Has anyone used a throttle body other than the 13b one? I want to find a way to make like a big 65mm or larger work with the 13b. It's for a new intake manifold design I'm working on.

 

I've seen people use independent TBs for NAs. I always thought it'd be cool to run a dull turbo/dull intake system. Make each rotor with it's own turbo, intake, and TB. Of course, this would require a lot of plumbing and i don't if it'd fit in the car.

 

you could use small turbos. CT-12a's or 12b's from a TT supra, or whatever the FD uses, could be run...but it would take a lot of plumbing..

 

Iwant to use something like this:

http://cgi.ebay.com/ebaymotors/ws/eB...category=33558

I'm wanting to do this for TII's. I'm wanting to make a dual "Y" manifold that will wrap over the top of the engine and face the TB towards the front of the car...kinna toward the battery area (easy lumbing for FMIC). It'll have longer, equal length runners and no plenum. I've been wanting to do something like this for a long time.


The TPS is the only problem I can really think of, but it's just activated by the degree at which the buterflies are open. On an axis, no matter how big, 20* is 20*...so I think that I might be able to find a way to mount the stock TPS to it and use that.

 

You probably could, or you could go after market ECU and aftermarket TPS. Do you think that TB would be bigger then the 3 ports in the stock TB though?

 

I think you'd be suprised at how much area there is in our throttle bodies.

 

3 X 30 mm = 2129.5 sqmm

1 X 75 mm = 4415.6 sqmm

...holy crap that math seems WAY off...

 

If I remember correctly from another thread, people found that going to a single large throttle plate caused insanely touchy low throttle behavior, making around-town driving nearly impossible. Something to consider.

-=Russ=-

 

i think our tb is like 90mm anyway, my freinds eclipse has like a 62 and it fits inside mine

 

The 13b actually has three throttle bodies...30mm a piece. My calculations above are correct. Our 3 throttles have about the same flow as a single 52mm body.

I've never seen a 13b with a single-butterfly tb. Pics or links to people with problems? I can't imagine someone having a problem unless they didn't do it right.

 

Found the perfect donor: MKIII Supra 60mm throttle. It's an easy design to work with and, if need is there, it's easy to find a larger body that will bolt up to a flange made for it.

 

Wrong and even more wrong. The FC's TB has three 45mm bores, not 30mm. That's a combined area of 4771mm2, equivalent to a 78mm bore. In reality though it would flow similar to a 65-70mm TB, meaning your Supra TB would be a nice downgrade. Unless you're making a lot of power, a TB bigger than stock isn't going to make much difference. Not enough to justify all the costomw work anyway.

The sequential thottles are there to improve drivability. Using only the engine's primary ports at light throttle increases port velocity, which improves fuel atomisation, air/fuel mixing and hence torque, throttle response and driveability. If you were going to chuck all that away it better be for a good reason (i.e. big gains elsewhere).

 

Oh....I guess I'll have to find a larger TB then. I thought the ports were only 30mm a piece...picked it from some random thread. And I'm not trying to find a larger one, really...just an adequate one that'll be easy to work with.

Everything that you do for a gain in one area, will be at the sacrafice of something elsewhere. I have my plans.

 

I didn't thoroughly read the thread so I am not sure of your application. But if you feel like doing some work, the FD throttle body is a tad bigger I do believe. You'll need to get the FD upper to fit though, which can be a PITA. The adapter tends to be expensive. I'm not even sure if the FD upper will even mate correctly to a N/A lower... But I do believe its been done on a s5 TII manifold. If you're N/A then You could use a turbo lower and then use the FD upper, but you would sacrifice your 6PI system. Again not sure how much hacking would be required to make it work.

 

it will go on a custom manifold.

 

Personally I think your proposed manifold design is not a good one. I've been around rotaries for a long time and I've never seen anyone build anything like that for the street or track. There's probably a very good reason for that. Just because a tri-Y design works well for exhaust manifolds doesn't necessarily mean you can flip it around and use it one the intake side.

I'm no expert on intake manifold design, but I know enough to doubt it will be much (if any) better than stock. The reading (yes, actual books) I've done on this topic have shown me that it's a lot more complicated that it looks. If you read Mazda's engineering papers on the DEI and VDI manifolds you'll know what I mean.

