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flosho
Joined: 01 Jul 2004 Posts: 3155 Location: Eau Claire, Wisconsin
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Posted: Tue Aug 28, 2007 12:49 pm Post subject: |
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What if you did what you are describing but angle the TB more, and cut more of the original plenum away? _________________ [This Space For Rent] |
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ideola
Joined: 01 Oct 2004 Posts: 15548 Location: Spring Lake MI
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Posted: Tue Aug 28, 2007 12:54 pm Post subject: |
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Yeah, that's an option, particularly if the coolant reservoir can go (which in my case it is)...the big concern right now is the issue that Steve brought up. I just read the intake manifold chapter in Maximum Boost. Mr. Bell confirms that symmetrical is the best design for optimum flow. Less desirable would be the approach of tacking the TB on the front end of the intake. I think the best solution so far that retains the spirit of my original concept is to use the NA manifold and position the new TB runner exactly perpendicular to the plenum. It might not need to be a 90 degree bend...I'll have to take a look in the morning at the NA to see what kind of space is available...
This is freakin' awesome! We might actually come up with a design that works I'm pretty stoked. Thanks for the great insight, everyone! _________________ erstwhile owner of just about every 924 variant ever made |
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-nick
Joined: 16 Nov 2002 Posts: 2699 Location: Cambridge, MA
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Posted: Tue Aug 28, 2007 1:48 pm Post subject: |
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By the way - don't use a silicone elbow between the throttle body and the plenum. It will collapse under the vacuum without hesitation. _________________ 1980 931S
15psi boost, MS-II, EDIS, 951 IC, custom intake, Ford 5.0L throttle body, Forge BOV, WB o2, G31 w/LSD, 964 wheels, 968 rear sway, Bilsteins, 200# Welt. springs. A laptop, and a partridge in a pear tree.
1991 964 C4 Cabriolet |
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ideola
Joined: 01 Oct 2004 Posts: 15548 Location: Spring Lake MI
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Posted: Tue Aug 28, 2007 1:50 pm Post subject: |
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that would suck! _________________ erstwhile owner of just about every 924 variant ever made |
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Min
Joined: 04 Nov 2002 Posts: 2368 Location: Vernon, British Columbia, Canada
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Posted: Tue Aug 28, 2007 1:58 pm Post subject: |
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-nick wrote: | By the way - don't use a silicone elbow between the throttle body and the plenum. It will collapse under the vacuum without hesitation. |
If you go to your local large truck dealer, you can get reenforced silicon hosing that has metal wire in the hose to prevent this from occuring.
Also a nice place for inexpensive silicon hosing in general, just isn't as nice looking as the ricer stuff.
Min _________________ Custom means it didn't come from a box.
1980 n/a with EDIS and Megasquirt II Injection. 7 different colors and counting. |
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endwrench
Joined: 07 Dec 2002 Posts: 1631 Location: Victor, Montana
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Posted: Tue Aug 28, 2007 2:02 pm Post subject: |
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Have you considered some sort of hybrid diffuser style intake? This would keep the clearance requirements to a minimum towards the back of the motor and would give you nice even distribution. It would take a little more fabrication and welding though I think.
Todd
Some photos: http://www.bufkinengineering.com/intake%20manifolds.htm _________________ '79 924NA. Rebuilt 9.5:1, MSDS header, Mega Squirt Injection, MJLJ-EDIS Ignition, 1.6L Whipple Charger and Intercooler, 10lbs Boost, 944 Trans, Custom HD Clutch.
"simsport" said....superchargers are better than turbos its official!.... |
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Raceboy
Joined: 01 Mar 2004 Posts: 2326 Location: Estonia, Europe
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Posted: Tue Aug 28, 2007 4:34 pm Post subject: |
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I made this for my 931. It's complete now, with diffusor and shortened runners (brake booster clearance) but you'll get the idea. ITB's are from GSXR750. They cost me 80$, have EFI injector bungs, have TPS and are separable (different cylinder placement).
_________________ '83 924 2.6 16v Turbo, 470hp
'67 911 2.4S hotrod
'90 944 S2 Cabriolet
'78 924 Carrera GT replica
'84 928 S, sold
'91 944 S2, sold
'82 924S/931 "Gulf", sold
'84 924, turbocharged, sold.
http://www.facebook.com/vemsporsche |
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endwrench
Joined: 07 Dec 2002 Posts: 1631 Location: Victor, Montana
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Posted: Wed Aug 29, 2007 2:11 am Post subject: |
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Very nice Raceboy! I'd like to see it with the diffuser in place.
GSXR750, is that Suzuki? What size are the TB's?
Todd _________________ '79 924NA. Rebuilt 9.5:1, MSDS header, Mega Squirt Injection, MJLJ-EDIS Ignition, 1.6L Whipple Charger and Intercooler, 10lbs Boost, 944 Trans, Custom HD Clutch.
"simsport" said....superchargers are better than turbos its official!.... |
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flosho
Joined: 01 Jul 2004 Posts: 3155 Location: Eau Claire, Wisconsin
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Posted: Thu Aug 30, 2007 2:32 pm Post subject: |
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endwrench wrote: | Have you considered some sort of hybrid diffuser style intake? This would keep the clearance requirements to a minimum towards the back of the motor and would give you nice even distribution. It would take a little more fabrication and welding though I think.
