ESE's works engine tuner

[F5 Dave]

Funny usually the first runs are the best until the crankcase warms up. I always run through gears a few times before taking any real note of readings.

[TZ350]

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It was suggested at the time that the pipe was a little long for the porting and as it heated up it mached it better. Possible I guess.

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[SS90]

F5dave makes a good point, there is always a "slightly better" run when the engine is warming up, and once it is up to N.O.T, the runs remain constant. (always good for the customer who want's to beat his mates), of course until the engine gets too hot, when it drops dramatically.

With the pipe temperature I have actually seen 3 pipes that work really well (older designs) but, lets say you where racing in a 20 lap race they actually gradually overheat the engine and sometimes actually seize, (or worse and hole a piston) whereas in a 12 lap race, they work fine.

You notice it late in the race, when for no apparent reason the EGT starts slowly climbing.

To be honest I really have not been able to put a real reason to this happening, but notice that it's the stinger (pipe "bleed valve") that seems to be the cause.

Not so much the diameter, as I suspected, but more the design of the muffler.

For example, the "modern" 2 stroke muffler hasn't changed since the eighties, and there seems good reason other than styling, the older style (that you see in older books) effectively muffle the exhaust, but it seems does cause the pipe to overheat (in longer races)

Like you say Teezee, your pipe could well be too long, or even, you may just need to take a look at you stinger design, not so much the muffler, (as you have a modern design), but more the diameter and perhaps length.

I simply use the old technique of having the stinger section as a "sliding joint", and where the stinger meets the baffle cone, instead of welding it in place (for testing) simply have a screw clamp joint, so you can slide a (longer, or indeed, shorter) stinger section in and out of the baffle cone.

You can find power this way (surprisingly), and you will instantly lose noise!

Just don't go past the medium point of reflection!

There are plenty of two stroke exhaust now that essentially have the muffler attached straight to the baffle cone, and the stinger section (that what does not include the muffler portion) is simply "slid inside" the baffle cone.

[TZ350]

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Interesting SS90, a lot to think about there. Currently my muffler is an old one of an RG250 that has had the crud burnt out of it a typical Bucket muffler. I recently acquired of Trademe two very near new mufflers from 125 MX bikes. I figured they would be a better design than I could make myself.

Apparently the customers wanted a better sound????? suits me, I want a quiet Bucket, which is better for sneaking up on the competition with. I have found, if they don’t know your there you stand a much better chance of diving under them into the next corner.

Speedpro also recently talked to me about people slipping the stinger inside the chamber. My new mufflers have different stinger diameters so I should be able to try your suggestion.

I want to make a new pipe, actually several straight pipes with sliding mid sections for testing on the dyno like I saw in an attachment you posted. I could also incorporate a sliding stinger as well, in fact that’s a very good idea, thanks.

There is a lot of work in planning the chambers and making them so it wont happen overnight but it will be worth the effort. I have spent nearly 100 hours building a new motor to try the “unmasking of the transfers” “port/time/area” and larger “inlet port” ideas of breathing better and for the right time talked about before, a lot of work for just a little more torque!!!!.

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[SS90]

Yea, I can relate to that.

The big gains are the easy ones, and the stuff that "sets you engine apart from others" takes time, but it all adds up.

20PS is really good though, and like you say, getting it at lower RPM is what it is all about.

It helps your sanity when you think about any gains in a %age of your base run.

1 PS (or 1NM) becomes a bigger number when you think of it that way!

[gav]

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Interesting SS90, a lot to think about there. Currently my muffler is an old one of an RG250 that has had the crud burnt out of it a typical Bucket muffler. I recently acquired of Trademe two very near new mufflers from 125 MX bikes. I figured they would be a better design than I could make myself.

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Wonder what these would be like? $89- each.
http://www.trademe.co.nz/Trade-Me-Mo...-247170189.htm

[TZ350]

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A while ago Thomas told me that if I wanted more power the pipe had to be made longer. Well like most, I new that a pipe needed to be shorter the higher the RPM and thought he was wrong.

