I'm having a heck of a time tuning GSC S1 cams. I just got back from tuning it for about 3hrs, although I'm no pro. I started with a tune that gave me on avg. 320hp on DLL. Run to run, I was getting anywhere from 2-6 counts of knock in random places, and sometimes only 1-2 counts. Keeping AFR the same throughout the powerband, I lowered timing in all applicable places until I could minimize the knock. I even lowered it to the point that my target timing in my map was lower than the actual ECU readout! Anyways, I was still getting the same amount of random knock counts througout the band, this time with only 290hp. These cams are the only thing I changed recently. Before I had the cams, I was only getting 0-2 counts here and there. Does anyone else have problems with tuning GSC cams, or any other cams for that matter? Is it normal to have this much noise going on?

 

Cams do make the valve train noisier and potentially induce phantom knock, but often times not enough to trigger the knock sensor up to the extent you are describing. Did you try email Greg @ GSC about the issue you are experiencing?

 

I am curious what RPM range? I seem to have issues in the 5k-6k range that is independent of timing and boost. Just reading the plugs I know that the car is not knocking significantly enough to hurt anything but there is def some noise happening.

 

Yeah, you may want to talk to GSC. I have the S1's for my 8 (268* I/E, not sure what revision the cams are as I think there are a few revisions out there). I get knock here and there (1-2 counts). When I first installed them I had to pull timing ~100-120%Load and some up top as well, other than that I haven't had knock issues like you are having. I don't think I am overly conservative either, DLL says on avg high 350's (havent been on a real dyno to get a real number yet for comparisons). Try some 100 octane to see if the knock count goes down or to 0. Maybe try colder plugs to draw more heat from the combustion chamber. Do you have huge timing changes from load to load or RPM to RPM in your timing map or log large timing changes near the instances of knock?

 

I have only 2 counts of knock right before spool up, and thats about it.. with my Gsc s1's

 

In the event that was directed at me, I have tried 100 octane leaded and it didnt help. I first closed the gap on my plugs, then opened it back up, then went to new plugs. I think my issues might be related to other things I did at the same time and not the cams. I know lots of people that are running them with no problems. Cursed sometimes is all.

 

JB, thanks for the great info. What changes did you make that you think attributed to your knock situation?

 

I also did valvesprings and used air pressure instead of the rope trick to keep the valves up. The first time I put air to the engine I forgot to keep the crank pulley locked (this was done in car) and it spun so I had to pull everything off the front of the motor to verify timing and make sure the balance shaft and oil pump were sync'd. After reassembly it made this weird squall from the power steering resivoir idler pulley (which was factory cross threaded...again the curse). It ended up being a bad bearing so I replaced it and the accesorry belt. Noise is better (still there) and the knock isnt as bad but if the car loads up right I will get knock. I can lift and immediately get back into it and the knock disappears. I have removed the lower tie bar that was close, spaced out the remaining one even more, yet there is still knock where there wasnt when I had first put the Green on. I had had an HKS 280 exh for the longest time and then threw the S1's. Dont get me wrong I AM NOT BLAMING THE CAMS AT ALL for my problems. They work exactly as described.

The only other thing that I am thinking is that the combo of the Green and my aggressive MIVEC that I developed for the S1's might not play ball so well.

That or I am cursed.

 

you are not cursed....My car has the same issue. What type of srings did you use for the valve train. I have cosworth 272 M2s and supertech springs and retainers on my car and it did the same. The valvetrain got much louder and is causing ghost knock. We later figured out the problem was that my lifters were not bled during the install causing the system to get loud and trigger the knock sensor. When we bled the lifters later, and the knock went away.

 

There is almost always 1-3 counts at 2500 at 120 load. Then there's 3-6 anywhere else in the powerband, and if I can see a pattern, it tends to be around 4000, 5500, and 6500rpm (not always in all those rpms though). Out of about 12 runs, about 8 of them had counts in the 4-6 range, some had only 1 or 2 counts, and the others had 8 counts or 3ish counts.

 

how did you bleed your lifters?

 

I used BC's with Ti retainers. I didnt rebleed my lifters but there is no lifter noise. I have encountered it on other cars so I know what I am listening for but dont hear it audibly. Maybe I need to do this just to be sure though.

 

With GSC S1/green turbo I have some knock 3-6 early in 3000-3500 rpm range, on 100 octaine tune, but using 110 still knocks, no knocks above 3500. Not too worried about it.

 

I didn't bleed my lifters either and I don't have any ticking noise. I have a friend who's had the ticking noise and he told me my car doesn't have it.

 

Do you guys think if I gapped my stock plugs smaller than stock, it'll help?