Twin Throttle Bodies

[demuire]

Was speaking to the fabricator today and looking at all his Speedway bits (he does speedway), and got to talking about how much it would cost to make a manifold to bolt on 20v 4AGE quad throttle bodies. Or to get a set of his custom made slide throttles...

 

Anyways, no real figures were discussed as he needed to think about it, but he did suggest something that apparently is quite common among the V8 boys, which he recons would be easier and cheaper to set up, esp considering how much the 20v quad throttle bodies actually go for.

 

His suggestion was to make a pair of plenums, and get another standard throttle body (or off some other car, apparently the Ford Falcon ones are like $20 a piece from the wreckers) and use a twin setup instead. Sort of like, twin webbers. Except, like, well, you get the idea. Plus, it would be easier to balance the manifold vacuum too (since there is a plenum), for the MAP sensor, although fabricator highly recommends use of Motec computer for lots of fun :thumbsup:

 

Has anyone tried this before? What do you think? Any thoughts, ideas, suggestions?

 

The main difficulty I can see would be making the linkages to balance the throttle bodies, but seeing the stuff he's made, I have no doubt he'd be able to make something up.

 

Also, he tells me of a KE10 that's never been street registered, and started out life racing at Bathurst, and is still racing, now with a 3SGE in it. He's supposed to call me the next time the car comes in for me to have a looksee, sounds interesting!

[ancullen]

The twin-throttle setup on the Giocattolo and most other Holden V8's is just the one off the VL Group A (or a copy of that setup). Billzilla suggests turning an old Weber or Dellorto into a throttle body. Sounds like a reasonable idea to me, provided the Weber/Dellorto is completely useless as a carb, otherwise it's a bit of an expensive waste.

 

Surely bike carbs would be an option too. I've heard that it's becoming very popular in the UK with old school fans. See magazines like Retro for example.

[Super Jamie]

whatever magazine it was that did up the excel ages ago, found massive increases by changing to a twin throttle body setup

 

of course, this was just fixing the factory restrictive throttle body setup. if you do the same thing to an sr20 you'll be lucky to get 5hp out of it, because the stock stuff is already well designed and efficient for the needs of the motor

[demuire]

Well, I would be guessing that the main advantages to running 20v quads (over the stock single) would be (and this is just a guess):

 

a) allow more airflow (assuming the combined surface area of the quads is bigger than the single stock one - anyone know the sizes of the throttle bodies?)

 

b) better airflow, less pulsing etc in the plenum due to each throttle having it's own butterfly (and not having the one butterfly on one end of the plenum)

 

Judging by the way the 4AGE fires it's pistons, I would be guessing that running a twin throttle setup with 2 different plenums for pistons 1-2, 3-4, would achieve a similar thing. More potential airflow, and better airflow?

 

Stock single throttle bodies are cheap. Quads (and webbers, etc etc) aren't really. Well, none I've found anyway.

 

Then again, you can buy off the shelf manifolds to fit webbers on, and all you have to do is buy some stuffed webbers and fill in all the holes so it's effectively just a butterfly, and off you go. Let's go see how much a set of stuffed webbers would cost...

 

Hmm.

[Jason]

Isn't the fuel injected after the throttles? (on efi) Mine is

Edited June 30, 2005 by Jason

[demuire]

Good things I've figured out from having a quick look around at running Webbers on a 4AGE:

 

Good:

- Redline make a manifold, part number 12-22, approx $300.

- Redline also make throttle linkages, so that problem is solved. No idea on price

- I'm guessing you should be able to get dead Webbers for not too much money (45DCOE)

- Easy to get filters, horns etc.

 

Bad:

- Webbers are kinda big, and there isn't all that much space in the engine bay. Esp since in order to keep the MAP sensor I'd need to have a plenum of some description. Aftermarket computer would make this much easier.

- Need to custom fit the TPS onto the linkages somehow

 

It's kinda nice that the 4AGE has the injectors mount on the head and not the manifold, makes adapting the manifold so much easier.

 

Have also discovered that the 20v quads don't line up AT ALL to the 16v head, makes making a manifold just that little bit harder.

 

Ah well, one of those things to ponder about more.

[mikeys toy[RL]]

i actually thought about having a 4age t/b welded onto my 4ke plenum, i figure bigger is better, right?

[demuire]

I wonder if there's such a thing as, too big? More air is never a bad thing, is it?

[Mr Revhead[RL]]

i reckon i can supply manifold and 20v TBs for $800ish nz all up landed in oz. maybe less. theres a few places over that makes the manifold needed.

2nd TBs can be had for anywhere form $100 to $250 here

[demuire]

i reckon i can supply manifold and 20v TBs for $800ish nz all up landed in oz. maybe less. theres a few places over that makes the manifold needed.

2nd TBs can be had for anywhere form $100 to $250 here

 

That would make the manifold... about $500???

 

I actually almost got a gen2 SVT set of quads for AUD100, but they sold before I could make up my mind (unsurprisingly)...

[demuire]

The 2nd gen SVT ones are pretty good too. AFAIK, exactly the same as blacktop ones, except slightly smaller throats. Does anyone know what the actual sizes of the throats are (for both SVT and BKT)?

[demuire]

Acoustic's write up about Gen 1 and Gen 2 SVT quads

[Super Jamie]

you can get dcoe-style throttle efi bodies with injector bungs already in them. you just hook them up to a dcoe manifold for your engine, have a custom fuel rail made and bob's your uncle. i'd like to see that :thumbsup:

[Xany]

mmmmm......i wish i could afford it atm.....cause it would be mine along with the computer.....

[Felix]

why not just fit a complete 20v engine, with factory computer?

 

probably simplest/cheapest way to go.