[csimo]

This thread is a very interesting read. What gain in HP, torque, and mpg could I expect if I burned premium fuel in my RL? Would the benefits outway the extra .20 per gallon. I would gladly pay it if I could actually see a difference. Thanks.

Extra horsepower = approx. 10HP. Since the Ridgeline produces peak horsepower at 5750 RPMs we can calculate that the engine is making about 225 lb-ft of torque on regular gas and just under 235 lb-ft of torque on premium (at 5750 RPMs).

If we could actually produce that extra 10HP across the band (which we can't) and had minimal driveline losses we could potentially gain about 3% in fuel economy. You won't actually get that much, but there's the potential.

So if you averaged 20MPG on regular gas you could may get as high as 20.6MPG on premium. So how much does this cost or save you.

Let's go for a figure of cost per 1000 miles. I'll use $3 per gallon for regular and $3.20 per gallon for premium (using your 20 cent figure).

Regular gasoline: You would burn 50 gallons in 1000 miles for a total cost of $150.00

Premium gasoline: You would burn 48.54 gallons in 1000 miles for a total cost of $155.33

There are a lot of assumptions in the above variables, but it's good enough for an example.

Can you actually feel 10 horsepower on a ~250 horsepower engine? Nope. You can measure it, however a "butt dyno" is not that accurate. Manufacturing variations probably account for more than 10 horsepower variation between engines to start with.

Hope this info helps.

 

[Gary_Flint]

Joe – the peak torque and power gain with premium fuel is not the greatest benefit for using this fuel. The biggest benefit is honestly at torque converter stall temperature (mid-speed torque band). This is also the RPM range you are frequently using when cruising and is therefore the greatest merit for fuel economy. If this is your sole justification – it will be difficult to financially justify. The key merits are in power, “g-feeling” or seat of the pants acceleration response at ¼ throttle, shift busy (how much it un-locks the torque converter or down shifts), and of course towing (which is essential at maximum load which is why it is recommended when towing).

Premium fuel increases the peak torque at 4500 RPM from 32.4 kg-m to 34 kg-m. The torque at the torque converter stall speed is increased from 30kg-m to 32.4 kg-m (~2400 RPM). Premium fuel in this speed range improves the torque margin which will increase the time spent in 5th gear with the torque converter in lock-up mode. This will result in improved fuel economy depending on the grade and temperature conditions (low temperature is good for power – but bad for aero). The ignition timing is also advanced further in this mode which reduces the fuel consumption (leaner burn rate). The greater the grade, the more the difference in improved fuel economy due to the increased power.

Peak power is at 5740 RPM – 247 HP with Regular fuel. Peak power with premium fuel is approximately 258 HP (However, this is only true if you are wearing your copper bracelet. I am offering those for $29.99 for anyone that is interested in this tremendous opportunity.). The torque falls off at peak power between 5,000 and 6,000 RPM. This is operating mode is usually at WOT under extreme acceleration.

I hope this clears up the engineering merit of premium fuel.

PS- A Honda engine is not fully broke in until it has between 7-10,000 miles on the vehicle (depending on the manufacturing tolerances). Do not worry about achieving your optimum fuel economy until you get the vehicle broke-in according to the recommended guidelines described in your owners manual.

 

[Ridgetalker]

Thanks Gary and Joe. This is the kind of feedback that makes this such a great site.
I think that I will start using premium. Sounds like I will see some benefits.

 

[csimo]

Gary,

Thanks for the better numbers. So if we map this out we see that at 2400 RPMs we're making 99.16 HP on regular and 107.07 HP on premium... results in a 7.98% increase in horsepower at torque converter stall.

When we move up to 4500 RPMs (peak torque revs) we increase from 234.3 HP on regular up to 245.9 HP on premium... results in a 4.95% increase.

At peak horsepower RPMs we go from 247 HP on regular up to 258 HP on premium... a 4.45% increase.

So if we were to drive in such a way as to take advantage of all that premium fuel had to offer (which is contrary to normal driving conditions) I'd say my previous 3% fuel mileage increase is a pretty good number. Under normal driving conditions you'd maybe get 1% better mileage (if any at all).

