 What's the consensus about individual throttle bodies?, injectors in the manifold or in the tb? |
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| daveyboybadion |
 Aug 25 2009, 10:10 AM
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Member  Group: Members Posts: 108 Joined: 19-January 06 From: Seattle, WA Member No.: 5,437 Region Association: Pacific Northwest  |
I am building a 2056 with aftermarket itb's and ecu and a crank fired ignition. I'm getting ready to order a cam from Jake Raby and wondered if anyone has any hard info on which set up produces the most torque: Injector bungs mounted closer to the valves in the manifolds, or farther away with the injectors integral to the throttle body? thanks...daveyboy
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| underthetire |
Aug 25 2009, 10:34 AM
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914 Guru Group: Members Posts: 5,062 Joined: 7-October 08 From: Brentwood Member No.: 9,623 Region Association: Northern California |
Must be a reason all the OEM's went away from throttle body injection and went to multi-port as close to the valves as possible. (IMG:style_emoticons/default/idea.gif)
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| zymurgist |
Aug 25 2009, 12:09 PM
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#3
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"Ace" Mechanic Group: Members Posts: 7,411 Joined: 9-June 05 From: Hagerstown, MD Member No.: 4,238 Region Association: None |
Here's what Porsche did with MFI... one throttle body per cylinder... (IMG:style_emoticons/default/driving.gif)
(IMG:http://farm3.static.flickr.com/2223/2405540262_18519a8a08.jpg) |
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| gothspeed |
Aug 25 2009, 12:20 PM
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#4
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Senior Member Group: Members Posts: 1,539 Joined: 3-February 09 From: SoCal Member No.: 10,019 Region Association: None |
Here is the ultra high RPM method ...... (IMG:style_emoticons/default/wink.gif)
http://www.youtube.com/watch?v=oFm0m6sbOi8...feature=related |
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| Jake Raby |
Aug 25 2009, 07:30 PM
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#5
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Engine Surgeon Group: Members Posts: 9,394 Joined: 31-August 03 From: Lost Member No.: 1,095 Region Association: South East States |
On an engine so mild you won't see any benefits of one over the other location wise..
I have tested them low in the manifold, in the TB and high atop the velocity stack with results that were nil. Install them where they are easiest to service and keep the fuel coolest... |
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| tomeric914 |
Aug 25 2009, 09:36 PM
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#6
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One Lap of America in a 914! Group: Members Posts: 1,259 Joined: 25-May 08 From: Syracuse, NY Member No.: 9,101 Region Association: North East States 
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What a coincidence, Cupomeat and I were discussing this earlier tonight. Jake is right, you won't notice a difference on a mild motor. But with something more aggressive, individual TBs close to the valve should allow for a faster throttle response. My beef with individual TBs is the additional linkage and synchronization of both. Much easier to have a single TB into 4 runners with injectors at the heads, IMHO.
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| CliffBraun |
Aug 26 2009, 12:46 AM
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#7
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Member Group: Members Posts: 252 Joined: 26-April 06 From: San Luis Obispo,ca Member No.: 5,933 Region Association: None |
Another reason OEM's do it is because it helps with cold start, you get less fuel stuck on the walls of the intake tract and the valve gets hot first so the fuel vaporizes better.
Edit: There's actually a whole video about wall wetting compensation, I can't find it at the moment online, but I have it here and I could host it if anyone is interested and can't find it. |
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