The TL uses premium fuel because:
07-29-2005, 05:48 PM
#81
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Originally Posted by 2003 Acura TLS260-Silver
Been there, done that. 
Here are the facts:
Acura recommends running a minimal 91 octane rated fuel. That means you can run 91 premium and higher. Use of a lower octane gasoline ( Regular unleaded with an octane rating of 87) can cause occasional, metallic knocking noises in the engine and will result in decrease engine performance.
They recommend gasolines containing detergent additives that help prevent fuel system and engine deposits.
Using gasoline containing lead will damage your car's emissions controls and this will contribute to air pollution
Gasolines containing an octane-enhancing additive called MMT will damage your emission control sytem, performance may deteriorate and the Malfunction Indicator Lamp will be activated.
I have tried using regular unleaded with 87 octane, no difference at slow speeds because the ECU adjusts the timing by retarding it. At high speeds, there is a decrease in acceleration performance. Occasional use of 87 octane gas will not be detrimental but in order to optimize vehicle engine performance, you should use at least 91 octane or higher ( depending on your budget)
Here are the facts:
Acura recommends running a minimal 91 octane rated fuel. That means you can run 91 premium and higher. Use of a lower octane gasoline ( Regular unleaded with an octane rating of 87) can cause occasional, metallic knocking noises in the engine and will result in decrease engine performance.They recommend gasolines containing detergent additives that help prevent fuel system and engine deposits.
Using gasoline containing lead will damage your car's emissions controls and this will contribute to air pollution
Gasolines containing an octane-enhancing additive called MMT will damage your emission control sytem, performance may deteriorate and the Malfunction Indicator Lamp will be activated.
I have tried using regular unleaded with 87 octane, no difference at slow speeds because the ECU adjusts the timing by retarding it. At high speeds, there is a decrease in acceleration performance. Occasional use of 87 octane gas will not be detrimental but in order to optimize vehicle engine performance, you should use at least 91 octane or higher ( depending on your budget)
2003 Acura TLS260-Silver, I agree.
I own (2) 04' TLs. One is early an production 5AT SSM (wife's car, and is leased) and the other a late production Anth 6MT (my car, and we own it). My wife doen't "run" the car hard at all. And on the AT, before ~10,000 miles on the odo we ran 91+ octane, getting a consistant 24 mpg on the MID. Since then we have switched to using only 87 (lowest grade), the odo is now at 24,000 mi and the MID still shows 24 mpg. The 5AT feels identical for 95% of the time. Putting serious pressure on the right pedal and getting the engine wound up above ~5000 does reveal some loss power. By no means does it feel slow with 87, maybe "less quick" at the top end.
My 6MT only gets 91+, I use it's full potential about 20% of the time and frequently accelerate briskly. The 6MT has ~11,000 on it and the MID bounces between 25 and 26 (depending on rush hour congestion) so it must be around the high end of 25. With the way the car is driven I can't complain. Especially since I owned a 01' S2000 which ate fuel like there was a hole in the tank (of course many smiles were obtained from this).
BTW, my wife has never driven the 6MT (she can't drive a MT) and I have driven the AT about 20% of it's mileage. The AT is very rarely driven "hard" by myself (a few times, once to test out the unbelievable-dealer replaced P-Zero Neros, god they make the car soooo much better). My 6MT is still rolling on the crappy ELs until I get them worn out.
Just thought I would share my real world experience.
07-29-2005, 08:34 PM
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this should stir up some more debate
quick somebody check the gas cap and see if it says "recommended" or "required". for the record im on the 91 side, never will our car taste anything lower.
http://www.edmunds.com/advice/specia...3/article.html
quick somebody check the gas cap and see if it says "recommended" or "required". for the record im on the 91 side, never will our car taste anything lower.
http://www.edmunds.com/advice/specia...3/article.html
07-29-2005, 10:06 PM
#83
Registered Abuser of VTEC
Originally Posted by massr1
this should stir up some more debate
quick somebody check the gas cap and see if it says "recommended" or "required". for the record im on the 91 side, never will our car taste anything lower.
http://www.edmunds.com/advice/specia...3/article.html
quick somebody check the gas cap and see if it says "recommended" or "required". for the record im on the 91 side, never will our car taste anything lower.
http://www.edmunds.com/advice/specia...3/article.html
Over at the Temple of VTEC, they've proven with dyno charts that the J30A4 in the 7th gen Honda Accord gets 10 more hp with 91 octane fuel rather than 87. The CR is 10.0:1 . Obviously the engine is advancing the timing.
07-30-2005, 04:09 PM
#84
Perhaps I can help here...
Allow me to educate some of you.
First of all, the higher the RON (octane), the LESS volatile the fuel. The lower the RON, the MORE volatile the fuel. In simple terms, lower octane fuels are easier to ignite than higher octane fuels. If you think different, you are wrong.
