TWO Stroke POWER, Port TIMING and PORT MAP

[@KrustyKlown]

GREAT content dude!! I've been building racing kart engines for 4+ decades, love what you're doing here, keep'em coming.

[@AutoBeta2T]

Cheers Krusty! Hopefully some more videos coming soon.

[@fullsendmarinedarwin7244]

Love two strokes. Subbed.

[@AutoBeta2T]

Cheers 😊 me too.

[@andli461]

Why haven’t I thought of using the microwave for melting my Vinamold?! 🤷‍♂️🤦‍♂️😄 Great to find a EngMod2t user channel. 👌

[@AutoBeta2T]

Haha - I'm not sure...? How do you melt it? Hopefully I'll get to do a bit more on EngMod2T siming some pipe designs.

[@andli461]

@@AutoBeta2T LOL 😂 Metal bowl and a heat gun. 🙈 The microwave, 4 meters away at the other side of the door, was to hard to think of. 🤦‍♂️🤣 Looking forward to future videos. A dyno vs engmod compare would be very nice. But maybe a bit to many details and nerdy? Probably not the most successful or mainstream KZbin video. 🤣 But I would love it. 😁

[@AutoBeta2T]

Brilliant! 😂😂😂 And yes I'll do some EngMod v reality vids and maybe a look at the gas-dynamic stuff like the pressure wave timing etc...

[@Op1zilla]

Kool high tec stuff, Port Master knows his stuff as do you, enjoyed z- 👾👽👍

[@AutoBeta2T]

Cheers buddy

[@2strokepipes471]

Engmod is great but must be used in conjunction with an engine dyno in my opinion. Get a baseline test ASAP and plot the curve into post2t, as you will likely need to adjust the temperature files in data2t to match the real world results. After I did that I was able to actually use the sim for development. Excited to watch where you go with this.

[@AutoBeta2T]

Totally agree 🙂 and pleased you are excited to see how it goes - cheers for the support. I plan is to hook-up some thermocouples in the pipe when testing. I'm interested to see what the temp difference is between the header and somewhere down the baffle cone is on the Dyno and then on the road. I imagine the pipe should run cooler on the road and need the tuned length tweaking...

[@andli461]

Had the opportunity to run two EGT’s at a friends dyno (one in the header and one in the belly). Really interesting and helpful. Tried to find out a decent average temp for baseline FOS pipe calculations. (Tried Jeff Henise/Highwaymans weighted temp approach that wasn’t to bad but needs more tweaking in my case.) Find the temperatures quite difficult to get right in EngMod. Thankful for any advice to a working approach. Hopefully I can finish my dyno soon and get some lost inspiration back. Videos and comments like this certainly helps though. 👍

[@AutoBeta2T]

​@@andli461hi, I just noticed your comment... Must have missed the notification - apologies. Ref temps I try not to use the temp correction at certain rpm points to get the graph to match reality. I prefer to just adjust the overall exhaust temp and settle for what ever curve I get (which is usually pretty close). Peak rpm in the sim maybe higher but I put this down to the sim acting like a load dyno so a bit more heat in the engine and pipe compared to the inertia dyno. I'm keen to use Jeff's method for working out a good mean temp too. The test pipe (when I get it finished) is planned to have header and belly egt probes but I may stick on in the baffle cone too. I'm interested in the Dyno temps throughout the pipe v temps when it's run on the road. I think it may run cooler because of the extra air flowing over the pipe at speed... How did you get on with your Dyno?

[@AndrewBiffin]

Hay mate Thanks for the videos Very informative Just wondering if you know or can find out the best design exhort/expansion chamber for Yamaha pw50 for best power and efficiency I want to have a go at building a pipe any help would be greatly appreciated thanks Regards Andrew

[@AutoBeta2T]

Hi, I don't really have much of an idea about these. Do you have the engine port timings?

