 Common plenum or individual runners???, for gas milage and drivability |
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| Mueller |
 Dec 16 2004, 10:04 PM
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#1
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914 Freak!  Group: Members Posts: 17,146 Joined: 4-January 03 From: Antioch, CA Member No.: 87 Region Association: None 
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for my 2316 it seems that the stock plenum might be reaching it's limits as far as volume goes.....so, I either fabricate a larger common plenum, or go with individual throttle bodies such as TWM or Jenvey*
single plenum would be easiest, but the individual throttle bodies look better (IMG:style_emoticons/default/smile.gif) has anyone switched from one to the other on the same motor with everything else being the same??? *Jake Raby is the U.S. distributor of these.... |
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Replies(20 - 39)
| Bleyseng |
Dec 17 2004, 05:36 PM
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#21
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Aircooled Baby! Group: Members Posts: 13,034 Joined: 27-December 02 From: Seattle, Washington (for now) Member No.: 24 Region Association: Pacific Northwest |
Got a pic of what you are talking about?
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| SirAndy |
Dec 17 2004, 05:57 PM
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#22
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Resident German Group: Admin Posts: 41,644 Joined: 21-January 03 From: Oakland, Kalifornia Member No.: 179 Region Association: Northern California |
QUOTE(Bleyseng @ Dec 17 2004, 03:36 PM) Got a pic of what you are talking about? yes. take a 3.2L upper intake with TB and cut it along the green lines in Pic 1. take off the 2 front runners and weld the plenum shut. the mounting position of the remaining runners (yellow arrows in Pic 2) alomst perfectly mate on a dual carb intake (yellow arrows in Pic 3). they're only a few mm off on each side, so it would be easy to make a small adapter to mate them together. you can use the 3.2 TB, Air Filter, the fuel rails and injectors and just run a MS Brain for the Injection ... Pic 1: (IMG:http://www.914world.com/bbs2/uploads/post-11-1103327445.jpg) Pic 2: (IMG:http://www.914world.com/bbs2/uploads/post-11-1103327524.jpg) Pic 3: (IMG:http://www.914world.com/bbs2/uploads/post-11-1103327481.jpg) |
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| Jeroen |
Dec 17 2004, 10:16 PM
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#23
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914 Guru Group: Members Posts: 7,887 Joined: 24-December 02 From: The Netherlands Member No.: 3 Region Association: Europe |
Mike, do a search on the pelican taildraggers forum
Some guys there are modifying motorcycle throttle bodies (which can be bought cheap) |
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| Mueller |
Dec 17 2004, 11:27 PM
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#24
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914 Freak! Group: Members Posts: 17,146 Joined: 4-January 03 From: Antioch, CA Member No.: 87 Region Association: None
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QUOTE(Jeroen @ Dec 17 2004, 09:16 PM) Mike, do a search on the pelican taildraggers forum Some guys there are modifying motorcycle throttle bodies (which can be bought cheap) thanks...read 'em all and now I'm on eBay (IMG:style_emoticons/default/smile.gif) |
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| Qarl |
Dec 17 2004, 11:40 PM
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#25
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Shriveled member Group: Benefactors Posts: 5,233 Joined: 8-February 03 From: Florida Member No.: 271 Region Association: None  |
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| SirAndy |
Dec 18 2004, 02:33 AM
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#26
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Resident German Group: Admin Posts: 41,644 Joined: 21-January 03 From: Oakland, Kalifornia Member No.: 179 Region Association: Northern California |
QUOTE(Mueller @ Dec 17 2004, 09:27 PM) read 'em all and now I'm on eBay (IMG:style_emoticons/default/smile.gif) trust me, you want a single TB ... (IMG:style_emoticons/default/wink.gif) Andy |
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| Brett W |
Dec 18 2004, 08:07 AM
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#27
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Advanced Member Group: Members Posts: 2,856 Joined: 17-September 03 From: huntsville, al Member No.: 1,169 Region Association: None
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The common plenum system will make more power than an IR manifold. The IR will allow instant throttle response, therefore making them a much better choice for a situation where rapid and frequent throttle position changes occur.
