When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
I purchased my 2011 grand sport this past may, and the car is amazing , best car I ever owned by far.
The car has a vararam air intake, Nick William 102 mm throttle body, fast 102 , Titan 1 cam from cam motion (considered a baby cam, very mild) American racing headers 1 7/8 and high flow cats on the stock 2.5 inch pipes. (470+ RWHP)
Ever since I bought the car it got very bad city mileage , most of my driving is city and im averaging 125 to 150 miles (200 -250 kms) per tank which to me is abysmal compared to my last vettes.
Highway Is a lot better , I can get 300-350 miles per tank, still slightly lower then expected but liveable.
Im starting to realize that for such a mild cam, this seems very extreme, is something wrong with the tune ? or what could be causing this?
Number one....check your actual mileage not guess. 2nd check the other obvious things like air filter, tire pressure, is it running pig rich etc... etc..Most of the mods described on your car should not adversely affect the gas mileage imo. Also assess your driving habits...honestly. The go pedal has the most affect. As others gave said getting 350 miles on the highway says it isn't off much. I get that in the winter in rural driving here in SC.... I fill mine at the first chime and most of the time a little over 15 and less than 16 gallons...In the winter average is 360 to 370 that is close to 23. In the summer I have achieved 400 to 410 several times...
Good luck...Hopefully you're just enjoying the fruits of those mod by using the go pedal.
Agreed. Driving habits and tune also make a difference. The cam might make you drive more aggressive. That said, the numbers dont seem that bad.
Im not driving very aggressive, I do have fun with the car but nothing crazy , its my third vette so I feel I have a pretty good idea of what they should be getting and im not anywhere near there in the city driving.
Im also wondering if it needs a re-tune
Thanks for the reply
Originally Posted by hawkgfr
Number one....check your actual mileage not guess. 2nd check the other obvious things like air filter, tire pressure, is it running pig rich etc... etc..Most of the mods described on your car should not adversely affect the gas mileage imo. Also assess your driving habits...honestly. The go pedal has the most affect. As others gave said getting 350 miles on the highway says it isn't off much. I get that in the winter in rural driving here in SC.... I fill mine at the first chime and most of the time a little over 15 and less than 16 gallons...In the winter average is 360 to 370 that is close to 23. In the summer I have achieved 400 to 410 several times...
Good luck...Hopefully you're just enjoying the fruits of those mod by using the go pedal.
Air pressure is good but my air filter could very well be dirty
Its a vararam and I cant figure out how to get the damn thing out to check
I am forsure having fun with it though, that's why I haven't said nything in the 6 months ive owned it, but now that its down for the winter im starting to make a plan for the spring
Im glad to hear that im getting normal highway driving , its a shame most of my driving is in the city though
It's been 3 years since I owned a Vette with a Vararam but iirc there should be two clips on the opposite end of the "snorkel" that allow you to pick up and remove the filter. Due to the filter being placed damn near in the bumper they are known to get dirty very easily.
I have a 2013 GS which is supercharged and makes 500HP at the wheels along with an A6 transmission. On the highway running 75-85 and with spirts higher I get around 21 or 22 MPG. I have never really checked or been concerned about mileage while just hopping around town. At the end of the day, who cares about mileage. Have fun and fill her up as needed!!!
i seem to get about 16mpg whether im in the city or the highway, which is about 240 miles per tank. i have a 468 with 25x/26x camshaft. your around town is crazy low and highway seems reasonable.
I have a 2013 GS which is supercharged and makes 500HP at the wheels along with an A6 transmission. On the highway running 75-85 and with spirts higher I get around 21 or 22 MPG. I have never really checked or been concerned about mileage while just hopping around town. At the end of the day, who cares about mileage. Have fun and fill her up as needed!!!
I recently changed the filter in my Vararam for first time. The car is a 2008 Base Vert 6AT. You must remove the two bolts holding the filter to the radiator shroud, the MAS, and the clamps holding the air intake to the engine. When all is loose, just pull straight out, a lot harder than you would expect. The large hose clamp holding the filter tends to catch on the radiator shroud. Just wiggle it and pull hard and it will come free. Once out, it is simple to clean, refill, and reinstall. Good luck!
It's been 3 years since I owned a Vette with a Vararam but iirc there should be two clips on the opposite end of the "snorkel" that allow you to pick up and remove the filter. Due to the filter being placed damn near in the bumper they are known to get dirty very easily.
Originally Posted by OkieTim
I recently changed the filter in my Vararam for first time. The car is a 2008 Base Vert 6AT. You must remove the two bolts holding the filter to the radiator shroud, the MAS, and the clamps holding the air intake to the engine. When all is loose, just pull straight out, a lot harder than you would expect. The large hose clamp holding the filter tends to catch on the radiator shroud. Just wiggle it and pull hard and it will come free. Once out, it is simple to clean, refill, and reinstall. Good luck!
thanks guys, ive been told there also a rubber gasket around the flter which is hard to get out and put back in , im going to try this winter while the car is down, im sure it will need a good cleaning, hope that helps a bit.
Originally Posted by TrendSetter
i seem to get about 16mpg whether im in the city or the highway, which is about 240 miles per tank. i have a 468 with 25x/26x camshaft. your around town is crazy low and highway seems reasonable.
crazy low indeed, im surprised many people are saying it sounds normal
If it was just tuned on a dyno, a good street tune will pay off in better economy. Some tuners spend very little time actually tuning for economy and drivability. Just tune mainly for the impressive dyno number. Any tuner worth his weight will tell you that tuning for power is the easiest part of the tune.
You have the heaviest of all the C6's. That and the fat/heavy tires and rims a GS uses will have a negative effect. And 6th gear on a Grand Sport has your engine turning faster at cruise than a base C6 or Z06.
What kind of engine coolant temps are you seeing? If the previous owner installed a 160* stat, you're going to see worse MPG numbers in cool temps as the engine never gets up to operating temp.
I have a bigger cam than yours and usually get mid 20's on the highway (closer to 30 if I'm forced to drive 60) and high teens low twenties in mixed driving. I'm lucky enough not to have to do any pure city driving any more.
Also, If you're seeing 470rwhp, you have a much bigger cam than a Titan 1 (217/225 114LSA). That small of a camshaft isn't going to make 470rwhp without a whole lot more tricks added than what you have listed in your first post.
Last edited by old motorhead; 12-11-2019 at 10:47 PM.
12-11-2019, 11:29 AM
Horrible gas mileage on modded Grand sport
As others gave said getting 350 miles on the highway says it isn't off much. I get that in the winter in rural driving here in SC.... I fill mine at the first chime and most of the time a little over 15 and less than 16 gallons...In the winter average is 360 to 370 that is close to 23. In the summer I have achieved 400 to 410 several times...
