ESE's works engine tuner

[jonny quest]

Do you guys think this pipe would be worth a try? My target peak rpm is 10,000. This is a vintage piston port, single exhaust port, 450cc parallel two cylinder snowmobile engine with a CVT. Exhaust duration is 202° with 35° blowdown. I have physically built 6 sets of pipes for this particular engine thus far and they are all worthless. None look anything like this pipe. Some longer, some shorter, most fatter. Based on the minimal info I am providing, is there anything with the design that stands out and screams “you are wasting your time!” Normally I would just build them, and try them, Attachment 348575but my ego is already dwindling at this point.

Run 32% hdr 3deg total. 66%total diffuser and a pretty short tailcone 30ish included angle.

Don't try an get fancy with sharp diffuser angles, somewhere around 7 first, 13 second, 15third. Adjust 3stage lengths to sort of end up close to those angles.

Probably a 4.5" to 4.7" center diameter

[Condyn]

Thanks, That results in a very different pipe than I am used to seeing with a very stubby baffle cone.

[andreas]

Somehow the 7.2 taper is now incuded in the header, just go 3* for 32%. And also when the tuned length is measured at the end of baffle it have to be shorter when the cone is shortened, it can be converted by using to the center of cone length ,sort of. Or let Wobbly sprinkle som magic over it.

[Condyn]

The 7° angle is the first diffuser, not the header on the second pipe, and 1% shorter than the first pipe. I will be rolling cones until I am blue in the face at this rate. And yes, the magic is being sprinkled.

[41juergen]

Hi, juergen

NS 400 stock ignition timing curve is too advanced for correct squish height ( 0.8 mm /1 mm). Std NS 400 squish from factory variate from 1.8 to 2 mm with aprox 15,5 cc head volume with plug hole.
I dont know exactly, but DMR cylinder heads volume looks like too small, with very wide squish band.
Some time ago, when I started endless testing with NS engine, first things was to correct squish height to 0,9 mm and 13.5 cc volume with std cylinders and heads. And gains in upper range, comes only after retarding std ignition with additional plate (add photo ). Very important too harmonized ignition and new 500 cc set up before goes deeper. But of course first thing after 500 cc kit, must be zeeltronic or ignitech ignition. They made nice special kits for NS 400.

Very interesting about head volume on 500 cc kit.

Hi Katinas, the combustion volume of the DMR setup is approx. 10,7ccm with a squish band of 11.8 mm. With a squish of 0,9 mm that gives a MSV of 38,9 m/sec at 10.000 rpm (I know, a little bit high maybe).
Do you have detailed data of the stock ignition curve for the NC19?
Re the exgas temps not going down when going rich: I played a bit more with the sim and Wob might smile, I think the problem are the Jim Lomas pipes. They were designed for the stock NC19 with a belly diameter from only 102 mm. So for me it looks like that the pipe volume is too small. When using a 120 mm belly even a 22 mm stinger venturi brings the temps down to an expected level....

[SwePatrick]

Today the weather finally approved for some 'opengaragedoorthingstodo'

Dyno!! =)

I have this winter setup a simple nitroussystem just to add some power if needed, today was the day to test it.
Graph below is a comparison between 'best curve no nitrous run' and a short burp nitrous run.
Result: 98.4Hp to the crank.

I run the system totally pump less, and by that i shoot the nitrous dry and have a couple of homemade powerjets activated by a solenoid fed directly from the tank above them, gravity and ejector pulls the fuel from the tank.
I setup the jets for the nitrous to add 15hp, it became 12.9hp running a tad rich, but i´m happy with how nice it worked without fuelpump, and i can always tune off a little bit of fuel at the track when having more at stake, so to speak

I also don´t purge the nitrous, this to make a 'soft hit' as the fuel takes a little time for it to reach the carbs bore.
I figure this is easier on the engine also.

As the pipes were always tuned to give peak at 12000rpm with nitrous i´m happy that the seem to do just that, i chickened out and let off the throttle just at 11700rpm

I use ignitech to control it, no need for doing anything, it is activated above certain rpm and above certain throttle.

How much nitrous do you people think is possible to run?
20? 30? 40hp?
This was with the smallest jets i could find.

I have also updated the dyno software between the runs, this makes the 'before run' have a another smoothing setup.

[palezu]

I'm designing a new 50cc cylinder to be cast. Currently working on the water jacket. Almost done, but I started to wonder around about the placement of the inlet nipple near the exhaust duct, or rather should it be the inlet or outlet nipple. Would it be beneficial to have the water flow in "reverse" direction, to have the water enter from the head above boost port, then flow around cylinder to the exhaust duct jacket and then exit upwards right before the pipe adapter? I have read about wobbly's trials of reversing the water flow, but I'm not sure if the routing was comparable to this. I think the KZ has the water entering from the case, but I don't have this option.

I think it would make sense, it would follow the natural thermal gradient of the cylinder that the exhaust is always hotter. If the cold water entered the exhaust first, it would shift the balance and more like move the heat from exhaust into the cooler side of the cylinder. Of course we want to keep the cylinder head portion the coolest. If this is a good idea, then I can make the exhaust water core have the outlet upwards above the exhaust duct and not sideways.