While I was at work last night, I was thinking about coming up with a couple of prototype Common Plenum manifolds. I was trying to decide what throttle bodies and fuel injectors to set them up with. The Djet stuff in my opinon is not a good choice for fuel management, but Kit Carlson might be up for the task. What kind of interst would I see. Since I don't have a running injected car, and am not planning on building one anytime soon, I need someone to do some testing. Jake, got anything running Kit Carlson with an engine with more capacity, 2270+.? Here is the problem. IT would only work for a teener, because anyone running any kind of Upright cooling system would not be able to run this. Don't think I want to try and design one for an upright motor. |
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| Mueller |
Dec 18 2004, 01:31 PM
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#28
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914 Freak! Group: Members Posts: 17,146 Joined: 4-January 03 From: Antioch, CA Member No.: 87 Region Association: None
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QUOTE(SirAndy @ Dec 18 2004, 01:33 AM) QUOTE(Mueller @ Dec 17 2004, 09:27 PM) read 'em all and now I'm on eBay (IMG:style_emoticons/default/smile.gif) trust me, you want a single TB ... (IMG:style_emoticons/default/wink.gif) Andy why??? some of the new BMW's use what appears to be a combination of both, individual throttle bodies just a few inches away from the intake ports, but all of the t/b share a common plenum for the air? Brett, I think the best choice for the throttle body would be something from a newer car that has aftermarket support for....I've noticed on eBay, a bunch of Ford Mustang and Focus throttle bodies, both stock and aftermarket such as BBK Now about the placement of the throttle body if going with a plenum design??? cross off how the 1.7/1.8s are mounted......the 2.0 seems like it would be ideal for even flow, but it sure as hell looks goofy with the t/b just sitting up on top.....having the intake on the underside of the plenum similar to 928s (and even some Cosworth Indy motors) is an option, but you have to worry about clearance between the motor and the t/b...also there might be an issue with heat and also the overall height of the plenum would have to be higher for the t/b and aircleaner/ducting now we go back to the intake that Andy posted, do we want 2 seperate plenums connected together with the t/b in the middle or make one single plenum with the t/b mounted to it (top like 2.0 or front, similar to a newer GM V8)?? |
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| Aaron Cox |
Dec 18 2004, 01:42 PM
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#29
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Professional Lawn Dart Group: Retired Admin Posts: 24,541 Joined: 1-February 03 From: OC Member No.: 219 Region Association: Southern California |
heres a wild thought....use carb manifolds.... weld injector bungs on them.... make a common air box that has a throttlebody on it and connect it to the two carb manifolds (IMG:style_emoticons/default/wink.gif)
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| TimT |
Dec 18 2004, 02:09 PM
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#30
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retired Group: Members Posts: 4,033 Joined: 18-February 03 From: Wantagh, NY Member No.: 313 |
Mike the GT3RS we just tore down has a big box plenum, that sits on individual throttle bodies.
The air intake is tuned with different restrictors that are plaed at the air inlet for the plenum... Ill shoot some pics. its all carbon fiber and say Porsche Motorsports on it (IMG:style_emoticons/default/ohmy.gif) |
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| Mueller |
Dec 18 2004, 02:17 PM
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#31
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914 Freak! Group: Members Posts: 17,146 Joined: 4-January 03 From: Antioch, CA Member No.: 87 Region Association: None
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QUOTE(Aaron Cox @ Dec 18 2004, 12:42 PM) heres a wild thought....use carb manifolds.... weld injector bungs on them.... make a common air box that has a throttlebody on it and connect it to the two carb manifolds (IMG:style_emoticons/default/wink.gif) that is sorta what Andy posted...the question(s) is how to make the plenum and of what design? here is my 1st grade type sketches Attached image(s) 
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| Mueller |
Dec 18 2004, 02:21 PM
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#32
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914 Freak! Group: Members Posts: 17,146 Joined: 4-January 03 From: Antioch, CA Member No.: 87 Region Association: None
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QUOTE(TimT @ Dec 18 2004, 01:09 PM) Mike the GT3RS we just tore down has a big box plenum, that sits on individual throttle bodies. The air intake is tuned with different restrictors that are plaed at the air inlet for the plenum... Ill shoot some pics. its all carbon fiber and say Porsche Motorsports on it (IMG:style_emoticons/default/ohmy.gif) interesting....how much difference in area do the restrictors have between each other?? |
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| Aaron Cox |
Dec 18 2004, 02:24 PM
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#33
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Professional Lawn Dart Group: Retired Admin Posts: 24,541 Joined: 1-February 03 From: OC Member No.: 219 Region Association: Southern California |
beautiful drawings (IMG:style_emoticons/default/smilie_pokal.gif)
pony up for the jenveys and be done with it (IMG:style_emoticons/default/biggrin.gif) |
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| Bleyseng |
Dec 18 2004, 03:25 PM
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#34
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Aircooled Baby! Group: Members Posts: 13,034 Joined: 27-December 02 From: Seattle, Washington (for now) Member No.: 24 Region Association: Pacific Northwest |
Aaron, I was thinking along those lines last nights as I have a set of carb manifolds on the shelf. Just need to get some tube bent, weld on some flanges and bolt that to the manifolds. The plenum could be anything and weld on a TB. The sizing is the key as how big should stuff be?? The 3.2 looks way too big! I read that the runners should be about 10% larger than the intake valve or velocity suffers.
