DIY Reverse Flow Cinderblock pit

[tonyjohnson619]

I love the new version of the pit. Can't wait to see the food pron

[sleebus.jones]

Originally Posted by 55Drum

Great build!!! Where's the chimney??

For right now, it's accomplished by sliding the plate on the top back to create a slot. Cheap & cheerful approach. I had a shot of the top in the other post, but it looks like this:



I am thinking about putting a stack on it, but that would require a 4" hole in the plate, a stack (duh!) and a damper. Maybe in the future when my torch skills develop!

Originally Posted by rus_bro

Would anything be better than showing up at a competition with the back of the truck full of cinder blocks on thursday afternoon. 45 mins later you have built an amazing reverse flow pit.

Now we just need to drill some holes for the TelTru Thermo and some spray paint to get the team name on the outside. :)

i LOVE this build and it would ALMOST be worth the a$$ chewing i would get from the wife to build this in the back yard.

rb

Ha! I'd love to see that! That would be so awesome. It's definitely doable too, but it's gonna be ~1,500 lbs of blocks! Might need to split the load. Honestly, it doesn't look too bad once it's all together. Some paint on the outside would go a long way to making it look acceptable.

For a thermo, I drilled a hole in the top, and then I just drop a thermocouple down there. Since the only access to the inside of the pit is by just simply lifting the top off, I'd be concerned about breaking the probe part of the thermo off when you set it down, unless you were really careful. Also, with the thermocouple, I can feed enough wire to get it to hang right at cook level over the meat.


BTW, I have a great idea for a team name: "Some Assembly Required"

Originally Posted by daninnewjersey

That would be insane. Imagine beating some of those dude with their $6000.00 smokers..plus you'd have a lot of onlookers for sure.....

There'd be a lot of and and then when they taste what comes off of it. I'm doing the first cook today on the new configuration, but if it's better than the previous configuration (which cooked awesome BTW) it's gonna be downright silly.

This was the results from the conventional flow configuration:



Those were done with rub only, no wrapping, cooked straight through at ~275°. The were freakin' delicious.

Originally Posted by Stlsportster

For the inlet you could just mount a large ball valve on that sheet metal. Then you could adjust airflow at a granular level. Still noodling the exhaust....

Well, this thing does love air. For the inlet, calcs are recommending a 19 SqIn opening. That would be a HUGE ball valve. For an intake, I really like this design:



Cheap and gives you micrometer control over the intake, and you can open it way up with no restrictions. Also, remember these are just stacked blocks; the firebox is naturally leaky.

Calculated dimensions for the stack is 4" x 25". The reverse flow sheet is 15.5" x 28". I may have some further tips for reducing the throat size, calcs now say it's 27% oversize, but I have ideas for reducing that. I'm going to probably draw this thing up in SketchUp so everyone can see how it goes together.

Cool thing is that it's scalable. You can make it as big as you need. Blocks are cheap!

[roncoinc]

Made my morning !! :)

[newtwoq]

This is pretty epic!

[jason&egla]

Originally Posted by daninnewjersey

That would be insane. Imagine beating some of those dude with their $6000.00 smokers..plus you'd have a lot of onlookers for sure.....

Season 2, Episode 6 of BBQ Pitmasters had the teams doing a whole hog on cinder block pits. It aired back in 2010. Fun to watch, really leveled the playing field.

[gtr]

Loving this - thanks for posting!

[cats49er]

You surely make Hank Jr proud. A Country Boy Can Survive . This Redneck country boy loves it.

[bbqwizard]

Way cool!

[JDM46]

Will it cook your Killer Sausage?

[dsp2]

That is freaking beautiful. Thank you for sharing, and congrats!!

[Happy Hapgood]

Very Cool!

[m-fine]

Originally Posted by sleebus.jones

Well, this thing does love air. For the inlet, calcs are recommending a 19 SqIn opening. That would be a HUGE ball valve.

It would be a large ball valve, and sliding or rotating dampers are a lot easier and cheaper to build...BUT I hate to sound like a broken record, but the online calcs are a big pile of BS with no valid science or engineering behind them. Pay them no attention and rely on your observations and experience. You likely already know way more about cinder block pits than the guy who published the calculator.

[sleebus.jones]

Originally Posted by JDM46

Will it cook your Killer Sausage?

You bet! I originally put this together to use the "free" pecan sitting around in my yard, rather than buying pellets. I'll be able to hang it on smoke sticks and let it rip...although with summer here it'll be hard to hold temps down enough to do it. Sounds like you're still enjoying it up there!

Originally Posted by m-fine

It would be a large ball valve, and sliding or rotating dampers are a lot easier and cheaper to build...BUT I hate to sound like a broken record, but the online calcs are a big pile of BS with no valid science or engineering behind them. Pay them no attention and rely on your observations and experience. You likely already know way more about cinder block pits than the guy who published the calculator.

Yeah, a 5" valve which is big by itself AND a non standard size. all of which means $$.

The online pit calculators may be a big pile of BS, but they give one a starting point and they don't seem to work too bad. Before I made the changes, the firepit was more like a rocket stove, and I'd get flames about a foot into the cook chamber...not good for holding the temps down! With the new config, even though I haven't been able to choke down the inlet to the pit, the reverse flow plate is sized for the smaller inlet, so I'm getting some benefit from that. This has helped by making the temp control of the pit more manageable. It has much less of a tendency to run away. I tend to believe the stack size, and once the fire stabilizes, a 5" round hole would provide plenty of control. I keep it pretty choked down because there's a fair bit of leakage between the blocks that feeds the fire.

Sorry folks, no cook pics from yesterday. Didn't have my phone with me out there. Just did some thin pork chops, cooked slow. I will say that the heat is VERY even across the surface of the grate. No more hot spot by the firebox inlet. My bigger problem is that with all this cooking on the pit lately, I've run down my stock of pecan, hahah! Need to wait for the trees and wind to drop more.

[JDM46]

[B] Sounds like you're still enjoying it up there!

Best Sausage Recipe that i have found in a long time.
Have passed it on to a dozen or more.

[Big Swole]

Sub'd to refer back to soon. Want to build one someday. Thanks for posting.