I'm completely upset that I've poured this much time and money into this project and have almost no gains to show for it. After installing a 228/228 .577/.577 114LSA cam and underdrive pulley, I'm getting 10 hp gains because my tuner is saying I'm my temps are too hot and I'm getting and I'm gettting early detonation and thus he is unable to advance the timing to where it needs to be. Currently its advanced about 17 degrees which you all are probably laughing at, but any higher and it detonates. What the heck do you think is causing this. Below are the best guesses thusfar, but I wanted to hear your opinions.

Right how our best guess is that its the coated headers locking in the heat, or that the engine is/was sucking oil (although I didnt' see much oil at all in the intake when I stuck my hand in there yesterday):

Tuner wrote this:
"Not quite sure why Ryans car has such a huge detonation problem. It absolutely "could" be the headers, however anything is possible. The problem is quite pronounced. It runs pretty good now for what it is, but something is definitely causing detonation which is the reason his numbers are so low. If I could lean it out and add some timing, it would wake up like crazy. But you can't do that if all that does it makes it detonate worse and blow carbon out the tailpipes! Don't want to start blowing aluminum out the tailpipes! Pistons are expensive to replace!"

And he wrote this, months earlier about coated headers:
"This is just my experience from what I've seen in making headers. Another thing we could go into is coatings, and how much I dislike them on headers Ceramic coated headers always seem to cause detonation. Why? Well everybody jumps on this bandwagon of wanting to keep underhood temps down. Which is great, I love it, whatever you can do to keep underhood temps down is going to help make the motor produce more power. But what we're doing by ceramic coating the headers is we are locking that heat inside the exhaust... Not allowing it to dissipate... This heat now acts as an agent in producing detonation. Almost every car I've ever tuned that had ceramic coated headers, was not able to take as much ignition timing as a car with uncoated stainless steel headers. So the power was greatly reduced because instead of tuning for all out power, I had to tune for detonation. Extra fuel, and less timing... Things that have a great effect on what kinds numbers your car will put down on the dyno, and at the track."

Have anyone heard of this before? Other ideas to what it could be, or easy ways to eliminate possibilities?

 

If coated headers are such a problem, why do so many people run them? I assume he is talking about the heat building up and reverting back into the cylinders causing detonation? I'd say it could be a possibility but not as likely in the whole scheme of things. What size are your primaries and what headers are they?

Also, just b/c you don't have oil in the intake doesn't mean you're not burning oil, it's just means it's not sucking it in through the PCV/intake. It could still be getting past the rings into the cylinders. If your engine is/was sucking oil that's the major cause of detonation at this point. I would try to find out why that was happening before turning to the headers causing all of this.

 

This was my initial thought to. I had never heard of this coated header thing, myself. I 'm running TPIS headers 1 3/4" primaries.

How would you suggest I do this? Pull the heads? Decarb?
I did notice that my PCV seemed to be stuck open and backwards. I've since fixed it, but I doubt that that would do it alone.

 

I would do a compression test to see if any cylinder is down a bit and possibly getting blowby.

 

you said you did a cam swap... did you install this straight up or did you advance or retard it? did you degree it in?

any history of detonation before all this? did you change plugs? are they gapped correctly? Octane of fuel you are using? are any cylinders detonating more than others? how much oil are you going through

list off what you have done to the car prior to this happening.. you also might want to try the PCM tuning board and post your file/tables over there for someone to take a look at.

 

I did the cam swap myself, lined up dot-to-dot perfectly, the cam has +4 degress in it, I did not degree it in

No history of detonation before, I believe the octane was 93 but I did buy the gas at a small place I never go to for the tune so perhaps it was a lower octane or crap gas, all cylinders are detonating the same I believe, the car eats maybe a quart of oil every 3000 miles

A few months ago I had MTI install the TPIS headers, Random Tech X-pipe and cats MTI Houston and change the plugs (NGK), so I believe they are gapped correctly but have not checked myself. MTI also tuned it afterwards and they advanced the timing 29 degrees across the board and I would get lean fuel trim codes regularly.

I'll ask my tuner for the files.

Thanks for the help. Hope this info helps.

 

check that PVC.. get a cheap catch can and hook it for now.. you can get them for 25$ on ebay.. check the level often if you are going through a quart every 3k miles. You seem to have done everything right so far.. but that bad of detonation is not common. I wouldnt suspect the ceramic coated headers.. since about 60-75% of the people with headers are coated ones.

is this detonation occuring at all RPM ranges or just Wide open throttle?

 

I've replaced the PVC and I've always been running a catch can. I don't know if I was clear, but since the timing is so conservatively advanced now, I no longer have a detonation problem. Put during the tune when the timing was advanced to where it should be, in the high 20s, I did.

Detonation is occuring at all RPM ranges, based on the fact that it was noticed during the part-thottle pulls, during the dyno tune.

 

i concure then with the previous suggestion.. compression test.. if this shows to be OK.. I would then recheck all the simple things 1st before you start ripping into the thing.. re-check the plugs, wires.. what series NGK did they put in?

after all that.. start looking into the tune..

something is off somewhere.. just start small.. check and recheck.. leave nothing unturned.

 

I'll do that...

Instead of pulling the heads I'm going to just do a de-carb with some sea foam. That way I'll be forced to change the plugs.

Why do ask for the series of NGK? I don't know what series they are, but should I be looking for a particular series when I replace them?

 

NGK TR55's.