And I have always been curious about why someone at Buckets was able to run an RS125 pipe on their TS125, I couldn’t understand how a pipe for a high rev high power motor could work so well on a low rpm 18hp bike.

Recently I wrote a spread sheet based on Blairs work so I could sort out a pipe for my new engine. What I didn’t realize is that a pipe needed to be longer for higher Hp engines because of the higher average exhaust gas temperature. So a pipe gets shorter as the rev’s go up and longer as the hp increases.

Here I have graphed the tuned length as a function of Hp vis RPM for an Ex port duration of 198 degrees.

……….….18hp…….20hp……..22hp……..37hp
RPM
..9,000……917…….1005…….1085….. Tuned length in mm
..9,500……868……..952……..1028
10,000…..825……….904………977
10,500…..786……….861………930
11,000…..750……….822………888
11,500……717…….…786………849
12,000……688…….…754………814……..840 Honda RS125
12,500……660….……723………782

Ex Temp…350………475………600……...650 average exhaust temp Oc
BMEP……5bar………8bar……..9bar……..11bar

It makes sense that a pipe gets shorter as the rev’s go up because there is less time for the pressure wave to travel out and back through the pipe.

Hp and Ex Temp are functions of BMEP the higher the BMEP the higher the measured Hp and hotter the average exhaust temperature is.

A pressure wave travels faster in a hotter exhaust so the more hp the motor makes the longer the tuned length needs to be. It was a surprise to me that a Honda RS125 pipe with a tuned length of 840mm could be used on a 9,750rpm 18hp TS125.

Exhaust port duration also has an effect on the tuned length. Keeping the Hp and RPM the same I graphed the change in tuned length for a range of exhaust port duration’s.

Ex Opens ATDC Duration Tuned Length

…….87………...……186…....….943
…….85…………...…190....…….964
…….83…...…………194…....….984
…….81……...………198…......1004
…….79………...……202…......1024

And that makes sense too as the longer duration means more time so the pressure pulse can travel further.

So there it is:- more rev’s and the pipe becomes shorter, more power and/or duration and the pipe becomes longer. Not what I had thought at all.

So Thomas was right, a pipe needs to be relatively longer for a motor that is making more Hp.

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[TZ350]

Wonder what these would be like? $89- each.
http://www.trademe.co.nz/Trade-Me-Mo...-247170189.htm

Tempting, certainly worth a look.

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[SS90]

As a sidetrack,

These 2 pictures arrived today, I'm not 100% sure, but the cylinders are off a Yamaha from the early eighties belonging either to Johler Harald or Emmerich Stenger.

Evidently this engine was (apparently) faster than Anton Mang's Kwaka, but I havn't seen any evidence of that.

I imagine that ring life would be somewhat "short".

There are some pretty harsh marks on the bore directly above the transfers, I would surmise that is due to the "boost channels".

I'm 100% sure that it would have any gains, but it seems it may have.

I wonder if Boysen started off with this concept before ending up with the transfer boost's we know today?

[F5 Dave]

Quite a torturous path to follow for the boosts, but no more so than as an extn of the 2ndrys as per Suzuki of the era (late 70s). That must have been from a TZ500 where they were still running piston port rather than reed hence couldn't run normal boost port. Early 80s? More late 70s. But they kept with the piston port engines a they made more power than reed at the time. No sign of powervalve but there is a ex boost port. Sidecars kept these going somewhile longer where the high output was important & the peaky nature not so with many spin off engines from Dutch tuners (memory failing Henkel or Heiniken or something, it will come to me). [edit Krauser was one). When did they start with electrofusion over chrome? that may id the cylinder a bit.

Must have run a single ring peg centrally.

[TZ350]

These 2 pictures arrived today, I'm not 100% sure, but the cylinders are off a Yamaha from the early eighties belonging either to Johler Harald or Emmerich Stenger.

