165MPHGT500 Posted January 19, 2013 Report Share Posted January 19, 2013 Anyone calculate HP increase with drop in ambient temperatures in the winter? 662 @ what temperature? Link to comment Share on other sites More sharing options...
440sprint Posted January 20, 2013 Report Share Posted January 20, 2013 Anyone calculate HP increase with drop in ambient temperatures in the winter? 662 @ what temperature? The 662 hp is at the crank with the engine on a test jig for SAE certification. It would be interesting to know the environmental conditions for the official certified measurement. SC'd engines don't depend on atmospheric pressure as much as NA engines. Temperature & relative humidity greatly affect the available oxygen for the most fuel combustion, thus power on both types. Atmospheric oxygen density is inversely proportional to both the temp & RH (but directly proportional to atmospheric pressure, think DA). I got my '13 GT500 on July 9th during LA basin's summer coastal weather, 80* avg temp & 40% avg RH. Now in Jan., the avg temp is 65* & avg RH Is 65%. Since SoCal summer/winter conditions offset each other, my engine power seems fairly constant using 91octane gas, so I mixed in 100 octane to give 93 octane. I could not even then discern any power diff! I'll report back if there is ever a cold & dry day here and I feel more power. IMO, without a sensitive dyno, power changes at the 662 hp level must be rather large to easily feel! Link to comment Share on other sites More sharing options...
svtkeith Posted January 20, 2013 Report Share Posted January 20, 2013 Dense cool air will give you more HP..like at sea level..how much more I would say in a high atl place like Denver you'll feel the diff..other than that like 440 sprit said at 600+ hp it'll be hard to tell anywhere else. Link to comment Share on other sites More sharing options...
2010KonaBlueGT Posted January 20, 2013 Report Share Posted January 20, 2013 Dense cool air will give you more HP..like at sea level..how much more I would say in a high atl place like Denver you'll feel the diff..other than that like 440 sprit said at 600+ hp it'll be hard to tell anywhere else. I'm at 6100' down here in Co. Springs. That equates to a 20% drop in HP from Sea Level. So my 750HP Whipple can only really give me 600HP up here in the clouds. And THAT is why dyno's have correction factors. So you are comparing apples to apples. I *think* the temp. correction factor on a dyno is 70d F. I say, I THINK. Ask one of the dyno guys around here and they should be able to give you the exact number. I know I noticed a HUGE difference in performance between up here in CoS to when I was down in Las Vegas (around 3,000-3,500' ASL iIRC). I can't imagine what it will feel like when I finally get out to the Coast. Phill Link to comment Share on other sites More sharing options...
svtkeith Posted January 20, 2013 Report Share Posted January 20, 2013 I'm at 6100' down here in Co. Springs. That equates to a 20% drop in HP from Sea Level. So my 750HP Whipple can only really give me 600HP up here in the clouds. And THAT is why dyno's have correction factors. So you are comparing apples to apples. I *think* the temp. correction factor on a dyno is 70d F. I say, I THINK. Ask one of the dyno guys around here and they should be able to give you the exact number. I know I noticed a HUGE difference in performance between up here in CoS to when I was down in Las Vegas (around 3,000-3,500' ASL iIRC). I can't imagine what it will feel like when I finally get out to the Coast. Phill Yeah the thin air more so than the cool or warm air really plays heck with the power output...nothing like sea level for that power. Link to comment Share on other sites More sharing options...
Husky44 Posted January 20, 2013 Report Share Posted January 20, 2013 I've got cool, dry, sea-level air here in Anchorage, but nothing else to compare it to, and no time on a dyno yet (maybe next spring when it comes out of hibernation). Butt dyno says it runs like a striped-ass ape. :D Link to comment Share on other sites More sharing options...
bergenfelter Posted January 20, 2013 Report Share Posted January 20, 2013 Kind of a catch 22 - cooler air = more HP = Goodyear G2's turn into hockey pucks Link to comment Share on other sites More sharing options...
