Detonation at WOT

[shelbydoug]

I'd suggest running the timing events of that camshaft through the "dynamic compression" calculation.

My initial impression is that you need to go to more camshaft to bleed off cylinder pressure. In other words, your cam is too mild and creating static compression that the fuel octance cannot handle.

[Kent]

exactly Shelbydoug thats what I also tried to explain in my school English. Regards to the 95 octane question I mean 95 octane US not EU in EU it would be similar to 98 I think.

[pbf777]

     First, although "Octane-Booster" is convenient and quite popular in the effort to better the anti-knock quality of a lesser than needed fuel, I (and many others) really don't recommend its' use beyond 'emergency' situations were for example you find yourself a long way from "good" fuel and it can be conveniently stored in the vehicle for such instances.  Better, is to utilize 'actual' fuel that presents the necessary octane value, even as mixed with the poorer fuel from the pump. 

     As far as for what it might be as pumped into your vehicle, regardless of that which you might have selected at the pump, this is not a new issue!  As I have worked at a gas station at one time and have known both others of the same, owners of establishments, and even the tanker delivery drivers, and I can assure you that "93" ain't always just that!   

     Scott. 

[pbf777]

    As far as for the camshaft timing, yes, that profile as outlined is definitely on the "conservative" side, and although may not necessarily be 'the' culprit alone, it certainly is intended to create peak cylinder pressures at the lower revolutions, in the application presented.    

    Now as for whether it's the "wrong" cam or not, this has more to do with what one might consider as acceptable drivability characteristics within the intended engine revolution range; and it could perhaps be just the right camshaft, just not coupled to the surrounding engineering that permits such with said fuel. 

    Scott.

[Bob Gaines]

First, although "Octane-Booster" is convenient and quite popular in the effort to better the anti-knock quality of a lesser than needed fuel, I (and many others) really don't recommend its' use beyond 'emergency' situations were for example you find yourself a long way from "good" fuel and it can be conveniently stored in the vehicle for such instances.  Better, is to utilize 'actual' fuel that presents the necessary octane value, even as mixed with the poorer fuel from the pump. 

     As far as for what it might be as pumped into your vehicle, regardless of that which you might have selected at the pump, this is not a new issue!  As I have worked at a gas station at one time and have known both others of the same, owners of establishments, and even the tanker delivery drivers, and I can assure you that "93" ain't always just that!   

     Scott. 

So you are saying is given the owner doesn't want to rebuild his engine with lower compression different cam change timing etc. and it is determined that the detonation is the result of too low of octane that keeping a 55 gallon drum of race fuel to doctor your tank is ideal. The octane booster would be the next best thing. If this is not what you meant then please clarify.

[shelbydoug]

As far as for the camshaft timing, yes, that profile as outlined is definitely on the "conservative" side, and although may not necessarily be 'the' culprit alone, it certainly is intended to create peak cylinder pressures at the lower revolutions, in the application presented.    

    Now as for whether it's the "wrong" cam or not, this has more to do with what one might consider as acceptable drivability characteristics within the intended engine revolution range; and it could perhaps be just the right camshaft, just not coupled to the surrounding engineering that permits such with said fuel. 

    Scott.

You can make it as complicated as you want to. For modern gas, you need a modern cam ground for it. That one is ancient history for a station wagon.

[Rich Herr]

Thank you for all the information.  After reading comment and going back to engine builder, the compression was not measured but determined it was way more than 10:5 as many commented.  I found 100 octane fuel near me and that fix the issue.  I appreciate all the advice.