Inliners International Forums General Discussion Hi Performance Individual Throttle Bodies on a Chevrolet 6.

So while I'm a ways out from starting my engine build (still slowly working on the truck)I just moved and having to move all my parts got me thinking about it again. So I've started to do some research on fuel injection. I searched and read through the forums here but most of the info is on TBI injection.

My plan had been to run triple side draught Webers on the original 230 but I see companies like Jenvey, www.jenvey.co.uk are making Weber replacements and I must admit the thought of individual throttle bodies sounds pretty appealing. I would control it all via a MegaSquirt ECU and back it up with a T56.

I;m pretty sure this hasn't been done before and I know it's not exactly budget but it's this or an LS1/3 swap and I like to be different.

Any thoughts?

Historically, these siamese port engines haven't been very friendly when using EFI and TBI has always been the better option. There have been mechanical FI intakes in the past but they seem to have been replaced with carbs as a better option as well because of the siamese ports, and the fuel robbing issues experienced between adjoining cylinders. In the end, you may end up spending a large amount of money to also realize the siamese port head is a hard animal to tame.

Yes, I had thought about that and that's why I thought that since the throttle bodies replaced the Weber DCOE carbs that this problem could be avoided as the fuel is being delivered in a similar manner as the Webers albeit with electronic fuel injection.

Hey CNC-Dude. How well would the fuel injection work with the Kirby/Sissel 12 port head? I don't think the op knows about them yet.

How many throttle bodies would you use, 3 or 6? A side draft carb has 6 barrels, one for each cylinder, even though the head only has 3 ports. If you only use 3 TB's, you will see quickly that one TB can't supply fuel/air to 2 cylinders very well. If you are thinking of gutting the Webers and converting them to EFI functioning, that might work and be interesting.

By removing the siamese port design, you will achieve great results with individual port injection just like any other normal cylinder head design. But at significant cost to swap over to that configuration unfortunately.

There would be 6 throttle bodies, one for each cylinder.

I would need 3 of these.

http://www.jenvey.co.uk/products2/twin-t...m-single-tbsxxi

So you can see that the work of "gutting a Weber" and converting them to EFI has already been done.

I was aware of the 12 port head too but they aren't cheap. How streetable are they and how much power naturally aspirated can they make?

They have a street 12 port head and a race 12 port head. Both have rather large valves and high flow characteristics which may require more cubic inch. I saw an ad in the Power Manual of one of their 12 port heads that said it was a 60 hp bolt on.

That would be a conservative estimate. There have been several to experience over 100 HP gains with more aggressive engine combos over a lump head. It is a sizable upgrade in cost, since you have to have specific add-ons to also go along with the head that cost extra above just the cost of the head unfortunately.