Bad news for my new red arrow 34cc engine
- Thread starter Rep732
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The last pic is factory. Not ported. Idk why they arnt cast like that, but you can see it's been done before the cylinder was plated, buy the ring of plating that extends into the port.
Correct. And minimal exhaust porting to the esp and none to the ra. Shame we cant get pics of the transfers for the esp.
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My blown up esp
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I'm assuming that's the stock port configuration?
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Yeah I just looked at my 1st order at ddm and its just an esp modified??
, no porting. I didn't know the difference then.
, no porting. I didn't know the difference then.
buzzkill
Mad?scientist
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now THAT looks like proper porting to me , the port is widened and smoothed ALL the way from outside to inside , my understanding is that smoothing the port improves airflow , widening increases airflow hence increase in power. More Air/Fuel = More Power , you cant see the casting marks in those pix ( except the transfer port covers , those are casting marks )
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?The listing doesn't mention porting tho.
buzzkill
Mad?scientist
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It may be that those ports are not widened and just cleaned up ? they have been worked that for sure , the casting marks have been removed.
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If anything they just got polished a bit. Go find my dbxl thread, I think I showed my ports after porting. I was experimenting with dimples on the intake side. don't know if it helped or not. Just thought I'd try it out and see.
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sorry sean that last one looked ported to me ?..can't say i know too much about how and where the porting is done. My esp transfer covers are stock and untouched on both esp engines i have. I don't think he messes with the covers but if you look at my TR/OBR covers even tho they are machined I see the difference
..can't say i know too much about how and where the porting is done. My esp transfer covers are stock and untouched on both esp engines i have. I don't think he messes with the covers but if you look at my TR/OBR covers even tho they are machined I see the difference
buzzkill
Mad?scientist
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builders mess with EVERYTHING Lol , nature of building I suppose, Ya those are polished for sure , you really have to measure the ports to really see the effect or how much material is being removed , air flow is the other part of porting ,
When I see a porting job and its NOT smoothed thats just lazy IMO , On my race Kart motors they were always smoothed and opened up to the max specs allowed for the class we ran.
We had the same thing in racing cars , they would pull heads on you randomly to check the valves and any ,mods that were not approved.
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I went back and looked at the stock head pics from my dbxl thread. Same machine Mark's on the exhaust side of the head.sorry sean that last one looked ported to me ?
We were visited by this guy that specialized in surface finishing at the machine shop. One of the mods he said sold quite a but was this simple finish technique. Something about why a golf ball flys so far or whatever. Only ever did it on the intake though 2 and 4 stroke. He was trying to sell it to us for turbo applications, didnt see the benefit when you using forced Induction. I cant say my engine really performs so much better or worse then my esp engine, but I guess to be fair they should be in the same platform running the same pipe.
Not so much any more due to modern fuel injection, but in the olden days a rough surface in a carb application helps with fuel atomization. Too smooth a surface and the fuel would have a tendency to fall out of suspension and puddle up in low velocity areas. I don't know enough about it to know if it's a major worry in a 2 stroke or not. I know puddling can be an issue, but is typically observed as an off idle rich bog in poorly made intake tracks. Exhaust go as smooth and shiny as you like.
szaki75
Well-Known Member
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appreciate your efforts sharing these things...
i did similar cutting at the bottom part of the cylinder at the transfer passage.
on this picture the piston is in the position where it just open (or close in up-stroke) the transfers:
as for the transfer ports, they are not so wide (imo) for ring snagging concerns , but would well worth the effort to chamfer them.
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I've found matching the transfer opening to the case is much more beneficial. Make sure there are no "shelf or ledge" where air has to move around it. I can't remember how much, but there was a good bit of material removed from the case area, taking caution to not increase case volume too much. Anywhere you can smooth over a transition is good in my book, path of least resistance concept in the bottom end. Somewhere I had a formula for intake to exhaust port ratio, and the % of piston diameter you could go (with nice chamfered ports) before you had to really worry about ring snag. As I'm more into saw engines then these little buggers I tend not to favor raising the exhaust roof too much, but favor a lowering the port floor with out getting into Freeport territory. There is a claim that free porting with a good tuned pipe can yield more performance, but I have neither the time nor finances to experiment with such. I also would like to try incorporating booster ports in the piston up above the intake inline with the transfers. Again time and finances have dictated I don't get to play with such ideas atm. At any rate post up your ideas I like seeing what others are doing.