on other sites More sharing options...
Tony D Posted November 2, 2006 Share Posted November 2, 2006 If anecdontes are O.K. then I can add we picked up 3mph at ElMirage swapping from the stock steel wheels and driveshaft to Convo-Pros and Aluminum Driveshaft. The Convo Pros made for more of a noticable difference in acceleration "feel". I have a 15# japanese lightened flywheel that accelerates much harder than my 13# Centerforce Aluminum unit, almost as hard as the Tilton 11# unit I have in another vehicle. Where the weight is removed is almost as important as how much. This gives more credence to why the Convo Pros felt like more of an improvement than the driveshaft alone--weight further away from the rotational centerline. Quote Link to comment Share on other sites More sharing options...
Guest Mike Posted November 2, 2006 Share Posted November 2, 2006 Tony D... This seems logical to me. The effects of centrifugal force diminish toward the center of the object in motion. Since the circumferences of drive shafts, half shafts, etc. are relatively small, the effect of using lighter materials is less noticeable than when applied to flywheels, wheels and tires. That having been said, I'm sure there is some benefit to installing lightweight components everywhere possible. BTW, I'd like to include the effects of lightened internal engine components such as crankshaft, rods, and pistons in my record. However, that's not fiscally sound for me at this time. Quote Link to comment Share on other sites More sharing options...
Tony D Posted November 2, 2006 Share Posted November 2, 2006 some piston manufacturers are offering custom lightening for pistons now, reducing reciprocating mass adds to power down the driveline---or at least accelerating... Less weight on the bobweight end means less crankshaft counterweight required---less wounterweight required means quicker revving crank... If you have ever seen a Ferrari Crankshaft, it's a work of art: very little counterweight hanging out there, very thin, with weight added using Mallory Metal in dowel form to keep all rotating mass as close to crankshaft centerline as possible. No wonder they rev like they do! VW's are hard on crankshafts (Type 1 Air Cooled) when they have a light flywheel due to loading during clutch dumps. The solution was to add a 7# balancer on the opposite end (belt end) of the crank to keep torsionals under control. The engines seemed to rev just as fast with that Berg Equalizer on the end---because the diameter of the weight was close to the centerline of the crank. But that added weight on the other end was enough to keep the dowels from twisting out of the flywheel, or snapping the crankthrow at the fillets! Quote Link to comment Share on other sites More sharing options...
Guest Mike Posted November 2, 2006 Share Posted November 2, 2006 Tony D... I'll look for the lightest internal components I can find/afford for my 434 build that will stand up to the HP/torque/RPM's specs. Correct me if I'm wrong but V12 and L6 crankshafts need less counterweight correction than any other designs due to their already well-balanced design. That's why they can rev up so quickly while not under load. Are you talking about the 4 or 6 cylinder VW motors? Quote Link to comment Share on other sites More sharing options...
johnc Posted November 2, 2006 Share Posted November 2, 2006 Less Mass * Same Force = Higher Rate of Acceleration Pretty simple if you ask me. Quote Link to comment Share on other sites More sharing options...
Guest Mike Posted November 2, 2006 Share Posted November 2, 2006 johnc... It is indeed a simple concept... like shaking a 1 ounce weight in your hand as opposed to a 20 pound weight:wink: My question references "how much" difference each change makes and why:grin: Quote Link to comment Share on other sites More sharing options...
2126 Posted November 2, 2006 Share Posted November 2, 2006 johnc... It is indeed a simple concept... like shaking a 1 ounce weight in your hand as opposed to a 20 pound weight:wink: My question references "how much" difference each change makes and why:grin: Well, John just answered the why......how much difference each change makes is just a matter of analysis and calculation. Tom Quote Link to comment Share on other sites More sharing options...
Guest Mike Posted November 2, 2006 Share Posted November 2, 2006 Okay... we all know the most basic concept of "why", which is explained nicely by the phyiscal laws of motion. I guess I'm posting with too much ambiguity I'm no mechanical engineer so I'll not persue mathematical theory or analysis. I just want bottom line numbers at the dyno and via quarter mile ET's. Before anyone mentions it, I realize varaibles such as ambient temperature, barometric pressure, and track conditions at time of testing will affect results. However, assuming I minimize these differentials, the real-world numbers should remain "relatively" unperturbed by these variances compared to the mechanical changes:wink: I'd like to know "how much" each component change will make and why its affect is substantial or miniscule:? Quote Link to comment Share on other sites More sharing options...
Sven Posted November 2, 2006 Share Posted November 2, 2006 A few years ago Muscle Mustangs & Fast Fords ran an article in which they tested flywheels, steel vs Aluminum. The idea was to look into the myth that a heavier flywheel is better for a drag racing launch (this is beyond anecdotal, it's just my memory). IIRC they got a 3 tenths 1/4 mi improvement from changing to the alum flywheel, on an almost stock Mustang. Sorry, but I have those magazines packed, or I'd dig it out (I'm moving). Quote Link to comment Share on other sites More sharing options...
Guest Mike Posted November 2, 2006 Share Posted November 2, 2006 Sven... Thanks for the post. I consider .3 seconds substantion if we're discussing a 12 second car but much less so with a 15 second car. Good luck with your move!! Quote Link to comment Share on other sites More sharing options...
JMortensen Posted November 2, 2006 Share Posted November 2, 2006 One .3 second reduction is not spectacular. But .3 here and .3 there start to add up. Light flywheel first, then light wheels next would be my suggestions. Those two things will make a huge difference. As Tony said, where the weight is is also important, which is why I haven't gotten around to a light driveshaft. It's such a small diameter piece that there are a lot of other places to lose weight before you go there. It's not one big thing that makes a car faster. It's a hundred little things. Quote Link to comment Share on other sites More sharing options...
olie05 Posted November 2, 2006 Share Posted November 2, 2006 So the ultimate setup would be a Lightened and fully balanced crankshaft, lightened pistons and rods, lighter harmonic balancer, light flywheel with a 5" clutch, CF driveshaft, 10lb wheels... I'm sure you would notice a huge difference after all those mods now, I'm assuming cv's are lighter than the heavy U-jointed halfshafts, but I have heard that U-joints have less friction, so either one is ok? Quote Link to comment Share on other sites More sharing options...
Guest Mike Posted November 2, 2006 Share Posted November 2, 2006 Thanks JON. I may decide against the Dayton wire wheel replicas for my Alpha 1 and go with something much lighter. It's a tough decision though... I really like the Daytons!! RECAP... (please correct me if I'm misinterpreting): 1. Ultra-light wheels and flywheel can make a substantial difference in responsiveness and ET and are definitely worth the $$$ within reason. 2. Lightweight drive shafts/half shafts make some difference but not nearly as much as #1... not really worth the time/$$$ for most street applications?? 3. Lightweight internal engine components (mainly crank shaft and pistons)... somewhat ambiguous information thus far. Quote Link to comment Share on other sites More sharing options...
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