ESE's works engine tuner

[Grumph]

Thanks Wob. Re lack of info - I'd doubt if anyone's bothered to collect the data and put it into Enginemod for a 197 Villiers.....and i'd be very surprised if anyone ever does.
Cutting finger transfers is something I've been contemplating for some time. One day it will live again.

[SwePatrick]

Sadly the balloon analogy is fatally flawed by physics. At TPO the Blowdown pressure exceeds the case pressure created by the piston dropping.
This is how stagger works - the Blowdown pressure across the port that opens first , reverses the initial flow down the duct.
What pulls mixture into the cylinder , in a race engine is solely the increasing depression created by the diffuser action , maxing out around BDC if done correctly.
Only a weed eater uses piston compression of the case to push flow into the ducts.

Yes ofcourse, i just use that balloon term to simplify it for people that don´t understand that the crankhouse need to be designed different from the intakesystem.
Flow behaves much different.

[jamathi]

Sadly the balloon analogy is fatally flawed by physics. At TPO the Blowdown pressure exceeds the case pressure created by the piston dropping.
This is how stagger works - the Blowdown pressure across the port that opens first , reverses the initial flow down the duct.
What pulls mixture into the cylinder , in a race engine is solely the increasing depression created by the diffuser action , maxing out around BDC if done correctly.
Only a weed eater uses piston compression of the case to push flow into the ducts.

Edit : The last 250GP season was won by Aoyama on a semi works Honda RS250 run by the Scot team in 2009.
He won the title pretty easily , with poles and lap records as well.
Sure , the Aprilia riders didnt do themselves any favours by stealing points off each other , but the HRC was faster , more often than not.
Would seem that the geniuses at the factory tuned Jans jewel to a standstill by 2009.

Edit - Spelt balloon wrong - in case ballon was fuckoff in Belgian or something.

Edit - I dont think you can enlargen a small end eye , as the case hardened surface must be a minimum of 0.5mm deep for rollers to run on - dont know if re case hardening can be done a second time.

They may have reduced the crankcase volume on the 250 as well.
It did'nt help that Simoncelli broke his wrist one week before the first race.
And bautista had too many crashes, he still does the same...throwing away world championships....
The Scott-Honda was fast because they finally fitted the updates Honda had sent them during some years....
A friend of mine tested all this on his dyno! 98HP

[husaberg]

Thanks Husa, are you linking me to Ken or is there something buried in there? I did not have a proper look, however did not find anything of relevance right away.

I was quoting ken, to flush him out. That post was the first one that came up under his user name.
Ken started Strike products
http://www.strikeproducts.com.au/
He's an Aussie, but hey no ones perfect.

Sorry dude i thought you were talking piston not conrod.......

[yatasaki]

Thanks Wob. Re lack of info - I'd doubt if anyone's bothered to collect the data and put it into Enginemod for a 197 Villiers.....and i'd be very surprised if anyone ever does.
Cutting finger transfers is something I've been contemplating for some time. One day it will live again.

Each pair od fingers (2 pairs) spreads powerband for 1000 revs earlier in our buckets without affecting max power or overrev.

[crbbt]

They may have reduced the crankcase volume on the 250 as well.
It did'nt help that Simoncelli broke his wrist one week before the first race.
And bautista had too many crashes, he still does the same...throwing away world championships....
The Scott-Honda was fast because they finally fitted the updates Honda had sent them during some years....
A friend of mine tested all this on his dyno! 98HP

I am under the impression that the RSA/RWS 250 had 120hp?

Not sure where I got this number from however but guessing that was at the sprocket and not the wheel?

[F5 Dave]

Mine makes 140.

But it has 2 Ryger barrels on it.

Send money to. . .

[jamathi]

I am under the impression that the RSA/RWS 250 had 120hp?

Not sure where I got this number from however but guessing that was at the sprocket and not the wheel?

Cylinder tests at Aprilia were always done with a single cylinder engine.
We got 53,9HP
twin cylinder engines were never dyno-tested.
So at most it could have given 107HP....

[Niels Abildgaard]

Cylinder tests at Aprilia were always done with a single cylinder engine.
We got 53,9HP
twin cylinder engines were never dyno-tested.
So at most it could have given 107HP....

Was it measured on end of crankshaft or chain sprocket shaft and what was rpm?

[crbbt]

thanks for the correction!

[husaberg]

Was it measured on end of crankshaft or chain sprocket shaft and what was rpm?

[Niels Abildgaard]

Thank You for numbers but the photo does not look like a world beating dyno exercise?

[Frits Overmars]

Thank You for numbers but the photo does not look like a world beating dyno exercise?

Well spotted Niels. The photo shows Jan Thiel's Aprilia flowbench test setup.

[husaberg]

Well spotted Niels. The photo shows Jan Thiel's Aprilia flowbench test setup.

Bugger, i knew it was the flow rig but it assumed it served as the mule engine as well.

looking back through your posts its written any times that the Aprilia's outputs were always measured at the gearbox shaft.

Tyre pressure? Tyre type? Haufen, you do not seriously think that you can develop an engine to the required level by measuring rear wheel power, do you?
Tyre rolling losses are dependent on tyre deformation which is dependent on tyre pressure; those rolling losses heat up the tyre, which changes its pressure and the rolling resistance during the dyno run. Need I go on?

The RSA power was measured at the gearbox exit shaft, as has been mentioned repeatedly. The data-example I posted above is not from a 54 hp dyno run but from a different run, which by the way was not far short of 54 hp either.
I do not intend to start a language course of Italian technical abbreviations here, but anyone with a bit of two-stroke background should be able to deduce by the numbers what they are referring to.

The ambient factors were 27°C and 1013 mbar. Initially the ambient temperature was kept at the standardized 20°C, but in order to bring the circumstances more in line with the average circuit conditions it was later raised to 27°C. And because of the constant ambient factors there was no further correction required.
Anyway, most correcting algorithms are useless if not downright misleading when high-performance two-strokes are involved.

I assume inside cell dyno photos were frowned upon so i only have these


i did have this below from Frits one but i am not sure what it was from.


this looks to be off the crankshaft

Okay Jan says Honda...

[jamathi]

Was it measured on end of crankshaft or chain sprocket shaft and what was rpm?

Chain sprocket shaft.
Max torque at 12250
Max power at 13000

Measuring power at the crankshaft is very impractical....