actually i was getting about 31-33mpg driving between 65-80mph

 

windows down most of the way also

 

did 900 miles over the 4 th weekend, 15 1/2 city, 22 hiway mountans and flat land, A4- 3500yank,3.23 gear, 231/237 STOCK HEADS

 

I have the g5x4 and last week I went racing and I still ended up with 20mpg. On the freeway I get low 30's.

 

TSP 231/237, 3800stall, 3.23 gears at or slightly above 20mpg, Hawaii is all "city" driving! Cant wait to take a long stretch of road tour though.

 

i am getting about 12-15mpg in the city, and about 20-22mpg with FMS's 236/239 rj cam. but it is also untuned with an exhaust leak

 

1999 c5 m6 4.10 228/230 xer 232ccheads

24mpg mixed

 

227/231 cam, AFR 205 heads. Just got 31mpg over the weekend on a 2 hour trip; only 200 miles on the new motor too.

 

Some of you guys need to learn how to figure gas mileage...Because there is no way that you guys are pulling down 30+ mpg modded, when stock the LS1/LS6 will not get that kind of mileage...

This thread reminds me of a fishing story...The more times it is told and the longer it goes on...The bigger the fish gets...

Not sure where some of you are getting this great gas mileage from...But I wish you would let the rest of us in on your secret way of holding the gas pedal so we could all save a little money...

Peace...Gman

 

Not necessarily.

My gas milage went up after doing intake exhaust and headers (tuned) thanks to the increased efficiency of the engine.

Whats more, people with good sized cams bleed off a lot of compression at lower rpms, wich means less air fills the cylinder, and with less air, you add less gas. Comparing my VE tables from stock internals vs. my f-13 cam and you can really see the numbers fall off under 2500 rpm. With a gentle foot and good gas (non ethanol mixed) I could see people touching 30 MPG being well modded.

 

Well, I'm running a G5X3 and I did not see 4+ mpg increase in my mileage in the 2500 rpm range and under...

Whether your VE table is adjusted or not...Even if a VE table is off, the Ltrims will adjust for it...I have my tune dialed in to the point where my Ltrims are between -1 and -3 percent at all cruising rpms...Basically running very near the perfect 14.7 A/F ratio...

Which we all know is the stoic. value that everyones engine is going to run at if they are still using the MAF sensor...

Well, I guess we will just have to leave it at the, If you all say you are getting 30+ mpg after adding a big duration cam, well more power to you all...

But my 234/238 duration cam likes gas...Not fish stories...25 mpg or so @ steady 70 mph...

Peace...Gman

 

Agreed. But realize that you dont have a big cam, you have a REALLLLY big cam. If you can get 25 MPG out of a 234/238 monster, Id say thats as amazing as those that are getting 30 out of the more docile bumpsticks. I should have stated that in my opinion, increasing the cams size and overlap, bleeding off compression does not absolutely increase low rpm gas milage, if you go to far, im sure it drops off again. Theres probably a sweet spot that a few pwople have stumbled upon. Unfortunately I havn't stumbled on it, but all things considered, I as well as yourself should probably be pretty happy with mid twenties.

 

No doubt...I'll take the 25 mpg that I get...I just don't see the high mpg #'s that alot are getting, when stock, I would only get 27 mpg @ 70 mph...To gain 12% in fuel economy AND gain hp is quite a major feet...

I just don't see those numbers in my real world driving...And the original poster is asking "230 cam and above guys"...That's what is really perplexing to me...Very big cam and still improving mpg by 4+ mpg...

Peace...Gman

 

232/228, 16mpg. half city and half hwy

 

230/224 111lsa I get 14mpg around town. If it's all highway, I can pull off 22-23mpg if I'm lucky

 

242/249 110lsa just got back from a trip to austin...on the way up averaging 70-75 mph got 31 mpg. coming back from austin averaging 85-90 got 19 mpg. gotta love the double overdrive

 

I haven't driven the car enough with the heads and 30lb injectors, but with the cam 232/240 I would still average 32-35 on the highway.

I used to make the trip from Jacksonville N.C. to my house in North Port Fla and checked it several times. Before the cam I would get about 38mpg.
I drove a constant 80-85 the whole time and A/C on and off.

 

OK...Now this is getting interesting...

38 mpg driving 80~85 mph...

Are you sure you didn't have your speedo set for Kilometers???

Is North Port Fla. 10,000 feet lower than Jacksonville N.C.??? And you just put the car in nuetral and coasted???

Because that is the only way you got 38 mpg...

This just gets better and better...The fish just grew by another few inches...

Peace...Gman

 

I got over 500 miles on a tank of gas while making one of the trips.
In 6th at 80-85 the car is at like 17-1800 rpm's. I set the cruise and ride, I put 75,000 miles on the car in 3 years. Making the NC-FL trip several times.

 

I owned an '00 FRC before the Z...And stock it would pull down about 28 mpg with the cruise set at 70 mph, strickly highway driving...

The only way I would see 38 mpg on the DIC is when I would be in 6th gear driving 45 mph...At 80 mph, I would see about 24~25 mpg...

Peace...Gman