Retuning 91 Octane Car To Benefit From 98  

  • Alpine
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Post #1 post 26th December 2006 - 08:00 AM
Retuning 91 octane car to benefit from 98


Read in many places that if I am running a stock 91 octane-tuned car that I won't benefit whatsoever from pumping in 98 octane as the car won't benefit at all from this. They say that the car needs to be "retuned" to run on 98.

So how does one go about this? Where do you take the car to? Is any additional hardware required (like a new ECU etc) to retune to 98? How much does this kind of operation cost?
Post #2

mmm I've never heard of this before. I run a tank of 98 through my car (91 VN commo) every so often and I can notice the difference. Better economy, runs better etc.

Rookie ROX
Post #3

It is partly true. Running 98RON on a stock car that usually runs 91RON won't give any massive gains unless there's been some tuning done. However it will give you some benefits, usually including better fuel economy and can give a slight increase in power.

Full understanding available here at Wikipedia -


Post #4

A benefit of running higher octane is it gives you the ability to advance the timing by several degress.

You can only advance with timing when you run on higher octane fuel otherwise you run the risk of pinging/detonation which is not good.

Post #5

The other benefit of useing the 98 octane fuel is that it burns cleaner, maintaining a cleaner engine, and therefore it runs smoother and more effiently.

I run ALL my cars on 98 octane, regardless of thier "tune"........the extra klms you get per tank offsets the extra cost, and your engine runs better.

Post #6

totally depends on car...

i know for a fact the benz dosent like anything but 95RON, no ethanol either..

i ran it for several months with 98, and it was much better and fuel efficient with 95.

and if you HAVE TO run 91 in it, there a special plug you remove so the ecu knows.

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