Post your ITB Setup

[sp_cs]

Originally Posted by fanaudical

I love seeing this stuff - it's always fun to see what others are playing with.

Regarding the setup shown in the picture of post #150 - Are the push-connect fittings and poly tubing used to gather a vacuum reference? (Most push-connect fittings are not rated for vacuum applications and tend to leak under light vacuum.)

That was a drive by wire development setup I photoed at Neil Bainbridge's workshop in the UK last year sometime, so unsure if carried into Production. He's rebuilding my engine and has been involved in the development of these ITBs with ATPower. My set should be received by Neil shortly.

[stephen1070]

I don't want to divert this thread but would a shaftless single TB (cable actuated) design benefit a 3.2 carerra?

The individual TB set up looks great.

Regards,
Steve



QUOTE=Lowrance10;9582075]Hi,
Brian from Reno Rennsport. A customer of ours informed me that there were some posts on here regarding the Shaftless throttle design from AT that we adapted for 911 engines. Happy to answer any questions.

We originally developed these for our Spec 911 cars as competition is very high in the class and small gains are of high value. But now we have been using them on street cars as well because the performance was a bit more than expected.

In short we have seen improved port velocity leading to power gains starting as low as 3500 and of course top end power was much improved also.
Throttle response is also greatly improved as the butterfly can be placed closer to the head and still have clean air.

We are currently working with AT on a drive by wire single throttle which should be ready sometime this summer.

thanks.[/QUOTE]

[911GT2]

Subscribed... working on one now.

Does anyone knows where I can get a half tea air filter setup?

Thanks

[JJ 911SC]

Originally Posted by 911GT2

Subscribed... working on one now.

Does anyone knows where I can get a half tea air filter setup?

Thanks

I get them at Walmart...

Just normal tea ball split in two. You need 6 as only one side of the tea ball is usable.

[al lkosmal]

I was going to use these at one time, but some knowledgeable friends of mine mentioned that they had problems with tuning while using the real tea ball filter halves ......., that the mesh is too fine and they are very restrictive. There are some filters available that resemble the tea balls style, but are less restrictive. Your experience may vary.

regards,
al

[sp_cs]

These turned up with the engine builder today:

[Ferrino]

Looks like the hardware is 3,250 GBP / 4,160 USD.

Porsche 911 45mm Throttle Bodies (for 42mm Ported head - 102-102-00133 | Design 911

[Tremelune]

No idea how it'll perform, but the silver gleaming off the black looks outstanding...

[panzerfaust]

Originally Posted by gearheadgreg

i haven't used or built any shaftless style throttle bodies, but i've been around them and talked with people that have built and used them - so for what that's worth: The slide throttle setup seems to be hard to make easily progressive at lighter openings, because the vacuum is pulling the slide against it's runner/guide etc. Barrel throttles don't seem to have that issue, but more of a seal/leak issue due to the machining involved.

These shaftless ones - i'd be interested to hear about as well. From old flowbench work, of course reducing or removing the shaft increases max flow, but if the throttle bodies flow more air than the engine can use at redline, it's no benefit...

+1

[merlinfe]

Reading older threads on the Triumph forms indicates that you can pick up 6-8% on the top end by eliminating all the airflow restrictions in the intake path. This included filing down the throttle plate shaft and knife edging the throttle plates.

It looked like a tremendous amount of work for small benefit, however on a motorcycle every bit counts.

I'd like to know the optimum intake length from velocity stack to intake valve. I feel a lot of the set ups we have available leave power on the table in the low rpm band for the sake of looks and ease of install.

I've tried using this site Intake Runner and Peak Torque Calculator And it spit out 18-24 inches depending on inputs given. If anyone else has a more relevant calculator please share.

-Steve

[CBRacerX]

A first move in this direction I'm considering is grinding down the split plate screws. The other changes are something better done on a full race motor.


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[gearheadgreg]

Originally Posted by merlinfe

Reading older threads on the Triumph forms indicates that you can pick up 6-8% on the top end by eliminating all the airflow restrictions in the intake path. This included filing down the throttle plate shaft and knife edging the throttle plates.

It looked like a tremendous amount of work for small benefit, however on a motorcycle every bit counts.

I'd like to know the optimum intake length from velocity stack to intake valve. I feel a lot of the set ups we have available leave power on the table in the low rpm band for the sake of looks and ease of install.

