# can MPG be improved by a performance tune?



## enjracing (Jun 7, 2006)

will a diablo or other performance tune help with MPG? i would think that it would as the a/f mixture is leaned. what have people discovered with that?


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## Groucho (Sep 11, 2004)

enjracing said:


> will a diablo or other performance tune help with MPG? i would think that it would as the a/f mixture is leaned. what have people discovered with that?


:confused 

I _gotta_ ask.

There seems to be a _lot_ of threads here reflecting your concern over the fuel efficiency of our cars and the fretting over the higher price of the premium fuel it requires.

When you purchased your car, you _knew_ you were buying a 3725 lb car powered by a 400 hp pushrod V-8 engine, _right_?

If one's primary concern is the number of miles you can squeeze out of a gallon of cheap gas, isn't this somewhat like obsessing over the best way to get a sheet of plywood in a Porsche Carrera S?


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## SJAndrew (Sep 28, 2004)

I have to agree with Groucho here.

I don't like paying anything for gas...but I feel awkward bitching about gas prices when I have a 6 liter V8 under the hood.


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## Walked (Jun 22, 2006)

I have to say I tend to agree. I'll bitch to some friends jokingly from time to time, especially the girlfriend who drives a Z3 with a 12 gallon tank that last longer than my 18 gallon tank 

Gas prices suck, low gas mileage sucks. But I'll be damned if it isnt worth it having one of the nicest cars on the road


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## 6QTS11OZ (Mar 27, 2005)

I think you guys are missing his point. I don't think he's worried, bitching or complaining about having a pig of a car with a big engine that gobbles fuel. He just want to know if a tune will improve on the gas mileage which really isn't too bad for a car with the weight and power that it has. Since our cars run rich, which in a sense is wasting fuel, you should get better fuel mileage once it's leaned out a tad. How much better? Not much probably. But anything is better than nothing.


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## Mickey21 (Jun 18, 2006)

Except for the fact that he has 5 threads started in the last couple of days obsessing over gas mileage and gas mileage related gains. Not counting the 2-3 gas pedal, gas tank, and weight reduction threads...

http://www.gtoforum.com/showthread.php?t=8288

http://www.gtoforum.com/showthread.php?t=8529

http://www.gtoforum.com/showthread.php?t=8517

http://www.gtoforum.com/showthread.php?t=8506

http://www.gtoforum.com/showthread.php?t=8475

Obsessing??? Maybe that word was a little too strong...

It's all good I guess...


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## ShoddyHog (May 17, 2006)

Mickey21 said:


> Obsessing??? Maybe that word was a little too strong...
> 
> It's all good I guess...


Have to agree with Groucho, and "obsessing" is not too strong. Sure, I'd love to get a 400 HP car that gets 50 MPG, but they all came with stickers in the window that says it is not going to happen.

I reset my computer today, drove from the airport in St. Louis to the dealer in Farmington, MO. It was 1:30 when I left...light traffic. I set the cruise on 70 most of the time, but bumped it up to 80 on I-55. I made sure to put myself into a position where I didn't have to use the brakes. Terrain is gentle, rolling hills, and the temp was 90+ and very humid. I hovered around 23 MPG the whole time with the A/C going, and I think that is frickin' phenominal for a fire breathing dragon. That is just barely below my 3.8 Bonnie. I'm not going to b!tch about that mileage.

I filled up this morning, and put in O-93. It took 15 gallons, and to put in O-89 I would have saved $1.50. I think I'll be putting the good juice in her most of the time, if not all.

Gerry


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## enjracing (Jun 7, 2006)

other than the 1 member, you are all jumping on my cae and missing the point. i really am not obsessing on it, i just like to know what is up since i am new to the car. i actually think the that the mileage it gets is phenominal. instead of getting on my case, how's about answering the question? that is why we are all here, correct? if this was a road-racing "driving" forum, i would help any of you guys out with whatever "obsessive" or what you deem as "useless" questions.