[@2strokecarbtuningportingin187]

Great channel what was that material you melted and poured into the ports and where did you get it

[@AutoBeta2T]

Hi it's called Vinamold. I just bought it online. 😊

[@2strokecarbtuningportingin187]

@@AutoBeta2T thanks shared your vid told folks to subscribe. Next question that 2 stroke software is 400$ correct

[@AutoBeta2T]

Hi many thanks and yes - $400 last I checked. And worth every penny.

[@SpeedofCheeseRacing]

Hey David. I just found your channel. Good stuff. I need to make more power out of the stockish road race RD400 this winter. I was trying to model the ports but if I pulled molds and then scanned them it might work better/easier. Ill try that, thanks for the inspiration!

[@AutoBeta2T]

Cheers Mark - hope all is well :) Sounds like a good plan to me to scan the ports... I guess you could modify them and CNC them out?

[@SpeedofCheeseRacing]

@@AutoBeta2T Yes. Good luck with this project and ill follow along.

[@AutoBeta2T]

Thanks Mark 😊

[@akos127]

I have seen Mark Atkinson latest video where he mentioned your channel! Thanks for him, you got another subscriber! Good luck with your AR, it sounds great! I hope you'll achieve that triple digit. It was very interesting to see this silicon filling port poring method to see the port shape WOW! I have been watching 2 stroke stuffing and Mark Atkinson. Now you are on my GREEN list. Subscribed.

[@AutoBeta2T]

Hi Akos - I've just watched Mark's vid 🙂 and thanked him for the shout out. Pleased you are enjoying and thank you for the sub. Hopefully I get there with the AR... Time will tell ☺️

[@sidecarbod1441]

Your aim off 11000 rpm is reasonable, I agree in that you have way too much transfer duration for that PRM figure, all that duration is eating into your blowdown angle. Lowering the ports is a little tricky, I guess skimming the bottom of the barrel might be an option as long as the piston does not end up poking out of the deck height too much. Clearly lowering the barrel will change the timing of the other ports, it maybe a good thing for the inlet but the exhaust port might need to be raised. Anyway I'm sure you know all of this. Your CR seems fairly low (I think it was 11:1), I guess that is uncorrected?) Also you might want to consider a thermocouple under the spark plug, Trail Tech do a nice one, you can then keep an eye on the head temperature. AG Bells book states that you will get power fade if you go much above 200 C on the head, I've tuned up a Honda MT5, nowhere near to the level that you are aiming for, it is doing about 55-60 MPH on the flat, I can feel the power fade when the head goes above 160-170 degrees C. I've made a fibreglass air scoop which 'collects' extra air and forces it over the head, I've not done much testing with it but it does seem to help. My MT is running 14:1 static CR, 8.4:1 corrected. This might be a little high but I can't detect detonation so hopefully its OK. I think that you can push the CR up fairly high because the flame path is so short. You do need to run a 'proper squish-band head of course!...EDIT, just spotted that your engine is 100cc, not 50, I guess that you can't push the CR up as high as mine. Also you are cheating! LOL, (so am I, I run a 65cc big bore kit)

[@AutoBeta2T]

Cool - an MT5 was my first motorbike before I got an AR. It did about 45 as I remember... Giannelli pipe and hi power reeds 🙂 I was going to machine the barrel to get the timing down but it's been suggested to try epoxy first so I am. If I machine it then the dykes ring will pop out a bit and as you say it needs a good squish band. Comp wise I was going to shoot for 12.5:1 and move up. The PS mag bike was running 15:1 uncorrected... I had trail tech CHT on my X7 racer, I found 225 was fine, even 245 at Brands was okay but at Pembrey it went pop at 278 😔. I'm gonna definitely get another as I found it very useful. I like the idea of a cooling air duct. I think cooling will be the main issue particularly at sustained high rpm/load. Lots of fuel to keep in cool. Yes a bit of a cheat but in my defence the magazine went this route so I'm blaming them 🙃

[@RyanMcIntyre]

Are you willing to experiment with methanol for your cooling issues? I’ve even had great success controlling temps with Ignite E90.

