DIY Paramotor Engine pt 2: Predator 212 Hemi Head Port and Polish
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- Опубликовано: 12 сен 2024
- Here's a video of my head Porting and Polishing for the Predator 212 Hemi.
I will be using this engine in my DIY Paramotor Project. It will at least double the horsepower and pick up RPM from 3600 (governed) to around 8k
I've been porting many years and you know what your'e doing that's for sure. Pretty much everything you did is spot on good work! And I'm so glad you know to keep the intake rough so many ppl polish the intake which lets the gas bead up into a liquid.
You have amazing production value and music choice!
I'm not letting you talk me out of this though, I'm flying with my 212 lol.
Be my guest. I got a ton of extra parts of you need any 😁
Find me on Facebook. I'll gladly share how I would do the project if I were to do it today.
You got the best video for this on youtube👍🚀
If you think this is the best RUclips video you haven't seen very many videos on porting and polishing 212 heads i take it. I mean kudos to this guy for attempting to port and polish a head With out any kind of flow bench He has no idea where he started at or finished as far as CFM goes. Highly recommend you going over to the youtuber Paul's karts There he will explain in high detail on what to do and what not to do I trust his advice through the sheer fact he has a flow bench and a smoke machine to be able to monitor flow and CFM
Intake ports are better off rough than polished! Also the sharp lines in the port while the may cause turbulence ... also will shear the wet flow fuel off the port wall!! My father built the first billet cylinder head used in drag racing. You got a lot right. But if you can never ever touch the sort turn in the intake port. People get lost in bigger os better when actually intake port velocity can mean a lot more than the cfm a port flows. A predictor 212 is a very low VE engine. Volumetric efficiency. A lot of what you would do to make a race engine port better will actually hurt Performance in low VE engines. Look up reversion dams . Any time you work a port the easiest way to look at it is... how can you remove metal to make the port straighter! Often guys will actually JB weld the bottom of the port and cut out the top to raise the roof and make the port straighter. The biggest mistake made is to take a low efficiency engine and try to make the ports look like a race engine🤣 some times sharp corners are good just like some times having a step between the manifold and cylinder head port will actually help you if it’s pointed in the right direction. The valve seat profile in a predator is a lot more important than the intake port shape
Groom Lake noted, thanks for sharing. Hopefully, others will see this comment. I actually wanted to go with bigger valves and don't have the tools so I ended up switching to heads from nr racing.
Riiiiiight. The first. Bold statement.
Ufo man knows what he is talking about!!
I did not know porting could be so sexy. I was falling in love with that intake port!
Look up David Vissard he does a lot of seminars and is a very smart guy. Also remember that application drives engineering and the best thing you can do is let the engine talk to you and tell you what it wants instead of trying to out smart it and tell it what to do. Are you familiar with the “quench”? It might help to weld up some of the chamber across from the spark plug. If you can get a flat quench pad on the head it acts like a below rolling the fuel air charge toward the plug as the piston reaches TDC. If you can’t do that , adding a spark plug on the opposite side of the chamber might also give great result.
oh yeah I build heads for a living for GM buy the way. I lol the burr finish might seem extreme but trust me it really helps throttle response.
Hemi’s are the perfect engine @wot wide open throttle , but that’s usually at a sacrifice of bottom end power. By the looks of that casting the intake looks pretty decent but that deck where the valve guides goes through on the exhaust looks horrible . You need to be carful when porting the ports of what I like to call the toilet bowl effect. In manny cases increasing port volume will kill power every where but WOT@ high rpm. In a NA engine 70-85% of the fuel air charge is brought in to the cylinder via the exhaust in take over lap and the scavenging effect of the energy rich exhaust gas rushing out of the exhaust port pulling the new charge in through the intake port. MIT confirmed this buy monitoring the pressure across the top of the piston. Even in forced induction engines the exhaust port velocity will make or break the power curve. I bet you could actually fill some of the ex ports floor with high temp jb weld and remove some material from the top of the port to straighten it out and actually make it smaller and flow better. There some great vids of guys using a shop vac as a flow bench and although it’s not going to give you real world cfm numbers it will tell you if your going in the right direction or not. Also you might measure how much valve guide there is and be able to bullet nose or removed the guide all together from the port. It’s very cool what your doing. Cylinder heads and the poppet valve its self are the biggest restriction/ opportunity in the whole engine. Things for you to learn would be... reversion dams, how Intake port cross section directly affects where peak power is made in the rpm band, resonance , intake & exhaust over lap theory and scavenging , exhaust and intake pressure waves, and the effect of the quench between the cylinder head and the top of the piston across from the spark plug. Hope some of this helps I’m looking forward to see you results . You can also make a make shift dyno with a water pump and a measured tank of water.
Groom Lake what would be a really good motor for a paramotor setup can your name a few for me I’m thinking about doing this for when I goto the lake
Always informative and enjoyable reading your comments
Hi Dmitri! Congrats for your video! I'm from Brazil and I have a standard go kart motor (Honda GX 390) and I'll start the process of porting and polishing also (this is my plans for the weekend, hehehe). I'm curious about how many hp you expect to gain? Did you tested the motor after the polish? How Its going?
Thanks for your video!
Leandro Carvalho the motor is now finished and runs awesome. It should be around 17hp with current mods which include the head ( milled down to 14cc for high compression and full port and polish), billet rod, billet flywheel, mamba cam, #36 springs, chromoly 1/4" push rods, makuni 22 mm carb, walboro pulse fuel pump. stay tuned for the next video which goes over the assembly procedure.
Btw. before push rods the motor revved up to around 7400 rpm and going above, the thin stock ones would flex and pop out of their seats. should now get to 8000rpm.
Any update Leandro? The GX 390 is almost double the weight of the predator engine. How did you progress with it?
next time use a small carbide burr in the intake on the walls roof and short side radius and blend the short side radius into the port floor being careful to not remove material front the floor just leaving a burr finish on the floor. the walls roof floor and bowl for better fuel atomization. the exhaust surface finish should be as smooth as you can get it polish it just like the combustion chamber.
Thanks for the tip, noted. Do you know if this applies to carburetor engines or fuel injected too?
Dmitri's Gallery you want a burr finish after where the fuel is introduced but not in the combustion chamber.
Can you talk about what you used to polish the combustion chamber?
mrbrusky it's a polishing wheel attachment for the die grinder and I just have a bar of polishing compound. I actually believe it's not even for metal but rather plastic. any polishing bar for metal will do the job!
Match your head exhaust port to the header for flow.
What ever you do at ALL COSTS try not to ever touch the floor of the port! Think straight, your always trying to make it straighter, and by removing the material from the floor aka the short turn your just making it want to turn more
Idid subscribed and liked too
Did you sand before polishing?
Which part? I technically used sanding attachments for most of the work so technically yes although they are pretty coarse grit. I do remember sanding areas by hand before final polish.
Dmitri Zyuzin for the combustion chamber
Are you still working on this build??? I am trying to do the same with a predator 212 as well.... We should trade information man I could really use some advise. I have owned a Powered parachute in the past and would like to make my own PPG...
Send me a message please!
kyle guillory yes I am. you can find my progress on a Facebook group called paramotor homemade. I'll be posting more videos soon.
Will sandpaper work?
No, it will take years. I'd recommend at least a Dremel
yes it will work just requires more effort , Flathead briggs have been sanded for years and years .