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## kwiktsi (Apr 5, 2006)

Not to beat a dead horse- but he also was specifically comparing his MPG with posts of people mentioning up to around 28mpg- now if people are claiming 26-28 mpg and the BEST I could muster was 23- regardless of what the sticker says, I would want to know how the hell they are doing it and why the hell mine isn't . I kind of got his point from the start, but I can see how it looks bad too..
Joe


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## kerno (Apr 6, 2006)

I think a performance tune will actually improve the mileage. I've had a tune done to a 2003 Lightning (I know, its the "F" word, but there were no GTO's in 2003), And found the drivability was really improved. I am going to have the 2006 goat tuned to get a baseline before I start the serious mods, so I'll be able to give more than a guess when I get it done. With that said, I am astounded at how good the mileage is, considering the performance level of the car. I've got a 1970 El Camino with a 572 in it. Ya know the one about "It'll pass everything but a gas station"? 10 mpg on a good day. I actually _*save*_ gas by driving the goat!!!


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## socal gto (Mar 10, 2006)

Hey kerno is there a tuner in the Los Angeles area that you would recommend? In about 2 months I will have my basic mods done and would like to get it tunes. I remmember a while back you posted something about alot of previous car experience and since you are relatively in the same area I was curious whom you would suggest.


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## UdnUdnGTO (Jan 30, 2006)

:willy: Internal combustion engines are not the most efficient means of travel. Most of our gas energy is wasted in heat. That is the way it is. Before we can truly talk about MPG and high power, we must address the short comings of the engine design itself. In other words, until we come up with something different to power cars, we got what we got. ENJOY. On the FUN MPG, I am getting well into the 50 miles per gallon. On the power acceleration, I get right around 49.5 FUN MPG. Attitude is what makes it worth it, not what we pay at the gas pump or in that little half circle on the right. Ya, ta, Hey!


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## tap goat (Jun 15, 2006)

There's also the factor of how the driver drives. Unless I'm feeling like flooring it, I usually keep it in a low RPM range, which means more money in my pocket  .


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## GNX231 (Dec 12, 2004)

*exactly *


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## AndrewZPSU (Jun 8, 2006)

This thread is rediculous. He wanted to know if the diablo sport or any other tune helps (at all) with mpg.

None of you have answered the question. The closest we got was from a 2003 Supercharged FORD.

I would like to know as well as I just got my car, 4 days later I got the diablo sport, and I really don't know what the mpg was before it.


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## enjracing (Jun 7, 2006)

thanks andrew..............serioulsy people. can you just answer the question?


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## raven1124 (Sep 23, 2005)

I did notice about a 1MPG gain after I had my tune with the Diablo. I average about 24.5 MPG on my three hour trips to my parents house.


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## 6QTS11OZ (Mar 27, 2005)

enjracing said:


> thanks andrew..............serioulsy people. can you just answer the question?


I thought I did :confused . Just Kidding! Once again I say, "Yes". I just don't know by how much. I had mine tuned and even though I didn't notice much in increased gas mileage, I know for a fact that it idles a hell of a lot better and is much smoother on acceleration.


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## ShoddyHog (May 17, 2006)

raven1124 said:


> I did notice about a 1MPG gain after I had my tune with the Diablo. I average about 24.5 MPG on my three hour trips to my parents house.


Can I ask how much that performance tune (or any others can reply as well) cost?

You saw a 1MPG improvement from a tune, so the calculation should be easy to make after that. It will be something like...you have to drive 10,000 miles with that tune to recoup the cost of the tune in gas savings.

Not saying that a performance tune isn't worth it...just trying to help enjracing to find the best approach for the goal.

Pardon my ignorance too...what is a "performance tune" vs. a Goat tuned to specs?

Gerry


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## ShoddyHog (May 17, 2006)

raven1124 said:


> I did notice about a 1MPG gain after I had my tune with the Diablo. I average about 24.5 MPG on my three hour trips to my parents house.


By the way...I know this is off topic, but I have to ask. Where did your avitar come from. That looks just like I'd envision The Trash Can Man from The Stand, a Stephen King novel...perhaps my favorite.