Geoff (IMG:style_emoticons/default/smile.gif) |
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| Aaron Cox |
Dec 18 2004, 03:26 PM
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#35
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Professional Lawn Dart Group: Retired Admin Posts: 24,541 Joined: 1-February 03 From: OC Member No.: 219 Region Association: Southern California |
QUOTE(Bleyseng @ Dec 18 2004, 02:25 PM) Aaron, I was thinking along those lines last nights as I have a set of carb manifolds on the shelf. Just need to get some tube bent, weld on some flanges and bolt that to the manifolds. The plenum could be anything and weld on a TB. The sizing is the key as how big should stuff be?? The 3.2 looks way too big! I read that the runners should be about 10% larger than the intake valve or velocity suffers. Geoff (IMG:style_emoticons/default/smile.gif) cool...im not the only crazy one then (IMG:style_emoticons/default/biggrin.gif) |
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| SirAndy |
Dec 18 2004, 04:32 PM
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#36
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Resident German Group: Admin Posts: 41,644 Joined: 21-January 03 From: Oakland, Kalifornia Member No.: 179 Region Association: Northern California |
QUOTE(Bleyseng @ Dec 18 2004, 01:25 PM) The 3.2 looks way too big! actually, each individual runner on the 3.2 is only slightly larger than a stock 2.0 runner. they are the *perfect* size for a 2.1 - 2.3 engine. in fact, there is a formula that porsche used on all their aircooled FI engines. using that formula and the displacement of your engine (per cylinder) you can calculate the dia. of a individual runner. (and vice versa) ... the one thing that is much larger is the volume of the plenum, which is gud ... (IMG:style_emoticons/default/cool.gif) Andy |
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| Mueller |
Dec 18 2004, 05:09 PM
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#37
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914 Freak! Group: Members Posts: 17,146 Joined: 4-January 03 From: Antioch, CA Member No.: 87 Region Association: None
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the 3.2 upper might work, my issue with it is that's going to be ugly
Andy, any thought on the single t/b plenum verses a single plenum with multiple t/bs such as the car Tim mentioned? |
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| SirAndy |
Dec 18 2004, 05:25 PM
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#38
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Resident German Group: Admin Posts: 41,644 Joined: 21-January 03 From: Oakland, Kalifornia Member No.: 179 Region Association: Northern California |
QUOTE(Mueller @ Dec 18 2004, 03:09 PM) Andy, any thought on the single t/b plenum verses a single plenum with multiple t/bs such as the car Tim mentioned? i believe that as long as you have a single plenum to draw air from (all cylinders share the plenum and therefore are connected), both versions should produce good results. the multiply TB/one common plenum setup will probably give you faster throttle response but then you have to deal with syncronizing 4 TBs ... as far as *ugly* goes, we all know that beauty is in the eye of the beholder ... (IMG:style_emoticons/default/biggrin.gif) Andy |
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| Aaron Cox |
Dec 18 2004, 05:34 PM
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#39
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Professional Lawn Dart Group: Retired Admin Posts: 24,541 Joined: 1-February 03 From: OC Member No.: 219 Region Association: Southern California |
QUOTE(SirAndy @ Dec 18 2004, 04:25 PM) as far as *ugly* goes, we all know that beauty is in the eye of the beholder ... (IMG:style_emoticons/default/biggrin.gif) Andy beauty is in the eye of the beer holder (IMG:style_emoticons/default/beerchug.gif) |
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| Mueller |
Dec 18 2004, 05:59 PM
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#40
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914 Freak! Group: Members Posts: 17,146 Joined: 4-January 03 From: Antioch, CA Member No.: 87 Region Association: None
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QUOTE the multiply TB/one common plenum setup will probably give you faster throttle response but then you have to deal with syncronizing 4 TBs ... hmmmmm, I wonder if a setup like this would make slide-valve throttle bodies work better thru out the entire rpm range???? |
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