If you worked the hell out of the engine and drivetrain (100% load near stall) you could justify premium fuel, but you wouldn't have to worry about it for long.

 

[Gary_Flint]

Joe- I have never done a engineering comparison to quantify the FE merits of premium. It is directionally better. I personally always run premium fuel in every vehicle and engine I own – motorcycles, lawn mowers and even the weed- whacker. The dirt bikes I own also recommend premium. With the Ridgeline compression ratio – it is not essential to use it – except when you are towing. This is not marketing hype – this is driven by engineering need. It will also help reduce the transmission temperature in heavily loaded low-speed maneuvers due to the reduced torque converter slip (because you have more engine torque).

If we mandated premium for all driving situations, we could raise the compression ratio and improve the power and fuel economy. However, that is not the strategy for the Honda channel.

On the EPA cycle, premium will make a difference. I do not know the absolute difference when measured on the dyno. It sounds like an intriguing evaluation if we ever have time to play.

I thought I would provide some absolute torque and HP data on a center spec engine ran in controlled test modes (engine dyno). The data is absolutely true. Don’t waste your time listening to marketing hype about air cleaners and exhaust systems to achieve HP or fuel economy. Safe yourself the cash and buy the fuel which actually achieves results.

My offer still stands for the copper bracelet if anyone is interested. Should I also prepare some vitamin supplements for the fuel tank?

 

[Raplon]

Joe- I have never done a engineering comparison to quantify the FE merits of premium. It is directionally better. I personally always run premium fuel in every vehicle and engine I own – motorcycles, lawn mowers and even the weed- whacker. The dirt bikes I own also recommend premium. With the Ridgeline compression ratio – it is not essential to use it – except when you are towing. This is not marketing hype – this is driven by engineering need. It will also help reduce the transmission temperature in heavily loaded low-speed maneuvers due to the reduced torque converter slip (because you have more engine torque).

Thank you, Mr. Flint for your great input. I also always run premium fuel in all my engines, including lawn mowers. It makes me feel better. With all those discussions all over the web about waisting money with premium, I was about to begin feeling a little silly. With your two posts, I got my justification to continue using premium.

 

[Chefelvis]

Yeha, well I kinda want one of those copper, gold bracelets, Gary. Ten bucks for gold right?

 

[Webwader]

Using premium towing my 3,500 lb trailer gives me about a 2 mpg increase in addition to the benefits in torque and HP that Gary mentioned. In watching the Scanguage, I can also attest to the ignition timing change. Thanks for the great explanation, Gary.

 

[weatherman]

This thread is a very interesting read. What gain in HP, torque, and mpg could I expect if I burned premium fuel in my RL? Would the benefits outway the extra .20 per gallon. I would gladly pay it if I could actually see a difference. Thanks.

Ridgetalker,
According to Gary Flint and his team at the the national meet, using premium fuel will get you an increase of about 10 HP.

Jim

 

[djeaux]

My offer still stands for the copper bracelet if anyone is interested. Should I also prepare some vitamin supplements for the fuel tank?

Thanks for the info about premium, Gary. I'll give it a try on my next fill-up!

 

[shovelhd]

PS- A Honda engine is not fully broke in until it has between 7-10,000 miles on the vehicle (depending on the manufacturing tolerances). Do not worry about achieving your optimum fuel economy until you get the vehicle broke-in according to the recommended guidelines described in your owners manual.

Mods, any way we can get this statement added as a sticky post in the appropriate "gas mileage bitch thread" forum? That way at least we can point the noobs to it.

BTW, Gary, my empirical experience with our 2003 Pilot and 2006 Ridgeline (we are gluttons for early-adopter punishment ) has been exactly as you say. Gas mileage and overall driveability improved around the 10K mark.

Thanks so much for spending time on the forum.

 

[djeaux]

BTW, Gary, my empirical experience with our 2003 Pilot and 2006 Ridgeline (we are gluttons for early-adopter punishment ) has been exactly as you say. Gas mileage and overall driveability improved around the 10K mark.

