ESE's works engine tuner

[seattle smitty]

(Back from a one-day holiday in which Americans traditionally eat themselves into immobility).

Reading Wobbly's account of his team's final rotten luck after blowing the rest into the weeds at the big kart meet, it strikes me that this should be said:

As endlessly pleased and grateful as the rest of us are to Frits and Jan Thiel for their wiilingness to unreservedly share the findings of their long 2-stroke careers, it seems to me that Wobbly goes well beyond the call with his open-handed assistance, because far from being retired from racing he still is fully involved and makes a living from it. Active racers generally want to keep some things to themselves, rightly feeling that whatever little edge they have gained over competitors is privileged, and further, that up-and-comers should understand that at some point you stop asking for more detail and start learning from your own cut-and-try labors. Frits may recall that after I asked the members about what 80cc powerheads were well-designed, he not only told me what engine, but then, to my great surprise, told me very specifically what port-timing to start with. Incredible! And Wobbly volunteers this sort of thing, too, despite being currently involved in racing at the highest level.

We would get nothing remotely like this kind of disclosure from active NASCAR or NHRA crew chiefs. Thank you for all of it, Wobbly. And I hope you can come back and take full revenge.

[seattle smitty]

To FastFred, who described bucket racing:

We do have a category of outboard racing that is conceptually similar to that. Called "Modified," it uses old production outboard powerheads such as Mercury and Evinrude, two, three, and four-cylinder in the traditional range of displacements, burning gasoline and mounted on short towerhousings with direct-drive lower units. The intent was to provide cheap racing and some scope for owner modification and creativity.

But the devil is in the details, and my personal opinion is that the Mod rules, established with the best intent, are really stupid rules with the result that most veteran alky racers aren't interested. I gather from comments here that some of you are not entirely happy with your bucket rules, as currently written.

[husaberg]

(Back from a one-day holiday in which Americans traditionally eat themselves into immobility).

Reading Wobbly's account of his team's final rotten luck after blowing the rest into the weeds at the big kart meet, it strikes me that this should be said:

As endlessly pleased and grateful as the rest of us are to Frits and Jan Thiel for their wiilingness to unreservedly share the findings of their long 2-stroke careers, it seems to me that Wobbly goes well beyond the call with his open-handed assistance, because far from being retired from racing he still is fully involved and makes a living from it. Active racers generally want to keep some things to themselves, rightly feeling that whatever little edge they have gained over competitors is privileged, and further, that up-and-comers should understand that at some point you stop asking for more detail and start learning from your own cut-and-try labors. Frits may recall that after I asked the members about what 80cc powerheads were well-designed, he not only told me what engine, but then, to my great surprise, told me very specifically what port-timing to start with. Incredible! And Wobbly volunteers this sort of thing, too, despite being currently involved in racing at the highest level.

We would get nothing remotely like this kind of disclosure from active NASCAR or NHRA crew chiefs. Thank you for all of it, Wobbly. And I hope you can come back and take full revenge.

No offence


That said, Frits Wob and Jan are extremely generous with their time, as frits mentions a few seconds to ask a question can result in hours to answer it.

[wobbly]

Sorry i missed the question about the cylinder I pic'd with the big Boyesesns - this is a CPI monoblock casting for a 400cc Superlight
bike - RZ based same as a Banshee.
But I have done a 400cc version of the TZ350 ( RD based of course for a Pre 82 Classic ) using the 6 port 3G3 TZ350 cylinder - added reed blocks/cavitys
from CR125 and this had a split intake port same as the CPI so I could add a couple of boost ports up the back.
All period legal, as Yamaha did the same thing externally for the 82 TZ500.
Big issue is the close stud spacing, not allowing Boyesens nor 3 port Ex layout,but it still made around 10Hp more than the best TZ350 and way wider powerband.

Thanks for the kind words about the finals disaster in Vegas, and yes we will return to get our title back.
My attitude re disseminating 2T knowledge is that I believe its incumbent upon the knowledgeable in this arena to pass on as much as possible ,now, or so much
will simply fade away and be lost forever.
With only a few niche sports still actually working on high performance 2T race engines there is still a chance for some of us to make a living doing clever shit
but for most even the things that were common place 10 years ago, are still a mystery, so anywhere I can help I am glad to.
We have hugely powerful computer code now that Neels has developed into a supremely accurate modelling tool, but you need real inputs to make real Hp as crap
in = crap out so the better the knowledge base is the better our 2T efforts will turn out on the track.

[peewee]

hey wobbly whats the best choice for a 115mm rod ? only thing i see is the hotrods which i dont really care for. or the prox rd400 rod but it appears to use smaller bearings

[wobbly]

Ask me for a good one.

