grinder11

I'm curious about a "regular fuel" tune. With premium rapidly approaching $4/gallon, I'm wondering if anyone has requested a regular fuel tune, in addition to the usual premium tune? I was asked years ago whether I wanted a regular tune. So I then assumed it was possible to put 2 tunes in the PCM, sorta 'piggyback'. The regular fuel tune would save a lot of money on a long trip, say 1,000 miles+. You could run regular fuel on the trip, and then run premium fuel upon arrival. Is this even doable?? Any input would be appreciated, thank you......

ArmchairArchitect

https://www.thedrive.com/news/31400/...rolet-corvette

wydopnthrtl

10+ yrs ago I used to tune my own cars. With a stock engine yes its not a problem. You'll need to have a flash device and work with a tuner to give you two tunes.

FYI..in my experiences I saw knock occuring at 1.1 deg of timing for each bump/reduction in octane. So as a starting point I'd take the spark knock table and just add/subtract 1.1 across all cells for each octane.

****IF**** you keep your foot out of it and below 4k rpms you could get away with just running 87 octane. (the knock sensors should send signals to the ECM and timing will be pulled)

1wholikescars

Even if it's not stock you can always have that backup "low octane" setup. When I drive a long distance to an event like more than a couple of hundred miles, I will put in a low octane tune, pulling out a lot of timing so I can run 87. Once I get to the track I then put back in the "high octane" tune. For the most part it was timing pulled (as mentioned above and in the video) in the cruise range, from 1400RPM to about 3500 RPM. I also call it my "is my car injured" tune, because if something is acting weird I will put that in to just be gentler on the engine until I can get it home. It will also have a reduced rev limit (like around 4000RPM) for those situations. When prices for gas was really high I had an extreme tune where I would unhook the supercharger as well and run it, especially at that time we were driving coast to coast to various events so 3000+ miles made a big difference in gas savings.
Anyway, it's an interesting subject, as when you get into it, there are all the hypermiler tricks like overinflating the tires and such that also help. You can certainly go overboard. I was learning about hypermiling and we setup a car with every trick we could think of like covers for the wheels, tape up the seams, remove the antenna, 50psi in the tires, belly pan, coasting to stops, taking off as slowly as possible, etc. I got well over 50+ miles to the gallon, which was cool but at that same time it ruined the driving experience fun factor.

Not4spd

No tune is needed to run regular unleaded on a stock car.

TheBac

Would the C5 ECM support a DSP2 setup with a switch?

katanaman

There is a possibility that the fuel level sensors will not play as well with the lower octane fuels -- we have to remember that, or at least anticipate losing the accuracy of the gauges while using the lower octane fuel.

ChiliPepperGarage

Personally, I would punch the numbers before doing a "detune" to run regular. How many miles do you plan to drive? What is the actually price deference between regular and super? Will the car get better mileage running super or will the detune to run regular reduce gas mileage?

Let's say you are going to do a 5000 mile road trip. Let's say you average 25 miles per gallon so you will use 200 gallons for the trip. What is the price differential between regular and premium? Let's just go high and say it is 50 cents. So you will save 100 bucks in gas costs for the trip. Is it really worth it? I'd much rather have the full power potential of my Corvette, especially on a road trip where you will be encountering amazing driving roads, than save a measly 100 bucks.

Another way to look at it is you save $100 over 5000 miles which is a $0.02 per mile saved. Not worth it to me.

EDIT: Just checked Gas Buddy and it shows difference to be somewhere around .15 to .25 difference. So you'd save $50 or less.

grinder11

Going 'high' with 50 cents/gallon is going LOW!! On my recent trip from Florida to Michigan, I never saw less than 50-55 cents, and saw several, no, actually the majority, of stops, were 70-80 cents, with 1 place over $1.00!! $2.899 regular-$4.01 premium!!! Also, my motor isn't stock. Actually, it's a built LS7. I do have all forged internals, but from what I'm reading/hearing, the LS7 has a tendency to crack the cylinder sleeves before a forged piston will crack, usually taking the block out with it! So I have to be careful!!

Mr. Black

That's a pretty large detail to leave out lol.

Smoken1

You could drive your Prius so you don't have to worry about gas prices

grinder11

Wow!! Things are sure different there than here on the Eastern/Midwestern area!! It's been many years since premium here was within 20 cents of regular. Enjoy it while it lasts. I just filled up at Marathon. $3.599 for premium/$2.999 for regular......Cost me $26.00 for 7 gallons......

grinder11

Yup. OOOPS!! I hear ya!! I even gave you a like!!

grinder11

I hear you too. Cept I don't own a Prius.....YET!!

GoldenFlame

Might as well do an E85 conversion.. 10 cents cheaper than 87 and you get 105 octane from it, so you can ADD timing!

Westy R

I thought I was the only one here whose other car is an Eco-Weenie Prius!

Mr. Peabody

How does the octane rating impact the accuracy of the fuel level sensors??

Mickeyrx70

————
ChiliPepperGarage has a valid point. Even at $1/gallon difference, you’ll save a whopping $40 over a 1000 mile trip assuming 25 mpg. Not worth it in my view.

Westy R

The only conversion kit I've seen for the C5 is $900, plus the effort of installing it ... so if E85 were $1.00 cheaper per gallon than 93-octane (and the price difference is less in many markets), you'd have to burn 900 gallons of E85 to just-barely break even (and that assumes you installed it yourself). That's 22,500 miles of driving -- and I'll bet there are plenty of people on this forum who won't put 22,500 miles on their garage-queens in ten years or more.

I'm "politically opposed" to E85 made of Federally-subsidized corn-squeezin's. Consider this -- every gallon of Federally-subsidized car-fuel alcohol is one gallon less of High Fructose Corn Syrup for your sweet tea and high-calorie sodas. It also takes a gallon of moonshine out of the "liquid entertainment" market at your local Alcoholic Beverage Control store. (Okay, I'm sarcastic, but making ethanol fuel from corn is woefully inefficient; it's "34 percent efficient," which means it takes three gallons' worth of energy to produce one gallon of corn-ethanol fuel.)

That said, I'd better look at the political side of the problem, especially since EVERYTHING in these hyper-partisan times seems to "circle back" to politics! E85 is cheap because it's heavily subsidized, and I suppose it's blessed as "carbon neutral." Fossil fuel is scorned as "the spawn of the Devil," and the Wokerati are religiously-bound to curse the Petroleum Industry, even as they rely on it to fuel their transport to the next protest, the next riot.

My rationale for buying my Corvette was partially based on the notion that I'd better enjoy it while I can, before the Powers That Be tax it or regulate it out of my reach to enjoy it!

C5MSG2004Vert

It doesn't, but high octane fuel may have more detergent in it. Helps keep the fuel senders clean