I've tried using this site Intake Runner and Peak Torque Calculator And it spit out 18-24 inches depending on inputs given. If anyone else has a more relevant calculator please share.

-Steve

Good input. Removing restriction in the intake is only a benefit if the engine can flow more than the intake. When I was young I did a lot of work on a SuperFlow flowbench with watercooled VW engines. There was a popular throttle body upgrade - which wasily flowed a lot more than the engine would likely ever need, so was really only worth 2-3hp. Because I was a starving student, I modified my stock throttle body by grinding down the screws (after red loctiting them) and the shafts, and knife edging the blades. I got to within a handful of CFM of the larger throttle body, and on my mild engine, likely did all the same power or close enough for free.

Now, if modding those triumph throttle shafts and screws gives 6-8% on a 150hp (I have no idea, just guessing) engine, if your 911 engine makes 300hp, it could be a roughly similar beneft. If your 911 engine makes 200hp, would likely be a minimal benefit - depends on what the bottleneck is, of course.

Optimal intake length depends on a lot of variables (valve event timing, displacement, rpm etc), and I've only dabbled in it over the years. I'm sure some engine builders/tuners could weigh in on it with some authority. With an ITB setup like this, part of the benefit is removing the long, possibly restrictive intake of a CIS setup (again, depending on the engine).

If I was building a hot rod NA engine, I would go with ITBs for a couple reasons - sound, cleaning up the engine bay, and a likely increase in power over factory manifolding. Plus, in an older car, they look more period, IMO, even if there are fuel rails and injectors poking out here and there.

[Shaun @ Tru6]

There is a great discussion on runner length, etc. on this 928 thread. May have to go back a page and read through the next several pages but worth it I think.

https://rennlist.com/forums/928-forum/961748-highwayman-bringing-the-devore-928-back-from-the-dead-45.html

[gearheadgreg]

Originally Posted by al lkosmal

I was going to use these at one time, but some knowledgeable friends of mine mentioned that they had problems with tuning while using the real tea ball filter halves ......., that the mesh is too fine and they are very restrictive. There are some filters available that resemble the tea balls style, but are less restrictive. Your experience may vary.

regards,
al

Agreed. The testing I did years ago, and reading about airflow testing of similar items bore out the same thing. Anytime you have minimal filter area, you are likely restricting airflow. And tea strainers aren't made for airflow. Besides, if you drive down a dusty road, they are only going to keep out rocks, not any small particles.

I know there are some newer style ones out that claim they aren't restrictive, but I haven't seen anything empirical or scientific to prove it. When you work so hard to make power on a 911, then kill of some hp just to run some inadequate filters makes no sense to me.

[Clay.0]

Current setup with rain hat filters on top

[quint22cp]

Here's mine.



3.5 conversion with Nikkies.
SDS ECU
Twin plugged
Home brew manifold for the Triumph TBs

Lots of time and money spent but love every minute of it.

[billjam]

Bored tonight so I pulled together a bunch of pics of my ITB journey for your viewing pleasure
ITBs are from a Triumph Daytona 675 on home-built intake runners. Engine is a 3.6 with 12 Toyota COP ignition and MS3X. And yes, it flies!
I bought the ITBs new on eBay for $100 each and spent maybe another $300 for various materials and the filters.

[billjam]

A few more pics ...

Fuel rail is standard 3.2 part.




The oval shape of the TBs below the butterfly was opened out to the same diameter as the buterfly (44mm).



Injector ports in TBs were tapped M12 and plugged with short grub screws. One set of vacuum ports are brought together at a manifold to supply brake vacuum and a second set are used for idle control.





Air cleaners have been through a few iterations. I started with these in carbon fibre but they weren't robust enough for my liking and were too close to the engine cover. I tried six foam type socks but kept blowing them to bits or melting them due to backfiring during initial tuning problems. Current arrangement is with top and bottom aluminium plates. Small rain shields are fixed to the underside of the engine cover to deflect rain water.





Throttle linkage is two cables connected to a modified adjustable bell crank.

[cnielsen]

2.8L built on an early sand cast aluminum case with PMO throttle bodies and controlled by MoTeC. I backdated as much as I could to make it appear period correct.

[al lkosmal]

beauty Chris....and that dyno run is excellent........nice power and flat torque curve.