Phantom Posted January 27, 2006 Share Posted January 27, 2006 Mike Kelly, Sounds like your 'vette has an accurate computer which is not what I've experienced. I've had them in a mini-van, jeep, and now a suburban and they all errored high compared to actual calculations. Those were/are totally stock so no induced errors from oversized tires or changed gear ratios. I guess that is one of the uupgrades you get on a 'vette for the extra $$$? The worst mileage I've gotten in my LS1 Z is 10 mpg the day I ran at Texas Motor Speedway although that was mitigated a bit by higher mpg on the 30 minute drive there. The best is 24.5 cruising on the highway at 70 mph. It has the stock 75mm ECU and 28 lb injectors so that would account for it not being down around 8 like DaleMx has experienced with his. I challenged the MPG claims because, after 40+ years of driving, I know that most people don't take the time to really calculate it right. Now I know some on this board do. That's good to hear. Quote Link to comment Share on other sites More sharing options...
Mikelly Posted January 27, 2006 Share Posted January 27, 2006 I thought I saw about 8mpg at VIR last spring. I'm pretty sure most of the guys running with non-stock heads/cam are seeing 4-6 mpg at VIR. And Phantom, You suffer from the same thing I do. Doing the math and getting exact numbers for mileage is something I do on all my cars and trucks. Drives my wife nuts! Mike Quote Link to comment Share on other sites More sharing options...
gwheeler Posted January 27, 2006 Share Posted January 27, 2006 72 240Z with Mustang GT 5.0 HO and Mustang T-5, R200 3.36 diff running 225/50R16 tires. 30 mpg highway 25 mpg mixed Couldn't be happier! That's better mileage than my 2003 Mazda Protege5! Greg Quote Link to comment Share on other sites More sharing options...
Lewis Maudlin Posted January 27, 2006 Share Posted January 27, 2006 My last conversion was a SBC w/about 400 hp at the crank and a 700R4 tranny, 3.54 rear end. I got about 12 mpg with the way I drive. Read as foot always in the gas. My new conversion is an SR20DET, 5 spd, 3.54 rear end. Running 15 psi of boost with my foot always in the gas, I get 24 mpg. I think I would see 30 if I dropped the boost and accelerated gracefully from a stop. I am very happy with the SR20DET. It is a wonderful daily driver and should run a 12 second quarter. I have to get it dynoed soon, but it should have 275-285 hp at the wheels. Quote Link to comment Share on other sites More sharing options...
johnc Posted January 27, 2006 Share Posted January 27, 2006 12 to 15 gallons per hour. Quote Link to comment Share on other sites More sharing options...
BrandonsZ Posted January 27, 2006 Author Share Posted January 27, 2006 72 240Z with Mustang GT 5.0 HO and Mustang T-5' date=' R200 3.36 diff running 225/50R16 tires. 30 mpg highway 25 mpg mixed Couldn't be happier! That's better mileage than my 2003 Mazda Protege5! Greg[/quote'] For some reason, that gives me a reallly good feeling... something like "BITE ON THAT MAZDUH" But I never drove the Protege, I'm sure it's nice. They should put LS1's in the Protege and get better mileage. really. Quote Link to comment Share on other sites More sharing options...
crazy280 Posted January 28, 2006 Share Posted January 28, 2006 EPA mpg for a stock C5 with the 6speed is 19 city/ 28 highway, and EPA ratings have been proven to be overestimations...something is off here. Quote Link to comment Share on other sites More sharing options...
DeckSetter Posted January 30, 2006 Share Posted January 30, 2006 I don't know if I'd say EPA estimations are high, it varies a bit. I've driven a '94 Accord on a trip and it got 28mpg. I pulled 30mpg out of an '89 Delta 88 with a 3.8. It's all about the miles you drive. The Accord is taching almost 3 grand when the Delta 88 is around 2000 in overdrive. In the city the Accord would probably still be in the mid 20s and the Delta would drop to around 20. That's why C5's do so great on the highway, the .5 6th gear keeps them around 2000rpms at, what 75mph or so? That said, I drive mostly highway miles (sometimes 500-600 a week) and I got 29mpg on 3 straight tanks (shifting around 2500 most of the time) in my '82 ZX (n/a) this past fall. I've never got less than 23mpg, even layin rubber. I love the 21 gallon tank, I've topped 525 miles on a tank once, and over 500 another time. Quote Link to comment Share on other sites More sharing options...
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