I did a DIY alky kit on my T-type late last summer. My problem is sometimes I see a lot of knock and it goes away. Sometimes I see a little knock every 2 or 3 frames. Sometimes none at all.
147K mile stock motor, new bearings, timing chain, valve springs, all seals and gaskets at 119K. Good even compression numbers, good vacuum, etc. Stock turbo w/ ported inlet bell and compressor inlet and outlet, stock intercooler, blue tops, afpr, 307 pump, ported elbow, 2 3/4" DP, 3" single shot exhaust.
Before the alky kit I was running a Jim Testa chip on 92 octane and 14-15psi. I really dont remember exactly, but I would see knock every now and then, nothing over 4*KR.
When I did the alky setup, I started tuning it in with that chip, and a .035 NOS jet in the alky, coming on at 12-13psi. Initial test runs yielded serious bogging! I stepped up to a 20* JC chip, same deal. Boost level was 20-21psi. No knock w/ either chip. Eric Marshall did a chip for me, and it helped. Car felt pretty good. I went to the track and ran low 14s, EGTs were 1520s, rich, with some knock on initial spoolup. So I bought 3 new jets, .028, .026, .024. With the .024 jet in coming on around 12-13psi, sometimes I would see lots of knock on initial spoolup, and it would be gone for the rest of the run, but still rich at the top end. Im pretty sure it was not false knock cause I could hear it under the hood. I tried lowering the spray on point to 10psi or so, and it didnt help much. I havent messed with it much since then. The few times I have floored the car since fall I just watched the SM to see if the initial spoolup knock went away in the next frame. It usually did.
Today I filled up the alky bottle for the first time in over a month since it was nice out today, mid 50s. (Isopropal I think, 70% from walmart). The car is currently set on 20psi solid. And I have changed the jet to the .026. Im stuck between wanting to lean it out for higher EGTs and lower 02s, but afraid of the knock Im already getting with it being rich.
So........today I floored it after filling the bottle........10mph roll. The boost comes up pretty freakin quick in this car, and as soon as it jumped over 15psi I heard the most godawful sound under the hood. Rapid tapping noise, aka popcorn, but NO knock on the scanmaster. Oh yeah, a huge cloud of black smoke puffed out of the tail pipe too, and it has done this before. Obviously I let out of it. 02s said 898. Okay, checked temp, BLMs, INT, vacuum, etc to make sure I didnt blow the thing up and cruised down the road a little ways. 35mph roll I let off the gas and stomped on it again. Boost came up, heard the popcorn noise again, but it wasnt as loud or long this time, and yes, I stayed in it through 2nd gear and let out. It registered 12*KR at 40ish mph. Dont remember the 02, probably 830s or 840s. Hrmm, okay. Get on the highway, with my other GN buddy behind me I slowed to 10mph and brought up the boost on the brake and hammered it. It kicked to first and spooled hard, tired hazed a little, no knock. Hrmm, bangs 2nd gear, no knock, 02s in the 8-teens. Boost solid at 20psi, 2-3 shift comes (flares badly, like 1.5 second flare), and I heard the popcorn sound again briefly, glanced down and saw 5.4*KR. It went away in the next frame and continued to pull in 3rd gear. Recall on the SM showed the lowest 02 at 804 at like 74mph. EGT was 1535 max (I did not run the car up much in 3rd, probably close to 100mph. My buddy said no smoke this time? What gives. Seriously.
Info on my chip, Eric Marshall chip, 23* timing in 1 and 2, and 21* in 3rd. Maybe its too lean down low on spoolup? But what about the rich condition!?!?! Sometimes Ill see a lick of knock midway through a gear, but not often. Maybe there is something mechanically wrong with the car? I know the possibly slipping trans does not help things. What about a flat cam lobe? Ive got other things going on the GN, but I would really like to straighten this car out and get it to STOP knocking. I know if it keeps doing this Ill eventually hurt something, even if its just knocking on spoolup. I know this is long and winded, but Im hoping somebody has some input for me. Thanks fellas, any responses are appreciated!!!!!!!!!!!!!!!
