I am currently running the 259E cam in my 110 with Screaming Eagle Tuner and Thunderheader 2 into 1 exhaust. I am not happy with my Dyno numbers 103 HP and 108 torque. The HP # seems a little low but I have a nasty dip in the Torque at low end and then recovers nicely. Dealership can not seem to program the dip out, and are claiming that it is my exhaust. I was expecting about 115 to 120 torque at the rear wheel based on feedbacks from the mechanics. Thanks!
The Dip in the tq at 2500 rpm area is caused by the Thunder Header over scavenging at that rpm....other than that the Thunder Header isn't a bad performing pipe.
You can tune the pipe to slow the gasses down by bending the four sides of the baffle toward the collector inside.
The exhaust gasses should travel 280 to 300 feet per second, this is where the best performance is found. If the gasses are escaping faster than 300 feet per second the mixture is being pulled out of the cylinder during valve overlap at low rpms...if you can't keep the mixture in the cylinder you can't burn it...the more over lap the bigger the problem and the bigger the dip.
If the gasses are escaping too slow...below 280 feet per second the exhaust pipe doesn't have enough time to clear it's self before the next blowdown cycle so the spent gasses enter the cylinder through the exhaust valve which gives you a dulitude mixture and this kills power also.
By bending the baffle in the Thunder Header you can slow the gasses down at the lower rpms and actually remove the dip and enhance your power a bunch.....if you bend the baffle too much it can effect the top end power so by doing this on a dyno you bend it a little at a time until you see the power drop off on top....then you are done. If you don't have a dyno or access to one simply bend the baffled with a old broom stick and a hammer until the space between the collector and baffle is about a 1/4'' away on all 4 sides. You will be surprised and you won't be disappointed....believe me.
Doc
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Topic: Which exhaust (Read 1390 times)