Umarex Notos - CRC Precision 25cc Plenum

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Floridaman2005

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Oct 11, 2024
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Stuart, FL, USA
Just installed the CRC Precision plenum on my Notos and I’m definitely impressed. It was $100 on eBay and claims to add 60-100 fps to the Notos. Haven’t been able to grab a speed reading yet because my FX chronograph doesn’t seem to like the Notos, but I will report back when I have a chance to test it out. I can tell it’s faster and more powerful already 👍

EDIT: After testing it seems like my new average is around 795 fps! No adjustment to the regulator or anything else but the plenum install got me around 70-75 fps boost and put me around 22.5 fpe. Very happy with the results!

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After testing it seems like my new average is around 795 fps! No adjustment to the regulator or anything else but the plenum install got me around 70-75 fps boost and put me around 22.5 fpe. Very happy with the results!

Will be curious to see how it affects shot count. It uses more air per shot I assume, but also increased the total cylinder size from 66cc to 91cc. Overall very happy with this modification.
 
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Floridaman2005 said:
After testing it seems like my new average is around 795 fps! No adjustment to the regulator or anything else but the plenum install got me around 70-75 fps boost and put me around 22.5 fpe. Very happy with the results!

Will be curious to see how it affects shot count. It uses more air per shot I assume, but also increased the total cylinder size from 66cc to 91cc. Overall very happy with this modification.
Click to expand...

Once I ported mine and got her to 845fps with 15.89 I was still getting 17-19 shots on the tube you shouldnt lose too much.

At 29fpe I get 12 shots per tube
 
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RabbitofCaerbannog said:
Once I ported mine and got her to 845fps with 15.89 I was still getting 17-19 shots on the tube you shouldnt lose too much.

At 29fpe I get 12 shots per tube
Click to expand...
Can you tell me of the porting process? Is this something I can do with home tools? I’m pretty happy with 800 fps with just the plenum so I’m not sure I’d want to do it, but I’m very curious.
 
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Floridaman2005 said:
Can you tell me of the porting process? Is this something I can do with home tools? I’m pretty happy with 800 fps with just the plenum so I’m not sure I’d want to do it, but I’m very curious.
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I did. You'd have better resale and less risk having it done with someone equipped better.. but I did it at home.

Open the port in part 66 to 4.5mm, do the same to the exhaust port in the valve seat, the transfer port in the breech of the barrel, and from the valve housing through to the breech from the bottom through the flathead screw hole uncovered when you take off the trigger frame.

Remove part 66... Replaced by your already widened port crc plenum...so one step is done.
Knock out the pin that hold the valve seat from the side, push the valve seat out of the front from behind, through the hammer channel.
Unscrew the flathead screw at the bottom drill vertically through the port from the valve house into the breech.
Drill the port out of the barrel breech to 4.5 deburr, polish. Replace parts.
Simplified. That's it. Forgive the lay terms. I forget the exact nomenclature.
Basically it. Honestly if you're good with 800. Stay with it. You could get a little more velocity without porting. Longer barrel kit, higher reg pressure. More hammer spring tension. Or shimming the spring or getting a stiffer spring whichever if you raise the pressure. From the get go I had the intention to beef up the notos as much as possible. I had fun
 
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RabbitofCaerbannog said:
I did. You'd have better resale and less risk having it done with someone equipped better.. but I did it at home.

Open the port in part 66 to 4.5mm, do the same to the exhaust port in the valve seat, the transfer port in the breech of the barrel, and from the valve housing through to the breech from the bottom through the flathead screw hole uncovered when you take off the trigger frame.

Remove part 66... Replaced by your already widened port crc plenum...so one step is done.
Knock out the pin that hold the valve seat from the side, push the valve seat out of the front from behind, through the hammer channel.
Unscrew the flathead screw at the bottom drill vertically through the port from the valve house into the breech.
Drill the port out of the barrel breech to 4.5 deburr, polish. Replace parts.
Simplified. That's it. Forgive the lay terms. I forget the exact nomenclature.
Basically it. Honestly if you're good with 800. Stay with it. You could get a little more velocity without porting. Longer barrel kit, higher reg pressure. More hammer spring tension. Or shimming the spring or getting a stiffer spring whichever if you raise the pressure. From the get go I had the intention to beef up the notos as much as possible. I had fun
Click to expand...
Awesome 👏 thanks for all the great information! I will probably see what I can squeeze out of it first without drilling or opening up quarts for now, but I appreciate all the information in case I want to go down that road in the future.

I guess my first step should be increasing the hammer to see if I have any wiggle room and if not bumping up the regulator a little bit.

Appreciate the write up and help 🙏
 
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Floridaman2005 said:
Awesome 👏 thanks for all the great information! I will probably see what I can squeeze out of it first without drilling or opening up quarts for now, but I appreciate all the information in case I want to go down that road in the future.

