ESE's works engine tuner

[TZ350]

Finally I know what it's like to work at ESE, 1:26pm on a Fri, browsing Kiwibiker. Excellent

Boss, not me I was out on a job at that time.

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[bucketracer]

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Here is a xls spread sheet that can be downloaded that is based on MacDizzys work and covers blowdown time area:- www.essjayar.com/motorbikes/2_stroke.xls

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[TZ350]

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Thanks Bucketracer for the link, very interesting, I have had a look at it.

I always thought of the blow down phase as starting when the exhaust port opens and ending when the transfer ports open. But I recently came across a better definition that makes more sense.

Its “The blow down phase starts with the opening of the exhaust port and finishes when the pressure inside the cylinder equals the pressure in the exhaust pipe”. from "The Internal-combustion Engine in Theory and Practice"

Makes sense to me, from this I can see that blow down may/or may not be complete by the time the transfers open. Then after blow down I guess there is a period of suck down, from the kinetic energy of the slug of gas traveling down the exhaust header before/as/or while the transfers open.

I am not sure about the ideal timing of this suck-down phase.

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[TZ350]

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Thomas and Tuti have got themselves a new toy to play with, a V8 Maserati engine.

Beats mucking about with those old Leyland P76 alloy V8's.

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[TZ350]

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NedKellys team ESE bike was run up on the dyno again after Thomas had done some porting work, he managed to get a similar flat torque curve like Chambers 18hp bike on post 1222 page 82 but NedKellys makes 2 more hp.

Suzuki GP125

Pic-1 Ex opens 84 degrees ATDC at 64% of bore width. Trans open 114 ATDC, Inlet opens 145 BTDC and Closes 55 ATDC ignition 24 BTDC non-squish std open chamber head. 24mm carb 105 main jet and RM pipe.

Pic-2 Changes are:- Ex opens 79 ATDC at 70% bore width.

I have not been able to analyze the port/time or blow-down yet but suspect it will be revealing. I am still working on my own cylinder and bottom end where I have been working on unmasking the transfers like SS90 suggested. I am finding that converting the idea to reality is a bit tricky but if I can get more torque from my own bikes engine it will be worth the effort.

Team ESE now have 2 bikes at 20rwhp and 2 at 18rwhp the difference between them seems to be the width of the exhaust port, in every other way they are much the same.

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[ajturbo]

ok..... on this note... is there somewhere in wellington that us Bucket racers can get dyno'ed for free..???

is there anyone out there(here in welly) that has one (eg: like Pete sales has ) sitting in back of garage, just wanting to be used?... just so we can tune/brag/laugh????

[F5 Dave]

Of course, people are always offering dyno services for free. Pete never charges does he?

[koba]

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NedKellys team ESE bike was run up on the dyno again after Thomas had done some porting work, he managed to get a similar flat torque curve like Chambers 18hp bike but with more hp (20rwhp).

Suzuki GP125

Pic-1 Ex opens 84 degrees ATDC at 64% of bore width. Trans open 114 ATDC, Inlet opens 145 BTDC and Closes 55 ATDC ignition 24 BTDC non-squish std open chamber head. 24mm carb 105 main jet and RM pipe.

Pic-2 Changes are:- Ex opens 79 ATDC at 70% bore width.

I have not analysed the port/time or blowdown yet but suspect it will be revealing.

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Thats looking pretty good!

[speedpro]

extending the base line like that really distorts the curve

[bucketracer]

extending the base line like that really distorts the curve

Not sure what you mean, both graphs are 6k wide along the base line, in fact all the ESE dyno graphs are 6k wide. Do you mean that if they were charted over a 12k base line they would be more realistic?

The graph in the first pic is making power from 7.5k to 9.5k a power band 2k wide more or less and the second graph has the power from 8-11k, a 3k wide power band. A 50% increase, not too shabby.

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[speedpro]

The increase is good, it is all about area under the line, to a point. I'm just used to looking at graphs that show a wider range of revs. My old MB sidecar made over 14hp from 9-13,000rpm with a peak of 19.9hp over about a 1000rpm. 28mm carb and single sided reed with one big petal.

[TZ350]

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extending the base line like that really distorts the curve

I agree, even a very peaky power curve would look flat if it was drawn on a six foot wide piece of paper.

The dyno data was only recorded in the rev range of interest and I imagine that the dyno software adjusts the axis of the graph to suit the rpm range and power curve its graphing and automatically fits it all to the A4 size paper printout.

And certainly if the dyno data was recorded from a much lower rpm the torqe curve would appear relatively shorter on the graph.

Your right the printed torqe curve would only be half the size if it was graphed 0-12,000rpm instead of 6,000 to 12,000.

But the torque curve would still cover a band of 3,000 rpm although it would be harder to see and half the graph would cover a lower rpm range that's of no interest.

Reality can be very hard to measure.

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[SS90]

Your right speedpro, but think of it this way,

When you Dyno soomething like, say an RS125 (which you only operate above 8500 RPM anyway), why would you bother graphing anything below that.

I think it would be fair to say that not many tuned 2 stroke buckets are operated below 6,000 RPM anyway, so why even bother "testing" then at that rev range.

Personally, I start dyno runs on the stuff I do at 4,000 RPM.

There is just no reason to measure lower.

Another point is that it is important to keep a constant exhaust temperature when making a two stroke dyno run, or rather, allow the exhaust to (at least) get to the correct temperature.

If you "bog" the engine down when trying to do a run, you can often cause the exhaust not to get up to the right temperature, giving incorrect readings. (exhaust temp gauges are really helpful)

The best thing is to operate the engine during the run, so that it accelerates the same way as it would if you where "on the track"

I.E, if you shift from 2nd to 3rd gear, the revs arent likely to go below 4,000 (or 6,000 in this case) anyway.

If they did, you are doing the run in the wrong gear!

I also feel that by the design of the pipe they are using, there will be a "resonance hole" about, 4,500RPm anyway....... no point in measuring that!

[TZ350]

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Chambers and Thomas checking the vertical wheel alignment of one of the Team ESE bikes after it had taken a heavy hit. The whole frame had become twisted.

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[TZ350]

Another point is that it is important to keep a constant exhaust temperature when making a two stroke dyno run, or rather, allow the exhaust to (at least) get to the correct temperature.

If you "bog" the engine down when trying to do a run, you can often cause the exhaust not to get up to the right temperature, giving incorrect readings. (exhaust temp gauges are really helpful)

I had not realy thought about it but it makes sense and might explain why my bike allways ran better when the pipe got hot.

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