V-Twin Forum banner
1 - 20 of 43 Posts

·
Hellbound Train
Joined
·
5,595 Posts
Jim, I have been asking for that proof for over two years but it has never surfaced. The internet theory is that "reduced mass equals 4 HP" :laugh: .
Others claim "more precise timing equals 4 HP" :laugh:
Maybe the combination of the two equals 4 HP :laugh:
I say, Show me the dynos
By the way, paint your bike black and you can get the 4 HP (everybody knows that)
 

·
Premium Member
Joined
·
946 Posts
Dirty Jim said:
Wheres the proof that you can gain 4 horsepower by changing to gear driven cams?
I don't have any numbers for you but our local HD shop has two cam plates on display in the service area. One has gear drive cams and the other has the chain drive with just the rear chain and tensioner. The gear drive spins very easily. The chain drive is a bear to get to turn (and thats without the outer chain and tensioner). You actually have to grab one of the cam lobes to get enough grip to turn the thing. Like I said I don't have any #s but this has to give you a few ponies!
 

·
Banned
Joined
·
249 Posts
csoday said:
Jim, I have been asking for that proof for over two years but it has never surfaced. The internet theory is that "reduced mass equals 4 HP" :laugh: .
Others claim "more precise timing equals 4 HP" :laugh:
Maybe the combination of the two equals 4 HP :laugh:
I say, Show me the dynos
By the way, paint your bike black and you can get the 4 HP (everybody knows that)
what do you know?...you think S.E. parts are fast
 

·
Registered
Joined
·
3,981 Posts
pa-glazier said:
I don't have any numbers for you but our local HD shop has two cam plates on display in the service area. One has gear drive cams and the other has the chain drive with just the rear chain and tensioner. The gear drive spins very easily. The chain drive is a bear to get to turn (and thats without the outer chain and tensioner). You actually have to grab one of the cam lobes to get enough grip to turn the thing. Like I said I don't have any #s but this has to give you a few ponies!
Yes, but you can turn em, right? Do you think your hands are as strong as 4 horses? think about your lawnmower....
4 HP is alot. I am gonna change out my 37b's for 37g's probably before summer, I'll post the baseline dyno's from each and make sure they are done on the same dyno under the same conditions.
Then we'll have at least one example....
I am thinking negligable difference and nothing you can feel. 4hp you should be able to feel, shouldn't you.
I am a skeptic for sure....
 

·
Banned
Joined
·
249 Posts
adlerx said:
Yes, but you can turn em, right? Do you think your hands are as strong as 4 horses? think about your lawnmower....
4 HP is alot. I am gonna change out my 37b's for 37g's probably before summer, I'll post the baseline dyno's from each and make sure they are done on the same dyno under the same conditions.
Then we'll have at least one example....
I am thinking negligable difference and nothing you can feel. 4hp you should be able to feel, shouldn't you.
I am a skeptic for sure....
now this sounds like a good plan..be intresting to see how much differance it makes
 

·
Premium Member
Joined
·
946 Posts
I didn't say 4 horse power. If you turn your air conditioner on in your car you lose some power. Any additional drag that you put on the motor will cost you HP. How much I do not know. I'm not an engineer.
 

·
0043--Licensed to Doof!
Joined
·
4,369 Posts
All I know is my chain tensioners and chain will never wear out sitting in the closet in my shop! %[email protected]
 

·
Nice to ride again :-)
Joined
·
1,802 Posts
Most of what I have read and seen written on the "4HP" was "can provide up to....".

This has to do with a more precise timing as Chuck stated, and I think I saw parasitic loss from the chain, sprockets, verses just gears.

It don't matter to me as for my build, gears were the ticket.

I don't think anyone should be making a choice of gears versus chain for the 4 HP.
 

·
Premium Member
Joined
·
946 Posts
LAF said:
Most of what I have read and seen written on the "4HP" was "can provide up to....".

This has to do with a more precise timing as Chuck stated, and I think I saw parasitic loss from the chain, sprockets, verses just gears.

It don't matter to me as for my build, gears were the ticket.

