viven44 Posted March 24 Share Posted March 24 about correct on range. with the 300 I'm getting almost 14 but with 32/11.5/15s. that is with c6 and 3.08 gear. now it is 4.10 with overdrive and rpm is at least 400 less at 70 so I'm trying tuning, drive style to see how much better I can get. but I'm always driving different vehicles while my personal truck sits for weeks. Thats really good. I'm stuck at about 8mpg with my 460 in the city with 3.06 gears :) Link to comment Share on other sites More sharing options...
ArdWrknTrk Posted March 24 Share Posted March 24 Thats really good. I'm stuck at about 8mpg with my 460 in the city with 3.06 gears :) I can get 12 hwy with 4.10's and a Zf-5. Always 10 in town. My 4wd truck's tare weight is 6270 and it has a lumber rack. Hard to imagine that a 2wd w/ 3.06 can't do better. I suppose that says a lot about the C6's ability to turn torque into heat? Link to comment Share on other sites More sharing options...
emunder Posted March 24 Author Share Posted March 24 I can get 12 hwy with 4.10's and a Zf-5. Always 10 in town. My 4wd truck's tare weight is 6270 and it has a lumber rack. Hard to imagine that a 2wd w/ 3.06 can't do better. I suppose that says a lot about the C6's ability to turn torque into heat? Mines not doing too bad then with the DSII swap and new carb. Have the NP435 w/ 33’s and 3.08 gears. Getting right around 14 MPG. I need to get my speedo gear sorted out though, clocks in abt 7-8 miles slower than I’m actually going. This week I’ll probably pull it out and see what color it is and L/R gear orientation. Link to comment Share on other sites More sharing options...
ArdWrknTrk Posted March 24 Share Posted March 24 Mines not doing too bad then with the DSII swap and new carb. Have the NP435 w/ 33’s and 3.08 gears. Getting right around 14 MPG. I need to get my speedo gear sorted out though, clocks in abt 7-8 miles slower than I’m actually going. This week I’ll probably pull it out and see what color it is and L/R gear orientation. You can use the speedo gear calculator, here on the site. If you have a GPS speed, or distance from your phone. 💡 Link to comment Share on other sites More sharing options...
mat in tn Posted March 24 Share Posted March 24 You can use the speedo gear calculator, here on the site. If you have a GPS speed, or distance from your phone. 💡 mine has always gotten between 12 and 14 since I bought it. a bit worse when pulling a trailer full of shingles or whatever. as far as range the best it ever did was 260 plus one time when I was trying to be extra careful and go as far as I could. but that was certainly not the norm. heat generation is an absolute waste of stored energy yet a loss that cannot be eliminated. reduced is all. my biggest issue is keeping the speed down. its so hard to do. Link to comment Share on other sites More sharing options...
viven44 Posted March 24 Share Posted March 24 I can get 12 hwy with 4.10's and a Zf-5. Always 10 in town. My 4wd truck's tare weight is 6270 and it has a lumber rack. Hard to imagine that a 2wd w/ 3.06 can't do better. I suppose that says a lot about the C6's ability to turn torque into heat? Does the gearing matter a whole lot in the city (I know I made it a point to mention gears but wondering) ? I assume you would always be on the proper gear to keep between 1-2k rpm. On hwy the advantage is clear. In fact I think you are more likely to be able to pull at lower RPMs in the city with a 4.1 vs 3.06 I miss "Big Red" 460/T-19/4.1... I was driving city all day at barely over 1K rpm Link to comment Share on other sites More sharing options...
emunder Posted March 24 Author Share Posted March 24 You can use the speedo gear calculator, here on the site. If you have a GPS speed, or distance from your phone. 💡 Thx ArdWrknTrk…I’ll check out that calculator for sure. I have a MPH app on my iphone that works well. Link to comment Share on other sites More sharing options...
emunder Posted March 24 Author Share Posted March 24 Does the gearing matter a whole lot in the city (I know I made it a point to mention gears but wondering) ? I assume you would always be on the proper gear to keep between 1-2k rpm. On hwy the advantage is clear. In fact I think you are more likely to be able to pull at lower RPMs in the city with a 4.1 vs 3.06 I miss "Big Red" 460/T-19/4.1... I was driving city all day at barely over 1K rpm I’m fine driving anywhere in the City as far as my gearing. The only time I have a slight issue is getting up to speed on the highway. The NP435 is strange in the sense that 4th gear has a high gear. So even if I rev out third once I shift to 4th it kicks in at a really low RPM so it takes a sec to get up to highway speeds. Must be the way these tranny’s are, I just had mine checked internally and new clutch, flywheel, ect installed about a week ago. Link to comment Share on other sites More sharing options...
Gary Lewis Posted March 24 Share Posted March 24 Thx ArdWrknTrk…I’ll check out that calculator for sure. I have a MPH app on my iphone that works well. The calculator is at Documentation/Driveline/Calculator. Link to comment Share on other sites More sharing options...
mat in tn Posted March 24 Share Posted March 24 I’m fine driving anywhere in the City as far as my gearing. The only time I have a slight issue is getting up to speed on the highway. The NP435 is strange in the sense that 4th gear has a high gear. So even if I rev out third once I shift to 4th it kicks in at a really low RPM so it takes a sec to get up to highway speeds. Must be the way these tranny’s are, I just had mine checked internally and new clutch, flywheel, ect installed about a week ago. gear ratio is a major factor. often misunderstood. I try to consider total gear ratios meaning the gear ratio of the axle multiplied by the gear's ratio of the trans. 4.10:1 gear multiplied by a manual shift 1:1 fourth gear is a good starting point. that converted to an od of .70 is equivalent to a 2.87:1 final gear. now consider the other end of the scale. if first gear is 3.0:1, multiplied by that same 4.10:1axle then the total first gear ratio is 12.3:1. to put in perspective. a c6 with a 2.46 first gear and a 1.1 third through a 3.00 gear axle would be a total first of 7.38 with a third of 3.0 plus hydrostatic loss. this would be a typical f250 of the early 80s. also when the national speed limit was 55. rolling down the highway about 1750 rpm. today that same truck is doing 2700rpm trying to save face among the average camry crowd and running a bit above the efficiency of the 2barrel. Link to comment Share on other sites More sharing options...
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