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THESE NUMBERS DON'T MAKE SENSE
March issue of MOTOR TREND has an article (page 68) on the CAMARO SS 1LE and the Mustang GT Track Pack.
The article indicates a gross weight of 3860lb for the 1LE, about 10 lb heavier than the "standard" SS. Yet the 0-60 acceleration figure indicated is 4.3s which is about 0.3 or 0.4 seconds quicker than other SS samples previously measured by the same magazine these past years. Equally, the 1/4 mile came down some 0.2 or 0.3 seconds faster than previous SS coupe models (tested over the past three years by the same publication) at 12.7 seconds while going 111.8 mph at the quarter mile mark (about 3 mph faster) The engine specs and drive train remain the same : standard LS3 with same HP and Torque output connected to the six speed Tremec. The final drive ratios remain about the same 1.96:1. I noticed however that the axle apparently went down to 3.91:1 while previously was reported at 3.45:1 This however, would not account for the improved acceleration figures which are one third of a second. I waited, thinking than someone will catch this up an bring it forward in the forum but I did not found any such entry (if I missed it then my apologies) so I'm bringing it in now. MT usually is very meticulous in their test data gathering process and in the figures they publish, so except for an error on their side (and a significant one this time, I must point out) there has got to be some extra oomph in the new 1LE. But, from where is it coming??; as that model is heavier while having the same powerhouse and tranny than a regular SS, how come the acceleration figures are so markedly quicker????? Has GM stated the 1LE was intended to achieve better acceleration figures than regular SS cars?? I thought this model was supposed to introduce changes only in suspension dynamics and driving response for track use. Anyone care to elaborate? :noidea: The Flash |
You already caught the fact that the 1LE has a 3.91 ring and pinion, but the 1LE also has a different version of the TR6060 transmission which has close ratio gears for 1st thru 4th. Combine that with rear tires which are both wider and stickier, and you have your answer.
On my last Camaro, going from 3.45 gears to 4.10s gave me 3 tenths by itself. |
Also adding the forged wheels saved rotational mass. This too adds to performance numbers. You answered your own question. Lighter wheels, stickier/wider tires and the gear ratio changes add up to the additional acceleration. Other changes include heavier duty wheel bearings which could also offer less resistance. Hard to say exactly where the new found speed comes from as it is probably a combination of it all.
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And if you look at the people that have had their 1LE dynoed the stock 1LE's are putting down some impressive numbers.
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Although small. A change from hydraulic power steering to electric will remove some parasitic loss from the engine. Combine that small number with the NPP dual valve exhaust which is worth 6hp peak on the Corvette and the 13 should have picked up a few HP there. (6-10?)
Matt |
What's your source on this tranny info?
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@JeffInDFW: Thanks for your input. I not only agree that a substantial pinion gear aspect change like the one you indicate (getting a reduction from 3.45 to 4.10) will produce an equally substantial improvement in acceleration figures, in fact I have actually experienced such effect first hand in my Pontiac FIREBIRD. However, the ratio change from 3:45 to 3:91 is not enough, in my experience to yield a third of a second in 0-60 times, let alone in the quarter mile, all other factors remaining the same. It surely can ad from two to three tenths of a sec at the 0-30mph / 0-40mph range, but as speeds goes up the gain is further diminished. A 0.2 secs quicker time at the 0-30mph will cut down to 0.1 by the 60mph mark; at the moment the vehicle reaches 110mph (around the quarter mile distance) it will be about 0.08 - 0.07 secs or even less since other detracting factors increase their effect in a non linear manner as speed grows, such as rolling resistance from drive-train components and aerodynamic drag just to name two of them. The one thing which you mention that can possible explain the results published in MT would be a revised TR6060 tranny yet I do not seem to have read anywhere that GM had an altered or different version of this transmission for the 1LE models as you indicate. If they indeed are offering a different tranny for the 2013 1LE then I assume it would have figured out prominently by GM in the promotional material about the car and in its debut, pointing out the differences in