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Does this flat line starting at 6,300 rpm look weird to anyone else? C6 z06, cam, ported stock heads, ported mad, NW 103, 1 7/8” longtubes, sbe. Im think maybe the heads can’t flow enough up top for the cam. 248/260 .657”/.655” 111lsa
I wouldn't be super concerned. Who did all the porting? Is the 103 ported? If not, could possibly be your intake manifold. If it is could possibly be valve float. Subbing to see some of the responses.
Looks like the same dyno in the same shop. Garner, right? Mine does exactly the same thing...except mine falls off. My power damn sure doesn't "feel" like it falls off like that. This makes me wonder if there's a high drum speed issue with their dyno? Notice the RPM is the same where the "anomaly" occurs. If we both have 3.42 gears, OEM tire size and trans gears, this is happening to both of us at the same time. I was about to make changes to my car and stuff before you posted this. Now I'm going to book a dyno appt at another place. Thanks again man. Side note...where you located? We should meet up and compare notes sometime.
Last edited by Pb82 Ronin; Apr 12, 2021 at 01:43 PM.
Does this flat line starting at 6,300 rpm look weird to anyone else? C6 z06, cam, ported stock heads, ported mad, NW 103, 1 7/8” longtubes, sbe. Im think maybe the heads can’t flow enough up top for the cam. 248/260 .657”/.655” 111lsa
Engine airflow has flatlined. Intake, head, cam or exhaust are maxed out.
What was the MAP during the run? This will tell you about intake side.
Looks like the same dyno in the same shop. Garner, right? Mine does exactly the same thing...except mine falls off. My power damn sure doesn't "feel" like it falls off like that. This makes me wonder if there's a high drum speed issue with their dyno? Notice the RPM is the same where the "anomaly" occurs. If we both have 3.42 gears, OEM tire size and trans gears, this is happening to both of us at the same time. I was about to make changes to my car and stuff before you posted this. Now I'm going to book a dyno appt at another place. Thanks again man. Side note...where you located? We should meet up and compare notes sometime.
my OEM heads are ported and TSP assured me they are capable of flowing more than enough.
I have TSP heads as well. I know from looking at flow sheets that these heads fall off big time at like .630” valve lift. They also have big issues on the exhaust port from the factory design.
If the dyno is working properly, which may be a concern in this case, I also noted the following after several dyno sessions:
1. Valve float, these little LS valve springs will do that. I checked mine they were okay.
2. Clutch slip - mine did that and the torque curve suffered - as did power.
3. Timing retard - I had crappy gas and knock retard pulled timing and killed power. Glad I logged it.
4. Oil in the intake manifold. This can be a problem and could cause timing retard.
Possibly just out of airflow, possible some more timing after peak torque would help it keep going up, also possible it'd start knocking so they didn't do that for a reason
he mentioned the MAF graph was solid up top and followed power curve.
MAF doesn't tell you anything about pressure drop.
MAP will tell you about intake side pressure drop. If its holding 98 -99 kPa (assuming a 100kPa ambient) the intake side is OK (air filter to intake manifold).
MAF doesn't tell you anything about pressure drop.
MAP will tell you about intake side pressure drop. If its holding 98 -99 kPa (assuming a 100kPa ambient) the intake side is OK (air filter to intake manifold).
I know the problem can’t be there. I have a new Halltech mf108 to new NW 103 to ne AHP ported MSD.
Dyno graph