[@AutoBeta2T]

Hi Ryan, the answer is possibly... I'd like to do it on pump fuel as per the original challenge but I think it's close if I'll manage it. Options are: methanol to keep the temps down and get more power or better aero with a fairing. I guess I need to exhaust options with pump fuel first then look at the other options. What sort of temp drop/ power increase have you had with the E90? Firstly I need to get my finger out and finish the pipe and sort out the ignition.

[@RyanMcIntyre]

@@AutoBeta2T I have to confess that I have no idea what temps I run in the 2 stroke watercraft. However, in my 4 stroke testing (in Phx AZ by the way at 110 degrees) average running and peak temps are about 10-15 degrees cooler just by switching to E85 from the pump.

[@maciejz6914]

How do you work out the transfer port area? In books i only found that i should widen them slowly and see the result with every modification Is there some universal formula for transfer port areas?

[@AutoBeta2T]

Hi Maciej, There are the Specific Time Area (STA) figures from Dr Blair's book - design and simulation of two stroke engines which were gathered from years of testing. These give you a good idea of what you need. I use Dat2T which gives you the Blair STA but converts it to what power the port area could support. However, these are just a guide and transfer area could be less or more depending on your engine; this is best derived from simulation or real world testing of different port specs. Note. As the height of the port increases the blowdown STA reduces (if you leave the exhaust port as it was). From what I have read the blowdown STA is key to getting the power. There is a lot of very good information on this thread - if you haven't read it, it's worth a read (if you have a spare few days...) www.kiwibiker.co.nz/forums/showthread.php/86554-ESE-s-works-engine-tuner/page1001 Cheers :)

[@maciejz6914]

Haven't seen this thread and didnt know about blairs book Will definitely read through that Thanks for the answer

[@AutoBeta2T]

@@maciejz6914 No problems. There's a lot of info on there and well worth a read. 😊

[@luckyrookie46]

May I make a comment …. I think a bit more work I can be made on the Reed cage … quite a few years ago I had an aprilia rs50 which after many modifications would do a clean 75mph … mind you it took an age to get there … the engine was port matched home built exhaust 26mm delorto 360 crank etc running on a airsal barrel and piston … my first option was to run a vforce 3 Reed cage on adapter block which worked ok … but most gains were made from when I machined and fettled my own Reed cage I didn’t have a rolling road but speed and power and width was massively improved funny now I have a 3D resin printer and I could make any design I like … wish I had it then lol

[@AutoBeta2T]

Hi Lucky, the plan is to work on the intake again once I've done a few more tests. I have another V-force to try... I'm interested to hear what your modified reed valve looked like? Did you stuff it more?

[@luckyrookie46]

@@AutoBeta2T hi … what concerned me on all Reed blocks was the nose of the vee there was always a big flat of aluminium there and the holes for the Reed petals were square … remember this was all before cad well at least before I had cad …the edge where the reeds were bolted to were rounded to stop turbulence from a square edge and in the nose of the cage the lead out into the intake I rounded like the front of an airplane wing … I then used resign to smooth out from round carburettor…. I have fusion 360 now I’ll try and draw it up so you can see the concept If i was doing the same now I would probably go for a belt driven disc valve … as when it’s open there is a clean passage into the crank case

[@AutoBeta2T]

@@luckyrookie46 Hi, thanks for the detailed explanation. I think I get what you are saying but if you do get a chance to do a 360 model that would be great. In just getting back into Fusion myself... Not that I was ever any good at it before. My email is: [e-mail]

[@jasonrathbone2937]

Great video mate ! Where does one still find the dat2T software?

