throttle body 50mm or 54 mm

zippo2 · #1 01-23-2008, 01:35 AM

Im getting ready to have a set of zippers 575 g cams installed in my 05 FLHRSE2. What about the Zippers thunderjet throttle body and manifold while I'm there, would you install 50mm or the 54 mm. along with the zipper aircleaner kit and larger injectors? How much performance do you really get by adding these products? Any feed back would be appreciated.

DI75 · #2 01-24-2008, 06:51 AM

I have heard positive and negative on the effects of the larger throttlebody. Depends on so many factors...Don't think you will see a difference either way..at least I haven't.

miacycles · #3 02-02-2008, 05:19 PM

Larger throttle bores would kill bottom end performance because the vacum would drop and a carb could not pick up enough fuel Thats why they have accelerator pumps)to keep the mixture right. This is less of a problem with fuel injection, but still affects performance. I would go for the 50 so that I would have a little more torque in the bottom end. If you are not sure call Zippers and tell them what you have and they will reccomend the proper size as they have numerous hours of dyno time with these.

Bannana Boat · #4 02-02-2008, 06:28 PM

Zippers recommended not going bigger than a 50mm for my 06 SEFB with 103". Told me the same thing, you lose bottom end torque. Also was told they are only goodfor a couple hp.

zippo2 · #5 02-03-2008, 10:56 PM

Thanks guys for your reply, I went with the 50mm tb, and now I'm installing the D D Fatcat 2 into 1 system. Now, the questions is do I install the standard baffle, or performance baffle/hi flo baffle. Not sure what they call it. Does it make a big difference? Has anyone tried these baffles? thanks for any response.

Mike

asuperheat · #6 02-09-2008, 07:19 PM

Get with Philm in the touring section or do a search on the subject I think he just did a comparison on a dyno with that pipe and baffles and it was posted in the touring section.