Comparison of TR590 to TR660

[838]

If all else is equal, on a big cube motor (say 113-124 range), what's the difference(s) here?

[kd]

Lift and some timing characteristics.  TR claims the 660 SM was designed to be the big brother of the highly successful 590.  Both of those cams went through some changes just over a year ago and have different designations. I have a couple of friends that are using the 590 in a 103 and a 117 (+130 / +130)  They are very strong runners and have fairly good manners.  I use the 660SM in my 120 at 11.3:1 (145 / 149 - over 130 tq at 2500) and it's VERY well mannered. Both cams are quiet in the set-ups I am familiar with.

[Hillside Motorcycle]

660 PS works very well.

[838]

How about the 660 set under 11:1? Or set at 10.8 like the 590?

[kd]

The 660SM was discontinued for the 660PS2. If you don't have an SM and are buying new the PS2 is your choice now. Apparently it is the same with some ramp changes.  I can't really remember but I believe the compression recommendations were the same as the PS2 is now.  A little searching might find an old spec. recommendation if you need that.  I set mine where Dan Basiley recommended for the goals I had and it worked.  Here's TR's present 660PS2 recommendations.

https://tmanperformance.com/product/chain-drive-2006-dynas-2007-present-models-twin-cam-t-man-660-ps2/

[Hillside Motorcycle]

How about the 660 set under 11:1? Or set at 10.8 like the 590?

We set the 662-2 at 11.
I have that in my personal 131".....brutal torque.

[kd]

Scott opened the door to the 662-2.  Here's an old (2013) comparison between the 660SM and the 662-2.  The builds are close so it's relevant I guess.  If not, it's interesting. Too bad the graphs are missing now but I do remember they were close enough that they were nearly indistinguishable from each other.

https://harleytechtalk.com/htt/index.php/topic,62386.0/all.html

Here's my 120 with a 660SM in 2017.

https://harleytechtalk.com/htt/index.php/topic,99409.0/all.html

If you do a search on here in the dyno section and archives with the cams you are asking about you'll find lots of examples with a mix of different components.

[Don D]

Next will the heads accommodate the lift, geometry and springs, plus have adequate valve to valve clearance

[kd]

Great point

[838]

Next will the heads accommodate the lift, geometry and springs, plus have adequate valve to valve clearance

This is more what I'm curious about. There are many more ancillary components involved in running the 660's specs over the 590's.  Where, and how much benefit would there be in the .660 over the .590 in a big cube motor?

[kd]

Next will the heads accommodate the lift, geometry and springs, plus have adequate valve to valve clearance

This is more what I'm curious about. There are many more ancillary components involved in running the 660's specs over the 590's.  Where, and how much benefit would there be in the .660 over the .590 in a big cube motor?

As far as benefit of one cam over the other, I think it will be tough to find many that have real life seat of the pants experience with both in the same displacement that you will use.  You haven't really committed on that.  Hopefully some tuners may offer what they have noticed or recommend.  I have no doubt that more power all across the rpm band will result from using the 660 lift cam.  As I said earlier, get into the dyno sections here (and maybe other places like builders and forums) to get a sense of how these cams perform (power and manners) in the different displacement engines. If your research is good and you are honest with yourself you should find satisfaction first time out.

Don has already pointed out that with the higher lift there are recommended cylinder head adjustments to accommodate it properly. Most are aware of coil bind and guide interference with the extra lift. that'll mean springs and fitting.  Roller rockers are not a must but are recommended above .600 lift to reduce wiping action and side force from the valve stem in the guides.  You will need to clearance the rocker boxes to make up for the higher lift and deeper tip with the roller.  A great help to longevity and even performance is correcting the geometry on the rockers for the 660 lift at the same time. Don has also pointed out that valve clearance at TDC to the piston now will have to be checked (and possibly corrected) if too close or interfering.  There is also the valve to valve clearance when both valves are open at the same time to be checked and dealt with if too close or touching.

A good head porter like Don (and there are a few others as vendors here) can do all of the above easily.  They can help you make your decisions between cams also.  There is an extra cost after a certain point if going with the higher lift cams.  The thing is, it may be the only way to hit your desired performance goals so it will be required.  You can only go so big with displacement before you have to start doing things like extra lift to push the air through the big pump.

[Don D]

Well said.

Now another point. I am usually not the guy to ask about a "good cam". There are no good cams there are good combinations. I want to know about the rest of the parts, the whole system and where the current constraint is. My customers use cams from many manufacturers including harley in some cases. So demand (engine size) and the potential for the rest of the components to deliver strongly should weigh the decision. Even a lot of "good parts" is no guarantee the combination is matched and will deliver.  It gets expensive to run high lift cams and do so in a reliable state for a bike that will see some miles. If all the other parts are matched and the compression is adjusted accordingly many times a cam with more duration is a better choice in my personal opinion. That said which one will depend on all the factors I mentioned and more. 

[Tail Ridr]

Preference being equal lift and duration, intake and exhaust or higher lift intake with a given duration and shorter lift exhaust with longer duration...or equal lift intake and exhaust with longer duration on exhaust? Cam patterns given different ways, how do any of the different grind combinations determine the hp/tq curve?

[Hossamania]

Preference being equal lift and duration, intake and exhaust or higher lift intake with a given duration and shorter lift exhaust with longer duration...or equal lift intake and exhaust with longer duration on exhaust? Cam patterns given different ways, how do any of the different grind combinations determine the hp/tq curve?

That is the very essence of cam design. What is your end goal?

[Don D]

How about telling the head porter how much horsepower you want and letting him choose the cam based on what he knows from previous combinations and also lead guidance on what other parts are needed to get there.

