212 Hemi Predator

[RonSnod]

Hey Guys, Doing 2 Predator 212 builds in hopes of using for an ultra light. Yeah, I know, but I'm not getting any younger.
I'd much rather fly '"Low and slow"' than haul Fast on the ground. Any-
way, got these Hemi stocks. and wondering how much horse power I
can achieve by adding 1. mod 2 cam with 22 lb. springs. 2. 6252 billet rod 3.348 .040 long kart. And 3. Billet flywheel, and removing the governor. I'll want to use a tuned exhaust, or at least a muffler to quiet it down a little. I am hoping to get in the 58 to 6 thousand rpm range,
with around 15 hp. Any body help me out here? much appreciated.

 

[bob58o]

Mod 2 is for target RPM of 7k+ RPM. So if your gearing is right, shouldn't be a problem reaching 6k. As far as HP, I have no idea. Some of the guys at Bob's Karting 4 Cycle might be more help. More of those guys have dynos and have done testing with different set ups.

 

[65ShelbyClone]

Would you trust your life to a Chinese rototiller engine making double the design power and RPM?

 

[Kartorbust]

You might be a head of the game just buying the 212 Tillotson from GPS, already modified for a good 10hp and a flywheel rated supposedly upwards of 10k rpm.

 

[bob58o]

Would you trust your life to a Chinese rototiller engine making double the design power and RPM?

With a billet rod and billet flywheel, is he really risking his life? I mean anymore than getting in a car and driving to work? Or stepping outside? Or waking up?

 

[65ShelbyClone]

With a billet rod and billet flywheel, is he really risking his life?

What about the rest? Think about every piece of the engine that could fail, how it could fail, and how such failure could lead to a loss of propulsion. Also think about conditions that could cause a stall without parts failing. This is called a Failure Mode and Effects Analysis (FMEA) and proper aircraft systems all undergo FMEA. Actually they get a DFMEA at the design stage first. I guarantee that Loncin did not do that for an aircraft application, if at all.

I usually avoid these discussions because IMO, people should not be prevented from getting Darwin Awards. My goal is more to present questions that encourage thinking beyond the project itself.

I mean anymore than getting in a car and driving to work?

Cars have many more passenger safety systems and structural integrity than an ultralight and they also don't (potentially) fall out of the sky when the engine stops. Unexpected engine shutdown is something auto manufacturers actively try to mitigate where possible. Some examples are ignition systems that continue to work when the ECU signal is lost or the ECU going into fail-safe mode when critical sensors go offline.

 

[J.S.@SMS]

What do you mean when you say "ignition systems that continue to work when the ECU signal is lost or the ECU going into fail-safe mode when critical sensors go offline." I ask this because last time I checked they do not have an electronic control unit for the ignition system on predator engines, and the only sensor that i'm aware of is the low oil cutoff sensor (definitely remove).

And for power, go online to gopowersports.com and order up a Stage 2 212cc Hemi Predator Performance Kit for $235. It comes with a mod 2 cam, an ARC billet flywheel, an ARC billet connecting rod, 18 lb. springs, and an AR 3910 sparkplug. This kit produces 15hp with a mikuni 22mm carb ($98 for an aftermarket kit) and a performance header pipe on their dyno.

Or you can order a stage three kit for a hemi predator which comes with all of the parts above (including a mikuni 26mm carb), a .010 head gasket, a AR 3910X performance spark plug and a sidecover gasket for $365. The stage three kit produced 15+ on their dyno. Shave the head and do some porting and polishing and you'll add a few more horsepower.

 

[65ShelbyClone]

What do you mean when you say "ignition systems that continue to work when the ECU signal is lost or the ECU going into fail-safe mode when critical sensors go offline." I ask this because last time I checked they do not have an electronic control unit for the ignition system on predator engines, and the only sensor that i'm aware of is the low oil cutoff sensor (definitely remove).

Have another look at that paragraph.

 

[itsid]

What about the rest? Think about every piece of the engine that could fail, how it could fail, and how such failure could lead to a loss of propulsion. Also think about conditions that could cause a stall without parts failing. This is called a Failure Mode and Effects Analysis (FMEA) and proper aircraft systems all undergo FMEA. Actually they get a DFMEA at the design stage first. I guarantee that Loncin did not do that for an aircraft application, if at all..

I'm with you I wouldn't want my life depenfing on a chinese built engine at all,
not even if I had replaced all of it's internals with professionally made swiss-checked parts.

BUT I have to say KT100

One of the most beloved go kart engines, it doesn't get any simpler than that..
tiny little japanese made parts spinning at insane rpms producing an insane amount of power for the little 100ccs it has.

AND.. it's tested and marketed as an ultralight engine as well!
There is no failsafe on those either.. if it fails, it's over.. (but it simply doesn't fail if maintained correctly)

Same holds true for many Rotax engines in the same ballpark of size (100-250cc) single and twin cylinders
Some just are to be found not only on karts but in ultralights as well.

And that list is far from complete ..

It's in fact the "chinese cheap" that makes me cringe
Chinese quality testing is essentially NONE
(they replace if it breaks in the customers hands .. that's it)

And that is alright for a kart (bad enough) but in the air.. I mean I'd happily roll 60 ft to the next curb..
I'd not so happily drop of out the sky for the same 60ft.


But hey.. he wants two.. maybe one's meant as a backup?
who knows...

'sid

 

[bob58o]

What about the rest? Think about every piece of the engine that could fail, how it could fail, and how such failure could lead to a loss of propulsion.

Ok, now I get it. I didn't know what an ultra light was. I assumed some sort of light kart. I was confused by his fly low and slow statement. Now I see how he is risking his life.

 

[Kartorbust]

Well Lifan and what is it Zongshen or whatever are supposedly the highest "quality" of the Chinese engines. Usually the build quality is great, but quality assurance/control is a bit lacking...in that your better off popping ot apart and putting it back together with locktite and torquing it down properly.

Realistically any engine can fail out of the box., doesn't matter whose name is on it, just some more so than others. Probably why most people will recommend Honda or Kohler for critical areas as far as back up generator or a tool used every day.