MONZTER Posted February 17, 2009 Author Share Posted February 17, 2009 Does your CFD software tell you a CFM rating at a certain pressure? If so you could compare to a couple flow benches to see how it pertains to real life. If so, what sort of flow are you looking at? If this was already covered and I missed it, sorry. Yes this is how the software works. I can apply a Mass flow to the inlet with a pressure outlet, or I can apply a depression to the outlet and see the CFM rating. Most of what I have been doing is to apply 25" on the outlet with a stagnation inlet. This is how I ran my plenum. I would apply 25" to each runner outlet and let the air flow. I tweaked the design until all ran very close to the same. After I got this dialed in I then ran it with 735 CFM on the inlet and measured the flow out of each runner. A while ago a talked to Kevin at accurate injection. He gave me some insight of what a ITB flows on his bench. I modeled it in the computer and then ran the simulation. I remember them being very close. When I run the plenum and port set-up above the computer says they are running about 220 cfm at 25" Quote Link to comment Share on other sites More sharing options...
1 fast z Posted February 17, 2009 Share Posted February 17, 2009 Can you stimulate just the head by itself, with say a velocity stack mockup on the inlet of the port, where the intake bolts up? If so, how much difference is there between that and with the intake bolted up in the simulation? Quote Link to comment Share on other sites More sharing options...
MONZTER Posted February 17, 2009 Author Share Posted February 17, 2009 Can you stimulate just the head by itself, with say a velocity stack mockup on the inlet of the port, where the intake bolts up? If so, how much difference is there between that and with the intake bolted up in the simulation? I just re-ran the intake and head last night with the new software. The flow came out to 200 CFM at .5 valve lift 25" I believe the 220 number was just the head alone and with the other software. I could run it just like you asked. any particular valve lift or special requirements. what type of velocity stack? just simulate a clay radius donut around the port? Quote Link to comment Share on other sites More sharing options...
1 fast z Posted February 17, 2009 Share Posted February 17, 2009 Yea, usually just a nice radiused velocity stack, so the air does not turbulate as it enters the port. Im old fashion with just a flow bench, and a dyno to test my therorys, but we get 230 cfm with a stock 44mm valve with a RADICAL port change. I am real curious to see how your entire setup will work as a whole. Should be amazing. Quote Link to comment Share on other sites More sharing options...
MONZTER Posted February 18, 2009 Author Share Posted February 18, 2009 Yea, usually just a nice radiused velocity stack, so the air does not turbulate as it enters the port. Im old fashion with just a flow bench, and a dyno to test my therorys, but we get 230 cfm with a stock 44mm valve with a RADICAL port change. I am real curious to see how your entire setup will work as a whole. Should be amazing. I ran the head again without the plenum, and it was 219 CFM at .5" lift 25" this was with a radius inlet on the intake port flange. At 28" it ran 136 CFM. I totally agree with you, except I think how you do it is not old fashioned. The computer stuff is just a tool I like to use to identify problems and spark ideas. It is by no means the end all be all. I believe it is simply a good first step in the process that includes flow bench testing and dyno time. Quote Link to comment Share on other sites More sharing options...
Jokeri Posted February 18, 2009 Share Posted February 18, 2009 This is really amazing project!! Monzter: Is it possible to get the drawing files of the intake plenum and cylinderhead, as you are really skilled with the CAD and i would like to see how have you drawed those parts. You did use Solidworks to make the parts, right? Quote Link to comment Share on other sites More sharing options...
Daeron Posted February 18, 2009 Share Posted February 18, 2009 I ran the head again without the plenum, and it was 219 CFM at .5" lift 25" this was with a radius inlet on the intake port flange. At 28" it ran 136 CFM. I totally agree with you, except I think how you do it is not old fashioned. The computer stuff is just a tool I like to use to identify problems and spark ideas. It is by no means the end all be all. I believe it is simply a good first step in the process that includes flow bench testing and dyno time. I think that FAR too often, this reality is overlooked.. Computer simulations are used because they are easy to manipulate without consequences; carve out your chambers in CAD, it only takes restoring a backup if you made a mistake. Carve out your chambers in reality, and if its wrong, well.. get the devcon!! It is good to see that reality and the CAD simulation seem to reflect each other fairly closely. Now, if only more of us had access to five axis CNC mills that we could CNC port our cylinder heads with... Quote Link to comment Share on other sites More sharing options...
1artworkz Posted February 20, 2009 Share Posted February 20, 2009 I know this is a bit late in this discussion but since this discussion started with examples of duel chambered plenums I thought I should toss this in here. See what Newman-Sharp Racing did to a 1987 (Z31) 300ZX 2+2 750 hp Turbo, winner of the 1987 SCCA Runoffs in class national championship. The pictures below are from: http://www.garymolitor.com/300zx/plenum/1.jpg http://www.vintagemotorsport.com/ Previous Issue, SEPTEMBER/OCTOBER 2007, page 22.http://tinyurl.com/b9eg8z http://www.garymolitor.com/300zx/plenum/Newman-Sharp-1987-Z31-1.jpg http://www.garymolitor.com/300zx/plenum/Newman-Sharp-1987-Z31-2.jpgI have an 84T Z31; the stepchild of the Datsun/Nissan Z lineage. I too am working on a duel chambered plenum for my car. I have posts on this project at. http://forums.hybridz.org/showthread.php?t=144523 & http://z31performance.com/forum/viewtopic.php?f=1&t=14536 & http://z31.com/forum/viewtopic.php?t=8388&start=0 I want to thank both MONZTER and turbobluestreak for their PM assistance. Quote Link to comment Share on other sites More sharing options...