147K mile stock motor, new bearings, timing chain, valve springs, all seals and gaskets at 119K. Good even compression numbers, good vacuum, etc. Stock turbo w/ ported inlet bell and compressor inlet and outlet, stock intercooler, blue tops, afpr, 307 pump, ported elbow, 2 3/4" DP, 3" single shot exhaust.
Before the alky kit I was running a Jim Testa chip on 92 octane and 14-15psi. I really dont remember exactly, but I would see knock every now and then, nothing over 4*KR.
When I did the alky setup, I started tuning it in with that chip, and a .035 NOS jet in the alky, coming on at 12-13psi. Initial test runs yielded serious bogging! I stepped up to a 20* JC chip, same deal. Boost level was 20-21psi. No knock w/ either chip. Eric Marshall did a chip for me, and it helped. Car felt pretty good. I went to the track and ran low 14s, EGTs were 1520s, rich, with some knock on initial spoolup. So I bought 3 new jets, .028, .026, .024. With the .024 jet in coming on around 12-13psi, sometimes I would see lots of knock on initial spoolup, and it would be gone for the rest of the run, but still rich at the top end. Im pretty sure it was not false knock cause I could hear it under the hood. I tried lowering the spray on point to 10psi or so, and it didnt help much. I havent messed with it much since then. The few times I have floored the car since fall I just watched the SM to see if the initial spoolup knock went away in the next frame. It usually did.
Today I filled up the alky bottle for the first time in over a month since it was nice out today, mid 50s. (Isopropal I think, 70% from walmart). The car is currently set on 20psi solid. And I have changed the jet to the .026. Im stuck between wanting to lean it out for higher EGTs and lower 02s, but afraid of the knock Im already getting with it being rich.
So........today I floored it after filling the bottle........10mph roll. The boost comes up pretty freakin quick in this car, and as soon as it jumped over 15psi I heard the most godawful sound under the hood. Rapid tapping noise, aka popcorn, but NO knock on the scanmaster. Oh yeah, a huge cloud of black smoke puffed out of the tail pipe too, and it has done this before. Obviously I let out of it. 02s said 898. Okay, checked temp, BLMs, INT, vacuum, etc to make sure I didnt blow the thing up and cruised down the road a little ways. 35mph roll I let off the gas and stomped on it again. Boost came up, heard the popcorn noise again, but it wasnt as loud or long this time, and yes, I stayed in it through 2nd gear and let out. It registered 12*KR at 40ish mph. Dont remember the 02, probably 830s or 840s. Hrmm, okay. Get on the highway, with my other GN buddy behind me I slowed to 10mph and brought up the boost on the brake and hammered it. It kicked to first and spooled hard, tired hazed a little, no knock. Hrmm, bangs 2nd gear, no knock, 02s in the 8-teens. Boost solid at 20psi, 2-3 shift comes (flares badly, like 1.5 second flare), and I heard the popcorn sound again briefly, glanced down and saw 5.4*KR. It went away in the next frame and continued to pull in 3rd gear. Recall on the SM showed the lowest 02 at 804 at like 74mph. EGT was 1535 max (I did not run the car up much in 3rd, probably close to 100mph. My buddy said no smoke this time? What gives. Seriously.
Info on my chip, Eric Marshall chip, 23* timing in 1 and 2, and 21* in 3rd. Maybe its too lean down low on spoolup? But what about the rich condition!?!?! Sometimes Ill see a lick of knock midway through a gear, but not often. Maybe there is something mechanically wrong with the car? I know the possibly slipping trans does not help things. What about a flat cam lobe? Ive got other things going on the GN, but I would really like to straighten this car out and get it to STOP knocking. I know if it keeps doing this Ill eventually hurt something, even if its just knocking on spoolup. I know this is long and winded, but Im hoping somebody has some input for me. Thanks fellas, any responses are appreciated!!!!!!!!!!!!!!!