Hmm, well after that post I am rethinking it -- I don't want to do anything to void the warranty, and I don't want to spend the cash on turbos, intercooler, and a new engine.

Looks like the best way to get more performance out of the car would be new wheels + tires, and maybe a new pulley (further reducing weight). Those cold spark plugs were also incredibly cheap, and seem to make a difference based on what I have read.

 

cheapest thing is remove weight. its absolutly free to do.

 

Okay now I may have to be a bit of a dick...

It is definitely not the required octane, it is the minimum acceptable according to the manual.

Greater octane content actually makes the fuel less resistant to ignition in general and as a by product of that, it resists detonation which is pre-ignition due to heat/pressure.

The motor was not designed for 87. It has tables that allow it to put up with only using 87 however.

The ECU runs richer with less spark advance on 87 to keep it from detonating. It also changes the rate at which the throttle plate opens, specifically it opens slower, among other things..

On an A/T it actually pulls more timing during and after shifts as well on 87 v. 93.

93 allows it to lean out at the same time it can run more advance. Throw in some colder plugs as well and it can advance timing even more.

In Open Loop operation (wide open throttle, basically) it runs directly off the hundreds of fuel/timing tables and relies on the knock sensor to determine which of the interpolated tables to use. In addition to that it monitors ECTs/IATs/TPS/MAP volts etc.

Honda recommends that you run 87 at the lowest. It doesn't recommend using 87. 87 is the minimum acceptable, and that is only possible because we have an advanced EFI system that can retard/enrich as necessary.

This is not controversial or up for debate, this is what actually happens and you can see it with a scan tool or a data logger.

Sorry, but this is a common misconception on this board. You can actually see what I am talking about when monitoring the data coming out of the ECU with a scan tool or a data logger.

On a carburated engine for instance you would never be able to get away with 87oct on a 10.4:1CR unless you were running rich, like 0.75 Lambda, with next to no timing and not revving out real high.

 

interesting theory. i have nothign to argue this, so ill assume its true.

now the question is, is the $0.30 more per gallon worth it? is your mileage going up proportionally? are you actually gaining (noticable) any hp? or is it simply just keeping your engien a little cleaner. and it it is only keeping your engien cleaner, how many mroe miles is it goign to get you out of your engine? over the life of the car, spening 30 cents more per gallon...what does that add up to?



some simmple math....
if your car is getting 35mpg with regular.
10 gallon gas tank x $3.75 per gallon = $37.50 per fill up.
now, put in premium @ $4.10 per gallon. its costing you $41 per fill up.
difference of $3.60. thats nearly an entire gallon of regular, which would get you another 35mpg.
so...is that tank of premium getting you an extra 35mpg per fill up?
(gas prices based on Long island ny prices)

as far as HP gains....whats really gonne be the difference? 1,2, maybe 3hp? are you ever gonna feel that? is there ever gonna be a time when driver skill cant maek up for it?

now, lets talk engien cleanliness/longevity. at 1200 miles per year, spending $3.75 per gallon for regular...your spending $1205 on fuel. if using premium at $4.10 per gallon, thats $1405 per year. differnce of $200 per year.
now for the big picture, a honda engine, tried and true, can easily run 200,000 miles using regular gas.
200,000/ 12k per year = 16 years. 16x $200 savings per year if not using premium is $3200.
enough for a full replacement engine.

 

I have to say, there are valid arguments by both sides on this one, but why are we mucking up this poor guys thread with debates?

O.P. I say do whatever you like. Unless your racing, your butt dyno is all that really matters right?

 

I was not commenting on mileage, simply performance purposes. If your main concern is economy you shouldn't be looking to pull more power or push more air through the engine..

But in the case of mileage, that will be driver/commute specific.

Some people, myself included (as well as SilverBullet, TexasCoyote, Klasse Act, Krimson Cardinal, etc who are all Scan Tool owners btw) see several benefits to running premium.

Premium fuels often contain extra detergents and top cylinder lubes, in addition to the higher octane content. As an added bonus around here, BP's 93 octane does not contain ethanol so the actual energy content by volume is about 6-7% greater.

So mileage gains are amplified because almost all the stations offering 87 or 89 have 10% ethanol.

The only way one can determine if this is beneficial is to try it and see.

