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View Full Version : 103" Upgrade On 2007 - What's My Problem?


01-26-2007, 10:00 PM
Mike:

First, your reputation is well deserved and the dealers in the Seattle area speak well of you. That said I really need your advice.

After much discussion with the local HD service had the 103" High Output engine configuration installed on my 2007 Road Glide with the Twin Cam Performance heads and the SE258 cams. The set-up was straight out of the 2007 SE Pro Racing parts book (pg 22 bottom left hand side). Put on SE air cleaner and kept on the stock headers. Put on SE slip-on performance mufflers (pn 65115-98B - bought new on ebay), a muffler I was told by the dealer was a free flowing muffler and would work great. In the course of trying to tune on the dyno (using the SERT), the tech has indicated that they are having tuning the motor and the the HP was pretty disappointing (around 85) at 4500 rpm, but that the tq wasn't too bad. He's expressing the view that perhaps the mufflers with the stock headers are too restrictive. I like the sound of these mufflers but if they are really restricting the benefits of the engine upgrade they may have to go. So my questions: (1) Are these mufflers too restrictive to get the benefits of the upgrade? (2) Would these mufflers be fine in a true dual configuration? (3) If the answer is that that these mufflers are too restrictive regardless of the header set-up, would the performance be better with rinehart slip-ons (which the dealer is now suggesting)? and (4) if I go rinehart should I just forget the idea of slip-ons and go with the true duals? I feel like I was encouraged to buy mufflers which aren't good for the set-up and I really don't want to buy something else that isn't going to work. Also, if not rineharts (because they are so loud) other options with maybe a deeper tone?

I apologize for the number of questions but was disappointed to hear the report and don't want to make sure that if I spend more money it will get be right.
Thanks much.

Mike
01-29-2007, 10:00 PM
If they are using 4th gear, SAE corrections and a 250i dyno, the numbers will show lower than those in 5th gear, STD, 250 dyno. Having said that, I would agree that the SE slip-ons are the main issue. We have an extensive dyno library on this site to help owners with these decisions and be aware of just how big of an affect the exhaust has on the shape of the torque curve. The info in that library is the same on which we make our recommendations. If you get a chance, review some of the charts as there are several for similar combo's with the SE mufflers and Rhinehart TD's.

Your choice of what to run will depend on where you want your power. For best power from 2-4k rpm, the Vance and Hines Classic round or oval slip-ons will work very well with your stock head pipes. We do a modification to resolve a restriction in the "y" pipe that helps gain apporx 4 hp on 103's. There are a LOT of other slip-ons that we have not tested but may work equally as well, including the RH slip-ons. If you want more power from 3k on, then the Rhinehart true duals will be good but they have a significant torque dip around 2.7k (see our dyno listings). But, if you run the Rhine Hart Quiet baffles in the true duals you'll regain some of that low end torque (with a similar loss up high) yet quieter with a deeper tone. Just to be thourogh, the SE's on true duals will actually decrease your performance. We also just answered a similar question on the letters section of this months American Iron Magazine (pg 186). With the RHTD's expect 105-110 hp/tq peak numbers, with the VH slip-ons (and "y" pipe mod) expect 95-100hp/110-112tq with much more from 2-4k vs. the RH's (5th gear STD corrections).
Thanks, Mike

01-29-2007, 10:00 PM
Thanks Mike. Your input is much appreciated. When we went with the 258 cams it was with the idea that it had good low-mid torq. If using that cam along with the Rinehart TD's would seem like I would have plenty of low torque and also good hp up top. Make sense?

Mike
01-31-2007, 10:00 PM
We have many examples of Rhineharts on this site and you'll see that the have a significant torque dip at 2.7k typically. More so as the cam duration and overlap goes up. But if you install the quiet baffles it improves greatly but will cost some peak hp.