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Old 10-30-2010, 12:13 AM   #251 (permalink)
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read THIS part...

The limiting case of the Venturi effect is when a fluid reaches the state of choked flow, where the fluid velocity approaches the local speed of sound. In choked flow the mass flow rate will not increase with a further decrease in the downstream pressure environment.


to wit....
if you increase your boundary layer by putting grooves in the runner to "disperse fluids", you are in fact decreasing the size of the runner and allowing the "choke point" to raise.

The next thing you are going to say is that it doesnt apply, but since there is air AND fuel involved, it is a fluid state. While not readily compressible, it still is bound by fluid dynamics more than by aerodynamics.

What you did to these heads is basically ruin them unless you completely port them to remove this issue... and if this is your version of porting, i would suggest you take them to someone that can actually USE a grinder and that knows what they are looking at.

looks to me like you could fuck up a shit sammich.

Why dont you ask Curtis Boggs to take a look at your port work and give you an evaluation, or Darin Morgan. Im sure both of them would be interested to find something new that would make power.. I mean hey.... any trick they could learn that would benefit their businesses would be a great tool, wouldnt it?

Too bad that neither of them use it currently... must be really secret...
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Last edited by Grumpy_old_fart; 10-30-2010 at 12:20 AM.
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Old 10-30-2010, 01:53 AM   #252 (permalink)
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Originally Posted by Grumpy_old_fart View Post
read THIS part...

The limiting case of the Venturi effect is when a fluid reaches the state of choked flow, where the fluid velocity approaches the local speed of sound. In choked flow the mass flow rate will not increase with a further decrease in the downstream pressure environment.


to wit....
if you increase your boundary layer by putting grooves in the runner to "disperse fluids", you are in fact decreasing the size of the runner and allowing the "choke point" to raise.

The next thing you are going to say is that it doesnt apply, but since there is air AND fuel involved, it is a fluid state. While not readily compressible, it still is bound by fluid dynamics more than by aerodynamics.

What you did to these heads is basically ruin them unless you completely port them to remove this issue... and if this is your version of porting, i would suggest you take them to someone that can actually USE a grinder and that knows what they are looking at.

looks to me like you could fuck up a shit sammich.

Why dont you ask Curtis Boggs to take a look at your port work and give you an evaluation, or Darin Morgan. Im sure both of them would be interested to find something new that would make power.. I mean hey.... any trick they could learn that would benefit their businesses would be a great tool, wouldnt it?

Too bad that neither of them use it currently... must be really secret...
I also thought the heads were ruined... But then i realized that the grooves didnt extend into the runners as far as i had initially thought .. The grooves are in an area of the port with realitively little velocity. This part of the port is not the choke point and probably wont hamper performance much at the rpms and power level this engine will likely see. I can see some potential merits to the grooving concept on a low rpm engine with excessive runner volume or as a bandaid on "dead" spots in mis-shapen manifolds and ports. For low rpm performance, personally i would have just used peanut ports, a short duration cam, and a dual plenum manifold.. Its nice to see guys trying different things, but i wish he was able to provide a before and aft comparo..

Last edited by cr480r; 10-30-2010 at 12:11 PM.
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Old 10-30-2010, 08:00 AM   #253 (permalink)
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Yep, the groves only go about 1.5" into the runner, the rest is finished off with 36 grit rolls
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Old 10-30-2010, 01:16 PM   #254 (permalink)
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Originally Posted by cr480r View Post
I also thought the heads were ruined... But then i realized that the grooves didnt extend into the runners as far as i had initially thought .. The grooves are in an area of the port with realitively little velocity. This part of the port is not the choke point and probably wont hamper performance much at the rpms and power level this engine will likely see. I can see some potential merits to the grooving concept on a low rpm engine with excessive runner volume or as a bandaid on "dead" spots in mis-shapen manifolds and ports. For low rpm performance, personally i would have just used peanut ports, a short duration cam, and a dual plenum manifold.. Its nice to see guys trying different things, but i wish he was able to provide a before and aft comparo..
I agree with your observation. Although he has done some interesting work, why take components designed for high flow and velocity and decrease their effectiveness? You could have just roughed up some peanut ports with some rolls and created the desired effect. As for saving money, plenty of folks would have traded him what he has for what he needed (to achieve the desired effect with less labor). The venturi effect really could be disputed in this application because he is trying create more of a tumble/atomization with the ribs than a true venturi (the restriction is not enough for a true venturi in my opinion). I have to say he has done tons of stuff to this vehicle that lots of folks can look at and use or not. Gotta hand it to him he has really done a number on the Burb and takes criticism pretty well, so keep it up and keep sharing. Your gonna get lots of help and critiqueing (most from folks who have great knowlege bases about big blocks). Most folks are looking at what you are doing as kind of trying to put a square peg in a round hole (with the intake and head mods) to achieve some kind of low RPM improvement. Technology has improved to the point that most of what you want to do can be done with out of the box components and some computer simulation programs...and picking the brains of some pretty smart guys on this board. Frankly your reference to Cup and drag race engines is like comparing apples and oranges. Those engines are designed for totally different operating parameters than yours is and a good part of that technology is not applicable in your engine.
One last thing about Grumpys comment on the tape with grooves for boat hulls and planes that reduces drag, we found out from the Australian guys that played with boat props that polishing boat props was causing slippage. They looked at leading edges of plane propellers and found they went away from polished to a sandblated type of surface that allows more grip for the prop to grab the air. Works good on boat props too! Now most of them are bead blasted instead of polished for better grab in the water.