There are certainly some people who will see an advantage, and others won't see any difference.

There is a lot that goes into fuel economy, and not all of it is fuel dependent. The other major factors are going to be the weather, driver and commute. The ECU will also have to get acclimated to the change in fuels.

Everyone's results will be unique. But for those looking to drive hard, premium is what you need.

Fuel economy is too complex to give a broad statement, but by the numbers it should give you a boost in economy. Will that gain offset the cost? Depends entirely upon gas prices and the size of the gain.

So experiment. Even if it comes out neutral for me, and I end up paying that much over the course of a decade I see it as an investment in longevity because of all the other advantages to premium fuel. Specifically the detergents and top cylinder lubes.

So, as the saying goes YMMV

 

Getting back on topic

You would be surprised what you can get away with under warranty. But that will depend on what your dealership will let you get away with.

And it sounds like you are on the right track!

Some easy effective mods:

• Lightweight, stock diameter wheels
• Sticky, 55mm or shorter side wall, tires
• Electronic Throttle Controller
• Underdrive pulley (I personally wouldn't run one but that is a whole other discussion and several people have for thousands of miles without issues, some havent been so lucky)
• 7 range plugs
• 91 or 93 oct fuel
• Piggyback/ECM (requires learning the basics of tuning and then get some hands on time, but certainly do able)
• Chassis Bracing
• Mild drop on lowering springs, like Swift Mach's
• Weight Removal

Then start doing bolt-ons.

• Intake
• Header
• Full Exhaust

After that your bigger gains are going to be more involved.

• LSD
• Light flywheel
• Pucked clutch disc
• Shorter Gearing/Final Drive

Then for the serious stuff:

• Boost
• Nitrous
• Engine swap
• All 3

 

Thanks for the informative post. I have NO experience modifying cars. The only thing I have done to them is put in a stereo, change my plugs, air filter, and oil.

I do have some friends who are into it though, and have access to a garage. I will do some more reading. Looking to add about $1000 to it this year, and maybe another $500-1000 next year. Tires/wheels seem to be the best bang for the buck, aside from the free stuff (like removing weight). Also, Exhaust/CAI seem relatively cheap compared to other things on here, and simple to do, though they may not be the most effective.

Back to more research!

 

I haven't seen any complaints from anyone that has added a CAI to their GE8. Obviously that doesn't mean DSM is wrong, but it would seem the "detune" effects are minimal.

 

From what I've read, regular is what Honda wants you to use.

For example, on Honda's website (2011 Honda Fit - Specifications - Official Site) they do state that regular is the required fuel.

Also, on page 198 of the owner's manual, it states "Your vehicle is designed to operate on unleaded gasoline with a pump octane number of 87," ... so that's where I'm getting this idea that Honda designed the L15 for regular.

I'm not saying premium WON'T make more power reliably. I just wanted to get more info on the theory that it does. I didn't think it would, but I'm always open to other ideas. I was hoping someone would have some dyno numbers to help shed some light on the subject, but I haven't found any. So I made a call and got a dyno set-up to test this theory. Now I just have to find some time to get over there and run different fuels.

 

this. or trade your car in for a manual trans fit, AT LEAST. putting money in an automatic fit to make it faster is the most silly thing you could do

 

Your numbers will be conclusive of nothing I hope you understand. Regular is the minimum acceptable, not what they want you to use.

They want you to use nothing less than 87 [(R+M)/2]

For your dyno runs you should be looking at the area under the curve and not the peak power produced.

Also no where do they say "required," and in the rest of the literature, particularly my manual they use the phrase minimum with regard to 87.

And just like I pointed out earlier, it can get away with 87, it was not specifically designed around the idea of using 87, because only in the US is 87 considered regular.. In russia the minimum is 85RON, in Japan you are looking at 98RON.

The ECU has maps for an array of fuels, just like every other OBD1 or OBD2 ECU going back to 1989.

But they designed the ECU to dial back the timing and enrich the mixture enough to use 87. That is all that means. This is what allows them to get the specific output they were looking for on regular fuel.

None of what I am telling you is "theory." And for the same reasons an intake or exhaust will make for minimal if any gains, are the same reasons you will not be seeing some dramatic spike in power from premium.

