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Modified l28et manifold


wax

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Im using a die grinder with a 9" shank

then im using cartdrige wheels to clean up the alloy afterwards

I build alot of race two stroke engines so my stock of burrs is quite big

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That looks a bit better.

I have a bit of a technical question.

 

When porting manifolds, do you have to try and keep the runner diameters and runner mouths/openings similar sizes across the cylinders so that each cylinder flows similar amounts of air?

 

If so, how do you manage to do this?

You mentioned ball bearings, is this your normal measuring tool? or do you have a long measuring caliper or something?

 

Cheers mate,

Brad

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Yes you need to keep them the same across the cylinders, Thats the hard part is keeping them the same.

No i dont normally measure with a ball bearing , but since I had some them i tried them down it. They did actually show me that the diameter down the runners was very close between them

I was looking to get the diameter up to help the flow.

The thing is with manifolds like this is unless you have sidedraft webers then or itbs then the flow is going to be different between them all anyway.

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Ok well more work on the manifold today

its ready to get welded up now

Took the egr right out of it

Also removed the centre rib out of the manifold and took all the casting marks of it

001-1.jpg

002-1.jpg

003-1.jpg

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are you going to polish ? Pics look like you need to sand before you can polish. I used a dremel with a flex shaft and a flapper wheel to sand and a polish wheel and proper polish. Turned out gem

Are you really planning to tig flat stockl to the cast ?

Thanks for the pics and good luck on your project

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No i am not going to polish it

I am just getting the casting marks out of it so i can get it resandblasted to give it that sand cast finish all over, i havent finished it yet , the welding will need cleaning up , until that time im not going to hard on the finish

Yes i will be welding flat stock to the cast , done it heaps before works very well

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I got socks just like those! I'm wearing them now...

 

Even the best ported stock intake manifold (at yes, 35mm diameter) will still be down on flow by about 30CFM over a properly ported intake runner.

 

If you have your head ported, don't go real crazy---that manifold will likely flow in the 170-190cfm per runner range, so keep that in mind if you are shooting for a 'balanced equation' and want to keep velocities up in the ports.

 

As for the question about measuring the ports---keep all those old intake and exhaust valves handy! Turning them down on a lathe and putting 'stops' on the stems allows you to make a progressively taperer runner FAR easier than eyeballing it. A little smudge of machinist's blue on the rim of the valve and dunking it down the port to a specific depth reveals high spots to be attended to, as well as insuring the taper you want is present. .5mm every 25mm runner length is hard to eyeball, but if you got some stepped gauges made from old valves. Then again, as a two-stroke man you're wondering why the hell we bothered with valves at all, right! LOL

 

Press on...

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the valve idea works well , thanks for that

 

yeah sock are the go in the house at the moment its raining again

 

if i average your estimation of 170-190 and use 180 then the manifold will flow 278 hp

Im not sure if many l28s are getting that in N/A trim

With boost it should get along just fine

Im looking to make about 350 at the wheels so i think it will be enough

 

As far as the head yeah i am just going to give it a mild cleanup to get rid of anything that impeds the flow

 

Thanks for the heads up

 

Oh and i used to be a car mechanice before i saw the light and went with the valveless engine hahaha

 

Not sure what this cam thing is however i have been using it as a lever bar .Is this bad??

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278? Probably not on that manifold as an N/A but easily supported on a turbo!

 

But a stock ported turbo manifold with a ported head and cam on a stock bottom end (turbo) will run 300+ at 10psi of boost. The same engine terminally made 465 to the rear wheels somewhere around 20 or so psi. (JeffP's latest experiment in torture...)

 

He knows his stock manifold costs him 30CFM over what the port flows when mated to a Cannon Manifold that was port-matched. Were he to change over to a plenum simply bolted to the Cannon Triple Manifold, and put the appropriate TB on the front, he could pick up another 30CFM per runner in flow, and undoubtedly that HP number would climb higher from the flow restriction removed.

 

We must be on the same timezone now...I just landed in Nagoya! (Was in Shanghai)

 

I grind naked. My wife freaked thinking I was getting 'greyhaired'...prematurely!

 

Just remember to be careful around things that can twist other things into a knot violently! LOL

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I was just working out the calculation off the cfm you posted .

170-190 cfm works out to be 278hp

 

http://www.speedwaybids.com/calcs/powerfromcfm.html

 

Grinding naked is not going to work for me.Cartdrige wheel to the testes is not a good look.

 

If it turns out to be a restriction i will just make another manifold, im thinking about getting it flow tested just to see what it does flow. a friend of mine has a flow bench

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