I don't think anyone should be making a choice of gears versus chain for the 4 HP.
Well said. @gree:
 

·
EvilMonger
Joined
·
8,793 Posts
adlerx said:
Yes, but you can turn em, right? Do you think your hands are as strong as 4 horses? think about your lawnmower....
4 HP is alot. I am gonna change out my 37b's for 37g's probably before summer, I'll post the baseline dyno's from each and make sure they are done on the same dyno under the same conditions.
Then we'll have at least one example....
I am thinking negligable difference and nothing you can feel. 4hp you should be able to feel, shouldn't you.
I am a skeptic for sure....
Just wondering why you would go from chain to gear with the exact same grind? Even though I had severe wear (down to the metal at 60,000 miles) if I was not changing cams and going with heavier valve springs I would not have spent the money?? But that is just me. It will be interesting to see your before and after dyno runs.

I actually have a new set of chains and tensioners that I had planned to put in until I decided on the woods TW6HG cams.
 

·
Registered
Joined
·
3,981 Posts
Thealien said:
Just wondering why you would go from chain to gear with the exact same grind? Even though I had severe wear (down to the metal at 60,000 miles) if I was not changing cams and going with heavier valve springs I would not have spent the money?? But that is just me. It will be interesting to see your before and after dyno runs.

I actually have a new set of chains and tensioners that I had planned to put in until I decided on the woods TW6HG cams.
DUH!! For the 4 horsepower of course!!!:roflback: :roflback:

Really, just really wanna be done with the motor. When I put the 37's in I wasn't sure they would be my final solution. Now that I have had a chance to ride my build a little, I will definately be sticking with em so why not swap out now and never think about tensioners again?

Of course, I could change my mind a dozen times before this actually gets done......
 

·
Registered
Joined
·
29 Posts
You are talking about 4hp!
I bet there will be not so mutch increase just of friction loss.
But say you get 4hp, will you feel it? I dont think so.

I read mutch about gear vs chain drive and to me its more about faith than knowledge. HD would never build its motors in such a way if their QA will not be happy with that. And even the SE products came with chains.

Talked to my best friend, a mechanic for over 20 years (Moto Guzzi Racing und now HD ;) ).
He told me that the TC motor is one of the best designed motors he ever saw.
He pointed out that we are talking about a 5-6000 RPMS motors and not about 14,000 RPM Superbikes, so up to 4 degree variance is no problem and he also mentioned that roller rockers were not needed.
For racing go with the gear drive, for normal life stay on chain drive and inspect them on a regular basis (20,000).

Just my $.02,
Saxxon
 

·
Premium Member
Joined
·
3,289 Posts
Saxxon said:
You are talking about 4hp!
I bet there will be not so mutch increase just of friction loss.
But say you get 4hp, will you feel it? I dont think so.

I read mutch about gear vs chain drive and to me its more about faith than knowledge. HD would never build its motors in such a way if their QA will not be happy with that. And even the SE products came with chains.

Talked to my best friend, a mechanic for over 20 years (Moto Guzzi Racing und now HD ;) ).
He told me that the TC motor is one of the best designed motors he ever saw.
He pointed out that we are talking about a 5-6000 RPMS motors and not about 14,000 RPM Superbikes, so up to 4 degree variance is no problem and he also mentioned that roller rockers were not needed.
For racing go with the gear drive, for normal life stay on chain drive and inspect them on a regular basis (20,000).

Just my $.02,
Saxxon
Primary reasons for people to convert to gear drive are:

  • A cam design that is not available in chain
  • Concerns about reliability of chain/tensioner system
  • More precise valve train dynamics
  • Worn out chain drive/bearings
  • Change something for the sake of changing

Bullet 1-3 apply to me

PS: No order or priority
 

·
Hellbound Train
Joined
·
5,595 Posts
Vienna Hog, I'll give you #1.
As far as #3, nope. I think you will find that most engines, car or bike with overhead valves use chain drive and those chains can be up to 36" long. What is their timing variance?
 

·
Arrogant Bastard
Joined
·
1,264 Posts
csoday said:
Vienna Hog, I'll give you #1.
As far as #3, nope. I think you will find that most engines, car or bike with overhead valves use chain drive and those chains can be up to 36" long. What is their timing variance?
Don't have a solid number but it's enough for most builders looking for power to go to gear drive. Also enough reason for Ford SVO engines to use gear drive.

Joe
 

·
Hellbound Train
Joined
·
5,595 Posts
jasilva said:
Don't have a solid number but it's enough for most builders looking for power to go to gear drive. Also enough reason for Ford SVO engines to use gear drive.

Joe
A lot of builders use billet cam support plates and platinum plugs also. :whatever:
 
1 - 20 of 43 Posts
Top