Re: Air Flow Research (AFR) 195's VS Trick Flow Specialties (TFS) 195's - Test within
Subject: Re: Air Flow Research (AFR) 195's VS Trick Flow Specialties (TFS) 195's - Test within by TonyMamo on 2009/7/19 19:59:38
Quote:
dan0617 wrote: I'm anxious to see what you end up running for overall timing at WOT with the AFR heads. I'm only running 28 degrees. 30 or more and I get audible detonation (with the knock retard system disabled). I even had it coming down from that 1 to 1.5 degrees every 400 rpms below 4400 and I still get detonation. Have to start at 28 from 4400 up and bring it down from there as the rpms come down.
With my old stock bottom end, reworked 113 heads, (about 10.7 SCR), 224/230 cam, everything else the same, it liked 36 degrees, no detonation till 38. I had the 36 all in by 3200 rpms and it had no detonation.
I'm now running the AFR Eliminator street ports, shaved down to 60cc chambers, and a 383, giving me 11.5 SCR and 9.2 DCR, and I only run 28 degrees. I know that with these heads and a free flowing exhaust that not as much timing is needed, and with the higher compression timing needs reduced but I was surprised to be down 8 full degrees at WOT.
My 1 time at the track with the new setup was a 12.22, timing at 34 degrees overall and I thought I was being conservative. That was before the heads were shaved down to 60 cc chambers though. I still have a feeling I was detonating up top and didn't hear it. I can't hear it unless I'm driving between buildings or in an area where there are trees on both sides of the road. I can, however, see tiny black specs on the sparkplugs, and it pushes more oil out the breather when it is detonating. It feels more powerful now than it did when I ran the 12.22, especially up top. I wonder if it was firing while the piston was not quite to the top....
I'm betting that you will end up finding out that it will want about 3 to 6 less SA than the TFS heads,and will make more power with that much less timing. Time will tell....
Is it up and running yet?
Why did you get so aggressive with the static CR?
A 23' engine even with our heads wont tolerate as much as a Gen III which has a superior chamber/quench design. You might have made more power with less compression and more timing (closer to 11.0)....in fact likely the case. Most of the dyno testing I conduct seems to favor low/mid 30's for optimal ignition advance. I would be curious what your engine would make with 100 octane no lead mixed 50/50 and more timing added. I bet it would produce even better numbers in that configuration.
IMO, you simply have all the timing your engine will tolerate with the octane fuel your running.....not so much that you optimized your package at that little total timing. Once again, less compression and more timing would have likely produced better results and been alot safer. Knock/detonation over the long haul is certain to cause cracked ringlands or worse depending just how bad it gets/persists.
