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[Jbbrown73]

I am curious about something. Maybe I think too much, but I am interested in knowing the answer to this question.

The SE255 cam comes in the 110 and is thought of as a very poor performer in that engine.  My own experience even tells me that.  However, that same cam is supposed to be a good performer in a 103.  My understanding is the 255 has a grind for emissions, in that it holds the cylinders shut longer to burn as much fuel as possible, making very high cylinder pressure and causing a lot of heat.  If that is the case in the 110, and I know that it is from personal experience, why would it not cause the same problem in a 103 engine or 96?  Obviously there are other factors to consider in each engine, so my question is what makes this cam perform poorly in a 110 and good in a 103 or 96?

 

[scotr]

I would like to know that also.

Scotr

[HD Street Performance]

Nothing wrong with the cam. It is not a poor performer in any motor as long as the associated parts cooperate and the tune is right.
It is very short and that has the effect of moving the torque band to the left at the expense of the top end wheezing for air. So for the guys that want low end torque these cams work. The compression needs to be on the low side or there will be problems and retarding the timing to compensate just makes them run hot and the torque gains are cancelled. In the 110 the heads work better than the 96 or 103 (bathtub chamber) so with a compression bump, more cam and headwork the 110 can retain most of that torque down low and pull like a freight train on top. Most of the builds are guys trying to build more torque down low and the stock cam is hard to beat below 3k.

[JP-FLTRSE3]

Thanks Dewey.  Is it true that the 255 contributes to the heat issue?  For instance if I were to swap them for say the 259E and retune etc., would I get a cooler running engine just due to the cam change?  The loss in low end torque would make that cam change more "valuable" if so.  Like most, I spend all my time at 4000 or below; usually well below.

[HD Street Performance]

Sure a cam swap to one with more overlap and a later intake close will help but the low end torque will be lower where you typically ride with the cam change and most don't care for the loss. Takes more gear changing.
The short cam (255) raises cylinder pressure which raises torque where you ride.
The heat falls into two catagories radiant / pipe and actual oil and head / case temperature. The motors are not always that hot but the pipe heat gives the impression of a hot motor.
All of that said with software the "Closed Loop Bias" can be raised to get the closed loop areas of the map into 14.2/1 AFR which helps heat a lot at the expense slightly in mileage. With the added fuel timing can be bumped up a tad, done by a professional, and verifying that there is not detonation (using the data mode to monitor Delphi ion sensing). Those two changes will lower temps of both the exhaust and the motor.
If considering a cam change and SE is a must consider the SE254 or SE204, but understand either will come with a hit to the off idle to 2.5k rpm throttle response and torque on a 110