You may get two more horsepowers - but of course a bit higher risk of detonation.

 

every little bit helps

 

Pre-detonation. You get detonation all the time (hopefully)!

The engine has to cope with a certain range of gasoline quality, and environmental conditions, so if you put in quality gasoline you are probably OK with an 0.3 compression increase.

 

Sorry, but the correct term is 'detonation', no such thing as 'pre-detonation'. You might be confused with 'pre-igntion'.

Detonation is NOT a common or desirable condition nor is pre-ignition. Either can lead to serious engine damage but it is unlikely that .3 higher CR will induce detonation under average driving conditions. The knock sensors will detect this in any case and adjust ignition timing to compensate.

 

Ooops, my only excuse is I normally drive a diesel

 

Yes, with stock boost. Please remember that AJ26 has weaker detonation protection than the later models.

 

I do not have stock boost, I have upper and lower pulleys from Eurotoys plus a retune of the ecm(not sure if this affects boost).

Re gas quality:
I run premium and always put in octane booster every tank.

Thinking about doing a snow performance methanol kit so I don't have to add octane booster at every tank fill.

 

Then I understand well why your stock head gasket gave up.

 

Should I not have done that?
Or do you just mean the more performance it has the more wear and tear?

 

4.0 composite gaskets do not like high boost and when you increase rpms of Eaton SC so much ( lower + upper pulley ) you increase heat very much. That requires better cooling or your heads/gaskets are in real danger. Do you have bigger intercooler radiator or something else which controls extra heat ?

 

99% of commercial octane boosters do nothing. Waste of money.

 

I have the upgraded kit from Eurotoys, but never installed it.
Obviously I should do so.

And I should replace my head gaskets with the 4.2 ones.
Are these stock for the 4.2s or where can I buy them from?

 

Well, I use the orange stp ones and I can actually feel the difference.
Also, when I don't run it I often get an error code that eurotek told me would happen if I don't use high enough octane gas.

Idk.

 

Coventry West, a forum sponsor. new chains, gaskets, front seal, metal tensioners, shorter bolts, etc etc etc. One part number, box of stuff to do it.

 

They are stock 4.2 V8 gaskets.

 

Not to go to far off topic, but that's one of the worst products on the market. I can post a dozen links showing lab and dyno testing demonstrating this, but even STP's own MSDS sheet indicates there's virtually no octane enhancing ingredients

http://www.stp.com/PDFEnglish/STP%20...r_01-2013_.pdf

The first two ingredients do nothing to increase octane

Hydrosulfurized Kerosene 64742-81-0 70-100%
Solvent naphtha (petroleum), light aromatic 64742-95-6 3- 15%

The sheer size of the container is not big enough to contain enough additives to make much difference even if the concentration was 100%.

Any gain would be in the order of 0.1% or so. Your 91 from the pump would become 91.1 approx.

 

Well, I'm no chemist so can't attest for actual octane changes.

I can attest to a seat of the pants change.

I have actually done placebo tests and had others put it in or not when I fill up because I was skeptical.

I can always tell when it's in there.

Same with other brands and products, I can feel the difference between them and what I use.

Meh, ymmv.

As a last question for you guys, for the moment at least:
What's the best place to find a repair manual for my car?
I used to use a website, but it's subscription based and I'd rather have something I can keep after bUying it once.

 

For you to notice a 'seat of the pants' difference, the engine would have had to be suffering serious enough detonation that the knock sensor and computers would have reduced ignition advance by a significant degree. The octane boost offered by the STP product would make no measurable difference.

Have you tried using JTIS as a shop manual?

 

I have not tried the jtis.
I did attempt to make it work a few years ago, but I don't think I ever got it going.
I don't recall why it wasn't working.

I'll give it another shot.

 

If you have a problem getting JTIS to load, try sending a message to Jim Lombardi requesting help.