Just a bit frustrated. I have all the supporting mods to run a 3.4 pulley including a tune and I'm still seeing knock! before the tune, I had close to 4 degrees of knock. today I took my cat for a spin since it was nice out, did a quick pull to test out the new pulley and tune... and for some reason my boost gauge only read 7pounds of boost and read 2.5 degrees of knock. I thought a tune would for sure let me SAFELY run a smaller pulley should I take it back to the tuner for my money back and try someone else?? any advice?

 

What are your supporting mods?

 

There's no such thing as having all of the supporting mods.

There's a recommendation of what you can run, but each car is different. That's why we tell people to MOD, SCAN, Tune. If your tune isn't sufficient for the pulley, then you have to change the pulley size back to a larger one.

You don't want the tuner to just dump fuel at the engine so you can run a 3.4. You want to run it correctly. So you either need to pulley up and tune again, or mod further.

 

Safe bet would be to go inter cooled... Or as said pulley up. Consider a 3.6

 

I have k&n intake speed daddy headers cat+ res delete aftermarket mufflers 180tstat colder plugs and thicker spark wires. when I had my 3.8 pulley I was seeing 0 knock. I went directly to 3.4 as zzp and intense racing recommended.

I wish I had the money for an intercooler lol

So now I gotta go back up in pulley? I'm going to try 3.6. should I re tune after switching back to a 3.6?

 

also, will I need to change the belt size or does the 3.4 and the 3.6 use the same belt?

 

not 100% but I'm pretty sure the belt size is different.

And yes, you should get a retune, you can probably run a little more timing and less fuel when you are at the 3.6.

Then I would save up and probably get modded rockers

 

Keep your timing at 16*. ALWAYS. It's not worth the extra 10 HP. Several people with fairly heavily modded L67's have told me keep the timing stock and run as much boost as you can w/o knock.

You may be able to use your stock S/C belt with a 3.6 pulley, but there may be belt slip issues.

+1 on the modded rockers idea, unless you want to go with a cam.

 

My timing is at 12 is 16 the stock timing? I Will look into the belt size difference, go back up to a 3.6 and re tune there.

should I tune with the stock pulley first before I drop to a 3.6? or tune after installing the 3.6?

what's weird is that I did another short pull and saw 0 knock my buddy thinks it could be a bad vacuum line?

I'm goin to cam once I have enough saved up I'm about half way there

 

12 is stock from what I've heard, when you get into tuning though a lot of people end up running 16-20. I don't know the specifics TBH, but if you scan at WOT you should get 16* timing plus as much boost as you can run without KR.