I guess my first step should be increasing the hammer to see if I have any wiggle room and if not bumping up the regulator a little bit.

Appreciate the write up and help 🙏
Click to expand...
No problem.
The one upgrade that I appreciate most is absolutely the FX barrel kit. I have a 600mm superior in now. But, for a year I used the 380mm superior, with the c88 plenum, and a small bump up in reg pressure. Was at 825-835 with 15.9s still getting 20 or so shots off of the tube .
 
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RabbitofCaerbannog said:
No problem.
The one upgrade that I appreciate most is absolutely the FX barrel kit. I have a 600mm superior in now. But, for a year I used the 380mm superior, with the c88 plenum, and a small bump up in reg pressure. Was at 825-835 with 15.9s still getting 20 or so shots off of the tube .
Click to expand...
I will definitely look into the 380 mm barrel kit. I’m kind of at a point where I don’t want to spend any more money on the Notos. I will have to look at the cost of the 380 mm barrel and see if it’s worth a little bit of an extra speed and probably a little more accuracy. I was really trying to keep this as a light and short as possible. I’m already debating selling this as is and just picking up something that’s got more potential from the get-go. At a certain point I feel like I am ricing out a Civic when I could just buy a real sports car.
 
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Floridaman2005 said:
when I could just buy a real sports car.
Click to expand...

The VTEC death squads are currently en route to your location. Hopefully you have hills or your neighborhood has speed bumps, if it weren't for their love of 3" straight pipe cat delete exhausts, idiot "stance", low skirt body kits, and their incessant need to rev they might be dangerous. You'll hear them coming.
 
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tonka said:
that’s awesome, i’m just looking for a little higher shot count , does this help in shot count at all?
Click to expand...
I think it could definitely increase shot count if you lowered the regulator. This increases the total volume from 66cc to 91cc and increases fps, BUT I suppose you could lower your regulator or hammer spring and dial it down to original fps and have a bit of extra volume. It would make sense in my mind.
 
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Floridaman2005 said:
I think it could definitely increase shot count if you lowered the regulator. This increases the total volume from 66cc to 91cc and increases fps, BUT I suppose you could lower your regulator or hammer spring and dial it down to original fps and have a bit of extra volume. It would make sense in my mind.
Click to expand...
and i see no need to modify the moderator, nice setup i haven’t seen this one before thanks for sharing
 
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Floridaman2005 said:
I will definitely look into the 380 mm barrel kit. I’m kind of at a point where I don’t want to spend any more money on the Notos. I will have to look at the cost of the 380 mm barrel and see if it’s worth a little bit of an extra speed and probably a little more accuracy. I was really trying to keep this as a light and short as possible. I’m already debating selling this as is and just picking up something that’s got more potential from the get-go. At a certain point I feel like I am ricing out a Civic when I could just buy a real sports car.
Click to expand...
keep it. it’s a nice accurate gun for a grab and go
 
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Floridaman2005 said:
Just installed the CRC Precision plenum on my Notos and I’m definitely impressed. It was $100 on eBay and claims to add 60-100 fps to the Notos. Haven’t been able to grab a speed reading yet because my FX chronograph doesn’t seem to like the Notos, but I will report back when I have a chance to test it out. I can tell it’s faster and more powerful already 👍

EDIT: After testing it seems like my new average is around 795 fps! No adjustment to the regulator or anything else but the plenum install got me around 70-75 fps boost and put me around 22.5 fpe. Very happy with the results!

View attachment 537668

View attachment 537669
Click to expand...
what's your shot count? how many turns in on the hammer adjuster? I just installed a crc plenum and power went way up but shot count is horrible
Jerry L
 
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glr59 said:
what's your shot count? how many turns in on the hammer adjuster? I just installed a arc plenum and power went way up but shot count is horrible
Jerry L
Click to expand...
I haven’t tested my total shot count, but it seems pretty similar to stock. I will do a full capacity test this weekend if I can. I didn’t touch the hammer or the regulator so those are still the way they came from the factory.

Not sure what the arc plenum is, but gaining 75 fps with the plenum is a pretty significant boost. More than 10% speed increase just from the plenum. Haven’t messed with hammer or reg because I wanted to preserve shot count, to a degree.
 
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Floridaman2005 said:
I haven’t tested my total shot count, but it seems pretty similar to stock. I will do a full capacity test this weekend if I can. I didn’t touch the hammer or the regulator so those are still the way they came from the factory.

Not sure what the arc plenum is, but gaining 75 fps with the plenum is a pretty significant boost. More than 10% speed increase just from the plenum. Haven’t messed with hammer or reg because I wanted to preserve shot count, to a degree.
Click to expand...
should still be 21-24 stock setting shots but with the added fps
 
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