6 speed Vs 5 speed how compared

[oldschoolR2B]

<p align="left">?</p><div align="left">Mike,</div><div align="left">Brand new to?board and have a question about 6 speeds and HP. </div><div align="left">Read where your seeing around 4 HP lost with OD 6 speed and 6 HP with DD6 direct drive 6 speed.?</div><div align="left">Do these losses show up from baseline run in 4th and or 5th?with 5 speed and then?after you install either OD6 or DD6 your losing 4 to 6 hp just from the change over in 5th gear? Or are you seeing those losses between 5th compared to?6th gear runs after installation? ???</div>

[Mike]

The published comparisons are based on bikes that were well tuned with the stock 5 speeds and then had 6 speeds installed with no other changes (though in some cases a fair amount of time may have passed and so should be considered; engine wear, environmental changes, etc.). The comparison is same gear, I.E. 5th gear runs. We actually ran some of the 6 speeds in 4th, 5th and 6th to see if we could get a correlation between say 6th in a six speed vs. 5th in a five speed. We found that 5th vs. 5th tended to be the most comparible based on the shape of the curves and that 5th gave best numbers in BOTH 5 and 6 speed transmissions. The losses make sense due to more gears wading through oil and the increase in mass of the gear set. The DD6 also showed an additional loss, in a predictable way, due to the decrease in primary drive leverage from the larger motor sprocket. Combined with the parasitic loss (oil drag), increase in mass and decrease in leverage all are seen by the dyno since these must be overcome to spin the dyno drum. Also, as predicted, we are seeing the similar results with the new 07's as they have followed a similar design philosophy to the DD6 in both the trans. and primary drive. The hp reduction in 07's has been osberved by others (see Hal's H-D website and their note regarding HP in later models relating to their engine kits). We believe the majority of those differences (vs. earlier models) is a function of the drive train changes. Note that the hp difference is typically outweighed by the utility of the 6 speed and the reasons or logic used for the descision to install one. Owners simply need to be aware of this affect so that they can make informed choices.
Thanks, Mike

[oldschoolR2B]

<p align="left">Mike,</p><p align="left">Thanks for the?reply and explanation. All the dyno graph I saw posted showed 6th gear making less HP than 5th so it had me wondering as I've been seeing post on other boards blaming their engine's poor performance on 6 sp.</p><p align="left">PS:One thing, can you fix the title of this thread to read "6 speed Vs 5 speed compared"?</p>

?</p>

[Mike]

We do have some charts showing the affects of making runs in different gears , I.E. 4th vs. 5th or 6th vs. 5th (in a 6 speed) same bike, same trans, back-to-back runs. These are not entended to be comparisons of 6 speed trans'. vs. 5 speed trans'. We have seperate graphs for that type of comparison, where the trans itself was changed.
Thanks, Mike

[oldschoolR2B]

By the way here's the reason I asked the question. 5th and 6th gear runs DD6, 124 S&amp;S crate engine with DME 630 Cam, CV51/Wood 50.5 and Supertrapp Supermeg 20 Disc closed end cap.</p>

http://photos.imageevent.com/jere/o2hdflhtaerocharger/websize/dd6%20124%20DME%20630%205th%20and%206th%20gear%20r uns.jpg</p>

[Mike]

GOOD numbers when you consider the 6speed and SAE correction (we use STD, which will give higher numbers). The difference between 5th and 6th gear runs is actually less than what we have seen, but Harley's are still Harley's and differ dramatically from bike-to-bike. A 4th gear run would be enteresting to see (many dyno shops use 4th).
Thanks for the info. and sharing with us, Mike