Gerry


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## raven1124 (Sep 23, 2005)

ShoddyHog said:


> By the way...I know this is off topic, but I have to ask. Where did your avitar come from. That looks just like I'd envision The Trash Can Man from The Stand, a Stephen King novel...perhaps my favorite.
> 
> Gerry


Never read to many of his novels, but I got it from a band called Megadeth. What can I say, I'm a metal head \m/

http://www.fanfire.com/cgi-bin/WebObjects/fanfire.woa/wa/product?sku=MDT38077


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## raven1124 (Sep 23, 2005)

ShoddyHog said:


> You saw a 1MPG improvement from a tune, so the calculation should be easy to make after that. It will be something like...you have to drive 10,000 miles with that tune to recoup the cost of the tune in gas savings.Gerry


Trust me, the last thing on my mind was good gas mileage when I got it tuned. Same goes for when I bought the car.


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## JoshieRoo (Jun 24, 2006)

I'm new but seen this thread and was thinking... I am just getting ready to buy the GTO and was surprised how GOOD the gas milage was. As compared to a new mustang GT with only a 4.6 liter that gets 17/25... Guess improving it is never a bad idea though.


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## ShoddyHog (May 17, 2006)

raven1124 said:


> Never read to many of his novels, but I got it from a band called Megadeth. What can I say, I'm a metal head \m/
> 
> http://www.fanfire.com/cgi-bin/WebObjects/fanfire.woa/wa/product?sku=MDT38077


I'm beginning to think you and I would get along just fine socializing...can't say I can list a half-dozen Megadeth tunes off the top of my head, but I love metal...I think seeing Judas Priest in Heidelburg, Germany was the turning point. I now have Sirius Satellite Radio, and listen to Buzzsaw (19), Octane (20), Alt Nation (21), and Hard Attack (27) when I can and depending on my mood. I also listen to a lot of classic rock, but I know how to get my blood a pumpin'.

In the novel The Stand, there is a standoff between "good" and "evil". At the end, the character "Trashy" emerges from the desert with a nuclear bomb. I recommend The Stand to everyone.

Gerry


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## ShoddyHog (May 17, 2006)

JoshieRoo said:


> I'm new but seen this thread and was thinking... I am just getting ready to buy the GTO and was surprised how GOOD the gas milage was. As compared to a new mustang GT with only a 4.6 liter that gets 17/25... Guess improving it is never a bad idea though.


Well, if my opinion is worth anything, it sounds like you are making the right decision. The fit & finish on this car is far beyond any I've purchased, and it has insane power when you want it...yet will average 18-20 even getting on it often. Driving in the city? Well, the mileage falls off dramatically, but it is a 400 HP Fire-Breathing dragon.

I'm at about 3500 miles, and can't wait until I get to drive her again. I've heard claims that she's "heavy" in turns, but I'm no racer. I downshift before a curve, and nail it half-way through, and she squats and pulls out of the turn like I'm going to just jump over the next few thousand feet. I guess that is the IRS I'm feeling...and it feels good.

Awesome power, wonderful craftmanship, and no major problems reported other than the "strut rub", but I got the 18" wheels...no problem.

And one of the most impotant things, IMHO...I can throw a grenade out on I-270 in St. Louis and take out a half-dozen Mustangs. They are a dime a dozen, but a Goat? You will own something special :cool 

Gerry


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## raven1124 (Sep 23, 2005)

ShoddyHog said:


> I'm beginning to think you and I would get along just fine socializing...can't say I can list a half-dozen Megadeth tunes off the top of my head, but I love metal...I think seeing Judas Priest in Heidelburg, Germany was the turning point. I now have Sirius Satellite Radio, and listen to Buzzsaw (19), Octane (20), Alt Nation (21), and Hard Attack (27) when I can and depending on my mood. I also listen to a lot of classic rock, but I know how to get my blood a pumpin'.
> 
> In the novel The Stand, there is a standoff between "good" and "evil". At the end, the character "Trashy" emerges from the desert with a nuclear bomb. I recommend The Stand to everyone.
> 
> Gerry


I love Priest too. They don't get the credit they deserve when it comes to being pioneers in metal. I used to have XM but they took off the metal station and I didn't renew my contract. Really pissed me off b/c that's one of the main reasons I bought the [email protected] thing.

