4th gear @ 5500

[farmboy]

I posted this in the FP3 thread but then thought I should start a new one.

So I changed out the Crusher mufflers for some CVO's and I've been pretty happy with them. The canned map from V&H runs pretty good but I can never seem to leave well enough alone.
So I'm back auto tuning again. Like some of you guys posted I've always been a little hesitant to redline her but I realized I needed to in order to get those lower right blocks filled. And after reading Spazz's tutorial and a couple of the other guys I started runner her pretty hard. I've been running through 1st, 2nd, and 3rd to the rev limiter ( seems around 6100) a lot. It obviously gets there quick in 1st, pretty quick in 2nd, and fairly fast in 3rd. But in 4th it just seems to fade out at around 5500 rpm. I'm staying on it WOT and it just seems like it wants to quit. At that point I'm rolling 110+. Just seems a little weird. Has anybody else experienced the same problem?

 

[BluesBelly]

Uhh

I posted this in the FP3 thread but then thought I should start a new one.

So I changed out the Crusher mufflers for some CVO's and I've been pretty happy with them. The canned map from V&H runs pretty good but I can never seem to leave well enough alone.
So I'm back auto tuning again. Like some of you guys posted I've always been a little hesitant to redline her but I realized I needed to in order to get those lower right blocks filled. And after reading Spazz's tutorial and a couple of the other guys I started runner her pretty hard. I've been running through 1st, 2nd, and 3rd to the rev limiter ( seems around 6100) a lot. It obviously gets there quick in 1st, pretty quick in 2nd, and fairly fast in 3rd. But in 4th it just seems to fade out at around 5500 rpm. I'm staying on it WOT and it just seems like it wants to quit. At that point I'm rolling 110+. Just seems a little weird. Has anybody else experienced the same problem?

Farmboy,
The problem your running into is that the stock SG cams are torque cams and make power from about 1800 to 5500 rpm. After that she's pretty much done and starts to fade off so it really doesn't matter much if the blocks are filled in cause it won't give you any more power. Now if you swapped to high rev cams you'd be pulling good HP numbers at high rpm but low end torque would suffer. I personally like to keep torque cams in a bagger. High revving high HP low tq engines are for lighter bikes IMHO

 

[farmboy]

Uhh

Farmboy,
The problem your running into is that the stock SG cams are torque cams and make power from about 1800 to 5500 rpm. After that she's pretty much done and starts to fade off so it really doesn't matter much if the blocks are filled in cause it won't give you any more power. Now if you swapped to high rev cams you'd be pulling good HP numbers at high rpm but low end torque would suffer. I personally like to keep torque cams in a bagger. High revving high HP low tq engines are for lighter bikes IMHO

Blues,
I'm on board with the torque cams vs the high rev ones, but if it revs to say 6000 pretty steady in 1st, 2nd, and 3rd. Shouldn't it also do it in fourth? I know I won't be able to fill all the blocks and really don't need them filled for it to run good. It's just seemed strange that it wanted to quit at around 5500 in 4th.

 

[BluesBelly]

Blues,
I'm on board with the torque cams vs the high rev ones, but if it revs to say 6000 pretty steady in 1st, 2nd, and 3rd. Shouldn't it also do it in fourth? I know I won't be able to fill all the blocks and really don't need them filled for it to run good. It's just seemed strange that it wanted to quit at around 5500 in 4th.

My train of thought is that in first, second, and third, the bike revs up faster allowing the rpm to easily jump past that 5500 mark just from the momentum of the engine revving up at a fast pace. Plus there is not as much wind resistance in those lower gears. Now I'm thinking that when your rocking at 100 mph plus your pushing a lot of wind and weight with a taller gear ratio and the power is not there to deal with those factors.
Buddy and I both with SGs were getting after it. When we shifted through the gears at the same time we stayed even. Next time I tried to wind mine up to around 6200 rpm in third and fourth gears he walked away with no problem. I was outside my power band.
My .02 and an interesting subject for further study maybe.

 

[farmboy]

Blues,
I'm starting get it. I didn't think to much about the whole resistance thing but that makes sense. SPAZZ chimed in on the other thread and basicly said the same thing. That to get there in 4th conditions need to be right.
So would it be safe to say if 4th was a lower gear then it would pull harder and make the 6100 easier but with a loss of top end in that gear?

 

[BluesBelly]

So would it be safe to say if 4th was a lower gear then it would pull harder and make the 6100 easier but with a loss of top end in that gear?

If fourth was a lower gear it would be third gear! LOL! And yes it would be easier to hit 6100 rpm because the acceleration inertia of the engine would bring the rpm past the cams workable rpm range even though no gains in power were made. So basically when the engine is revving up at a fast rate with less resistance it takes longer for it to slow its rpm climb down when throttle is released than if the revving proccess is long and slow with a heavy load and more resistance if that makes sense.
BTW, I'm just passing on info that I think I've learned over the years from many sources and from my experiences. I'm not extremely we versed in this but I think I will research this topic further.

 

[farmboy]

Blues, two 3rd gears, that would be interesting. I know you have been a life long hot rodder and I appreciate your input not only on this thread but the forum itself. If I get up that way before the snow flies I'll by you a beer, or two.
Thanks,
FB

 

[bugdewde]

It's definitely a resistance thing..... all internal combustion engines encounter this.
For example, boat motors will rev to a million at idle, but put the prop in the water and it will only get to about 9k rpm. Add speed/wind resistance and the max rpm will drop.

Torque turns the engine (power) and horsepower keeps the engine turning.
For example (crudely), standing on the pedals of a bicycle will get you started rolling or climb up the hill by using body weight to turn the crank (Torque), but sitting on the seat and quickly pedaling the crank once it's started going keeps you at speed (Horsepower).

Torque is FUN, Horsepower keeps the fun going.

When the bicycle starts going up a hill, horsepower plays a lesser factor in maintaining speed, when you have to stand back up and use your weight to pedal up the hill, torque takes over.

As said before, just like a bicycle climbing a hill, all engines have a balance of torque and horsepower.... Since a Harley is huge and heavy, torque is the preferred motivator to get the bike up the hill. So it's cams are timed to provide fuel ignition in the lower rpm ranges to create power.
High rpms usually aren't required for a large displacement V-twin, it creates torque.
So you simply shift gears to get the rpms back down into the useful power band.

 

[Aviator5456]

Your best bet is to put it on a treadmill thats rated for high-speed and and open her up....but as Blues and others have said, once you get out of 3rd you get in the realm of horsepower over torque....if you changed your gearing, ie put on a big fat tire on the drive side or something extreme like that, you might be able to get to the rev limiter quicker....but not faster, if you know what I mean.