ESE's works engine tuner

[husaberg]

Anyone talking up his supposed carnal pursuits that much is hiding something.

The sausage

I rescanned and reformated the last page that where the couple of morsels i found interesting were (the yellow stuff an't highlighting its the graphic designer trying to make it hard to read)

[husaberg]

Gee Have i killed this thread.
oh well here is Honda's new Motogp test rider. I think she brings an interesting array of new/old of skills to the table.

[ief]

Bit ot but less then husa's effort so here goes

I'm playing with an exhaust idear and was wondering if someone with engmod and the rd 350 ypvs data would be kind enough to run it to see if it is in the ballpark. Should be torqie - wide pb... I think (perhaps even (better???) suited for a 58mm stroker?)

tnx in advance.

edit: It should peak between 9000 -9500 rpm btw.

[wobbly]

I havnt constructed a stock RZ EngMod file but from the numbers given I can say outright the design wont work well at all.
The RZ has 50mm in the duct, and assuming no spigot on the cylinder ie the pipe fits flush on the cylinder face, then the header length is 36% - way too long.
Then the diffuser end is 58% and way too short.
The header angle at 2.35* is way too shallow, and the rear cone setup with 19* then 15.8* is back to front, and is a disaster on the dyno - been there ,tried that - no free lunch.
The stinger is way too big for anything but a full race setup,and the body at 116 dia is simply too fat, and will drag on the ground no matter how well the pipe is tucked under the bike.

[F5 Dave]

but it has a nice smile & can probably cook well right?

[wobbly]

With that pose going, the smiling cat will be looking you in the eye.

[F5 Dave]

I was talking about the pipe, I mean it must have some nice qualities.

[wobbly]

Yea, its round.

[2T Institute]

Anyone know what shopping centre that is???

[Gigglebutton]

Anyone know what shopping centre that is???

Dress for less :-)

[ief]

I havnt constructed a stock RZ EngMod file but from the numbers given I can say outright the design wont work well at all.
The RZ has 50mm in the duct, and assuming no spigot on the cylinder ie the pipe fits flush on the cylinder face, then the header length is 36% - way too long.
Then the diffuser end is 58% and way too short.
The header angle at 2.35* is way too shallow, and the rear cone setup with 19* then 15.8* is back to front, and is a disaster on the dyno - been there ,tried that - no free lunch.
The stinger is way too big for anything but a full race setup,and the body at 116 dia is simply too fat, and will drag on the ground no matter how well the pipe is tucked under the bike.

Cool, tnx wob!

Back to the drawing board it is then, only thing is i get diffuser end at 62%, don't know where i did go wrong there, will take a look at it later > work awaits. What would you say is a right figure then? (I just compared a bunch of known exhausts and they all seem to be around the 62 % mark)

ps: it's for a regular streetbike, non race, if that makes any difference.

[dinamik2t]

Dress for less :-)

Undress for more! ;-)

[wobbly]

Sorry,yes i forgot the 50mm in the cylinder with the diffuser end calc, its 678/1083 = 62%, a very old fashioned number..
For a street setup the longer header and longer diffuser expand the powerband width, but as it has a powervalve this changes everything,due
to the very low blowdown area when the valve is down.
Normal range for header = 30 to 33%, and for the diffuser = 64 to 68%, so I would be shooting for the longer on both for a stock add on pipe.
The longer diffuser gives better max case depression around BDC,later in the cycle, thus boosting mid scavenging efficiency.
Very long - 36% headers only work on piston port engines - like say TZ350,as this then allows a steeper initial diffuser angle, boosting power in the limited band the piston port can operate within.
There is no case for a header angle under 3* incl and dual angle rear cones are best with shallow then steep angles.
The main effect here is to increase the belly volume, thus smearing the wave amplitude over a lower, wider band.
Its always a combination of compromises, but helps you if the basic geometry suits the application,and the physical limitations presented.

[dinamik2t]

Thank you for the info on pipe building "ignorant" Wob

Say we have a big single 250cc (oversquare if it matters), for drag use, without limitations on belly D / ground clearance.
Firstly, is it a general rule that pipe-cylinder volume ratio should be close to 30 for hi-perf use? (I thought so because RS, TZ and RSA pipes' ratios are around there)
I originally have a pipe design with an 135D belly and a pipe-cyl volume ratio close to 23.
Using a larger belly D factor (~3.2), the belly became 155D and so I got a 28 pipe-cyl volume ratio. Ok, but that increases the baffle cone angle to >>30*, which I remember that is very high for overrev power.
So, I guess there is some compromise here also, when talking about big displacements? Is there a rule of thumb for such situations?


In fact, inspired from aprilia's multi sectioned baffles, I tried to seperate the one 32* cone to three, with a smaller angle of 27* for the middle longer section. Most likely, there are other more important factors I have messed up with, but the fatter desing yielded higher-rev power and better overrev -even with slightly longer tuned length.
Shouldn't the fatter pipe be less hot, due to more gas expansion, thus act longer?

(I uploaded the two pipe designs below just to show what I tried to do; I don't try to have you to "correct" them, ok? )




edit:
Now that I think of it, the slim pipe had a diffuser horn coef of 1.40, while the plump 1.45. But would this make such a difference?

[Frits Overmars]

I can't see the two pipe designs you uploaded, but from what I read I would say: don't worry about that cone angle. 32° with Dmax=155 mm ought to work fine.
My rule of thumb: trust your own calculations and build it. If you don't, you'll never know...