Individual Throttle Bodies

Chewievettte · Nov 22, 2006

I'm looking into building an ITB system for my new turbo engine and I wanted to get some opinions on it. Obviously its not necessary since the engine is mostly stock but it'll look cool and I've got all the parts to build it laying around. I'm going to be running a megasquirt so tuning it shouldn't be a problem. I really just want to get a feel for the reasons for and against it in this application aka, Why havnt I seen it before? Since you guys have more experience than me with these engines, here I am.

Dr_EluSivE · Nov 23, 2006

Chewievettte said:
I'm looking into building an ITB system for my new turbo engine and I wanted to get some opinions on it. Obviously its not necessary since the engine is mostly stock but it'll look cool and I've got all the parts to build it laying around. I'm going to be running a megasquirt so tuning it shouldn't be a problem. I really just want to get a feel for the reasons for and against it in this application aka, Why havnt I seen it before? Since you guys have more experience than me with these engines, here I am.

Well i suppose a Reason Not to do it would be that you will slow the air down too much. If you have too big of a pipe, you wont get the intake velocity you need for the best torque.

Dr.

88stangmangt · Nov 23, 2006

i agree....with DR. even a dual TB wouldnt be a good idea unless you have a intake set up to allow for it or else your just making a bottle neck some where else. just a plain 65mm tb with the intake opened to use it would be the best idea.

Chewievettte · Nov 23, 2006

I've been planning to run a better flowing head, like the round port or ranger head that I've read about. I need to do more research before I figure anything further. I was intending to build a plenum(log manifold) that would split the flow from the intercooler into the four tbs then make a mostly straight shot into the cyl head. I guess I dont understand the bottle neck theory, what I build will be designed to match the engine rather than just what is convenient. Obviously its not the most efficient for this application, but I really just want to make something unique, a little experimentation.

RustBucket · Nov 23, 2006

Well, now there's individual throttle bodies and then there's multiple throttle bodies. Multiple throttle bodies would be taking 4 stock TB's and plumbing one each to a dedicated runner feeding one cylinder only. It ain't gonna work for reasons posted above.

Now individual throttle bodies that were sized right can and will work. Old school mechanical fuel injection on A/FX race cars had a throttle body (or air valve) for each cylinder. They had 8 small stacks sticking out of the hood and were friggen cool!!

The trick would be balancing each throttle body much like you'd balance a multiple carb setup. To tune them right, you need to make sure each air valve is pulling the same amount of air. If not it'll never run at it's full potential if it runs at all. I've thought about this myself. Mostly just a daydream while I'm staring at parts in my garage. If you did this with an EFI setup rather than mechanical, it would have to be a speed density or alpha-n system since there's no way to use a MAF or any other air meter, and I haven't seen an EFI ECU yet that would deal with multiple air meters.

mg man · Nov 24, 2006

I don't understand all what you have to to size. I have MG's you can use a carb synochronizer to get all the same air flow You have to design a common throttle rod to be pulled by the accelarator cable. Then individual adjustable linkages. Custom everything throttle bodies intake etc,etc. The intake would have to be designed correct lengh size flow. Anything can be done with money but I seen a photo on a double he gave up. Good luck hope it works . Do some research on intake design , flow , and sizing. I wouldn't try it too much engineering and high failure rate lol

Chewievettte · Nov 24, 2006

Four stock throttle bodies was never a consideration, its just too much air. However I have a set of TBs from a much smaller engine and when paired (total of four) should give about the right flow. I know theres a ton of calculations and such to figure out the perfect intake, they will be researched and figured before I cut any metal. I am working on a simple synchronizer to be put inbetween each of the TBs to allow for balancing. So that shouldnt be a big problem. I am also planning to run a megasquirt on this car which is speed density, so like you said, it would allow the computer to know what the heck is going on and give me tunability.

Stinger · Nov 24, 2006

There is no such thing as "too much air". You can put 4 100mm throttle bodies on it if you want and it's not going to ingest too much air...the engine is still only going to suck as much as it can use on each stroke.

Chewievettte · Nov 24, 2006

Sorry, I used the wrong terminology.

What I mean to say is like the the first reply, it would slow the air down too much. It would become inefficient. I suppose a quick way to estimate the TB size would be to simply measure the size of the port, that should get me in the right area. Of course its never that simple.

mg man · Nov 24, 2006

carb synochronizer I am talking about is a tool that measures air flow of a car so you can get them all same. You sound like you already know thar beacuse you are making provision for synochronizing.Good luck we need pictures when done.lol

Chewievettte · Nov 24, 2006

I've got a 240z with dual carbs, I know a little about synchronizers.. Might upgrade to triple webers, then I'll have to know even more.

For TBs there is a little adjustment device that needs to be fitted between the shafts so that they can be balanced. I found a really simple one that I am modelling mine from. I will be doing some research over the next few weeks and hopefully I can start mocking up the intake soon.

I'm having trouble designing the front intake runner around the distributor. Any ideas? I thought about going to the later distributorless ignition but I'm not sure if I want to go that far.

mg man · Nov 25, 2006

Was looking around net. Found this on Turboford.com look under faq. "Intake Fabrication and Formulas" Yes time to go back to school. Math was not strongest class many years ago lol

Chewievettte · Nov 25, 2006

There is no turboford.com and turboford.net I cannot find "intake fabrication and formulas" under faqs. Could you maybe throw a link my way? I could always use another cross reference for my math.

I was acctually pretty good at math, could never stand math class but acctually doing it wasn't a problem. Perhaps thats why I like this kind of stuff.

65ShelbyClone · Nov 25, 2006

The most common way that I've seen to fabricate or retrofit ITBs onto an engine that never had them was to use a set from an I-4 EFI superbike. Something off a 1300 Suzuki would probably work. They are usually all attached together so no synchronizing is needed. The same thing has been done with quad carbs off the same type of bike.

However, running ITBs will incur much more noise on the MAP signal for the MegaSquirt because there is no common plenum to soften the intake pulses. You'll have to either put a fuel filter on the MAP line or figure something else out.

mg man · Nov 25, 2006

mucked up on turboford.net forums under faq page 1 dated 8-2-06 would do a link to it. I foul up on typing. My math class was 20 years ago.I am not one of the young ones here. Just a new one to these turbo.Built mine entirely from net info.here is the link. http://www.turboford.net/ubb/ultimatebb.php?ubb=get_topic;f=4;t=000313

Chewievettte · Nov 25, 2006

Thanks for the link!

Does the map signal need to be pulled after the throttle plate? If not then I can get it off the plenum before it divides into four.

65ShelbyClone · Nov 26, 2006

Chewievettte said:
Does the map signal need to be pulled after the throttle plate?

Yes. The MAP signal must be referenced from between the engine and throttle butterlflies.

Chewievettte · Nov 26, 2006

Figures... Time to get creative I guess!

Chewievettte · Nov 26, 2006

I found a couple reasons why I dont see more of this type of install. The distributor and the alternator, they are perfectly positioned to be in the way! But I think with a little fudging I can get it all in there. Problem is I need to have the engine in the car before I can mock it up so I guess I'll have to put off further development for a little while.

65ShelbyClone · Nov 28, 2006

How about tilting the ITB intake manifold on an angle so it points more toward the valve heads? Might get some extra clearance that way.

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