[F5 Dave]

Wob has explained this a few times if you search back. Put it in the back of the barrel first.

[katinas]

Hi Katinas, the combustion volume of the DMR setup is approx. 10,7ccm with a squish band of 11.8 mm. With a squish of 0,9 mm that gives a MSV of 38,9 m/sec at 10.000 rpm (I know, a little bit high maybe).
Do you have detailed data of the stock ignition curve for the NC19?
Re the exgas temps not going down when going rich: I played a bit more with the sim and Wob might smile, I think the problem are the Jim Lomas pipes. They were designed for the stock NC19 with a belly diameter from only 102 mm. So for me it looks like that the pipe volume is too small. When using a 120 mm belly even a 22 mm stinger venturi brings the temps down to an expected level....

It was long time ago when I measure ignition curve of std NS400 (NC19 ) and NS250 (MC11) and now can’t find these graphs.
From memory, both graphs started immediately at highest advance angle and holds steady until approx. 6000-6500 rpm (just before ATAC chamber closes) , then gradually retarding.
Difference between 400 and 250 cdi is that on 250, after 10500 rpm spark timing retarded drastically and drop of the operating range, this work like rev counter.
NS400 cdi didn’t have this restriction and holds some advance until 13000 or maybe more rpm. Other thing is, that NS 250 cdi generated weak spark, so engine is very sensitive to mix.
NS400 cdi is opposite, generate very strong spark that tolerate very rich mix.
Both generators flywheels are “criminally” heavy for such engines.

Very interesting about DMR head volume for 500 kit, thanks. DMR still made very nice things for NS/NSR street engines.
If its really 10.7 cc it is about 16.5 compression, looks too much for 166 cc, even on avgaz.
It looks like need to be very careful with this nice kit, as bore raised from 57 to 64.7 mm. Very interesting how your test goes.

I tried six different shape pipes for NS 250/400 engines ( single exhaust window) and every time the best was Honda RS125/250 copy, with 120 mm belly, just playing little with header length for lower rpm.

I still trying to adapt Honda RS125/250 cylinders to NS 400 engine with and 54 mm stroke crank with direct flow to transfers. Its not too much left, but small things usually needed time.

[RAW]

[QUOTE=wobbly
I noticed the Pankle silly money capped small end pin in your post , this is easy enough to do youself if you can do the cad drawing and have the caps CNC machined , then laser welded in.
The laser guy here has a standard charge , and will do one or 5 pins for the same money.[/QUOTE]

The Pankle pins are not laser welded, further the performance gain may not entirely be due to the capped ends.

[RAW]

Seems like somebody forgot to tell Neil Hintz
Attachment 348488 Attachment 348487 Attachment 348485 Attachment 348486Attachment 348489

Dolph has suggested to me that an in-line 250cc 256 type styled engine can be sufficiently balanced to be used upon a superkart.
What’s Your opinion Frits 🤷*♂️

[Frits Overmars]

Dolph has suggested to me that an in-line 250cc 256 type styled engine can be sufficiently balanced to be used upon a superkart.
What’s Your opinion Frits?

As far as I know all 250 cc Superkart-twins use that type of inline engine. But those are all counter-rotating simultaneously-firing twins, perfectly balanced with 100% balance factor for each crankshaft. The discussion with Wobbly was about inline twins that were not counter-rotating and/or not simultaneously-firing.
Did Dolph say anything about those cases?

[RAW]

As far as I know all 250 cc Superkart-twins use that type of inline engine. But those are all counter-rotating simultaneously-firing twins, perfectly balanced with 100% balance factor for each crankshaft. The discussion with Wobbly was about inline twins that were not counter-rotating and/or not simultaneously-firing.
Did Dolph say anything about those cases?

Hello Frits, sorry, a lack of information on my part. Yes Dolph was referring to a counter rotating in-line twin with a 180* firing order

[TZ350]

.
More from the genius of two stroke stuffing.
.

[ken seeber]

The Pankle pins are not laser welded, further the performance gain may not entirely be due to the capped ends.

Rick,
I seem to remember someone, was it Jan, say they were laser welded and very expensive. Assuming they were hollow, then they must have been made in multiple parts which are then welded, pressed or bonded together. Maybe there is some other magic out there though. I think Wob’s design is utilising the standard pin, so some form of retention is required and, in his case, no distortion of the OD of the pin

If the circlip is to be accessed to allow pin removal, then one could assume there would need to be sufficient annular gap to achieve this. Despite its end having a spherical and tight clearance to the bore, close. It could never be as good as a form fitting pin or plug. I believe Wob is on the case to make a comparison.

Any form fitting pin or plug needs accurate indexing and axial location.

Can't think of any other way the pin could change the performance, other than less short circuiting, change of mass or sealing off the central volume of the pin.

https://www.mondokart.com/en/engine-...in&results=147