I suggest you do a lot more research for yourself, and not just on forums. Books on modern race car design (not old school V8's) would be a good place to start.

 

Oh trust me, I read a lot. Most of everything that supports what I want to do is theory...but on the flip side everything that negates my project is theory. I've only seena couple of manifolds like this, but their build was not documented or tested in any way. I don't even think they were dyno-tuned. I went through very annoying effort to contact 2 different people associated with cars with a mani like this and all I got were "duuuuuuu...it went faster" type responses...bunch of rednecks...

Anyways...basically my theory goes...on an N/A engine this wouldn't do crap. It would probably be more of a hinderence, not having a vacuum plenum and all. But on a turbo car, a gradual seperation for each runner would benefit flow...actually I'm tired and reading over what I'm writing it doesn't describe what's in my head adequately. I'll have to wait to the coffee kicks in...

The big thing is, though, that I like building things and I've enver seen this done on a 13T...so I thought I'd give it a shot. If it flops, it'll be fun in the mean time....

 

This is about as big and easy to work with as they get... http://cgi.ebay.com/ebaymotors/ws/eB...spagename=WDVW

 

Here's my redneck response. I ran a 75mm Mustang throttlebody on a very heavily modified S5 intake. You need to remember that adding the total area of 3 throttle plates and comparing it to one large one does not mean the same flow. The single plate will flow more but only because of one very important fact. The plenum (dynamic chamber) is a dual plane design. You have 1 throttle plate feeding 2 ports and the other 2 throttle plates feeding 2 (or technically 4) other ports. You will hit a restriction in the primary side before you do on the secondaries. This is really more applicable in practice on a high power forced induction car as the n/a just doesn't make enough power to justify the extra airflow.

What I found in drivability was that throttle response was very touchy. It took very liitle throttle to get moving alot faster. This isn't necessarily a good thing. The top end was better though but the low end was much worse. It was a big tradeoff. You really need a much smaller throttlebody if you plan to use a single plate. A 65 mm would be better. It will still flow enough provided that you have a single plane plenum. If you just want to adapt a single plate to the stock dynamic chamber, you are wasting your time. Although I ran it nonturbo, I had actually built it for use with a big single turbo and a huge port job. It was a play car so I didn't care a whole lot about daily drivability. Your gas mileage will go down. For street use this isn't a good idea. The only reason that a single throttle plate works on the RX-8 is because other valves close different runners off depending on rpm so velocity stays high. Their throttle body is not a 75 mm either. It is smaller. If you do this to your car, make sure you have a standalone ecu first. It does run with the stock ecu but once I got the Haltech on it, it took off.

 

Thanls! What would you think of a plenumless design? That's what I'm wanting to adapt this to.


just to point out this IS a turbo project...

 

what about independant tb setups? i mean cut the head ( the big thing that says mazda 13b ) off and slap on some itb's?

 

I think one potential problem will be with TPS compatability. There is no guarantee that the output voltage will be the same between the two (new VS original) for a given degree of rotation.
I think you will unnecessarily sacrifice low end driveability with out a plenum. With out an air chamber to pull from the throttle could be very touchy.
Also, just because there is an plenum doesn't mean it will have bad flow. I think you will end up with competing pulse waves from the two rotors. A plenum will damp those out and allow for individual runner tuning.
All IMHO, of course.
I was thinking of using an LS1 throttle body on a custom manifold. After upgrading, those guys will give them away. A quick search on ebay found one for $5.
Good luck

 

Search ebay for BBK...

 

It is pretty close.

Area of a Circle = PI x r^2

3 x 3.1415 x 15^2 = 2120.51 sqmm
3.1415 x 37.5^2 = 4417.73 sqmm

 

I think there's a lot that can be done with the original TB without sacrificing drivability/mileage. Mazda went to a fair bit of trouble for a fully divided primary/secondary intake path. Why not keep those benefits?
BTW, here are some pics of what a little time and some (fairly) simple tools can get you. Power increase was quite noticeable in my NA, and throttle response is immediate. The primary still opens first, so mileage/drivability is still good. However, since I knife-edged the butterflies there is a bit more airflow at a smaller throttle opening making the car feel like it has a bit more torque.