exhausts questions

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Aladinsaneuk · #1 Post by **Aladinsaneuk** » Sat Dec 06, 2008 1:11 pm

Took the beast in for a dyno run earlier and had a chat with a chap who did seem to know his stuff

he was of the opinion that the falco top end is different from a mille and therefore runs better with two exhausts, unlike my two into one system

This is new to me, but am curious to hear if anyone else has heard similar

he also thinks my straight through pipe does not help the engines performance, in which case he may be right - I only got 118.1 - though I do badly need a new map

Samray · #2 Post by **Samray** » Sat Dec 06, 2008 2:11 pm

I seem to remember Gio being shot down in flames for saying much the same?

Aladinsaneuk · #3 Post by **Aladinsaneuk** » Sat Dec 06, 2008 2:31 pm

Aye and that is why I found the thought interesting and worth double checking
I do not think it would make any difference as in pipe layout but...
I chatted with d rider earlier who is going to check some information with Griff and then we see.
Obvious thing is to slung my blue flames back on and do another dyno . For 23 quid it might be worth it

#4 Post by **Kwackerz** » Sat Dec 06, 2008 3:27 pm

It's all to do with tuned length.

and back pressure..

Yours seemingly has neither..

On the subject of Flakkos and Zorsts..

I seem to recall (talking about top ends) Didnt DR mention different valve sizes? That'd explain it and.. possibly... account for it.

D-Rider · #5 Post by **D-Rider** » Sat Dec 06, 2008 5:51 pm

Kwackerz wrote: I seem to recall (talking about top ends) Didnt DR mention different valve sizes? That'd explain it and.. possibly... account for it.

Not convinced.
As far as I'm aware the Falcos got the same lump as the first milles but didn't get the bigger valves when they were introduced to the mille - sometime around 2000 I think.
The first Milles (and all up until the new shaped beasts in 2004) got 2:1 exhausts.
One thing that may or may not be relevant is that the 2:1 joining section did change at some point. I'd assumed they'd just improved it but it might be that it was introduced when the head work was done and is a linked modification (I don't know). I have the later style 2:1 on mine.
What's more, the engines have been run with a right variety of induction kits and exhausts so I don't think they are ultra-finicky about these things etc - though clearly, some will work better than others.

As Pete says, I'll see if I can catch Griff at the NEC tomorrow - hopefully he'll shed some light.

Aladinsaneuk · #6 Post by **Aladinsaneuk** » Sun Dec 07, 2008 3:39 pm

just heard from d-rider who has chatted with Griff

he reckons it is bollocks as the only difference is the cams

I may, just to satisfy my anally retentive mind pop the blue flame cans back on and do another dyno as a comparison - and if I can sweet talk the chap who does it enough, I will try to get three runs done - without baffles, with the tiny baffles, and with the road legal baffles....

I get curious like that
:)

D-Rider · #7 Post by **D-Rider** » Sun Dec 07, 2008 11:45 pm

Yeah - as Pete has said I met up with Griff today on the Club Aprilia stand at the NEC show and chatted about this.

For those who don't know Griff, he's the technical guru for Club Aprilia.
The brief version of his history is as follows:

Aprilia UK technical manager from 2002 till feb 2007

He left to set up Custom Resto & Race which has now just been relaunched as Aprilia Performance (website still to catch up)

He certainly knows his stuff
(He's based in Fazely near Tamworth if anyone wants work done on their bike)

Anyway, he confirmed that the only significant difference between the early Milles and Falcos was the cams - basically giving slightly different valve timing.
His view was that this is insignificant in affecting whether a 2:1 or 2:2 pipe will work .... which was good to hear as that was what I'd thought.

His opinion was that each will optimise power in different parts of the rev range - which is what we expected. He also pointed out that Edwards raced his SP1 sometimes with a 2:1 and sometimes with a 2:2 depending whether the track demanded mid range or top end power.

I've also found a couple of YouTube links that compare the two configurations .... they'll take 20 mins to watch but (despite the presenter) are quite informative. They are by Revolution Performance who do bits and pieces for those American 2-wheel tractors ... but we won't hold that against them as the principles are the same.

http://uk.youtube.com/watch?v=zwjpwC0ZM44
http://uk.youtube.com/watch?v=YfSOthdE6 ... re=related

What is explained may go a long way to explaining the 5k dip on the 2:2 exhaust equipped Falco.
Also, I noted the YouTube clips stated that valve timing can affect the mid range dips of the 2:2s - so maybe that's why the Falco had different cams to the Mille - they may have been optimised to address this. If so, I'm speculating that we may not get the ultimate very best from a Mille 2:1 with Falco cams .... but it also seems to suggest that a lot of this can be overcome by setting up the fuelling.

I digress. Griff felt that Pete's bike may not have performed too well if the fuelling wasn't set right as that will need setting up differently for the different exhaust configs .... PCIII dyno set up required .....

HowardQ · #8 Post by **HowardQ** » Sun Dec 07, 2008 11:50 pm

Not sure if it makes any difference in this instance, but as far as I am aware the compression ratio was also higher on the early Mille.

Aladinsaneuk · #9 Post by **Aladinsaneuk** » Mon Dec 08, 2008 7:21 am

Thanks andy

I did say that my map does badly need to be done as currently it sucks

Am not to bothered about the top end performance, but getting all round useability is the aim.

I was hoping, tbh to have a higher back wheel hp, but if the power is smooth all the way through, who cares?

(I never was that good at willy waving!)

May be an idea to drop off the top end power and have smooth power all the way through with fuelling to match)

I will consider the options :)