Wasted Tuning?

[drunkmunkey6969]

All restrictions cause pumping losses- The losses may have no appreciable effect on measured instantaneous power, but they will reduce a systems efficiency in the long term.

First you have to define exactly what is a 'restriction', then you have to decide what are the different types of restriction, and then... on what applications will they make a notable difference?

If the base transfers are already big enough and enlarging them makes no difference, is there a restriction?

[drunkmunkey6969]

so are you saying there isn't enough room to make enough of a difference, or if 43bhp can be acheived with no matching, are the ports already bigger than they need to be - has a margin already been built in? good article

I think there are a variety of factors as to why Darrells work has shown this data. To me, it certainly highlights the lack of usable wall space in the Lambretta cylinders, the lack of inner arc on the internal cylinder transfer, and the way the operation of these two motors didn't necessarily favour the additional work applied.

[drunkmunkey6969]

Of course what we are all waiting for with baited breath, are Darrell’s secrets of what DOES produce his big power gains

I don't think there is a secret as such, if you ever ask him a question, he actually answers in great detail. I think its a combination of commitment to research, years of hard work, combining into the knowledge of how to build a well-matched package of components which work together, and making the small adjustments which work, and avoiding wasting time/energy on those that don't?

[drunkmunkey6969]

https://flic.kr/p/WqMVME
is this overtuned then, i matched the size of the cylinder transfers to the ports on the cylinder, its a rotax cylinder from a snowmobile

Is it overtuned? Ive no idea...lol. The best sentence for me which came out of the article was this: "to test is to know" and if there is one thing DT does lots of, its testing! If I had to speculate, i'd say the use of the Rotax cylinder changes things massively, and that you would need the transfer size you have in order for it to work properly.

Some people on FB and YT have apparently been very critical of his findings (so I'm told) but I think those critics may be missing the message, it's not that these tuning methods don't work at all... its that they don't work on the engines he tested. The note about a 50cc 14000rpm GP rotary LC bike vs an air-cooled 7000 rpm vintage design scooter gives a lot of clues.

[drunkmunkey6969]

Wasted Tuning? At the moment, its an intertesting observation but until a reason is established and proven I'd say its too soon to say!

The tests have been done, 3 x articles published, reasons included. I've just summarised the articles online. Either it works on the motor you are running, or it doesn't. On these motors, it didn't, that is the conclusion.

[drunkmunkey6969]

Glad these findings have sparked debate

[Meds1]

Have a look at the link below - sudden contractions and enlargements cause turbulent flows and changes in fluid direction - energy losses, so reducing system efficiency.

This article proves that the the energy losses Due to fluid flows aren’t big enough to be seen on a dyno .
The point I’m attempting to make is - traditional tuning will definitely recover most of those type of losses - but are they worth recovering on our scooters - that’s a matter for further testing..
These type of losses are definitely worth Recovering in large system like power stations-
https://kdusling.github.io/teaching/App ... tionLosses

[Adam_Winstone]

I also wonder what the influence of primary compression ratios is on the performance results for any given motor, i.e. enlarging transfer feeds in casing and through transfer passage will reduce primary compression, which in itself may be of benefit or detrimental to performance. Those motors fitted with 110mm or longer rods may already have the reduction in primary comp ratio that gives benefit, however, that may not be the case for a 107mm rod or a shortened cylinder/piston conversion, e.g. Honda 205.

Again, this is quite likely a case of casing/transfer passage work perhaps only telling half or the story, specifically for the assembly in question.

I do love DT's testing, testing, testing and conclusion from measurable results, rather than the guesswork of pre-dyno days, where road testing to determine results way a long winded and less obvious affair.

Great set of features.

[coaster]

Wasted Tuning? At the moment, its an intertesting observation but until a reason is established and proven I'd say its too soon to say!

The tests have been done, 3 x articles published, reasons included. I've just summarised the articles online. Either it works on the motor you are running, or it doesn't. On these motors, it didn't, that is the conclusion.

But Wasted Tuning is a provocative statement Dan so bound to draw the inevitable comments

[mick1]

High Dyno readings can be achieved by advancing the timing, raising compression and other "unsafe" methods. These alterations can give higher Dyno readings but the engine would not last long under normal running conditions.

Without knowing DT's secrets, is it possible he obtains the high readings using these methods ? then alters them to more conservative settings for road use ?

The "normal" tuning methods may not increase the Dyno readings but may make for safer road use.

Just some thoughts...………………...