I know that they increase airflow and removal of exhaust gasses from the engine quicker than the stock manifolds, but what else does this affect?? I dont know much about this sort of stuff. Does the ECU then pump in more or less fuel due to the quicker release of gasses??? need a tech person to explain this to me.Anyway, had the headers installed today. Not much difference on take off, but more responsive during the rev range. I dont think I'm getting the most out of it at the moment, as bob will have to do some trimming on my Hitec to really get the most out of them. However, have also picked up 2 new noises. The first one is a loud metallic rattling noise when coming off the accelerator at high rpms. Have no idea what this is, will need to investigate. Any ideas?? The 2nd noise may just be due to the headers themselves, I dont know. At about 3000rpms, when I really boot it, the engine just sounds noisier (is that a word?) all the way through to "riduculous" rpms (say about 7000). I dont know if this is due to extra air or increased air flowing through the headers and into the exhaust. It sort of sounds like pinging, but not....if you know what I mean. Like a ticking noise, only really quick and sounds like lots of air trying to pass through something. Thats the best I can describe it. I dont think the car is pinging. There would be a loss in power if the car was pinging loudly right??? If I acclerate normally, its still a little noisy but not like if I really put the boot in. Dont know what to make of it.Also, was hoping the headers would remove more of my exhaust drone. While it didnt make it worse, it certainly didnt reduce it. Not noticeably anyway. Ahh well. However, the car sounds more "beefy" at idle for some reason..Cheers
Things I noticed... exhaust drone went, exhaust note good, took a few days for the computer to adjust, more flexible/responsive overall, definite power increase 3000 up, air fuel ratio went a bit leaner, less tolerant of hot days, poorer quality fuel,..pinging evident on these occasions (I'm still experimenting with timing..but the hot weather has gone plus laid up waiting heater fix!!)
You have to remember... ...that the OEM headers have a lot of insulation around them, so they are a lot more quiet than bare headers. Id say this is what is causing your noises, shock waves transmitting through the pipes(from the exhaust valves opening and releasing high pressure gas), and with no insulation to dampen the vibrations, you can now hear more noise. As for the rattling, my first impression is that it is the same phenomenon as I just explained, but with the added pressure of exhaust gas still burning hitting the headers. If it aint that, it could be one of the exhaust mounts further back rattling. My guess is that everything is fine and your just unused to the sound of headers, and I hope Im right:-0 You'll have to go for a run on the dyno to see how well your new mod is working
They actually... ...flow the gases out so that the pulses do not interfere with each other and cause turbulent flow when the pipes merge. This creates less backpressure and hence more power due to an increase in volumetric efficiency. The cylinders have less pressure in them earlier in the overlap part of the cycle as the piston approaches top dead centre and the inlet valve opens, thus providing an 'easier' area to fill with intake charge. This will in turn increase the amount of charge to be ignited and therefore the amount of power that will be made.As for the ECU it will receive a greater reading at the air flow meter due to the increase of air that can be sucked in and will compensate by pumping in more fuel. I'm unsure of exactly how the self learning feature of the ECU works but I'd imagine it will 'get used' to the increase in efficiency over a few drives and give you more power still. This must just work by recording series of how the engine reacts to certain inputs and optimising these for the best outcome. If anyone knows more about the ECU self learn I am very interested.
Pinging is possible I guess remember that because the headers will remove more spent gas from the chamber, that there will be more fresh mix taken in on the intake cycle. exhaust gas left behind in the chamber has a cooling effect (and thus slowing the burn rate) on the next round of air/fuel mix. By removing more gas, you are likely to increase the risk of pinging.two options if if does end up being pinging. Add more fuel, or reduce timing a bit. reducing timing will reduce power so your better off increasing fuel for the ranges were it pings.In the interem, get someone with a conzult and turn back the timing a few degrees and go for a drive. if it makes a difference you know it's pinging, if not then it's probably one of the other effects mentioned.AB