Daeron Posted February 20, 2009 Share Posted February 20, 2009 gary: they show up just fine for me; one thing I have found that helps with situations like that is to hold shift, then hit the "refresh" button on my browser. It is also good to go clear out all your cookies and browsing history once in a while to help keep odd problems like that from cropping up. Quote Link to comment Share on other sites More sharing options...
Tony D Posted February 20, 2009 Share Posted February 20, 2009 What does it say that this thread has more views than the 'Hybrid Z Rules and Guidelines, Please Read' sticky present in all the forums? I just noticed that now... Quote Link to comment Share on other sites More sharing options...
christoc Posted May 2, 2009 Share Posted May 2, 2009 So Monzter, when are you going to start selling your creations? My brother told me about something he saw in your office, I found this thread, amazing. Quote Link to comment Share on other sites More sharing options...
MONZTER Posted May 2, 2009 Author Share Posted May 2, 2009 So Monzter, when are you going to start selling your creations? My brother told me about something he saw in your office, I found this thread, amazing. Is Greg your brother? If he is then he knows I dont have any extra time to be making more plenums HAHA Quote Link to comment Share on other sites More sharing options...
christoc Posted May 4, 2009 Share Posted May 4, 2009 Yup, Greg's my little bro. Quote Link to comment Share on other sites More sharing options...
weirtech Posted May 31, 2009 Share Posted May 31, 2009 what cfd sofware are you using? amazing work. that is a tremendous amount of machining time in that plenum! just the material must have cost quite a bit. Quote Link to comment Share on other sites More sharing options...
Administrators RTz Posted May 31, 2009 Administrators Share Posted May 31, 2009 what cfd sofware are you using? . I have been using my new CFD software called Star CCM+. It is a really high end code, used in everything from military to F-1 - super powerful. Quote Link to comment Share on other sites More sharing options...
weirtech Posted May 31, 2009 Share Posted May 31, 2009 also, had you considered lengthening the runners into the plenum with velocity stacks on them to equalize flow? much like the cosworth xfe engines from the old champ car series? i'd be curious to test some of my own ideas as well as other ideas from intake manifolds from other cars. i'm hoping to build an intake manifold for a customer shortly (not a z car) and found this wonderful thread via google. Quote Link to comment Share on other sites More sharing options...
letitsnow Posted May 31, 2009 Share Posted May 31, 2009 I ran the head again without the plenum, and it was 219 CFM at .5" lift 25" this was with a radius inlet on the intake port flange. At 28" it ran 136 CFM. I totally agree with you, except I think how you do it is not old fashioned. The computer stuff is just a tool I like to use to identify problems and spark ideas. It is by no means the end all be all. I believe it is simply a good first step in the process that includes flow bench testing and dyno time. Is that a typo? Quote Link to comment Share on other sites More sharing options...
MONZTER Posted June 1, 2009 Author Share Posted June 1, 2009 Is that a typo? Yep Quote Link to comment Share on other sites More sharing options...
Porsche914 guy Posted August 31, 2009 Share Posted August 31, 2009 Word is getting around the net about this cool thread As you can see I don't own a Z, I'm building an engine for my Porsche 914. My engine build is N/A 2.5L (stock 2.0, 95hp) type 4, 4 cylinder "boxer" engine. You could say it's comparable to the build quality of your long block. With ITB's (IDF style) and SDS FI should get N/A 180bhp+ in a 2250lb car. I've always wanted to run just a single TB but the boxer design is wrought with turbulence issues. I've been looking into the Audi plenum design so to me this is a gold mine. I wish I had your budget and/or friends but I don't. Of course I need two smaller plenum's (2 cyl's each) and a "Y". I'm looking into doing this in steel or fiberglass. Steel would be the fastest (for me) to fab, so I'm leaning that way. Fiberglass, well I'm worried about fire and I have to spend a fair bit of time on the 4 piece mold (top and bottom X 2), but it could be more exact and have no sharp edges on each plenum's interior. The fins for the slot might be a challenge. I have my own little thread on another site. Is it Ok to link some of your pictures to that thread? Could you tell me the height between the floor and roof in your main plenum? Did the size (volume) of the main plenum stay the same as when you started this project? Sorry if this has been said, this thread is a lot to digest. BTW I want to thank you, most guys with this much into a "prototype" don't like to share and/or are profit driven. Excellent stuff! Quote Link to comment Share on other sites More sharing options...
Porsche914 guy Posted September 2, 2009 Share Posted September 2, 2009 My thread on the shoptalkforums (aircooled VW forum), but way low tech compared to this thread... http://www.shoptalkforums.com/viewtopic.php?t=126654&postdays=0&postorder=asc&start=0 Quote Link to comment Share on other sites More sharing options...
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