I've heard people say their car made more power with higher octane fuel. That is not exactly true. The higher octane fuel didn't increase the power output. Most likely more spark timing is what increased the power output. Higher octane fuel allowed the engine to be less knock constrained. All supercharged and turbocharged engines are knock constrained, so they require higher octane fuels.
Moving on, the chemically correct formula for heptane (which is gasoline) is 14.64:1. Some people say, 14.7:1, I'll except that, but it's really 14.64:1. The ideal Air Fuel Ratio (AFR) is then 14.64:1 or 14.64 parts of air to 1 part fuel. Theoretically, this is the air fuel ratio that the computer would try to maintain under cruise conditions. During wide open throttle (WOT), the AFR is richened from STOICH. All engines run rich at WOT (lean would be any AFR numerically higher than 14.64:1).
What determines power output of any gasoline engine is how efficiently it burns fuel. Air is a limiting factor in power production. However if we can get more air packed into the cylinder then it must be met with the proper amount of fuel.
Spark timing is critical to achieving maximum power output. The fact is, Acura/Honda has taken a 3.2L V-6 and got it to produce 270 HP. That's 84.3 HP/Liter. The Acura RSX Type-S makes 210 HP from a 2.0L I-4. That's 105 HP per liter. Amazing. Look at the new 2005 Mustang GT with the 4.6L 3V V-8, it produces 300 HP or 65.2 HP/Liter.
Take these numbers with a grain of salt. The Honda S2000 had a 240 HP 2.0L I-4, but it doesn't mean it has power everywhere. Those engines have to be reved high and kept in the rpms to make that kind of power. We're looking for the area under the curve, that's the important number. Also average horsepower and torque, not just a peak number.
My 1995 T-Bird LX has a 2000 4.6L Mustang GT engine and an Eaton M90S supercharger (intercooled). The engine was rated at 260 HP/302 TQ from the factory (56.5 HP/Liter). With the blower and a dyno tune from an ex-Ford engineer, the car made 325 RWHP/380 RWTQ (SAE) on a dynojet. That's with the torque converter locked in third gear (1:1 ratio on the 4-speed automatic).
You're talking 355 RWTQ at 2,000 rpm and 380 RWTQ at 3,200 rpm. At 5,600 rpm I still have 300 RWTQ. Horsepower peaks around 5,000 rpm and 325 came in at 5,600 rpm. The engine is limited to 6,050 rpm. This makes for a really nice daily driver.
Problem is I have about 19 degrees of spark at WOT and I must use 93 octane fuel all the time. Using 100 octane fuel by itself resulted in no power increase on the dyno. But if I added more spark timing, to 21.5 degrees, power shot up and there was no detonation or ping present. To be safe, the timing was pulled back and the power also dropped.
So why does the TL require 91 octane fuel? Simple it has a high compression engine that revs high and most likely has a decent amount of spark timing in it to produce the 270 HP.
A-Train
First of all, the higher the RON (octane), the LESS volatile the fuel. The lower the RON, the MORE volatile the fuel. In simple terms, lower octane fuels are easier to ignite than higher octane fuels. If you think different, you are wrong.
I've heard people say their car made more power with higher octane fuel. That is not exactly true. The higher octane fuel didn't increase the power output. Most likely more spark timing is what increased the power output. Higher octane fuel allowed the engine to be less knock constrained. All supercharged and turbocharged engines are knock constrained, so they require higher octane fuels.
Moving on, the chemically correct formula for heptane (which is gasoline) is 14.64:1. Some people say, 14.7:1, I'll except that, but it's really 14.64:1. The ideal Air Fuel Ratio (AFR) is then 14.64:1 or 14.64 parts of air to 1 part fuel. Theoretically, this is the air fuel ratio that the computer would try to maintain under cruise conditions. During wide open throttle (WOT), the AFR is richened from STOICH. All engines run rich at WOT (lean would be any AFR numerically higher than 14.64:1).
What determines power output of any gasoline engine is how efficiently it burns fuel. Air is a limiting factor in power production. However if we can get more air packed into the cylinder then it must be met with the proper amount of fuel.
Spark timing is critical to achieving maximum power output. The fact is, Acura/Honda has taken a 3.2L V-6 and got it to produce 270 HP. That's 84.3 HP/Liter. The Acura RSX Type-S makes 210 HP from a 2.0L I-4. That's 105 HP per liter. Amazing. Look at the new 2005 Mustang GT with the 4.6L 3V V-8, it produces 300 HP or 65.2 HP/Liter.
Take these numbers with a grain of salt. The Honda S2000 had a 240 HP 2.0L I-4, but it doesn't mean it has power everywhere. Those engines have to be reved high and kept in the rpms to make that kind of power. We're looking for the area under the curve, that's the important number. Also average horsepower and torque, not just a peak number.
