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World's fastest Harley street bike.

This kind of stuff

 

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As already stated, pipe length and dimensions are critical to specific engine
configurations, valve timing, RPM, etc.

Sticking on the exhaust system from my race car is likely thousands of dollars
more than the average street setup, and tuned quite well, but it would surely
provide losses on your motor.

Exhaust and intake pressure rely heavily on pipe length and diameter to flow
properly. Frequency and wavelength should be keywords used for this discussion.

 

We just got done with a 441 cid SBC with 230 cc Pro 1's, 11.5/1 compression, and a Victor Jr. intake. The combo made ~525 rwhp.

By switching from Hooker 1 3/4" LT's to Hedman 1 7/8" LT's, it gained 60 ft-lb down low and zero up top. Not a typo.

Backwards, eh?

Mike

 

WOW!! That's huge! So………would you do that again??!!

Isn’t that just the opposite of what most people would tell you would happen!!!. Who in their wildest dreams would expect that kind of gain unless your fuel/air was way off on the bottom end and the headers were able to correct it.

There are probably a half a dozen different urban legends going around as to what header size/design does. Problem is none of them seem to match each other.

The holidays got me behind but finally looking at finally doing springs and 1 7/8t's stepped to 1 3/4ers headers tomorrow. Hopefully be able to dyno/retune the same day. We’ll try it both with open headers and closed exhaust to see what the skinny is.

So far I’ve not found the urban legend of loosing power through closed exhaust to be true using a very good dual 3” system with four mufflers to keep it reasonable toned down. We’ll see if different header design changes that.

Nice gain!! I love this list!!

 

The very same car gained 100 rwhp (again, not a typo) by removing his 3" y-pipe and Borla cat-back exhaust. Overlap in the cam HATES backpressure.

 

Like the innocent and tender young lad that I really am, bit big time on the 60 lb torque, dunno about a 100 rwhp loss in the exhaust.

Humm………… stepped headers vs plain ol regular ones.

New springs finally arrive….time to put on the headers, dyno the sucker and post the results.. Seems on a set of $1,400.00 super duper headers the customer is the final quality control (typical aftermarket quality control protocol) and the flanges were backwards so they didn’t fit.

But hey, it’s OK. The people I bought them from told me it was OK. Just take a cut saw and remove that section. Ya……….Right! Ya pay that much money, have them coated and they want you to cut them up so they fit.

Anyway…….. I’ll post the results of the headers when I get them back but this thread may be dead and gone buy the time it gets done. Racers net right?