Question about detonation

[98ss]

The richness , we have found on the types of fuel we run GT-R's on in the US , they like to be rich. Pig rich. They still make plenty of power , just takes a ton of fuel to keep it from detonation on less than great fuel. Good stuff is available , but you need to plan for worst case.

What is detonation?

Would a octane boost additive help stop this?

What do you do to supply the engine with "a ton of fuel" the keep it from detonation?

Is 94 octane too low to safely drive a GTR?
:?: :?: :?:

[BigBlueR32]

give this thread a read...hope this answers your question..

http://forums.gtrcanada.com/viewtopic.php?t=63

[98ss]

Yikes! PONS, RONS, MONS.

What I got out of it was 94 octane was ok ... I think?

[spikeone]

yeah, 94 should be ok, as long as you don't run a ECU tuned for japan

[Unlucky Menace]

Heed Alan's Advice (UK Skyline Owner): Get your fuel mapped asap when you get your car. It'll solve a lot of problems.

[Murphy]

The richness , we have found on the types of fuel we run GT-R's on in the US , they like to be rich. Pig rich. They still make plenty of power , just takes a ton of fuel to keep it from detonation on less than great fuel. Good stuff is available , but you need to plan for worst case.

What is detonation?

Here is a quote from A. Graham Bell's excellent book Four-Stroke Performance Tuning.

Detonation and pre-ignition are both engine wreckers. Pre-ignition is self-ignition of the fuel caused by a hot spot within the combustion chamber, or due to the fuel becoming unstable because of excessive pressure or heat. Detonation is a violent burning of the fuel (almost an explosion) caused by colliding flame fronts after the spark plug has fired.

When engine damage results from either condition, the culprit can usually be identified after an examination of the pistons and spark plugs.

Pre-ignition damage is caused by extreme combustion temperatures melting the top of the piston and possibly also the ring lands. If a hole is present in the piston crown, it will appear to have been burned through with a welding torch, and the metal around the hole will have a melted appearance. Spark plugs exposed to sustained pre-ignition quite often have the centre electrode melted away, and in extreme cases the insulator nose may also be fused.

Usually, pre-ignition can be traced to combustion chamber or exhaust valve deposits becoming incandescent, but it may also be due to blocked water jackets creating a hot spot, or a glowing spark plug with a heat range too hot for the engine. In a few cases pre-ignition can be traced to an overheated piston, perhaps due to inadequate lubrication, improper clearance or a broken ring.

A piston damaged by detonation will show signs of pitting on the crown; in extreme examples the piston crown may be holed. The hole will appear to have been punched through, with radial cracks and a depressed area around it. A spark plug subjected to detonation will usually show signs of cracking at the insulator nose.

When detonation occurs, a portion of the fuel/air charge will begin to burn spontaneously due to excessive heat and pressure after normal ignition takes place. The two flame fronts ultimately collide and the resultin explosion hammers the engine's internal components. Detonation can be attributed to excessive spark advance and/or lean fuel/air mixtures. In supercharged and turbocharged engines, excessive intake charge temperatures can also lead to this condition.

So you can see that either condition is basically a result of either a) too much heat or b) too much pressure. This basically amounts to the same thing, because if you have too much pressure, as the intake charge is compressed during the compression stroke, the temperature of the charge will go up in direct proportion to how much it is being compressed. That is why an overly high compression ratio will lead to detonation.

Would a octane boost additive help stop this?

Yes. A fuel with higher octane burns slower than a fuel with lower octane. Thus if you slow down the speed of the flame front travel, you will be less likely to experience detonation.

Other things you can do to stop detonation are to use less spark advance, reduce your compression ratio, reduce your boost pressure, reduce the intake charge temperature by using a more effective intercooler, and reduce the charge temperature by using a richer mixture than optimum. This last works because the fuel must be evaporated before it can be burned; and since it take heat to evaporate anything, the more heat is used up to evaporate fuel the cooler the combustion chamber will be. It is not the ideal way to do things but it is safe and it does work.

What do you do to supply the engine with "a ton of fuel" the keep it from detonation?

You use your Power FC, piggy-back computer, or reprogram the stock chip to tell the injectors to stay open longer. Or, you can increase the fuel pressure.

Is 94 octane too low to safely drive a GTR?
:?: :?: :?:

You can be courting danger at 104 octane. Or, you can be perfectly safe at 89 octane. Depends completely on how the engine is tuned.

Cheers
Jason

[tyndago]

Run the best fuel you can put in the car at all times. One heat range cooler plugs for minor mods. Couple heat ranges or more if you start getting up there in power.

Detonation / pinging /pre ignition = all bad. Sounds like marbles in a can , shaken violently. If you hear it , get out of the throttle .

Some people can't hear it . I can hear it...... I have driven in cars , with people that never noticed a car detonating. I heard it the first time they stood into the throttle . Even at least once when I was in a car with a "Tuner".... a "famous" Japanese one.......

[Unlucky Menace]

Even at least once when I was in a car with a "Tuner".... a "famous" Japanese one.......

Tell the tale, tell the tale!

[tyndago]

Even at least once when I was in a car with a "Tuner".... a "famous" Japanese one.......

Tell the tale, tell the tale!

Try not to name names on public forums...... if I meet you in person , I may tell you some stories....

Some nightmares of "well respected" Japanese tuning shops..... aka jokes in my eyes....

[Unlucky Menace]

Even at least once when I was in a car with a "Tuner".... a "famous" Japanese one.......

Tell the tale, tell the tale!

Try not to name names on public forums...... if I meet you in person , I may tell you some stories....

Some nightmares of "well respected" Japanese tuning shops..... aka jokes in my eyes....

I was actually just wondering what you said to the guy when you heard his "tuned" car detonating lol.

[JZ]

He threw the keys at him and said "are you ******* deaf? this thing is knocking like crazy!"

Peel back some of the PR machine's spin and some of these tuners are not all they seem to be...

Atta boy Sean, thats telling him!

[Unlucky Menace]

He threw the keys at him and said "are you f*cking deaf? this thing is knocking like crazy!"

Peel back some of the PR machine's spin and some of these tuners are not all they seem to be...

Atta boy Sean, thats telling him!

I just gotta say that it's so nice to have Sean and Nick on this forum to help pull the facade off some of the misconceptions and pure b.s. that's peddled to us in magazines. In reading some of them, you'd think that some of the tuner cars are more sophisticated than an Enzo and flawless in design.

It's nice to learn the realities of tuning, that name brands don't mean @#$! when it comes to buying parts, and that a lot of the "JDM" parts are well-overpriced when there are easily acceptable parts, of better quality and cheaper prices over here.....PE, JE, Crower etc. When I first joined I was all about a certain tuner, because they were built up to be the ish, but after 2 months and a few pms from nick and sean I've been straightened out.

I just wanted to say thanks guys for showing me the "light" and keeping from making the mistake of dropping $2k on an exhaust when there's a better one for $560.

Thanks!

[JZ]

When I first joined I was all about a certain tuner, because they were built up to be the ish, but after 2 months and a few pms from nick and sean I've been straightened out.

*cough* top secret*cough*

[Unlucky Menace]

That information was classified and compartimentalized!

I do however, still think the Mine's R34 is a damn nice machine.

[JZ]

a little blurry but...