[fatbastd]

ProX Rd400 rods are fine at 75+ HP up to 11500rpm, fitted with decent big ends, in my experience. Have run them for years. Price is good too. Have 4 spare basic kits and could probably find decent big ends as well, if required.

[peewee]

rd400 prox rod crossed my mind. been using prox rods in other engines and theyve never let me down. however i had another idea. what about a samarin GP competition rod ?

[speedpro]

and you need a better more expensive rod than the one that would do the job because . . . . . ?

[peewee]

im just kicking around different ideas

[AndreasL]

and you need a better more expensive rod than the one that would do the job because . . . . . ?

For me it's because I'm a sucker for buying cool tech stuff.
Smart? Naaa…

[wobbly]

The RD400 based rods are narrower,thus would need spacing with another washer if used in a Banshee/RZ based crank.
I use rods that were made to my specs by Wiseco after they were fired by Kurt of Hotrods.
They had an international marketing exclusive deal, that Wiseco typical of them botched completely.
Not long after the deal collapsed, the CEO that had caused all the drama was fired, and I ended up with a box of really good sample rods
with no identifying markings, but they were made by Taiwans best rod/crank maker Shunchi.
At the same time I got some Peek coated flat race cages done to go with them.
Cheap and bulletproof and plug and play - the best combination known to man.

[seattle smitty]

No offense taken, obviously, and thanks Husaberg, I'll take a look.

But if it really is, as I expect, "NASCAR 101," that's not surprising because they aren't giving away anything of the sort we get from OUR instructors, who are teaching a graduate course. When I started racing outboards there was NOTHING, NOTHING on 2-strokes other than repair manuals for fishing motors, an occasional parts blow-up of a race motor in Outboard Speed Sport magazine (long gone!!), and an engineering book on DIESEL 2-strokes by Schweitzer (IIRC) translated from German that I found in the Engineering Dept library at the Univ. of Washington in Seattle. When Gordon Jennings little red book came out in about 1968 or so, we were blown away! Here was our Racing 2-Stroke 101, or even 201. Further enlightenment over the years from Kevin Cameron, John Robinson, and Graham Bell was invaluable. But I never imagined finding anything like the pearls that our esteemed profs are casting before us here. The contrast with fifty years ago is stunning.

[seattle smitty]

Okay, I have an idea. Maybe old-hat, but I haven't seen it discussed:

In the early era (MY era) of loop-scavenged 2-stroke bike motors and outboards, the boost-port (or as it is now called in discussions of more modern engines, the C-port) was not very wide, and was VERY short in length because it had to fit above a piston-ported intake tract. It was fed from a small matching hole in the piston, close to the crown and just below the ring. Nobody expected more than a small contribution to power, but it was thought that any A/F mixture flowing through the piston, under the crown and out the hole and into the boost-port should have a cooling effect on the piston crown. To what extent this was actually true, I don't know. Some people theorized that as the piston slowed as it approached bottom-center, whatever mixture that was trapped inside the piston tended to be accelerated out of the bottom of the skirt, so that there really was not much in the way of A/F remaining in under the piston crown for the boost-port to access, or to cool the crown. (FWIW, my personal experience with these very short, piston-fed boost-ports came from my 1963 FA Konig 250cc racing outboard).

In any case, I have read comments from our profs telling us that those old, short, piston-fed boost ports are nowhere near as effective as a modern full-length C-port fed from the crankcase area.

However, I wonder if a combination of old and new could be better yet. Suppose you take a modern (okay, Aprilia) cylinder with full-length C-port, AND have a hole in the piston, at the old location under the crown and ring, flowing into the side of the C-port, roughly halfway up. Would the very good flow and velocity of the modern C port draw strongly from that hole, and really have a good effect on piston cooling (any power effect of accessing mixture trapped under the crown would be incidental, piston cooling being the chief motivation). If this were done on a clean-sheet engine, you could specifically shape the long C-port to have a venturi section that might pull even harder on the A/F coming out of the hole in the piston, for added cooling.

And if this would work to good effect (piston cooling) on an Aprilia or similar cylinder, could it not be even better if applied to Frits' FOS concept, with its ring of transfer ports? Maybe you could have two or four holes (in a piston structurally designed for them) each one feeding one of two or four transfers, creating a cooling outflow under the piston crown.

Any merit to this idea at all, Frits? Prof. Thiel has taught us the importance of shaping and aiming the inside curve of the A and B ports to cool the outside of the piston crown. Might this idea help that cooling effect?

[husaberg]

That reminds me ages ago I said would post some pics of the TD1C Port slots.
No use these days, but more for giggles.