Squirrel 007 Posted January 21, 2013 Report Share Posted January 21, 2013 SAE horsepower is calculated at 70 degrees fahrenheit at sea level. For every 10 degrees drop in temperature a normally asperated engine gains 1% in HP. A force fed, I.E. Super Charged or Turbo Charged, engine gains 3% HP per 10 degree drop. Again these values are calculated at sea level. Higher altitudes have a gain in available horsepower that is proportional, which from the start is below SAE because of the altitude. Hope this helps. Link to comment Share on other sites More sharing options...
denohew Posted January 21, 2013 Report Share Posted January 21, 2013 The tires won't handle cold weather! I was racing a Camaro and I broke loose at about 100 in third. Scared the sh** out of me! Took luck and a little skill not to kill myself! The stock tires suck in the cold! Watch out! denohew Link to comment Share on other sites More sharing options...
SVT NAJA Posted January 21, 2013 Report Share Posted January 21, 2013 The tires won't handle cold weather! I was racing a Camaro and I broke loose at about 100 in third. Scared the sh** out of me! Took luck and a little skill not to kill myself! The stock tires suck in the cold! Watch out! denohew denohew, How cold was it when this happened? Link to comment Share on other sites More sharing options...
mullens Posted January 21, 2013 Report Share Posted January 21, 2013 The tires won't handle cold weather! I was racing a Camaro and I broke loose at about 100 in third. Scared the sh** out of me! Took luck and a little skill not to kill myself! The stock tires suck in the cold! Watch out! denohew Says it right in the manual. Driving 40* and below is hazardous. Link to comment Share on other sites More sharing options...
662HP631TQ Posted January 22, 2013 Report Share Posted January 22, 2013 The tires won't handle cold weather! I was racing a Camaro and I broke loose at about 100 in third. Scared the sh** out of me! Took luck and a little skill not to kill myself! The stock tires suck in the cold! Watch out! denohew I disagree, they won't handle "Punching it" They will hook up if you drive civil. If you want to push the car and really do what it was designed for it won't stay put, but if you are just driving to get somewhere like any other vehicle it will be just fine! Link to comment Share on other sites More sharing options...
Ezareth Posted January 22, 2013 Report Share Posted January 22, 2013 The G2s break lose when punching it even when it is in the 50s. I broke lose and was at least at a 45 degree angle after I downshifed to third on the highway doing 70 when trying to pass someone and the temps were in the low 50s (this was in early November). The road was cool and dry and I wasn't expecting that at all. Thankfully the computer systems kicked in before I could even think to react and the car corrected itself. There are few situations where turning the traction control off in these cars make sense. Most of the accidents we see happening in these cars and corvettes and such are from people who think their reaction times are better than a computers. Link to comment Share on other sites More sharing options...
440sprint Posted January 22, 2013 Report Share Posted January 22, 2013 Since it is OXYGEN that Trinity needs, think about these three important parameters (atm pressure, air temp & relative humidity) this way: > More atmospheric pressure causes all air molecules to pack closer together, giving more available oxygen molecules per unit air volume. This is the magic given our engines by our SC's! >Higher temperature thins all available air molecules, providing less oxygen per unit air volume. This is somewhat offset by our SC's intercooler. >Higher relative humidity means more water molecules in the air, thinning out all other gas molecules, including oxygen. All hail cold & dry sea level air! If interested, try this DA calculation method to normalize atmospheric conditions for power/speed comparisons at different locations or times: http://www.dragtimes.com/da-density-altitude-calculator.php Link to comment Share on other sites More sharing options...
165MPHGT500 Posted January 24, 2013 Author Report Share Posted January 24, 2013 Thanks to all for feedback. What I suspected is somewhat confirmed given your replies. Temperature here at sea level was mid 40's going home one night. Expect humidity was low. My beast would not hook up at 65 MPH in third or fourth gear. The tires they spun. She's a lot friskier in cold dry weather. I suspected she was easily producing > 700 HP. Big difference from summer time mid 90's and 50%+ humidity. Thanks again for feedback, Jeff Link to comment Share on other sites More sharing options...
SVT NAJA Posted January 24, 2013 Report Share Posted January 24, 2013 Jeff, If you still have the Goodyear F1 - G:2's on your GT500, they're part of the hook-up problem with temps in the mid-40's... Link to comment Share on other sites More sharing options...
