Is 91 octane really better then 87 octane?

Question

I have a 2001 Chevy blazer xtreme 4.3l v6 vortec. The motor has: cold air intake, throttle body spacer, MSD 8.5 wires, Bosche Platinum 4 plugs, MSD high output coil, dual flow-master 40s 2 1/4 pipe from the heads to the muffler, I also have the max energy programmer. I have it set on regular pump gas. Would it make much of a difference if I put it for the higher octane an would that hurt my mpg?

Answer 1

put in it whatever/all the rest of the junk aint doing anything either/cold air junk/manifold whater/the only thing that does anything is the ecm

Answer 2

Does 91 Octane Make A Difference

Answer 3

If the car is tuned for 91 octane you can get more horsepower out of it because you can have more timing advance with 91 and run higher compression ratios. If the car has not been set up to run 91 though, you will actually lose horsepower because 87 octane has more stored energy in the hydrocarbon. The power increase in 91 comes from being able to run higher compression rations and the timing advance. On your truck you should be able to set the tuner to 91 octane and get more power. Probably on the order of 10- 15HP, so you will notice the difference.

Answer 4

Ethanol is not as efficient as gasoline. Adding it actually decreases the amount of energy you get per volume. I'm not sure about the octane numbers, but I think you are backwards at the beginning. Ethanol has a lower octane, and when added lowers to octane of gasoline.

Answer 5

No, unless you have a high compression motor 91 octane will do absolutely nothing other than cost you more money. All a higher octane does is allow the fuel to be compresses more so it does not ignite prematurely, there is no additional power in it.

Answer 6

The octane rating of fuel will not make a difference in the mpg of the vehicle I know this from being a Cadillac tech. for 30 years.

Answer 7

yes it will make a difference if you use a higher octane gas. 87 octane gas is more flammable than 91 octane but 91 octane will burn smoother. if you look at race cars they run octane fuels rated at 102 or higher with there timing advanced more to allow the fuel to burn instead of explode. when fuel explodes, your car will start knocking. a higher octane, with the correct computer settings, will also help your mph increase as long as you keep your foot out of the gas pedal.

Answer 8

those bosch plugs are junk. Put Regular platinums back in. if the max energy programmer adds timing to run on premium then you can see a gain from it. But if it's like most handheld programmers, they don't do jack for tuning. www.pcmforless.com

Answer 9

Justin, you can't compare race cars and a run of the mill 4.3 V6 Blazer.



What does the programmer recommend you run? Does it say you have to run 91 or higher octane? If not, then stick with 87 or 89, you'll see no benefit from running 91..

Answer 10

This is an old question that gets rehashed all the time.



Higher octane than needed will slow you down and run worse than a lower octane.



The octane # is the fuels resistance to burn (or known as burn rate)



Higher octane fuels are harder to ignite



The only need in high octane fuel is when compression of engine and/or cyl pressure is much higher than norm. The compression and the higher chamber temps that comes from higher cyl pressure can cause lower octane fuel to ignite befgore its time too (as piston is starting back down)



This causes detonation (also known as ping and spark knock)



Timing also plays a role in detonation.



On my camaro, my engine is 10.34:1 compression, 221 psi cyl pressure. On the streets I dail the timing back to 29* total and can run detonation free on 93 octane. (will not run on 87, 89, 91 no matter what, pings too bad)



At the track I put 110 octane race fuel in it and turn timing up to 34* total

Answer 11

No, your car will run better only. If your car runs fine on regular stay with it. If it knocks move up to a higher grade! Thom