[@AutoBeta2T]

Hi, the software is available here: vannik.co.za/EngMod2T.htm#:~:text=EngMod2T%3A%20A%20multi%2Dcylinder%20two,GPB%2Dmethod%20for%20pipe%20flows. It comprises of a suite of programs: Dat2T, the pre-processer, which was used in this vid but there is EngMod2T, the main simulation program, and Post2T which is used to view the results. I'll stick a link in the description too. Cheers

[@nielgaming3155]

New sub ☺️

[@AutoBeta2T]

Cheers Niel. Hope you enjoy the future episodes ☺️

[@coeniecastelyn9112]

What is the red staff that you use

[@AutoBeta2T]

Hi - it's called Vinamold. You can get it here: www.ecfibreglasssupplies.co.uk/vinamold

[@shoominati23]

You'l need to go to 90cc at least to do it I reckon .. My friend got close to 80 on his Aerox with a ported 98cc 2Fast jug and big final drive ratio

[@AutoBeta2T]

Cheers Chuck. I just found your comment... YT had it in the spam folder and I only just found it. I'm at 97cc at the min with the big bore kit. One of the issues I have is with the motor being over square so it limits time area. What is the bore/stroke of the Aerox? Cheers, Dave

[@deinvaterlol8645]

@@AutoBeta2T47 51

[@stemun4084]

LOL a bit more technical than a few hours spent with porting files, jets, etc for 25 mins of raw power before killing the crank, Never understood why there was only a 93 kit for the AR as for the MB and TS ect there were 65 and 60 kits that were tunable without exploding, 16/17 33 sprocket combo at 18000 rpm will be over a ton! make sure your flat across the tank or you wont do it! Best of luck have fun.

[@AutoBeta2T]

Ste - thank you and yes, I like the technical and empirical side of 2T tuning but at the end of the day it comes down to porting files and jets etc... I'll need to be more than flat on the tank too. Currently I have about 3 stone of COVID weight gain to shed! 😬

[@stemun4084]

@@AutoBeta2T Yea me too i was a LOT smaller when i was 16 than now haha

[@VWPirates]

You mumble and the little bit I could hear.... you have cylinder and barrel confused

[@AutoBeta2T]

Yeah - getting used to this talking to a camera - I noted it myself and I'm trying to improve in subsequent videos. I used err all the time too which I'm working on. I tend to use barrel or cylinder to mean the same thing. To note: Haynes calls it a "Cylinder Barrel".

[@royrenschop2148]

😂😂😂😂 , degree wheel 😢😢

[@AutoBeta2T]

I've never used one. I've been told they are not as accurate. 🙂

[@royrenschop2148]

@@AutoBeta2T top racing never needed one, it's only people that don't really know their stuff will think about using a degree wheel, haha video fools. A lot of nonsense on internet. In the end it was just flow and pressure knowledge THAT Japan already did to his finest BUT restricted some a bit, some a lot. Just correct and upgrade with experience and not with nonsense talk and unnecessary tools and equipment. They really make asia and south America laugh sometimes.

[@paulfoster553]

Get your self the book by Graham Bell called two stroke tuning

[@AutoBeta2T]

Good shout... I do have a copy somewhere... I'll dig it out.

[@ianbertenshaw4350]

Awesom book as is the four stroke book !

[@sidecarbod1441]

I have that book and read it many times, it is a good book but things have moved on in some respects, software certainly makes things a bit easier to work out. One thing that Bell states is that the exhaust timing really affects at what RPM the peak BHP will be at, he does not think that the area has much to do with it. I think that it would be nice and easy if it was only the timing that matters but I suspect that the area does have an effect. The book is still worth a 'read'. (or should I say 'reed'! LOl)

[@AutoBeta2T]

@@sidecarbod1441 Yeah I've read it a few times but agree area does play a part... I like the specific time area concept but again just a guide. The motor will say on the Dyno or track when it's happy. I personally preferred John Robinson's book apart from the exhaust section. The Team ESE thread on KiwiBiker has some real gold in it and worth a read if you haven't already?

[@sidecarbod1441]

@@AutoBeta2T I've not read John Robinsons book, I'll check it out. Gordon Jennings book is also a good one. I've just come across your youtube video tonight, I'll check out your other vids as your project is right up my street! EDIT...Actually I just googled that book, I have read it years ago but must have lost my copy of it, I might try and find another copy.