This engine is for sale on amain,(Jan. '22) when you buy it, you receive the pt-21A0. As far as I can tell, the only thing changed is the graphics on the cooling head, which are blue instead of white. The plastic engine box that it comes in has a label stating it's a pt-21A0, and placed somewhat over that label is another label that says pt-2018. So apparently it's a direct replacement. I had to add a .2mm head shim to both of the 21A0's I recently broke in. They came stock with .1mm no-shim clearance, a .2mm shim installed, and a .1mm shim included in the box. So .3mm head clearance stock with the ability to add a shim and make it .4mm. Maybe they were set up for low-nitro European use? I run 25% and with that percentage nitro they need a total of .5mm head clearance(.4mm shim stack) add another .1mm if you run 30%. Tldr: not enough shims for the most popular North American fuels. I found break in quite smooth on both engines, carburators were solid and responsive. Paired them both with a pipe I've had success with SH 8 port engines in the past, the 2035. Finished break-in and ran each for a day with a tune approaching race. They were a pleasure to drive, looking forward to them loosening up a bit more. And speaking of, these come with a plethora of pinch, use plenty of heat when starting during break-in.
Awesome to see a good review of a budget engine! I have the 3 port version of this, running on a flash point 2146 pipe. The bottom end is absolutely insane. Like, it’s hard to shut the engine down by snubbing the flywheel
Sorry I didn’t read all the comments before posting this, so I hope I’m not repeating anyone. I’ve been told by some well educated 2 stroke engine/Novarossi racers is those holes/ports in the liner right below the exhaust port are to help cool the piston skirt. They couldn’t comment on whether it actually makes any difference in lowering the skirt temps, but that is why they are there. Best answer I’ve heard to that question so far? Keep up the videos, I really like that you measure and share the engines timing numbers!
Nice Review, This is the Engine I have used to win PNB twice, Silver State, and The DNC 30 Min 40+ Mains,,,and countless other Smaller Races, JBRL's, ect.. Ive been racing for them for 13 years.. But the 2018 on the head doesnt really mean the year,,, ever year they change the Head design, but the internals are the same...Also, No mods are needed as this thing is too fast, i reccomend the 6.5mm insert.. Use the T3 Plugs....
I hear from someone years ago that said the holes under the exhaust port are so the sleeve can expand more and allows less friction at BDC. Dont know how accurate this.
It's really touch to tune. I like the photon better it's a 5 port. Once you RTV gasket some areas on the carb it helps. Better get full ceramic bearings for it a double seal in the front makes the tuning more consistent
The SH competition line engines are pretty solid for the price. Good throttle response & decent power. They can be a bit finicky and have a pretty narrow tuning window. I recommend getting a new front bearing and a different carb if possible. The front bearing will usually have an air leak within a gallon or so and the carb is tricky to get right. It’s usable, but you gotta be really precise with the needle adjustments
yep, mine ran stable at break-in, then at the first few tanks on a parking lot at part trottle, i noticed a wet flywheel and chassis in this area. the carb is now really really tricky to tune
Awesome review, Rex.. I’ve been waiting for this one. Great engine for getting back into racing, good performance with little investment. Definitely a top end engine, in my experience.
I wonder what you could do with an OS 40LA airplane engine. They're so gutless from factory they're almost useless as anything other than something to run on the test stand and they're only two port sleeves so who knows.
I have on of those engines in my Buggy. Love it. But the carb is a very touchy one..very small twitches to tune. Trying it now with an old two needle Nova carb.
Hi. It is working Great! Did the track last sunday and on my way now. Engine has a good idle and acceleration.. now i have to really watch my trottle control.
@@naestrawe458still recommend the Novarossi 2 needle carb for the SH PT engines? I’ve got a PT21AO that’s been the best nitro engine I’ve ever owned, and the stock carb has been pretty much fine so far (4.0 gallons) but I’ve got a few of those Novarossi carbs I could try just to see.
How can i get the dimensions of the sleeve and connecting rod? Im looking for a kit to try rebuild my os max xzb, but i dont have money for os parts, unfortunitely
Hi, bro ! I’ve been looking for this engine recently, but it seems like it’s backordered on all sites. Not sure if it would be in stock again, and I also see the updated version of this one called pt21A0 xgb.
do you have a recommendation for a good bearings for a novarossi .28 if you cannot find original normal front ceramic rear as in different company that will work
Hey did u break in this engine? I just purchased this engine nd went to break it in and the thing was just stupid lean I had to adjust all 3 needles like allot I've never had this problem with any engine before was wondering if u had any problems like I did thanks rw modes ps will ur engine tools be back on ebay soon ?
Could someone please help explaining how to interpret the timming numbers that Rex always shows at the end of his reviews or pricide a link were I can find such info? How can one understand if an off road engine is good or powerfull enough for 8th scale nitro based in Rex's timming numbers?
Hello thanks for the video and for the nice explanation. Is this engine more powerful than the Kyosho NEO 3.0? I want to do speed run. I am looking for a budget powerful engine. Thanks for your advice.
Hello thanks for your feedback. I completely the change the setup of the Neo 3.0. Got a new chassis with the same size with the holes in it to put a 2 speed gears box. Now the Neo is running with 2 gears. The car has more power.
