This Part Doubles Power in a Two Stroke!

[Music] he [Applause] [Music] oh [Music] [Music] a [Applause] yeah [Music] [Music] wo m [Music] he [Music] [Music] he [Music] [Applause] [Music] [Music] w [Music] n [Music] [Applause] [Music] oh [Applause] welcome back to my garage you've probably figured out what's going on here I'm going to do some uh Machining and uh finish it off with a quick hand job and and uh I'll explain [Music] further [Music] a [Music] as you've seen by now I've lowered the exhaust duct floor which means the transition from from the duct shape to the round pipe shape happens much earlier than uh than what it has been doing this exhaust duct is a long story it started out as narrow as this and uh that was actually a mistake the reason behind uh the small area of the exhaust Port duct is to the duct exit is 100% of the ex uh effective exhaust Port area at the duct exit and the duct exit should be about two bars away from from the port from the piston this is smaller than that because I screwed up and I did uh cuz like the rule of thumb is 80% of uh Total Exhaust Port area but my exhaust Port used to be it's uh a little bit lower now but it used to be only blow down so no part of it protruded below the transfer roofs and uh I meant to make the exit uh the same as the as the port effective Port area but uh I screwed up and made it 80% uh 80% versus 100% off blowdown area and also what I think is going on because and this in a larger bike and probably with a much rounder exit this would have been best but I think problem number one I made this cuz there's also a thing where you want to promote flow from the outer flanks of the ports or the auxiliary ports in a three port configuration so that's why this weird oblong shape but I went too far I think and uh it's too flattened and uh and skin friction or uh like the drag from the and now that I'm going to talk about it I forgot the name um the boundary layer I think the boundary layer at the transition between the exhaust gases and the aluminium I think the boundary layer is thick enough to come into action and play a important role in a small engine like 50 cc and that's why I think the rule of thumb of the 2x bore 80% of Total Exhaust area exit I think that probably doesn't work as well in a 50 cc engine and at least and definitely not when the port is as flat as this so I did make this a little bit larger and that's what we've been running for a while now but now I've made it so that it becomes much larger much earlier so now the transition doesn't happen in here it actually happens like maybe uh 20 30 mm from the from the port and that's how the transmission happens in the ER 50 engine the cylinder not the engine but the cylinder I I've used on my old engine and that works really well so uh so let's see if this makes a difference it was a sof that got me into this and uh but he's not the only one who's been talking about how the the port is too small the duct exit is too small and also when I was uh when we did testing last time and it made 9 horsepower versus 6 with this pipe extension it got me thinking cuz it in effect this makes the pipe longer so you will have Peak power at lower RPM but it also makes so that it's sucking hardest cuz now the header is too long and that means it's the hardest suction is happening after bottom dead center so not in the most effective uh not where you want the pipe to suck the hardest you want it to suck the hardest when the transfers are fully open at bottom that Center but so I started thinking maybe it is the the transfers being overpowered by the exhaust suction and now making the pipe less effective sucking less hard when the transfers are fully open maybe there's more velocity in the transfers and maybe so that could still be it but uh but also I've never I never considered that it might be running out of blowdown area because the port is so huge and there's a bunch of area but the duct even though designed with good intentions might have uh or probably has restricted that effect Ive area to a point where it's actually it actually has been running out of blowdown and uh and that's why there's no power at high RPM and suddenly we gain lots of power at uh at low relatively low RPM like 13,000 or something and maybe maybe something will happen now we'll see let's [Music] assemble let's see how it behaves [Music] w w w w [Music] seems like I didn't save any of the runs I can't maybe I didn't press save or something I did press save and close so that last one should uh your dno disconnected it says anyways I think we saw like upwards of 11 horsepower we're going to try one thing cuz my runs are so short now let's uh switch out the primary food with a with a bigger one and uh see if we can get some longer run times [Music] this bus is too big for uh it'll hit the ignition [Music] trigger [Music] oh We R out of [Music] fuel [Music] one to one drive ratio seems to introduce too much friction early on in the transmission stages cuz uh what I thought would happen would be I could run longer runs cuz in with an inera Dyno if you have really short runs then you get really low numbers cuz uh because the inertia of the engine itself plays a a larger role so what I what I expected to see was that it I could perform longer runs and uh and see higher numbers I didn't so maybe this whole deal is not such a good idea regardless we're up at around 11 horsepower now up from almost twice the power so let's say twice the power from uh from with the smaller exhaust duct which is a huge win and now with the normal length pipe and uh looking at the EGT numbers while performing the last runs here they're really low now like below 500° C so we're probably running really rich and uh and timing is probably off too so it might be we're on the right track we're on the right track now we can start actually start tuning a little bit and then start experimenting with uh with stuff not just troubleshooting cuz uh I wish a win this time a win this time too see you next [Music] [Music] time

Channel: 2STROKE STUFFING

Views: 430,220

Keywords: 2 stroke tuning, two stroke tuning, scooter tuning, moped tuning, dirtbike tuning, diy dyno, two stroke explained, two stroke technology, peugeot spx 103, engine tuning, how to tune engine

Id: x-sDF17dWIo

Length: 17min 14sec (1034 seconds)

Published: Thu Nov 09 2023