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[DavidG]

I hope this is just a tuning thing but I just had the stock SE-255 cams in my 07 SERK replaced with Andrews 54 cams. About the same lift as the 255's but a little longer intake duration. I thought these looked like they would help mid-range. They put it on the dyno and did a quick run and now the bike makes about 5 HP less hp and about 7ftlbs less torque. They did not want to do a tune yet as they had recently replaced cylinders (liner slip). I hope the SERT just needs tweaking for the new cam. Spending money to replace cams to make less power is not what I had in mind. Any thoughts?

[sadunbar]

I hope this is just a tuning thing but I just had the stock SE-255 cams in my 07 SERK replaced with Andrews 54 cams. About the same lift as the 255's but a little longer intake duration. I thought these looked like they would help mid-range. They put it on the dyno and did a quick run and now the bike makes about 5 HP less hp and about 7ftlbs less torque. They did not want to do a tune yet as they had recently replaced cylinders (liner slip). I hope the SERT just needs tweaking for the new cam. Spending money to replace cams to make less power is not what I had in mind. Any thoughts?

put a few miles in it and then.....get it tuned....

[Twolanerider]

put a few miles in it and then.....get it tuned....

Couldn't agree more.  Better or worse or something else entirely.  You simply don't know yet.  You can't judge a part you haven't tuned for.  You can worry about it.  But you can't judge it.

[HILLSIDECYCLE.COM]

We seem to be having good luck with Wood 8 cams, set at the squeeze that is required for them.

[grc]

What is an Andrews 54?  I've heard of the 55H, and that one requires a little more compression for best results, as in 10:1, and it comes in stronger at mid to higher rpm.  Like the guys said, you won't know what you have until it's tuned properly.

Unless a cam is a true "bolt-in", there will normally be more involved than a straight swap of cams if you want good results.  Check with Andrews and see what they recommend with your particular cam. 

Jerry

[jfh]

Given the increased overlap from 13 degrees with the SE255 to 31 degrees with the TW54, it is not surprising that you gave up some low end torque. On the up side, you will have lower cranking compression and should see a decrease in operating temperatures. A tune should help recover the HP at slightly higher RPMs than the stock SE 255, but the heads will likely continue to prevent you from realizing significant HP gains beyond 5K RPMs.

[DavidG]

The Andrews 54 is a new cam for 08 Specs => 54H 16/42 Timing 238 Duration .555 Lift "Specially designed for 96 & 103 engines with CR up to 10:1 (2200-5600 RPM range). It was recommended to me by Andrews Tech Support for the 110.

The heads were ported and polished when I had the heads off for the product enhancement so I'll be patient until I get it re-tuned for the new cams (3 weeks or so).

Thanks

[jfh]

The Andrews 54 is a new cam for 08 Specs => 54H 16/42 Timing 238 Duration .555 Lift "Specially designed for 96 & 103 engines with CR up to 10:1 (2200-5600 RPM range). It was recommended to me by Andrews Tech Support for the 110.

The heads were ported and polished when I had the heads off for the product enhancement so I'll be patient until I get it re-tuned for the new cams (3 weeks or so).

Thanks

With the headwork done, the tune should do it.

[DavidG]

Thanks HDFR120. I can't wait to get it tuned to see what it will do once its tuned properly. BTW, I was at my dealer today and a customer was taking delivery of an 09 SERG like yours in the same silver paint scheme. Your picture doesn't do it justice. In real life, that's a gorgeous paint job, especially in the sun with the metallic silver paint.

[DavidG]

I spoke to Andrews and its definitely in need of tuning. They suggested 13.0 to 13.5 AFR for best power. That should also help with cooling. I'll post dyno results when done in a couple of weeks.

[Talon]

Given the increased overlap from 13 degrees with the SE255 to 31 degrees with the TW54, it is not surprising that you gave up some low end torque. On the up side, you will have lower cranking compression and should see a decrease in operating temperatures. A tune should help recover the HP at slightly higher RPMs than the stock SE 255, but the heads will likely continue to prevent you from realizing significant HP gains beyond 5K RPMs.

I agree, the more the overlap the less compression you'll have, so now your corrected compression is lower that stock.

[DavidG]

The static compression does not change but you are right that the cranking compression is less; and that's what really matters I'm sure. Increasing the overlap decreases the cranking compression (cylinder pressure) because the intake valve is open longer ABDC and bleeds some of the pressure. I believe that's why most cam companies recommend higher static compression ratios when going with longer duration cams.

Saw this on a cam website .....
"An engine’s compression ratio is actually a theoretical number. This ratio compares the cylinder volume of the piston at bottom dead center (BDC) versus top dead center (TDC). So if we have a volume of 45 ci at BDC and 4.5 ci at TDC, then the compression ratio is 10:1 since the volume at BDC is 10 times the volume at TDC. While this is a useful number, it ignores one crucial variable. The amount of actual cylinder pressure at low >> engine speeds is determined by the intake closing (IC) point.

All performance camshafts close the intake valve 50 to 60 degrees or more after bottom dead center (ABDC). The longer the duration of the camshaft, the later the intake valve closes. It should also be obvious that the engine cannot begin making cylinder pressure until the intake valve closes. Therefore, the distance that the piston travels up the cylinder at 60 degrees ABDC versus 52 degrees ABDC reduces the volume of the cylinder, reducing the cranking pressure.

Keep in mind that we are talking about a street engine here. Early closing intake valves (short-duration cams) tend to maximize cylinder filling at lower engine speeds, while late-closing intake valves (long duration cams) tend to move the peak power point higher in the rpm range. With a given compression ratio, adding a longer-duration camshaft will decrease the cranking compression and therefore low-speed throttle response and power.""

I'm really anxious to get it tuned correctly to see what they get out of the new cams.

[Talon]

Correct, the first part should have been cylinder pressure, the corrected compression would be lower.


From Nightrider:
LSA is the Lobe Separation Angle or the number of degrees between the intake and exhaust lobe centerlines. The LSA has a direct relationship to amount of overlap on a cam. Cams with identical duration and lift specifications can have very different LSAs. Generally speaking, a wide LSA will produce greater low end torque and a narrow separation angle will produce better top end power. For any given LSA, an engine will give similar torque curves and peak torque RPMs even with different overlaps. Refer to the LSA table above to determine how an increase or decrease in LSA is expected to change the performance of the engine.

[HD Street Performance]

These 110 motors have a lot of compression and a cam such as the 54 would just tame that and help the motor run cooler and perhaps not exibit the 110" maladies we have been seeing.
The heads are hurting any atempt to hot rod the motor. The cams later intake close and added overlap are twarted by a terrible exhaust port that in stock form does not flow any better than am 06 88" head. The Intake is not too bad but that can be improved drastically too by correcting the throat to valve head ratio.
All stuff covered in a Street Port job, low drama, not expensive

[HILLSIDECYCLE.COM]

The CVO 110" head is a good platform, and can be modified to correct several things to enhance the power output.
That combined with a cam swap, and they become a different machine, once tuned by capable folks.
Scott