My 1995 T-Bird LX has a 2000 4.6L Mustang GT engine and an Eaton M90S supercharger (intercooled). The engine was rated at 260 HP/302 TQ from the factory (56.5 HP/Liter). With the blower and a dyno tune from an ex-Ford engineer, the car made 325 RWHP/380 RWTQ (SAE) on a dynojet. That's with the torque converter locked in third gear (1:1 ratio on the 4-speed automatic).
You're talking 355 RWTQ at 2,000 rpm and 380 RWTQ at 3,200 rpm. At 5,600 rpm I still have 300 RWTQ. Horsepower peaks around 5,000 rpm and 325 came in at 5,600 rpm. The engine is limited to 6,050 rpm. This makes for a really nice daily driver.
Problem is I have about 19 degrees of spark at WOT and I must use 93 octane fuel all the time. Using 100 octane fuel by itself resulted in no power increase on the dyno. But if I added more spark timing, to 21.5 degrees, power shot up and there was no detonation or ping present. To be safe, the timing was pulled back and the power also dropped.
So why does the TL require 91 octane fuel? Simple it has a high compression engine that revs high and most likely has a decent amount of spark timing in it to produce the 270 HP.
A-Train
07-31-2005, 09:45 PM
#85
Compression ratio...
Whoever said the compression ratio changes when air and fuel enter the combustion chambers, is dead wrong. The static compression ratio doesn't change at all, the air charge compression ratio changes.
Give you an example, take an engine, let us say a Ford 4.6L SOHC V-8 from the year 2000. It has a compression ratio of 9.0:1. Add a supercharger at 6-psi without an intercooler. The Compression ratio is still 9.0:1, it won't change. However the air charge compression ratio has increased to 12.67:1. At 8-psi of boost, the air charge compression ratio is 13.89:1. The static compression ratio is still 9.0:1.
A larger photo of my dyno graph from the last post.
Pull #1 is the green line. It's basically an off the shelf or cookie cutter program that was flashed into my PCM by an ex-Ford engineer. The A/F ratio is off the wall and the car was running very rich at WOT. This program was safe and used to get me to the dyno so the combo could be dialed in. On the second pull, he adjusted the spark timing and leveled off the A/F ratio. As you can see the A/F ratio is dead on around 11.8:1. The car made 320.5 RWHP/379.5 RWTQ (SAE) like that. Pull #3, was with the beloved K&N conical filter. I attached it directly to the Mass Air Meter and we did another pull. No changes were done to the program. The car made a peak of 325.1 RWHP/379.5 RWTQ. Notice the A/F ratio remains close to pull #2 and spark timing was also very close. The K&N was worth 4.6 RWHP and ZERO RWTQ, but the gains were basically a PEAK number.
Close the hood and suck in hot engine bay air and what have you gained? Nothing. A stock paper element flows around 700-750 cfm or airflow. The K&N panel flows 750-820 cfm. The conical 9" K&N is said to flow 1,000 cfm. Problem is, even my supercharged/intercooled V-8 is only around 600-610 cfm. What good is a 1,000 cfm air filter for an engine that only moves 600 cfm?
A-Train
Give you an example, take an engine, let us say a Ford 4.6L SOHC V-8 from the year 2000. It has a compression ratio of 9.0:1. Add a supercharger at 6-psi without an intercooler. The Compression ratio is still 9.0:1, it won't change. However the air charge compression ratio has increased to 12.67:1. At 8-psi of boost, the air charge compression ratio is 13.89:1. The static compression ratio is still 9.0:1.
A larger photo of my dyno graph from the last post.
Pull #1 is the green line. It's basically an off the shelf or cookie cutter program that was flashed into my PCM by an ex-Ford engineer. The A/F ratio is off the wall and the car was running very rich at WOT. This program was safe and used to get me to the dyno so the combo could be dialed in. On the second pull, he adjusted the spark timing and leveled off the A/F ratio. As you can see the A/F ratio is dead on around 11.8:1. The car made 320.5 RWHP/379.5 RWTQ (SAE) like that. Pull #3, was with the beloved K&N conical filter. I attached it directly to the Mass Air Meter and we did another pull. No changes were done to the program. The car made a peak of 325.1 RWHP/379.5 RWTQ. Notice the A/F ratio remains close to pull #2 and spark timing was also very close. The K&N was worth 4.6 RWHP and ZERO RWTQ, but the gains were basically a PEAK number.
Close the hood and suck in hot engine bay air and what have you gained? Nothing. A stock paper element flows around 700-750 cfm or airflow. The K&N panel flows 750-820 cfm. The conical 9" K&N is said to flow 1,000 cfm. Problem is, even my supercharged/intercooled V-8 is only around 600-610 cfm. What good is a 1,000 cfm air filter for an engine that only moves 600 cfm?
A-Train
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