[Hossamania]

That.

[Tail Ridr]

Sorry to de-rail...started new thread

[Hossamania]

Mostly interested in understanding the differences...

There is no simple answer to your question, it is more of a study.
This is what I know, I think: short duration builds torque, long duration builds horsepower.
In between is the combo needed for a particular motor and end goal.

[Tail Ridr]

Thanks Hoss...

[838]

Well said.

Now another point. I am usually not the guy to ask about a "good cam". There are no good cams there are good combinations. I want to know about the rest of the parts, the whole system and where the current constraint is. My customers use cams from many manufacturers including harley in some cases. So demand (engine size) and the potential for the rest of the components to deliver strongly should weigh the decision. Even a lot of "good parts" is no guarantee the combination is matched and will deliver.  It gets expensive to run high lift cams and do so in a reliable state for a bike that will see some miles. If all the other parts are matched and the compression is adjusted accordingly many times a cam with more duration is a better choice in my personal opinion. That said which one will depend on all the factors I mentioned and more.

Agreed here. And what I'm asking is simply for my own knowledge, nothing more. So let's look at  the recent 124" with the 590 you put together, and my 117" with the CR595i very comparable builds with the 124" coming on a bit stronger at 2000-2500 (which I would expect). Now with that in mind, what build combo (11.0:1 or under) would it take to get both of those builds to keep building more horsepower all the way to the top of the range? Would you even feel the difference SOP if they pulled a little bit more during those last 750 or so rpms? And, if it can be felt, is the cost of the ancillary components worth the amount you would feel on the street?

https://harleytechtalk.com/htt/index.php/topic,109007.msg1304409.html#msg1304409

https://harleytechtalk.com/htt/index.php/topic,108862.msg1296724.html#msg1296724

[kd]

Usually intake makes that top end difference.  That includes heads (valves and machining), port size, manifold, Throttle body, injectors and breather all well matched to the job and working well together. The exhaust now becomes part of the intake so it can't be a plug. This is where the cam design plays into the mix too. As Don said, it's a package deal. The tune and tuning device capabilities help in this area too.   

As far as feel it (top end) on the street? That would depend on how long you can keep your drivers licence testing the new seat of the pants dyno.  What genuinely seems to capture everyone that is a street rider whether or not the admit it  is torque on the left side.  The HP on the right doesn't get too much sampling time.  Light bikes can sacrifice torque (because they don't need as much to launch) and use mid power to perform.  That usually means using more rpm and the gears in the transmission.   The faster you go speed wise the more air you are pushing as resistance so the power may not feel to be there so much but a time slip at a track would show the difference.  This is another time to be honest with yourself about where / how you ride. A singular focus designed package will be the most successful.

The 124 will automatically be stronger on the left because of it's brute displacement characteristics.  It is said (Grumpy Jenkins) "The only thing faster than cubic inches is cubic dollars." 

[Don D]

 It is said (Grumpy Jenkins) "The only thing faster than cubic inches is cubic dollars."

Love the guy. I was told and believe he could straighten a valve with a hammer and run it again between rounds in the pits of a race. This was when a sub 10 second pro stock car was fast.

One more:
Speed costs money, how fast do you want to go? Not sure the source.

Often times when they won't pull hard at the top and especially when the curve not only noses over but is raged it is from EGR, exhaust pumping losses and recirculation as the intake opens. Lack of air is another. Many possible causes for either including the wrong choice of cams, not the brand and not a bad cam just the wrong cam for the build.

[kd]

Don, IIRC back in the early 70's it became known that Grumpy was drilling .045" gas holes around his pistons and reducing his ring tension or even leaving out rings because the gas check holes did all the work with less friction.  Less friction equaled more power and still does. The thinner the ring the better gas porting works.  (that's 2 pluses for more power)   He was killing the big block guys with his small block Vega.  He ran right side power with high rpm where the big blocks spun too much weight to survive. If he didn't invent the gas holes (most think he did), he certainly was the one that was famous for making it popular and he most certainly was the first to run a dry sump race car.  He mostly used OEM parts cuz he said they were plenty strong enough if you put it together right.

Grumpy Bill Jenkins wrenched more racers to the trophy than most know. He was responsible for some of GM's performance head designs and planted the seed to de-stroke the 327 to a 302.

[838]

As far as feel it (top end) on the street? That would depend on how long you can keep your drivers licence testing the new seat of the pants dyno.  What genuinely seems to capture everyone that is a street rider whether or not the admit it  is torque on the left side.  The HP on the right doesn't get too much sampling time. 

Lol. Fair enough. Although I do hit the limiter quite often on my 117" in the lower gears, but, by the time my keister unpuckers i couldn't tell you if there would be a difference SOP from 5700 and up (it revs there so freakin quick), nor would I need any more horsepower... again the question was for educational reasons and you and Don gave me sone great info. Thanks!

[CVOThunder]

It is said (Grumpy Jenkins) "The only thing faster than cubic inches is cubic dollars."

Love the guy. I was told and believe he could straighten a valve with a hammer and run it again between rounds in the pits of a race. This was when a sub 10 second pro stock car was fast.

One more:
Speed costs money, how fast do you want to go? Not sure the source.

Often times when they won't pull hard at the top and especially when the curve not only noses over but is raged it is from EGR, exhaust pumping losses and recirculation as the intake opens. Lack of air is another. Many possible causes for either including the wrong choice of cams, not the brand and not a bad cam just the wrong cam for the build.

Thanks to you and KD for the Grumpy comments. Was thinking I had his autograph on a racing newspaper but I'm pretty sure it was Don Garlits around 1999/2000. Need to find that someplace, get it on the wall.