It's at high load and low-mid range rpm where the premium shines. If you are not monitoring TPS volts, ECT/IAT/MAP etc just the dyno numbers do us no good.

Also, make sure you have your radio code handy because you will need to reset the ECU to let it default to the MaxOct maps before each run.

Additionally if the ECT/IAT, ambient temperature altitude density/atmospheric pressure are not kept constant, again your numbers will not be useful.

A couple data points from your car do not illustrate the big picture that is everyones cars, so I wouldn't read too much into what your car produces.

You don't have to actually have pre-det for the ECU to pull timing or enrich the mixture.


Through my own OBD2 logger I see a healthy change in timing and AFRs between grades of fuel and when I changed spark plugs.

On the stocker 6 range plugs on stock gap on 87oct E10 pump gas I would see timing advance under cruise in the high 30s, usually 37-38* @ 45mph in 5th and at WOT towards Redline advance would be in high teens like 17-18

On 93 under the same condition I would regularly see 40-43* with WOT timing was in the 19-21* range.

On 93 with NGK 7's on stock gap last time I had the logger on the car Cruise advance was between 45-47* and WOT was approaching 25*

When I am out in the boonies where 93 isn't an option I can feel the knock retard after filling up with 87 or 89 E10 and getting on the gas for the first time.

Those were the actual numbers and the ECU don't lie. I will be curious to see your results and how they stack up to mine and other scan tool owners who have used both. But again, they will be nothing conlcusive.

Take down all the variables possible and control for what you can, that will help put some perspective on the out come for those of us that tune cars regularly.

I have never tuned a car that didn't pick up timing and/or lean up with a change from 87-93.

The easiest way to demonstrate how profound the effect on our cars is by starting with 93 or greater (you can add toluene 118oct) drive hard drain the tank, fill up with 87 and then you can feel it yank a good 10-12* advance. No dyno necessary for that.

I also hope you aren't making the mistake in assuming the dyno is anything more than a tuning device. DynoJet v. Mustang Dyno can also have a big difference in the numbers produced. As well as the correction factor used.

 

DSM and Texas Coyote said it all except show you what Honda ecu is capable of. You have to see it for your self and I will explain it if needed. Knock control tables

 

I think tuning, computers, flashing the memory, end ECU are far beyond my scope, was just looking for some simple installs -- I would probably need to get that installed professionally.

 

The flash pro is for the civic, but I believe they could release one for the GE8 but probably wont because of cost. You would spend over 2000 dollars to get a few more HP compared to Supercharging/Turbo or a K swap. I showed it again to show the Honda stock ecu and how it thinks. The first generation is a little different but still has advantages running premium.

My timing is MBT runs 47 light throttle to 27 full throttle on premium. I average over 40 in mix driving summer and 32 was the worst in Chicago winter driving but now average around 36. My wifes has the same kind of car and runs regular when she gets gas and gets 26 mpg. 93 is not that high and I could use even higher octane in my car. 100 octane racing fuel is for 9 to 1 stock car racing and up to 12.1.

Premium is the easies way to a more lively motor that you can feel. Taking weight out is another and lighter tires but have to be the same size. I feel the tire swap is not accurate because if the diameter is different and the car accelerates faster only because the speedometer is off, but a lighter tire would help if it was calibrated right.

 

Here is more info. http://delphi.com/pdf/techpapers/2010-01-0619.pdf This explains knock limited compression with different gasoline and alcohols.

 

I went with the different car option, for a variety of reasons. It's a good bit quicker, and the mileage is only slightly lower. Only driving a new car for 18 mos. isn't a great idea though.

 

Hey welcome to FF's Coppatop85,
I've just ordered a set of 13# rims 15x6.5" w/ the gd3 stock rubber 195/55/15 dunlops which are lite compaired to most tires out there. They are 328.00 to the door and the lite tires from tire rack would be way under 1k$'s.
Big Mike


15" WHEEL RIM HONDA CIVIC FIT CRX INTEGRA YARIS 4X100 - eBay (item 120698346941 end time Mar-28-11 18:46:47 PDT)

 

How they fit...They are listed as 4 X 100, but have 4 X 114.3 stamped on them...

 

The sport takes 16inch tires, dont know if I would want to put 15inchers on it, though they would weigh less.