[Guest]

hey gang,
browsing around on ducati.com and although i'm not in the market for either bike, i thought i'd compare the s4r with the st4s. they both the 996 motor with the same bore/stroke, 50mm throttle bodies, same gear ratios... but the st4s puts out more power across the board:

http://www.ducati.com/bikes/my2004/...13&modelName=S4R-04&part=comparison&x=17&y=13

pretty sure they run the same cams, but anybody know where the st4s gets the extra powers? different sized valves? i tend to doubt it. the exhaust? mapping? note also that the s4r has _slightly_ higher compression which would give it a theoretical advantage. anybody know the story? just wondering... maybe the s4r's exhaust is just really inefficient despite the expansion bulb in the header. hrmm...

 

[Guest]

Re: Monster S4R vs ST4S, where's the missing power

intake and exhaust all other things being equal..who knows what the real hp is though....and what is at the rear wheel.....

 

[elpato]

Re: Monster S4R vs ST4S, where's the missing power

The st4s is 42lbs heavier. Maybe they massaged it from the engine to haul around the extra weight? I don't think four HP is that hard to obtain from that type of engine... But IIIIIIIIII don't know? :

 

[Guest]

Re: Monster S4R vs ST4S, where's the missing power

the 01 996 was 1:11.5 comp +-0.5
112HP @ 8500 RPM
93NM

 

[Jasons03Corse]

Re: Monster S4R vs ST4S, where's the missing power

Ironically, just this last saturday this was explained to a group of us. It is the exhaust as stated by our local dealer. What about it, I don't know. He just said the reason the ST had more power with the same 996 motor is due to the exhaust set up.

 

[Guest]

Re: Monster S4R vs ST4S, where's the missing power

that's kinda what i figure... they pasted on that expansion bulge under the swingarm to account for the teenie mufflers, but flow can't be that fluid through there. i've gotta figure the s4r's headers are 45mm (as opposed to the 40mm's on the s4), but can anybody confirm? i'm trying to get my hands on a 748/996 header to turn over to mark (s4r owner on this board). if it fits, i'm guessing with some moderate welding work, he'll fab up a nice "full system" replacement without having to dish big $$ for sil motor's offering. i wonder if this'll make a big enough difference to put the s4r's power up over the st4s'...

 

[Guest]

Re: Monster S4R vs ST4S, where's the missing power

yeah besides exhaust I am guessing the airboxes are different too.....

 

[Speeddog]

Re: Monster S4R vs ST4S, where's the missing power

I had a fairly extensive post done, and I lost it. That's what I get for using IE here at work and Netscape at home.

ST4S airbox is different from the S4R.

S4 and S4R airboxes are visually the same, can't check for sure because ducati.com hasn't released the S4R parts catalog yet.

S4R looks weaker than the ST4S across the whole rev range.
Makes less power even revving 1000 rpm higher.

If it is the exhaust that's the culprit, S4R folks who swap to a Sil or other full system will be searching for a PC III or other unit to "rejet" with.

Ducati seems to be pretty truthful about the HP, their chart matches pretty well with what I got on my S4 when I dyno'd it.

 

[infoage1]

Re: Monster S4R vs ST4S, where's the missing power

i've gotta figure the s4r's headers are 45mm (as opposed to the 40mm's on the s4), but can anybody confirm?...

I measured them months ago; same size as the S4. Like Nick, I'm waiting for Ducati to put the parts list online. But I'm interested in which cams and valves they used. As it is, the S4R does have the lowered heads of the ST4s/S4. Just not sure what they put inside...

Anybody know what size headers are on the ST4 and the ST4s' ?

 

[Guest]

Re: Monster S4R vs ST4S, where's the missing power

if the s4r's headers are the same diameter as the s4's then i'd figure there's the "missing power". not sure about the st4s headers, but the st4 header i put on my bike is 45mm as opposed to the 40mm standard s4 header.

 

[infoage1]

Re: Monster S4R vs ST4S, where's the missing power

I hate to sound like the Ducati cynic, but, by sandbagging now, think about the horsepower gains Ducati will be able to claim by upgrading to a full, with ECU, 45/50 Termi system...

and, I don't think they could have designed the stock exhaust to be any uglier if they tried (hum), so it would seem an upgrade is a given...

especially if they can show decent HP gains...

Ka---ching!

Disingenuous, to say the least...

 

[Guest]

Re: Monster S4R vs ST4S, where's the missing power

i think you nailed it tom...

 

[TX907]

Re: Monster S4R vs ST4S, where's the missing power

How does the ST4S power compare to the 996? I know that they brought the power down in the band for the 916 in the S4. Maybe they did the same in the S4R but didn't modify the power much in the ST4S.

 

[Speeddog]

Re: Monster S4R vs ST4S, where's the missing power

Here's some condensed dyno curves, all of the ones shown as ducati.com are scaled from printouts of their skankyquality power curves. YMMV

 

[Guest]

Re: Monster S4R vs ST4S, where's the missing power

can anybody with an S4R confirm what the redline is? 10.5k indicated on the dyno-chart, but i'd venture to guess it isn't representative of a stock S4R.

 

[Guest]

Re: Monster S4R vs ST4S, where's the missing power

I hit 10K RPM yesterday, by accident of course ;D

Damn I need the sil exhaust or I might blow the engine up.

Dealer promissed me that he would have the system in a few days, can't wait

Yannick

 

[Speeddog]

Re: Monster S4R vs ST4S, where's the missing power

Yannick has been a very bad boy ;D
..the S4R owner's manual shows 9,000 as the max RPM.

His rev-limiter must be higher, as I've verified my S4 is set at 9,500.

Still no S4R spare parts catalog available on ducati.com yet.