That's been our experience with every Honda going back to our '85 Accord. My wife refuses to do gas mileage calculations on any of her Hondas until after the first oil change at 7500 miles. My daughter just refuses to do gas mileage calculations, but she drives hers like she stole it. (Which she did ... from ME!)

 

[Raplon]

Am I mistaken or this is really true? Long brake-in period indicate low tolerance (or is it high? Anyway, I mean low quality) during manufacturing. Ferrari, for instance, has very close tolerance and almost no brake-in period.

 

[arteegee]

Peak power is at 5740 RPM – 247 HP with Regular fuel. Peak power with premium fuel is approximately 258 HP (However, this is only true if you are wearing your copper bracelet. I am offering those for $29.99 for anyone that is interested in this tremendous opportunity.).

Who says Honda guys don't have a sense of humor?

 

[shovelhd]

Am I mistaken or this is really true? Long brake-in period indicate low tolerance (or is it high? Anyway, I mean low quality) during manufacturing. Ferrari, for instance, has very close tolerance and almost no brake-in period.

Break-in time is more than tolerance, and it's certainly not low quality. It's a function of many things, including metallurgy, component selection, manufacturing techniques, etc. A cylinder is a lot more than an aluminum slug inside a cast iron sleeve these days.

 

[MoosePond]

Thanks Gary and Joe. This is the kind of feedback that makes this such a great site.
I think that I will start using premium. Sounds like I will see some benefits.

I ran a little regular versus premium "test" on my trip to St. Louis for RidgeRun 2007. Ran regular (87 octane) on the way out and premium (93 octane) on the way back on a journey that was just shy of 3,000 miles (my 2007 RTL had just over 10,000 miles on it when I began this journey). In both cases I tested my cold tire pressure each morning (no adjustments were necessary on my stock size Goodyear Fortera TripleTreds) to make certain that all were at exactly 32.0 psi. Here are the results that I found (YMMV):

Regular - 18.8 mpg at an average of $0.144 per mile

Premium - 20.0 mpg at an average of $0.145 per mile

btw, my "lifetime" fuel economy on my RL now stands at 18.1 mpg and has shown steady improvement with the biggest "bump" in the curve at around 7,000 miles (interestingly, just after my first oil change).

I heartily concur with what others have said here about "bolt on" performance improvements. Today's drivetrains are so sophisticated that you've got to take all of the systems and their components and their inter-workings into account to have any hope of making any substantial gains in performance. Even then, there's usually a trade-off in terms of driveability, reliability, fuel economy, etc. Just my $.02 worth (sure was easier in my pre-emissions hot rodding days).

 

[Raplon]

Break-in time is more than tolerance, and it's certainly not low quality. It's a function of many things, including metallurgy, component selection, manufacturing techniques, etc. A cylinder is a lot more than an aluminum slug inside a cast iron sleeve these days.

True. But if all the parts fit very close there is no need for break-in. It simply won't do anything.

 

[MoosePond]

True. But if all the parts fit very close there is no need for break-in. It simply won't do anything.

If it don't go, chrome it!

 

[theLine]

A connecting rod connects the piston to the crankshaft. Even overhead cam engines have them.

An overhead cam eliminates pushrods... which is what you may have been thinking of.

My, my, my. I read that post as well. Such a supreme opportunity for dante-esque flaming of such an elemental lack of knowledge and yet you held back... your reply was courteous and direct. I must admit I would have been disposed to rub a nose in it. Nice, csimo... well done. Had I your restraint...

 

[shovelhd]

True. But if all the parts fit very close there is no need for break-in. It simply won't do anything.

I'm not sure you understand what happens during an engine break-in, any engine. The heating and cooling cycles cause dimensions of components to change. The cylinders are honed during manufacture, and as the cylinders run in, the cylinder diameter grows. Piston rings that start with sharp edges round off slightly as they run in. Same goes for the valves and valve seats. Sleeve bearings and bushings seat themselves, which causes dimensional changes to the things they are connected to. This is all normal during the break-in of any engine, and every manufacturer takes account of this as part of the engine design. Break-in is normal. The difference between a handmade Ferrari motor and a production line Honda motor is that the break-in tolerances for the handmade motor can be more closely controlled. It should be, for 10x the price.