ESE's works engine tuner

[wobbly]

Less metal mass in the divider = less heat input = less expansion distortion into the bore.
But way more important issue is to get the exit area ratio correct, and now the duct needs to be oval with the Aux ports outer wall
extending right thru the pipe spigot to the header.
This will need welding top and bottom as the duct exit is too big to start with.

[peewee]

now i know why hardly nobody bothers putting extra ports in the stock cylinders. its alot of damn work . got the hole punched through but still along ways to go

hey it seemed like you posted the duct exit should be 90% of the total exh area at the bore for a mono port if i recall correct. is it supposed to be like 95% if im using 3 exh ports ?

[TZ350]

now i know why hardly nobody bothers putting extra ports in the stock cylinders. its alot of damn work . got the hole punched through but still along ways to go

hey it seemed like you posted the duct exit should be 90% of the total exh area at the bore for a mono port if i recall correct. is it supposed to be like 95% if im using 3 exh ports ?

Yes, Triple Ex is a lot of hard work. And I think from memory, the smallest point of the duct area as it transitions from oval to round is supposed to be 75% of the total area of all the exhaust ports combined for a 3 ex port setup.

[wobbly]

The area ratio TeeZee has answered but here is the basic idea.
The exit area should be related to the Blowdown STA,as rightly pointed out by Frits, but i just havnt got that far yet.
3 port engines can generate alot more blowdown as well as total Ex STA when compared to a single port setup, and from general observation
the exit areas of these can , and usually do end up as 100% of the main port effective area - ignoring the Aux area.
This makes perfect sense when the general rule for the single port is best exit area is at 90% ie less blowdown, less BMEP, less exit area.

[peewee]

ok i just converted the duct exit diameter to area mm sqaured. its 77.3% of the total area of all 3 ports. sounds like im not far off from where i need to be

duct exit diamter 34.8mm = 951.149mm sqaured area

total area for all three ports 1229.5mm sqaured
951.149/1229.5 = .7736= 77.4%

remember the exh is only at 190 right now which wobbly said is to small so ill have to sort that out but if i raise the exh higher then i will probly be close to the 75% without needing to do much to the exit

[husaberg]

Here some pics (attached)if that helps, its no RSA of course. They I believe had a CNC finished Duct.

follow the path in this
http://www.kiwibiker.co.nz/forums/at...4&d=1419235154

[peewee]

i wont go to all the trouble of cutting off the spigot exit and making a new removable manifold. ill probly just extend the aux tunells pretty far down the main tunell like wobbly drew in the pic

[peewee]

sure wish i had a machine like this. hell even a simple drill press would probly do fine with a fixture to hold the cylinder. would save alot of time. machine could do the majority of the work making the rough hole then do the fine details with hand grinder

[Muciek]

ok i just converted the duct exit diameter to area mm sqaured. its 77.3% of the total area of all 3 ports. sounds like im not far off from where i need to be

duct exit diamter 34.8mm = 951.149mm sqaured area

total area for all three ports 1229.5mm sqaured
951.149/1229.5 = .7736= 77.4%

remember the exh is only at 190 right now which wobbly said is to small so ill have to sort that out but if i raise the exh higher then i will probly be close to the 75% without needing to do much to the exit

Did You used exit angle of port in calculations ?? Here's what Woobly wrote when I was asking about this (exh port dimensions)

In the port STA calculations the programs use the chordal width and the piston movement over the port height.
If the floor and roof of the duct are parallel exiting the bore then the area is simply Width X Height but if they are angled
then the height in reality is X the cosine of the angle.

[peewee]

i just used the area values from engmod. i assume thats the correct way ? it said total area of all 3 ports was 1229.5mm sqaure. roof and floor angle is around 15* . im not sure how to figure area with cosine involved

heres a cosine calculator but i dont know what number values to use http://www.calculatorsoup.com/calcul...of-cosines.php

[Muciek]

Cosine of 15 degrees is 0,965925826....
1229.5 * cos15* = 1187,60. I don't have engmod so I can't tell You is that 1229 vaue already with cosine or without it.

[husaberg]

sure wish i had a machine like this. hell even a simple drill press would probly do fine with a fixture to hold the cylinder. would save alot of time. machine could do the majority of the work making the rough hole then do the fine details with hand grinder

http://www.harborfreight.com/5-in-ru...ise-69159.html

i'm going to have a go with something similar to the top one, to mill a pattern in a drill press as I don't have access to a mill.
http://www.amazon.com/Wilton-11754-4.../dp/B009E0EBFM

[jasonu]

http://www.harborfreight.com/5-in-ru...ise-69159.html

i'm going to have a go with something similar to the top one, to mill a pattern in a drill press as I don't have access to a mill.
http://www.amazon.com/Wilton-11754-4.../dp/B009E0EBFM

Harbor Freight Tools sells cheap stuff mostly made in China. Some of it is good for one offs or home handy man applications but not for serious money making ventures.

[husaberg]

Harbor Freight Tools sells cheap stuff mostly made in China. Some of it is good for one offs or home handy man applications but not for serious money making ventures.

No Worries tis for wooden pattern for me...........I just can justify dropping mondo money on a decent mill, the rest i can do with a router, im not expecting it to do much else,I know Ya gets what ya pay for.
I used Harbour Freight as an example for pewee because I guessed he was in the Land of the free and home of Knave, same as you.
the NZ eq of Harbour freight is http://www.topmaq.co.nz/item/view/10...e?sku=MEVI1900

Still Chinese but they have this also.
http://www.trademe.co.nz/business-fa...-829460087.htm

Compound Sliding Table 450x168mm
Features:
- Working area 450x168mm.
- X-axis travel: 210mm.
- Y-axis travel: 140mm.
- Dimensions (LWH): 580x390x80mm
- Has slotted foot for secure mounting

[Flettner]

Like any other pipe resonance-dependent two-stroke.

Sure, also like on any other pipe resonance-dependent two-stroke: programmable ignition, power jet, power valves, trombone pipe.
But since I am under the impression that you can build anything you can think of: how about shrouds in the transfer roofs? If you lower them, you will lower the transfer timing, so wrongly-timed exhaust pulses will have less chance of shoving fresh cylinder charge back into the transfer ducts. Moreover, lowering the transfer timing while leaving the exhaust ports alone will increase the blowdown angle.area. That will put an end to the dreaded part-throttle detonation that plagued all Aprilia racing engines.
Taking this thought a little further, you could even use the movable transfer ceiling instead of a throttle.

.

That's actually quite hard to do, there is not much room as the exhaust ports are almost right there! BUT I have a plan, as you could imagine. The CNC will come in very handy, are you sure you don't mind me bastardising your FOS system?
How much are we allowd to angle the transfers up? To give room for the exhausts to angle down over them.