I always wondered how difficult would it to make a throttle body out of holley or dellorto carburetor for my 12a turbo application

I have both of them including RB intake manifolds laying around, holley has been already ergonomically ported on the intake top section by the filter, and my dellortos have jet hole cracked, so i could experiment.

I've seen holley throttle bodies, is here any writeup showing how to make one based on carburetor?

 

wouldn't be hard actually, just seal up all the circuits (idle, transfer, main, power valve, etc) with JB weld and rip out the venturis, i was thinking about doing this with a nikki. what about the manifold though, as you would need to find somewhere to mount the injectors.

best bet on a 4 barrel would be to wire the secondaries to open simultaneously with the primaries for quad throttle operation. i know how to do this on a nikki, not sure about your other carbs.

 

I've thought about it, too. Shouldn't be too tough. I was thinking of using only the throttle body section of a Nikki and mounting the injectors above it.

 

i would have to look at the details of the holley, but isnt there enough space under the flaps to drill in and weld reciever for injectors?

guys, look here thats holley throttle body, injectors are diagonally under, and they have a pressure U shaped bracket/fuel rail holding injectors in o rings
http://www.thesamba.com/vw/classifie....php?id=973695

for dellortos of webers i can drill injectors directly where needles are on the body are, or on the first curve of the intake after carburator.

would i have to make some kinds of bypass valve?

 

injector above it?

or under?

does it make difference?

please explain the simultaneous opening leverage?

also you might know more about bypass?

 

Wouldn't that kill your bottom end?

 

Shouldn't, since you're not dependent on vacuum to feed fuel once you go FI.

That's why pretty much all current OEM FI's just have the one big-*** manhole cover for a TB; no need to manage vacuum over the fuel orifices.

 

Try this out for size just thought of this. Use the bottom section of the nikki for ur throttle. Find a fab shop around to mill out a piece of aluminum, Make it a spacer. Idk how thick it should be but once thats done you can mill in the injector bungs and vol-la DIY FI for ur 12A. Lol. Then use a mega-squirt as ur comp

 

Doh, I read carb and forgot you guys were talking about FI

 

this is what i have on my 12a it fits in a RB intake. i have a also a BB t72 turbo turbonetics and a microtech ECU

http://www.jegs.com/i/DFI/310/74135B/10002/-1

 

You could do that too. I just figure it'd be easier to put them above the throttle plates. No need for expensive machine work and the fuel rails will be out of the way of the throttle arm and cable.

As I understand it, the distance of the injectors from the ports is what makes the most difference. Above the throttle plates or below shouldn't matter as much, and either way it'll be a lot better than a carb.

 

OEM 12a Turbo throttlebody (not my pics):



It's a two stage design just like the later 4 port EFI throttlebodies (especially s4 Turbo). The primary plate opens first (for the primary ports). The other two butterflies are for the secondary ports and open as the throttle rotates enough..



It was a downdraft style, bolting right to a single piece manifold like a carb. There was no plenum like the Turbo II and later engines.



TPS is mounted on the side, it's the same basic TPS as the GSL-SE and the series 4 FC (narrow range signal)



Dashpot in the middle, with the coolant hose barb on the right for the fast idle system (same as GSL-SE, all the way up to the s8 FD)

 

Nice pictures man!

 

In case you attempt this, please use a full range tps from an S5

 

I wouldn't even bother with a TPS, personally.

 

You may be surprised but on the Nikki it greatly improves part throttle power and response. My guess about why, is that you have higher velocity through 4 partly open throttle plates compared to two, delivering more air and a stronger fuel signal at the venturis (also 4 now instead of 2). The downside is that it's quite expensive on fuel at part throttle / cruise conditions

As I said it's easy on a Nikki, I'll take a pic. No idea how to do it on other carbs tho.

 

If you guys want to simplify this, just use a 13B center iron from a GSL-SE and you will have a center iron with injector ports already there. Then you can use a SE fuel rail. Been there, done that. Actually used a complete SE intake and everything on a 12A using a SE 13B center iron. The 12A turbo used the same center iron as the SE 13B for injector location.

 

I would go with staged mechanical secondaries. Higher velocity at part throttle with only the primaries. But then I'm also a fan of having the primary and secondary runners tied to the primary and secondary venturi with no overlap in between the 2, especially on heavily ported engines.

I had the same thought, wondering if I could use the Dual Weber DCDs as TBs. It could be fun, especially going turbo.

 

oh man its getting more and more interesting
i think i have 1 13b center section ready

thats pretty much set up i am aiming for. Do you run intercooler? could you share a photo?

i would like to use horizontal carb because of an ergonomic air movement, almost like a twist prior to combustion in motor.

injectors could go in where needles are. unfortunately my IC comes out on the pass side, so holley with turbo bonet fits better.

holley openings are bigger too

 

my car is not done yet but i could tell you i have spend some money on it.

yes it is intercooler. I have 12 a turbo rotors, custom turbo manifold, t72 turbonetics turbo. 4 injector throttle body, RB intake. Mcrotech ECU. its almost complete i have to get the engine rebuild. im just waiting for more fundings!!!!

 

[QUOTE = arghx; 10065363] OEM 12a Turbo throttlebody (no mis fotos):



es un diseño de dos etapas al igual que los últimos 4 puertos EFI throttlebodies (especialmente s4 Turbo). La placa primaria se abre primero (para los puertos primarios). Las otras dos mariposas son para los puertos secundarios y se abren cuando el acelerador gira lo suficiente.



Era un estilo de tiro descendente, que se atornilla a la derecha a un colector de una sola pieza como un carburador. No había plenum como los motores Turbo II y posteriores.



El TPS se monta en el lateral, es el mismo TPS básico que el GSL-SE y el



Dashpot de la serie 4 FC (señal de rango estrecho) en el medio, con la lengüeta de la manguera de refrigerante a la derecha para el sistema de ralentí rápido (igual que GSL- SE, hasta el s8 FD)

[/ QUOTE]
*

 

WHAT ....

 

damn noob. bump an 8 yr old thread and from what i can tell, didn't add anything useful.