Thanks, very interesting pictures, very radical, what I love is, its the sort of thing that can be tried on a bucket. I am impressed.

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[F5 Dave]

Ohh look, my Yamaha factory & Production road racing 2 stroke 1955-93 book has just today arrived from Amazon (along with Cameron's Grand Prix Motorcycle book). So I might be able to anorak an answer after a few nights.

[Kickaha]

Sidecars kept these going somewhile longer where the high output was important & the peaky nature not so with many spin off engines from Dutch tuners (memory failing Henkel or Heiniken or something, it will come to me). [edit Krauser was one).

Hummel? although I think he just did tuning or maybe his own barrels for TZ based stuff

Krauser, ADM, BRM, Swissauto http://www.flickr.com/photos/teamher...7594371961909/

[sonic_v]

.

A while ago Thomas told me that if I wanted more power the pipe had to be made longer. Well like most, I new that a pipe needed to be shorter the higher the RPM and thought he was wrong.

And I have always been curious about why someone at Buckets was able to run an RS125 pipe on their TS125, I couldn’t understand how a pipe for a high rev high power motor could work so well on a low rpm 18hp bike.

Recently I wrote a spread sheet based on Blairs work so I could sort out a pipe for my new engine. What I didn’t realize is that a pipe needed to be longer for higher Hp engines because of the higher average exhaust gas temperature. So a pipe gets shorter as the rev’s go up and longer as the hp increases.

Here I have graphed the tuned length as a function of Hp vis RPM for an Ex port duration of 198 degrees.

……….….18hp…….20hp……..22hp……..37hp
RPM
..9,000……917…….1005…….1085….. Tuned length in mm
..9,500……868……..952……..1028
10,000…..825……….904………977
10,500…..786……….861………930
11,000…..750……….822………888
11,500……717…….…786………849
12,000……688…….…754………814……..840 Honda RS125
12,500……660….……723………782

Ex Temp…350………475………600……...650 average exhaust temp Oc
BMEP……5bar………8bar……..9bar……..11bar

It makes sense that a pipe gets shorter as the rev’s go up because there is less time for the pressure wave to travel out and back through the pipe.

Hp and Ex Temp are functions of BMEP the higher the BMEP the higher the measured Hp and hotter the average exhaust temperature is.

A pressure wave travels faster in a hotter exhaust so the more hp the motor makes the longer the tuned length needs to be. It was a surprise to me that a Honda RS125 pipe with a tuned length of 840mm could be used on a 9,750rpm 18hp TS125.

Exhaust port duration also has an effect on the tuned length. Keeping the Hp and RPM the same I graphed the change in tuned length for a range of exhaust port duration’s.

Ex Opens ATDC Duration Tuned Length

…….87………...……186…....….943
…….85…………...…190....…….964
…….83…...…………194…....….984
…….81……...………198…......1004
…….79………...……202…......1024

And that makes sense too as the longer duration means more time so the pressure pulse can travel further.

So there it is:- more rev’s and the pipe becomes shorter, more power and/or duration and the pipe becomes longer. Not what I had thought at all.

So Thomas was right, a pipe needs to be relatively longer for a motor that is making more Hp.

.

Pipe length and exhaust duration are certainly the most critical factors in determining the peak power speed. Another important factor is ignition timing. Most modern two-strokes are running ignition timings of less than 10 degrees at peak power speed. Your typical bucket racer might be on 20 degrees. This alters the exhaust gas temperature with the more retarded timing having the higher exhaust gas temp and thus peak revs are higher.

[F5 Dave]

Hummel? although I think he just did tuning or maybe his own barrels for TZ based stuff

Krauser, ADM, BRM, Swissauto http://www.flickr.com/photos/teamher...7594371961909/

I thought I'd seen Hans Hummel barrels (note that pic of Krauser has HH marked on barrels). Sounds Dutch. Oops he's Austrian.

Either way I'm clearly no expert on the subject & someone is likely to come along & point out that the barrels are from a Griffen 360 marine compressor.