165MPHGT500 Posted January 24, 2013 Author Report Share Posted January 24, 2013 Thanks NAJA. I've been reading the tire threads too . . . I just can't afford a $1000 + right now for new shoes. I have to wait until I burn these off. LOLAL. Link to comment Share on other sites More sharing options...
03reptile Posted February 8, 2013 Report Share Posted February 8, 2013 I disagree, they won't handle "Punching it" They will hook up if you drive civil. If you want to push the car and really do what it was designed for it won't stay put, but if you are just driving to get somewhere like any other vehicle it will be just fine! OK, I've read enough. The stock Goodyears are a "Summer Only" tire. Door post warns you of that. Using the Goodyears when temps go below about 50 degrees is courting disaster....Period. What most of you seem to miss is the STOPPING distances INCREASE due to lack of traction caused by the change in the summmer tire rubber chemestry. That's more dangerous then worrying about "hooking up". Also when you push it around a corner, the summer tires are going to slide due to their lack of traction. Bottom line.. Don't drive during the winter on summer tires. I don't care how careful you are, if something sudden happens, you're going to slide in and join the fun. Incidently, there is a TSB on the Goodyears warning owners about the tires cracking on the side when used in cold weather. Do what you want, but don't say you've not been warned. I drive mine in Md winters if its clear and dry, but I also bought all season tires back in September. I have no issues to date. Link to comment Share on other sites More sharing options...
662HP631TQ Posted February 9, 2013 Report Share Posted February 9, 2013 OK, I've read enough. The stock Goodyears are a "Summer Only" tire. Door post warns you of that. Using the Goodyears when temps go below about 50 degrees is courting disaster....Period. What most of you seem to miss is the STOPPING distances INCREASE due to lack of traction caused by the change in the summmer tire rubber chemestry. That's more dangerous then worrying about "hooking up". Also when you push it around a corner, the summer tires are going to slide due to their lack of traction. Bottom line.. Don't drive during the winter on summer tires. I don't care how careful you are, if something sudden happens, you're going to slide in and join the fun. Incidently, there is a TSB on the Goodyears warning owners about the tires cracking on the side when used in cold weather. Do what you want, but don't say you've not been warned. I drive mine in Md winters if its clear and dry, but I also bought all season tires back in September. I have no issues to date. Let me give you a little context pal.... I live as far South in Texas as you can live for one. Also, if you take a calculated risk and are cognizant of road conditions and take care and are cautious you will be fine. I drove in 46 degree rainy whether for 4 1/2 hours with NO problem. I agree to be smart and understand what something is designed for. BUT IN MY EXPERIENCE, you will be just fine. Snow....I wouldn't do it. Rain....colder weather... I think you will be fine. The probalem is folks want to punch this car ALL THE TIME.... and never drive civil. TO SUM IT UP THIS IS MY experience and I'm not that good of a driver. I know how to be easy on the clutch and gas though. These tries are NOT for spirited winter driving, but if you are going to the grocery store to buy a gallon of milk and you can stay out of boost and off the accelerator....You should be fine! Link to comment Share on other sites More sharing options...
03reptile Posted February 9, 2013 Report Share Posted February 9, 2013 I would agree that if you drive sensibly for conditions, you might be OK. Still doesn't negate that your stopping distances will increase and if some bozo pulls out in front of you or some other similar scenerio, & you have to do a panic stop, you're more likely to have an accident. Thats a scientific fact given the chemical composition of a summer only tire. You could do the same with balding tires, taking it easy & you'de probably be alright. I would always counsel others to err on the side of caution & get a set of A/S tires to be safer. Granted you are always tempted to utilize the power of this car when driving & your common sense should prevail; however, your advise that "you'll be just fine" doesn't take into consideration things you can't predict or control. Taking chances is everyone's perogative. I choose to put the odds on my side, whenever possible. Link to comment Share on other sites More sharing options...
165MPHGT500 Posted February 12, 2013 Author Report Share Posted February 12, 2013 It's all about respecting the horse power of this beast regardless of conditions. Thanks again. Link to comment Share on other sites More sharing options...
jnf Posted February 12, 2013 Report Share Posted February 12, 2013 ^ Couldn't agree more. Link to comment Share on other sites More sharing options...
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