Quote:
Originally Posted by MST0118
Hey Scott, My muffler is a 2 in / 2 out sport muffler that I got from Pete Weber who’s shop was reasonably close. It’s quiet but I think it may be a bit restrictive at higher revs so I want to compare power on dyno with open exhaust and perhaps I can find a muffler that will gain a little.
I’m running a 100 LC on the DC 80 cam, and I was thinking that a 104 LC would move powerband up but for now I won’t change anything major. When it comes to rebuild time, I’ll probably rethink the type cams if the power isn’t there, maybe a custom grind?
I’m hoping with modified injection pump, less restrictive exhaust, and better ignition will get engine in a better state of tune regardless of the final numbers.
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I can't comment on that muffler. I know Pete Weber (RIP) did nice Fab work. I also know MFI is kind of 'particular' on muffler choice. This is fundamentally because it has no method for sensing airflow (like carbs do, with vacuum) or mixture (EFI w/O2 sensor). It just sends a predetermined amount of fuel--so tuning has to be optimized for each specific exhaust (see my previous #1 point about mixture for max power).
Why do you say your current muffler is restrictive?
DC80-100 should be great if they are ground properly and timed properly. It should feel like a superbike in character.
FYI, a 104 LC would move the power band *down* and flatten the curve, theoretically. It improves vacuum response at low revs (good for street driving) and reduces the 'supercharging' effect of scavenge at high revs, due to less overlap of I/E valves.