Author Topic: Turbo plenum  (Read 106034 times)

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Offline Jonny Hotnuts

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Turbo plenum
« on: September 13, 2008, 06:08:09 PM »
heres a few pics in progress of the plenum Im building for the car. Using 1/4" plate.....seems overkill but allows me to do nice round sides....doesnt weigh too much.


This is the very early stages....more to come soon.


God invented plasma cutters


Pre-tacks


All sides welded and ground
jonny_hotnuts@hotmail.com

"Sometimes it is impossible to deal with her, but most of the time she is very sweet, and if you caress her properly she will sing beautifully."
*Andres Segovia
(when Im not working on the car, I am ususally playing classical guitar)

Offline manta22

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Re: Turbo plenum
« Reply #1 on: September 13, 2008, 07:05:03 PM »
Overkill? Maybe not.

Calculate the area of top or botton plate in square inches and then multiply that times your turbo boost pressure in pounds per square inch. It is probably higher than one might imagine-- that's why a lot of intercoolers rupture.

Regards, Neil  Tucson, AZ
Regards, Neil  Tucson, AZ

Offline Geo

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Re: Turbo plenum
« Reply #2 on: September 13, 2008, 07:47:30 PM »
uuhh... Jonny

Looks fantastic!  :-)  but, you forgot the air holes :-D

Geo

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Re: Turbo plenum
« Reply #3 on: September 13, 2008, 08:01:17 PM »
Johnny,

the best plenums dont have any square edges on the inside... You should always try to keep the edges on inside rounded... Front what I understand this is why many rupture, flat square edges... Also depends on how much boost. Dahlgren would be a good source on info on that.

JonAmo


Offline Jonny Hotnuts

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Re: Turbo plenum
« Reply #4 on: September 13, 2008, 08:25:31 PM »
Quote
Johnny,

the best plenums dont have any square edges on the inside... You should always try to keep the edges on inside rounded... Front what I understand this is why many rupture, flat square edges... Also depends on how much boost. Dahlgren would be a good source on info on that.

JonAmo

I need to know if avoiding square sides is advised because of structural reasons or performance reasons. I know that you want to avoid square edges in a NA airbox to cancel standing waves. I did not think that this applied to turbo plenums.

I am confident that there is not a turbo alive that could split this plenum. I would feel that a box with these dimensions and type plate would be able to handle well into 100+ psi.

I figure I will be running between 18-20 psi. I am however building the motor to make 600+ and detuning to 375-425.....for our goals next year this will be about 50 more hp than I honestly feel we need.


If anyone knows for sure if the round sides are for structural reasons please let me know!
jonny_hotnuts@hotmail.com

"Sometimes it is impossible to deal with her, but most of the time she is very sweet, and if you caress her properly she will sing beautifully."
*Andres Segovia
(when Im not working on the car, I am ususally playing classical guitar)

Offline Dynoroom

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Re: Turbo plenum
« Reply #5 on: September 13, 2008, 08:33:12 PM »
Johnny I like where you're going with this. Do a little more research. I think you'll find the a bell or raised radius enty is still important in a turbo engine. So just don't cut a hole and weld a tube to your plenum chamber.
Have fun with the turbo build!







Michael LeFevers
Kugel and LeFevers Pontiac Firebird

Without Data You're Just Another Guy With An Opinion!

Racing is just a series of "Problem Solving" events that allow you to spend money & make noise...

landracing

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Re: Turbo plenum
« Reply #6 on: September 13, 2008, 08:40:10 PM »
dynoroom Knows his stuff... he also confirms what I was trying to imply... Ill see if I can get a couple shots of my plenum also which was designed by Dave Dahlgren

JonAmo

Offline Dynoroom

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Re: Turbo plenum
« Reply #7 on: September 13, 2008, 09:47:13 PM »

I need to know if avoiding square sides is advised because of structural reasons or performance reasons. I know that you want to avoid square edges in a NA airbox to cancel standing waves. I did not think that this applied to turbo plenums.


A turbo engine is a N/A engine running at a higher pressure ratio. A square plenum is not the end of the world though......





I am confident that there is not a turbo alive that could split this plenum. I would feel that a box with these dimensions and type plate would be able to handle well into 100+ psi.

