Single throttle body Pros/Cons...

[ecksrash]

I've been giving FI serious thought for several weeks now. Today I found an extremely nice looking setup. It has a single large TB mounted as a single carb and end castings with injector bungs at the end castings. This was on a NA engine. I have seen turbo engines with this set up, but I have no desire to go turbo. What are the pros and cons with a single throttle body configuration like this? How is it compared to a dual throttle body configuration like the IDF type throttle bodies? I am just trying to do my homework before making a decision on buying the required parts for my swap. Thanks DS

[volksbugly]

I haven't had single throttle body but if I was to do it over again I probably would go single. Its more simple, easier to fit and you get nice throttle response. With duals you run into fuel rail clearance problems, unless you put your rails inboard. For your first go at F.I. I say keep it simple and go only single TB.

just an fyi a TB thats 44mm will flow more air than a carb thats 58mm since you don't use a restrictive venturi. I currently have dual IDF 44mm TBs on a (I think 1641cc) and its WAYYY to much. a single 44 center mount would have been better, go with the factory TB and then Megasquirt it and you will be happy.

Mario has some nice kits from around 1500$ to 2500$.

[Piledriver]

If you go turbo, single TB by all means, but the engines power curve is still heavily driven by the intake tuning.

The factory TB setups have ~no intake tuning worth discussing so it's all turbo setup.

If you are going NA with a big cam, quad ITBs of a reasonable size for the engine...
Single TB and long cam NA no bueno.

There are other injector locations than "inside" or "outside": Down the bore hidden in the air cleaner works too.

I'm currently finishing off a 2466 T4, I plan to use 42mm ITBs, or 44mm IDFs w/o venturis if the 42s prove to small. (highly doubtful)
YMMV.

If you go with dual TBs a good cable pull linkage makes a day and night difference in the "living with it" area.

Most dual carb etc linkages on the market are garbage or very close to it IMHO.

[ecksrash]

Thanks for the info... I have a Web 86b cam in my 2276. Maybe that is too long (.575" @300*)? What to do???

[Jadewombat]

If this is a daily driver car, go with a single.

Like Pile said, if you're looking for max. power and go with duals, at least do a sync link system or something like it. It will reduce a lot of issues down the road of retuning and smoother pedal feel.

http://www.thesamba.com/vw/classifieds/ ... id=1381017

[Piledriver]

A Web 86B (260 [email protected]") is probably fairly deep into "ITB preferred" territory.
It might work OK with a long individual runner/plenum setup like stock T4...

... but on a T1 end-casting tyle setup there is so much overlap and reversion that you will almost certainly have issues with charge stealing/uniformity etc.

I'm planning on using a Web86B@112 LC, WITH a center "plenum" but it will really just be a huge tuned airbox feeding the ITBs.
(with a T4 motor w/stock cooling you have room for a small (and oddly shaped) suitcase on top of the block)

[Fiatdude]

Absolutely single -- played with all the different possibilities and single is the way to go -- I've got a TB from a V6 GM engine and it is perfect -- (I've since gone to a 65mm)

Just use the stockish intake and bolt the TB where the carb would go -- weld some bungs onto the intakes --- BAM your done

http://i586.photobucket.com/albums/ss30 ... date-1.jpg

[Piledriver]

Please note if you are recommending the single for NA or boosted use, and with what cam/head/CR setup.

The OP currently has a 300 degree cam/[email protected] Web 86B.

Most probably cannot imagine how deeply that will suck on a stock T1 intake manifold NA.

You would probably go from a 150+HP to <90HP and a 5K redline ~instantly.
Assuming you could get it to idle <2K.

[ecksrash]

Ok, looks like I'm going back to the drawing board. But I'd rather do that than have spent a bundle of money to learn the hard way. Thanks to those who have been in my shoes. I'm learning from your experiences! Thanks for saving my budget...

[Fiatdude]

That engine you see in the back of my Oval was a 2919 (angle port head 50/40, web 86c) and worked just fine in NA mode and as you know boost overcomes all LOL

The intakes weren't not exactly stock -- were 1 1/4" tubes and designed to look like stock

http://i586.photobucket.com/albums/ss30 ... 119842.jpg

I'm not world's best at anything -- but I got a bunch poop and shook it around and it didn't come out to smelly -- I did buy a set of Marty Skaggs intakes and I don't believe they work any better than the small ones

http://i586.photobucket.com/albums/ss30 ... 307126.jpg

[Dale M.]

Not really excited by center section, but look at end castings.... May not be to good for "big" engine....

http://www.thesamba.com/vw/classifieds/ ... ?id=519841

If you want the cool factor and efficiency (of short runners), the dual IDF "form factor" is way to go.... Lots of ITB to choose from ...

Dale

[Piledriver]

Posted pics of the mounted Waverunner ITBs.

IDF manifolds need 2 bits of weld so the mounting bolts have a place to go.
You don't have to run the bent velocity stacks shown, although I have a use for them.

http://www.shoptalkforums.com/viewtopic ... 0#p1205570