Dyno Results

[wild bill]

Mike

You dyno?d my 06 Screaming Eagle Fat Boy after I installed a Samson Big Gun 3 exhaust system; replacing the stock pipes and Cycle Shack mufflers. You warned me to expect somewhat lower readings due to the use of a new ?Dynojet?. The new machine indicated that the change from stock pipes/after market mufflers to the new Samson system reduced hp by 15 and tq by 12 representing a loss of about 13.5% and 10.5% respectively. Using your estimated 8% lower readings with the new ?Dynojet? means the Samson system resulted in a net loss of about 5.5% in hp and 2.5% in torque. I find these figures amazing when all that was changed was a relative stock exhaust system for a custom system from a top tier company. This is the first motor I?ve had modified by you that didn?t achieve a minimum of 1 hp per cubic inch! I would appreciate your thoughts on this and am wondering if you have any new information about using/combining a higher compression after-market piston with the rod used in the 103 screaming eagle engine? Thanks from Wild Bill??
:(

[Mike]

Well Bill, I tried to ponder this one for a while! It could be the Samsons do not perform as well as the Cycle Shacks on a 103 motor. Unfortunately, it is still very much unpredictable how any pipe will work with any given engine, even with all of our dyno data. One reason we have so many dyno charts on the web for exhaust systems is to demonstrate this variable. At risk of being politically incorrect, the Samson systems are not neccessarly "top tier" with respect to performance (with the exception of their new Caliber series). I still cannot see why a standard set of pistons would not work with the "parabolic" rods. The rod loading would be the same no matter how wide the wrist pin area in the piston is. The piston should see the same loads on the wrist pin bosses regardless of how narrow the rod is. There is a question of wrist pin flex in the unsupported area between the piston and rod on the top side with this combination but most of the loading will occure during the power stroke with the pressure on the bottom side of the rod bushing, which has the most support. It's mostly the question of what I may be missing here and what others may say (you guy's did what?????). So, if we are willing to experiment, then hi-comp pistons are readily available.
Thanks, Mike

[wild bill]

Well Mike:
It's that time of year again. Everyone putting bikes away for the winter and me thinking of what can I do with the motor for some extra numbers. We chatted about a head change that was the next step up [I think] from the screaming eaglle heads that were stock on my cvo fatboy 103ci. I think we were talking somewhere in the neighborhood of $1400 for the heads and whater labor came to. A couple of questions come to mind before committing are: 1. Will the cam you put in my ride work well enough with these heads or am I looking at another cam change? 2. Are there aftermarket or HD high compression pistons in the channel yet that will fit the tapered piston pin of the 103 engine or is it still just I take my chances with the current stuff? 3. I have given up on the Samson pipes and installed a stepped set of pipes [PHD 240?] from cycle-shack made for engines over 95ci. When we do the heads, will you do a before and after on the dyno so I know exactly what bang I got for the buck?

Thanks
Wild Bill :)

[Mike]

Bill, long time no hear!!! Yep, we'll do a "before" dyno. Probably a cam change to take full advantage of the heads. Just did a 103 on an 07 that netted 119hp/116tq with sim. heads and the SE257 cams. We used the SE cams since the aftermarket has not caught up with the 07's as yet (actually the SE cams are not bad). May do better with something sim. to T-Man or Wood cams. We used the SE flat top pistons and a Boarzilla exhaust (the air cleaner was removed to get those results, a restrictive unit was installed that cost about 3HP). Note that 07's with the six speeds and regeared primary drives net lower numbers than earlier models, so those numbers are very good.
Thanks, Mike

[zigzzagz]

A little late getting in on this one, but I for one don't need to be politically correct. Samson pipes are one of the worst out there for making power from all the dyno's I've seen. In a 95" I've seen a motor go from 85HP 90 lbs/ft to 100 HP and 105 lbs/ft just from switching from samson streetsweepers to a good 2-1. I can't remember which but it might have been a fatcat. This is not at all uncommon from what I've seen as well. They sound great, though I've not owned a set so I can't comment on quality of fitment or chrome, but they are absolute crud for making power.

[Mike]

The D&D's are very good quality. It's all about the pipes!!! Mike