Last edited by just4cuz; 10-30-2010 at 01:26 PM.
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Old 10-30-2010, 01:29 PM   #255 (permalink)
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I think I'm just going to throw my heads into the scrap pile since my heads are now worse than peanut port heads.
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Old 10-30-2010, 01:55 PM   #256 (permalink)
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Ha! Funny guy, you're a good sport though.
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Old 10-30-2010, 08:18 PM   #257 (permalink)
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I would clean up the ports as best you can with the cartridge roll and try to get rid of all the ridges you put in there. if you do that, youre gonna be closer to something you can use than you will think.

in this case, a hydraulic roller and LOTS of lift will help you... 1.8 rockers..216* duration at .050... try and see if you can get .620 lift out of that.

edit:
its all a bandaid at this point. get your compression to 9.6:1 if you can. if you have to, run a hydrauilic roller cam with solid roller lifters... keep your lash as low as you can. .012 if you can get away with it.

not the way i would do it... but it would work. if you call Jones cams or Bullet cams, you can get the RIGHT cam specifically for your application. they will ask you a shit load of questions. answer them truthfully.
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Last edited by Grumpy_old_fart; 10-30-2010 at 08:23 PM.
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Old 10-31-2010, 08:29 AM   #258 (permalink)
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My engine has been running for a few months now, I don't plan on taking it out any time soon

.597/.615 lift 231*/239* @ .50

Compression should be around 9.5:1
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Old 12-15-2010, 09:25 PM   #259 (permalink)
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Your rig

Bro, I will probably get blasted for this in one way or another (as this board is great for that) but here goes.

I really like your rig and am doing something kind of similar. I'm no expert in the off road world or much of anything for that matter.

A few points opinions I want to share though.
-Your rig is really cool. I have followed it since the beginning
- Obviously there are some things I would have done differently but I love your approach. Do what you want and see if it works like you want.
- The cylinder head idea with the ridges is a joke to me. I totally disagree with it. But it is cool you tried it. I have evidence and theory to back it up but it really isn't important. What is important is that you took the effort and tried it. Not everything will always work. I have done WAAAAAAAAAAY worse I can promise you that, lol. Liek putting bigger valves in 283 heads thinking I was going to set the world in fire. Flowed nearly 20% worse. with some bowl blending and a valve ob I pulled out of my ass I got ti close to where it was stock. the worst part of it all was that I was ever building a 283 to begin with! lol
- More regarding the heads, you have to work REALLY hard to screw up big block torque. Don't sweat it bro. I love displacement. All these people nitpicking things that you will never feel in the seat of your pants. Run your 5.38's and let that thing idle its way up about anything. You will be happy I promise.
- In the grand scheme of things NONE of us really no shit. Have fun with it and keep up the great work man. I enjoy watching you do it. If I ever get off my arse and find the time I will post up some of my projects so people can tell me I am doing it wrong or whatever. Chances are they will be right but I sure do enjoy doing it. It's good to see you have that fire and initiative.


and remember, I'm just another idiot internet guy who really probably doesn't know jack. Just wanted to share. Sorry for rambling.
Later on bro.

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Old 01-03-2011, 08:38 PM   #260 (permalink)
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Old 01-03-2011, 09:13 PM   #261 (permalink)
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If I were to build a chevy for a wheeler, I would start with a burb and hack the back off and give it a bob just like youre doing. Nice work so far.
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Old 01-03-2011, 09:16 PM   #262 (permalink)
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I'm doing the bob tomorrow maybe, I'm not 100% where to cut it yet
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Old 01-05-2011, 08:08 PM   #263 (permalink)
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Old 01-05-2011, 09:22 PM   #264 (permalink)
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I like it! How u gonna line up the top?
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Old 01-05-2011, 09:27 PM   #265 (permalink)
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It lines up a little better than thew picture makes it looks. I'm going to have to cut down the lip that holds the glass and weld the seam. It should be pretty good then. I'm going to make an angled piece also like in the picture below. That will save you time with cutting

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Old 01-06-2011, 02:29 AM   #266 (permalink)
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Cool deal
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Old 01-06-2011, 07:05 PM   #267 (permalink)
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Old 01-07-2011, 01:57 PM   #268 (permalink)
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I am really liking this idea, a little out of the box. If you are shooting for that black Burb, your rig is going to be sweet. Good wheel base, and 4 doors. Right on. Looks cool as well, although, that isnt what its about right? lol
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Old 01-07-2011, 05:07 PM   #269 (permalink)
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Wouldn't do it if it didn't look sorta cool

Yeah finishing of the inside is gonna be a pita though. I think I'll just half ass the connection and make some panels that go from the front and cover the speaker holes to the back over the seam.
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Old 01-10-2011, 01:58 PM   #270 (permalink)
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Old 01-24-2011, 07:54 PM   #271 (permalink)
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Old 01-24-2011, 07:55 PM   #272 (permalink)
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Looking good... I like the chop, that black one is great inspiration.
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Old 02-05-2011, 08:59 PM   #273 (permalink)
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Old 02-05-2011, 09:44 PM   #274 (permalink)
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Old 02-06-2011, 08:28 AM   #275 (permalink)
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I guess I never posted this

But here is the rough fitting of the soft top

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