Ducati Monster Motorcycle Forum banner

1 - 5 of 5 Posts

·
Registered
Joined
·
30 Posts
Discussion Starter #1
Hello all
I have joined this very informative forum to seek help. My wife says that I don't know much and should ask instead of assuming.
Here goes. I would like to increase the power of my S4. I already have the DP slipons, open airbox, and ECU. My big question is why is there more power with the full exhaust system as opposed to the half systems. I know that some say that it is the header than does the restricting. Could someone please explain to me what the sizes of pipes mean as far as power (42mm, 45mm, 50mm etc.)? I know that Strati is putting a ST4 header on his s4, but how can I keep what I have, and replace some pipes to get the horses up. Thanks for the help, as you know, I am a newbie
 
G

·
While the headers probably are a restriction currently to air flow unless you then recam the engine and remap the ecu again you probably will not see much of a change or more likely you will shift that torque curve around, and not for the better. Torque is king. Headers might add some power but only at the top end since it's an exhaust gas flow issue and you are only going to be very restrictive at high gas speeds, aka: high rpms. At lower gas speeds those stock headers probably flow as well as spaghetti headers and the restriction they provide helps tune that torque curve depending on the camming. You could also lose torque unless your entire intake/exhaust system is well matched and dyno tuned.

Not to discourage you or anything ;)

The one thing about engines to keep in mind is they are nothing more exotic that big air pumps with some spark generating bits and some volatile fuel added. There is going to be a ceiling that you just are not going to be able to go beyond without going to forced induction, ie: a turbo or supercharger or even nitrous.
1 or 2 HP here or there is great but it gets more expensive to find some serious gains. The amount of money spent making the S4 the street eater you want might be better spent on another bike. You seem to have made all the best mods people make and are at the crossroads.

I find my 750D has a nice torque curve and suits me. Once i've made some improvements (which ducati should have done) the bike is "done". Its my around town bike. Next spring I think i'll buy a big bike (probably a 'busa or maybe a old 916/900ss) for those times when I need an insane thrill.

After a pop up into the hills last week with my buddy on his R6 I quickly realized my perceived lack of performance wasn't quite so justified. His horsepower bike doesn't pull till the rpms are up there, hard to do in those hills, while my monster was easy to keep in the torque band and eat his tail.
 

·
Premium Member
Joined
·
463 Posts
if you're looking for more spooling up from your bike, consider getting some marchesini rims for your bike. they weigh considerably less than your stock rims and by lightening up that rotational mass you'll feel like you're bike is accelerating much quicker. they look cool too... and once you get those wheels, consider a lighter flywheel as well...
 

·
Registered
Joined
·
426 Posts
I agree with the lighter wheels for an overall improvement they can't be beat. The thing to do with the motor would be a 955 kit from BCM. That both increases displacement and compression ratio which will increase torque and therefore hp. You can improve air flow in the heads by having a pro like MBP do a "port job" on them. Then if you still have some funds left put in SPS or even better 748R cams. At this point it would start to make a little more power with a full exhaust like the spaghetti system high pipes from Termignoni.
 
G

·
The 2-2 full system Sil Motor has a spaghetti type header which makes more power across the range. You'll feel the difference but it is not huge like pistons and cams--but it is only a little more than slip-ons.
 
1 - 5 of 5 Posts
Top