Don't be too sure..............





Michael LeFevers
Kugel and LeFevers Pontiac Firebird

Without Data You're Just Another Guy With An Opinion!

Racing is just a series of "Problem Solving" events that allow you to spend money & make noise...

Offline Rex Schimmer

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Re: Turbo plenum
« Reply #8 on: September 13, 2008, 10:09:25 PM »
Dyno Room,
Love the pics of your plenum(s) but the big Binder lifting the block is fantastic!!! The tractor pull guys like to run 2 or 3 turbos in series and can get 125 psi of inlet pressure and it looks like the Binder had a contest between the crank and the block and the block lost!

Johnny, did you weld your plenum inside and outside?

Rex
Rex

Not much matters and the rest doesn't matter at all.

Offline Jonny Hotnuts

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Re: Turbo plenum
« Reply #9 on: September 14, 2008, 01:15:59 AM »
Take into consideration that this is the first time I have welded aluminum. I am using argon and alum wire without a spool gun. The guys at the welding shop said it could not be done. I kept the line straight and used a .35 tip with .30 wire and it did fine....not the best I have seen but VERY adequate.

Dynoroom....funny you would say this about the radiused intakes. I used some (rather expensive) Factory Pro aluminum velocity stacks before I read your comment. I didnt have prier knowledge that a tapered intake even for turbo apps is a better way to force air into the TBs.....it just seemed right to me. Plus I had the stacks sitting around and figured they would be better suited for this as apposed to giving them to Fred Vance (I almost did.....sorry FV.....Friends dont let friends use Factory Pro!).


And yes, I did weld both sides…..I dressed the outside for cosmetic reasons but both sides are welded.







jonny_hotnuts@hotmail.com

"Sometimes it is impossible to deal with her, but most of the time she is very sweet, and if you caress her properly she will sing beautifully."
*Andres Segovia
(when Im not working on the car, I am ususally playing classical guitar)

Offline Andy Cooke

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Re: Turbo plenum
« Reply #10 on: September 14, 2008, 04:33:35 AM »
and this is your idea of getting a few things done around the house?  :-D

what spec alooominum did you use?  not my subject, but I know that some will be a disaster.

How does the clearance to the back face of the plenum compare to the diameter of the trumpet - looks a bit close to me.  Not that you have a back face yet.

I went to see a friends turbo installation, he had a sexy looking rounded plenum reminiscent of early porsche race stuff.  I asked him how he made it, as it looked like a couple of weeks work.  He looked a bit embarrassed and admitted that he'd made it square and the boost had done the rest.  Don't worry, it was a lot thinner than 1/4".

Andy

Offline panic

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Re: Turbo plenum
« Reply #11 on: September 14, 2008, 10:56:47 AM »
"square edges in a NA airbox to cancel standing waves"

AFAIK it's not the corners but the flat surfaces that reflect a very strong discrete wave, while a radius scatters its reflection - think stealth.

I don't understand why the shape affects mechanical strength, though. The classic "square windows doomed the de Havilland Comet" argument isn't relevant - that was stress raisers in thin sheet metal over hundreds of hours. The only clue I can think of is the surface to volume ratio, which places more stress per square inch on a square shape. Comparing a cube with a sphere of the same volume, the cube's surface area is only 80.6% (or (1÷(6/Pi)^.3333), or 124% of the load per square inch.

Offline panic

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Re: Turbo plenum
« Reply #12 on: September 14, 2008, 11:11:11 AM »
Rough guess: if the rectangular plenum is 2 × 6 × 18", the volume is 216", the area is 312". At 20 psi that's 6,240 lbs. load on the walls.

Offline panic

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Re: Turbo plenum
« Reply #13 on: September 14, 2008, 11:19:41 AM »
IIRC Larry Widmer suggests the 1/2 donut (torus) sectioned through the thickness as the preferred entry shape in a plenum, as shown in one of the photos.

Offline Andy Cooke

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Re: Turbo plenum
« Reply #14 on: September 14, 2008, 12:57:56 PM »
these guys do some interesting bits and bobs

http://www.rossmachineracing.com/intakepartspage.html

for what it's worth, there are some pics of my plenum here

http://www.renaultpower.com/?rS=gallery&cid=56

Andy