AndyK

And the car feels like it has a new engine! I usually use regular gas, but decided to go to "plus" 89 octaine to see what happened. The engine runs smoother and quieter! Hard to belive going up one level in octane would show such good results.

Anyone else using 89 or 91 octane in their I4 cars?? If not, I highly recommend giving it a try.

accord_raffi

Well I use 93 on my car but it's turbocharged. Any of my friends that have used higher octane like the results on their dd's. Why not just go up to 93 octane? It's apprx a 20 cent difference between 89 and 93 and if you're filling from dead empty on a 17gallon tank, that's a $3.40 cent difference at max. No one should be filling from dead empty anyway.

sherwood

Use what your car calls for, there will be little to nothing to gain from going any higher. Some cars can make up for it with modifying timing, but usually it's all malarkey.

The only reason the higher octane gas is any better is that it doesn't take to being lit up as easily as lower octane. What this means is the compression ratio of the engine can be raised and as a result there's a power increase. The only thing the octane guarantees is that the gas will ignite when the spark tells it to, vs igniting too early.


Now I do respect your butt dyno testing, but overall there are many other things to consider such as ambient air temp, engine temperature, relative humidity and many other things. Basically don't waste your money, just follow the directions on the gas cap.

AndyK

Good advice actually! And, I'll be damned if my wife wasn't right. She always puts regular into her Accord V6, just what the manual calls for. And I always tried to get her to put in premium - I guess for no good reason.

Thanks.

Glenn Davis

Actually, in the case of the 03-07 Accord V6, running premium fuel will increase both horsepower and torque appreciably. I think it was an increase of 10hp and 8-12lb/ft of torque. The ECU in those Accords use info from the knock sensors to recognize better gas and will advance the ignition timing accordingly, resulting in the gains.

This info was in Honda literature a few years back, but doesn't appear to be readily available today. If you dig around, I'm sure you can find more details on it.

From another source:
http://www.vtec.net/forums/one-message?message_id=32993


Note this applies only to the 7th generation V6. Car and Driver, a few years back, tested the 6thgen (98-02) V6 with Premium fuel and found power/torque and MPG to decrease ever so slightly.

sherwood

Thanks, I wasn't sure what model but I was pretty sure it wasn't the I4.

I highly doubt the 10HP increase, though.

AndyK

I find I get more of an increase in performance if I turn the A/C off! Who needs the compressor to be running when it's 45 and sunny?