the transmission components, manufacturing tolerances and/or design, but I did not see such advertising. Can you clarify where did you get the info on the revised Tremec TR6060 so I can go check on that??? As for the wider tires influence in these results, while I agree that the standard tires in the SS are lacking I strongly differ as to the magnitude that the tire package offered in the 1LE has in achieving its quarter mile gains; it will represent at best a few tenths of a sec, not even a full sec. Once up to optimal operating temp the Pirelli Zeros are not too shabby at all. If GM got a different transmission for the 1LE coupled wth a more aggressive differential then that could begin to explain these figures. If so, I might be inclined to consider the value of purchasing a 1LE tranny to replace the original one on my SS. All things considered it might prove a better and safer investment to obtain quicker accelration than pursuing aftermarket mods. The Flash |
Flash, go to this thread:
http://www.camaro5.com/forums/showthread.php?t=270792 and you will see a link to a PDF that indicates the transmission gearing difference in the 1LE transmission vs. the SS transmission. The 1LE gearing does take away some of the advantage of the bigger rear end gear. Keep in mind that the gearing change was to help the car on a road course, not a drag strip. That being said, the video I have seen of the 1LE vs SS shows an extra shift required by the 1LE to get through the end of the 1/4 mile, so there is still some advantage to the larger gear. I would assume that the larger tire is allowing for a harder launch, which will carry through the entire 1/4 mile. I also assume that the lighter rolling weight with the ZLI style wheels is also a bigger benefit than you are giving them credit for. |
We're talking full 3 secs!!
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@newb: I beg to differ on answering my own question. You are entirely right in that a reduction in rotational mass (or unsprung weight, as I grew up calling it) creates an sizable improvement in acceleration and deceleration (stopping, changing direction) of an automobile. The different wheel bearings (which I did not know about, thanks for the info) add bits here and there too. I come from the same school. I have been successful racking up improvements that seem unattainable in my other (and previous) pony car, an unassuming normally aspirated V6 with which I have shamed a large number of V8 MUSTANGS of its same era, so I value and accept what you are pointing at. Yet to achieve just 2 full secs of 0-60mph quicker times required a large number of substantial modifications to very many major components in the vehicle, also representing a cost figure well above ten grand! Here, the 1LE purports to achieve about 3 full secs in the 0-60mph and the quarter mile stretch with the same powerhouse (no tweaks to the LS3) and the same transmission (although JeffInDFW believes a different transmission is sourced for the 1LE which I think is m the best bet for an explanation). Again, even though I agree with your point that a combination of several components factors in to achieve better improvements, the issues that we have discussed so far in this thread are not, IMHO, to justify the huge gap in the results posted. I'm beginning to wonder (more like suspect) if MT was actually handed either a close controlled manufactured vehicle (special one offs in which a crack team from the factory work the whole assembly line process to achieve 100% of the intended design tolerances and specs) or a test ringer by GM for that comparison article. The Flash |
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Thanks Dropspeed: Now we are getting a bit closer : reduced demands on the engine (no loss from a hydro pump as the assistance to steering is replaced by servos) plus a freer flowing exhaust. Still not enough to account for three secs, yet as newb pointed out, it all adds up. Yet I feel there is something amiss. Safe driving! The Flash |
Flash, What do you mean "We're talking full 3 secs!!"?
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1LE Transmisison ...
RPO MG9 Trans Name Tremec 85mm First 2.66 Second 1.78 Third 1.30 Fourth 1.00 Fifth 0.79 Sixth 0.63 http://www.vibratesoftware.com/html_...nsmissions.htm Also for drivetrain check ... http://www.gmpowertrain.com/VehicleE...nProducts.aspx 0.63 |
Just got a build date on my 2013 + 2SS + 1LE + RS + Performance Exhaust 6 speed manual ... 5/13
Can't wait to see the difference between it and the 2012 2SS |
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The MT articles indicates times 3 seconds faster for the 0-60 the time vs speed test and the quarter mile test as well. :noidea::noidea::noidea: The Flash |
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