I'll have to pick that one up. Sounds pretty interesting.

Oh, I would highly recommend Megadeth's Rust In Peace. That has to be best album I've ever bought and never get tired of listening to it.


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## sig229 (Sep 21, 2005)

You really shouldnt listen to Raven. He doesnt know what he is talking about. He wishes he had a torrid red GTO that unfortunately for him belongs to me!


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## purplehaze (Dec 27, 2005)

OK I have the Diablo tuner, and a rather nice exhaust system, and I must say the MPG has improved drastically. Now I can't give you an estimate on the whole 55 mph cause I maintain a 84 mph avg, and my mpg rate is steady around 24-25... Hope that helps :cheers


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## raven1124 (Sep 23, 2005)

sig229 said:


> You really shouldnt listen to Raven. He doesnt know what he is talking about. He wishes he had a torrid red GTO that unfortunately for him belongs to me!


Yeah, you wish. How's it going over there?


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## enjracing (Jun 7, 2006)

finally!!!!!!!!!! thanks purplehaze.


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## ShoddyHog (May 17, 2006)

purplehaze said:


> OK I have the Diablo tuner, and a rather nice exhaust system, and I must say the MPG has improved drastically. Now I can't give you an estimate on the whole 55 mph cause I maintain a 84 mph avg, and my mpg rate is steady around 24-25... Hope that helps :cheers


How much did that cost you?


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## purplehaze (Dec 27, 2005)

enjracing said:


> finally!!!!!!!!!! thanks purplehaze.



Finally I get to help someone in here... You are welcome:cheers


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## purplehaze (Dec 27, 2005)

ShoddyHog said:


> How much did that cost you?


Mine came with the SLP 455 Bobcat kit. But I have seen them on e-bay for around 250-500, big gap but that is the highest I have seen them. :cheers


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## kerno (Apr 6, 2006)

A perfomance tune can mean different things to different people. Here's what it means to me: The car is strapped down on a chassis dyno. Next, a calibrated O-2 sensor is screwed into the headpipe - which often requires adding an additional bung in the headpipe. You can't just remove one of the existing O-2 sensors, because the car's own computer needs 'em to run. The new O-2 sensor is hooked to a computer that also reads RPM, throttle position, timing and engine temp. The car is then started and the test begins. Typically the test would be run in a higher gear, like 4th, to increase engine loading. The computer then logs the actual air fuel ratio from the exhaust. The programmer then reviews the data and adjusts both the timing and the fuel curve to optimize the engine's efficiency. So, if you have to run 10% ethanol 91 octane, that's what it gets set up for. The goal is to put as much timing in as possible while also adjusting the fuel map to keep the mixture as close to optimium as possible. Then, an aftermarket unit like a Predator is commonly used to upload the new program into the car, while retaining a copy of the factoy tune. The Predator becomes matched to the car by the VIN, and cannot be switched to another vehicle. The process is not cheap. By the time you buy the Predator and a couple hours of dyno time, you're going to spend about $ 700.00. It is not free horsepower by any means. But since it actually measures _your_ vehicle's air fuel ratio, you're not getting a tune that was set up for some other part of the country and 93 octane fuel. I consider it essential to baseline a vehicle before the mods begin, or you have no idea what does what and how. It is not the cheapest way to do it, but by putting it back on the dyno as you add your various mods, you can actually tell if they help and by how much. Even better, you can also correct things like the mixture going too lean because you added headers, so the car's computer started pulling timing to keep detonation down. That way you don't wind up wondering why the headers everybody else said worked great made you lose a tenth in the quarter. Once you've bought the Predator and had the base tune written, updating it for new mods runs $200 or so. The good news is you get to sit beside the car while it is running WFO. It is a sound you'll never forget!!!!!
Oh, SoCal, I did find a local tuner and I'll e-mail the data to you when I get back intown next week.


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## socal gto (Mar 10, 2006)

Thanks I will be waiting.


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