Todd
Some photos: http://www.bufkinengineering.com/intake%20manifolds.htm |
Thats a very good link. The tapered manifold design seems to be a very popular design in the past and today. Many, many, cars use the same design, withouth diffusers. When I build a new intake manifold it will be something like you have mocked up dan, maybe angled a bit more. I think angling it more towards the front two cylinders would even out the flow.
Question: In a boosted application, can the flow rates really vary that much between cylinders, it would seem that the air being forced in would go where the least resistance is. Shouldn't the air in the intake manifold even out somewhat equally? I can see if the TB was aim directly at the rear two cylinder ports, or something that the front two might starve, but a tapered intake manifold design with a rather front mounted throttle body seems to work for most cars these days. _________________ [This Space For Rent] |
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ideola
Joined: 01 Oct 2004 Posts: 15548 Location: Spring Lake MI
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Posted: Sun Sep 02, 2007 7:31 am Post subject: |
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Great link, Todd, on the custom, two-piece manifold. This could be very do-able with our manifold setup. There is adequate space without having to move anything, and it would eliminate the 90 degree bend I am contemplating. It would allow me to stick with blocking off the original opening, and set up a tapered primary manifold, with the front-mounted TB. I understand the notion of the slot on the tapered portion of the primary, but how would you integrate the slot from the new, tapered manifold with the original manifold? Would you cut a slot all the way down its length, and simply have the two slots integrate between the primary (new) and secondary (original) plenums? Also, what about sizing? Would you start with 60mm (which is the inner diameter of the series II TB), and taper down to the size of a quarter or nickel, as indicated in the webpage that Todd linked to? _________________ erstwhile owner of just about every 924 variant ever made |
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endwrench
Joined: 07 Dec 2002 Posts: 1631 Location: Victor, Montana
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Posted: Sun Sep 02, 2007 8:28 am Post subject: |
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I can't remember but I think it was Racing that turned me onto this concept in intake design. The diffuser acts as a distributor rather than a plenum. Your ideas on diffuser size seems sound. The slot between the plenum and diffuser needs to be a little bigger in "area" than the TB. You don't want to create a pressure differential.
Todd _________________ '79 924NA. Rebuilt 9.5:1, MSDS header, Mega Squirt Injection, MJLJ-EDIS Ignition, 1.6L Whipple Charger and Intercooler, 10lbs Boost, 944 Trans, Custom HD Clutch.
"simsport" said....superchargers are better than turbos its official!.... |
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Raceboy
Joined: 01 Mar 2004 Posts: 2326 Location: Estonia, Europe
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Posted: Sun Sep 02, 2007 3:04 pm Post subject: |
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endwrench wrote: | Very nice Raceboy! I'd like to see it with the diffuser in place.
GSXR750, is that Suzuki? What size are the TB's?
Todd |
I'll take few pics when I get my a$$ near my 931 (200 kms away from me).
Yes, Suzuki GSXR750. GSXR600, 1000 and 1300 (Hayabusa) suit also (1300 are 55mm inlet and 46mm outlet IIRC).
Those are tapered: 46mm inlet, 40mm outlet so basically what is needed for 931 38mm intake port. _________________ '83 924 2.6 16v Turbo, 470hp
'67 911 2.4S hotrod
'90 944 S2 Cabriolet
'78 924 Carrera GT replica
'84 928 S, sold
'91 944 S2, sold
'82 924S/931 "Gulf", sold
'84 924, turbocharged, sold.
http://www.facebook.com/vemsporsche |
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ideola
Joined: 01 Oct 2004 Posts: 15548 Location: Spring Lake MI
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Posted: Mon Sep 03, 2007 6:44 am Post subject: |
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endwrench wrote: | The slot between the plenum and diffuser needs to be a little bigger in "area" than the TB. |
Todd, I think what you meant to say is the slot needs to be a little bigger in "volume" than the TB, correct? If so, then it should be a fairly simple matter to calculate the approximate volume of the TB by using its diameter and depth (of course, it is a somewhat more complex shape than a simple cylinder due to the tapers, but it should suffice for calculating the approximate volume). The slot would more or less amount to a simple cuboid. _________________ erstwhile owner of just about every 924 variant ever made |
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RC
Joined: 25 Mar 2007 Posts: 2636 Location: Australia
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Posted: Mon Sep 03, 2007 7:00 am Post subject: |
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I`m quite sure that Todd is talking about the AREA of the slot. Perhaps if he said CROSS SECTIONAL AREA it may be more precise terminology.
I read this to refer to the relationship between the throttle body butterfly(s) and the size of the slot opening, Please correct me if this is misinterpreted Todd. After all the volume of a slot only takes into account the material thickness.
Oh yea, BTW Raceboy, that does look excellent!. Sure it will perform as well as it looks.
Roger |
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ideola
Joined: 01 Oct 2004 Posts: 15548 Location: Spring Lake MI
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Posted: Mon Sep 03, 2007 7:10 am Post subject: |
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Ahhhh! OK...I'm nowhere near a car right now, so I'm guessing at the length of the intake manifold...but, using some approximate numbers, my Series II TB has a 60mm butterfly (I think), giving it a cross-sectional area of just over 2800 mm2; therefore, if the length of the intake manifold is about 300mm (give or take), the slot could be about 10mm high, accomplishing a larger cross-sectional area than the TB opening. Make sense??? _________________ erstwhile owner of just about every 924 variant ever made |
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