I'm actually more interested in the possible fuel savings in tuning an NA 8 with the IntX. Of course I wouldn't mind if leaning out the higher RPM points would lead to higher output.

I know there's been some talk about the possible fuel savings of tuning with the IntX, but nothing specific.

Do you still need a scanner to read AFR and chart it, or does the IntX with a WBo2 sensor allow you to output and analyse your results to a laptop?

 

Wouldnt the cost of the intercpetor completely outweigh the fuel savings for the next few years?

 

Yah... If you think about it, you might raise your mileage enough to save 5-7 dollars per fillup, likely closer to the 5 dollar side, which means it'd take you over 300 fillups, approximately, to save the money it cost you to buy the interceptor. And say you fill up your tank every 3 days, that's anywhere between 2.5 and 3 years before you've offset the cost.

Doesn't seem like it'd be worthwhile to me...

 

If you commute 100 miles a day like me it might be a worth it!

 

I don't think it would help much. Your car runs an AFR of 14.7 in closed loop. You're going to see improvements in open loop, but do you really drive for long periods of time over 4,500 rpm?

You could lean closed loop even more, but it's not going to give you huge gains.

It sounds like you're just trying to find justification in getting one

 

When you factor in getting to run regular gas, slightly better mileage, more power and upgrade to FI potential down the road, the X starts sounding pretty good.

 

I was using estimations of filling up, with the Interceptor-X, after ~270 miles, which would still be approximately every 3 days like I used. Which means it'd still take you 2.5 to 3 years to offset the cost.

 

I know they aren't huge gains, I'm wondering if people have leaned out the lower rpm area, not just the higher range (as mysql101 was saying). I don't know what the fuels savings would be. However, if it was a few hundred dollars a year and I got 20-30hp at a few points at higher rpm (which is possible with the Intx, especially if you 8 happens to run very rich, which a lot do) it may be a good deal. Also, if you get an intake, mid-pipe, exhaust, etc. you can re-tune and if you go FI you can re-tune again. Then it seems like a better deal.

I want to get one for the future, but if I can get some fuel savings now too, that might put me over the edge. I just haven't seen much info on tuning for fuel savings on NA vehicles.

Can the IntX change the rpm range that the additional injectors kick in?

 

I thought I'd run some numbers. Don't kill me if it's not correct for your area or car. It's just an example. Substitute your gas prices and mileage in. This also assumes that the Int gives a fuel economy improvement.

I'm assuming you have a 16 gallon fuel tank and fill it with exactly 16 gallons every time you fill up. Let's say that right now you average 18.75 mpg. That will take you 300 miles per tank. Let's say you need to pay $3.10 per gallon of high octane. That equals $49.60 per fill up. Now let's say with the Interceptor you go 325 miles per tank of gas. That will get you about 20.3 mpg. Now if you can use low octane gas let's just say you are paying $2.85 per gallon.

High octane, stock ecu gets you 300 mles for $49.60. Low octane, Int-X gets you 325 miles for $45.60. 325/300=1.083 Multiply $49.60 X 1.083 = $53.71. This is how much it costs you to go 325 miles with the stock ecu and high grade fuel. I had to convert this to get dollar per mile figures even.

So now we see that going 325 miles on the stock ecu and high octane costs around $53.73 and the Int-X costs around $45.60 to go the same distance. That is a savings of $8.13 per 325 miles. The Int-X costs $1600. 1600/8.13= 196.8. That's how many tanks of gas you'll need at the same gas prices to break even. If gas prices go up or down, and they will, this number and the time it takes to get there will change. 196.8 X 325 miles = 63,960 miles. That's how far you have to go to break even. Remember this assumes everything is constant and that these numbers are accurate. They are always changing. This is just an example.

Now don't think the Int is a bad piece that's not worth it. If your only intention is to save money on fuel, it's a very long term investment. After the above mileage figure is hit, you're saving about 2 1/2 cents per mile. The Int will give you more power wich is always nice. How many people spend money on exhausts and intakes that get no mileage increase and no noticable power increase? If you aren't getting mileage and you aren't getting power, what are you getting? Sound? That's worth it to a lot of people. How many people spend money on turbo kits that increase your power but decrease your mileage? You get one at the expense of the other. The power boost is nice though. At least this can give 2 benefits, even if one is more long term. Noticable gains in power but nothing miraculous and a slight mileage improvement. You can't expect it to do miracles but every little bit helps.

You also open the door for future forced induction, nitrous, different fuels...

If your only intention is to save money on gas, this isn't the best way to go about it. More frugal driving habits is where it is at. If you want to do other mods and get the most out of them as well as eventually save enough on gas to pay the unit off, this is a great way to do it. This is the mod that is more like a credit card bill. You have a balance and over time you eventualy pay it off. In the case of this example, it will be paid off in just under 64,000 miles. For some people that is 2 years. For others it is 5.

Even if you get no mileage increase, the difference in octane prices will take about 120,000 miles to get to the break even point. That's a long time but the product is still giving returns on the original investment even if you never get to the break even point. No other product out there does that. If you are using low octane now and don't switch but are getting a mileage increase, the same thing happens. The only way you can lose is if you get no increase of any kind in any area and we already know that isn't the case. Most parts for the car are purchases. The Interceptor is an investment.

 

BINGO!!!

^Nice post RG^

 

So this should really save some gas for those of us that love to rev

 

right if you go around at wot all teh time then you might see the savings quicker- since there is more to lean out higher up the rpm range

 

nice write-up rotarygod...that is a quality post.

 

I have a feeling that those of us getting around 14 mpg now & driving mostly in the city with lots of gearchanging and WOT will see a quicker return on investment

Although much of that could be offset by the increased tendancy to go WOT due to the extra fun factor of more power - oh well !

 

I wish I could pay $3.10 per gallon for premium. It's $3.15+ per gallon for REGULAR here, and it's slightly below the nation average last time I checked

And you pretty much ran similar numbers as far as miles/mpg or at least the ratios as I did when I came up with my figures, I just didn't type it out lol. Just goes to show you wont really see any offset for a long time...

 

It does save some fuel with the X where mileage spent goiing to the petrol station is saved for your trips.

 

I would say the avg is 2.70 - 2.80 right now:

http://www.gasbuddy.com/gb_gastemperaturemap.aspx

 

Hmm, I hadn't checked in about a month or so... No fair, it went down everywhere except the West Coast. I remember when the East Coast was paying almost 50 cents more per gallon.

 

premium out here for me is 3.50

 

Premium here is about 3.45.

IT went up to 3.65 for a day or 2, but came back down. and stays at 3.4~ ish for quite a while.

Man, this is still expensive. You know it kinda sucks to know that Im actually paying more money for gas than my monthly payment.

Nice post RG, I have one concern tho. Theres no "good" Rotary tuner that I can think of(or around) in New York. So ....

Is there like a IntX Tunning 101 kind of thing on this board? I searched but found nothing.

 

Kahren (aim name is kahren1981) might make the trip. He's in CT and goes to NJ every so often for tuning and such. He does rotary engine building and rotary/piston tuning for a living and has tuned rx8's before as well. He knows his stuff and is a great builder/tuner.

 

My Inter X is not maped for NA but it can be changed. But it is for sale, only two weeks old. Contact me if you might want it.