NEW ITB's for our aircooled 911's

[Nux]

Ladys and Gentlemen

I think it is time to unveil what we have been working on the last 6 months or so:

New direct to head tapered roller barrel throttle bodies for aircooled Porsche 911s



What is roller barrel throttle bodies your say? Well first of all, this concept is not new. Previously, this was constrained to F1 technology, but as design - and production price - got better, several companies started production for street applications. Perhaps the best known is Titan, who made roller barrel ITBs for Caterhams R-models.

So what is it?



It means, that there are no throttle plates - or shafts - to interfer with air flow.



The ITB's are linked as one, which means there are no adjustments needed other than bank-to-bank (don't worry - you can still adjust if you want to)



Does it work then? Well, yes! The air flow of these things is far superior to conventional throttle bodies. Below is a flow simulation for 45mm ITBs:



Besides the obvious benefit from better cylinder filling at WOT, the improved airflow also allows for smaller diameter designs, which will improve engine Torque at lower rpms.

What about throttle control? This has been a main concern and issue for the old barrel throttle bodies. The round design, made the throttle very very agressive and difficult to control at part throttle. The accommodate for that, these ITB's are oval and has progressive throttle opening. You will also notice the injector position, right in the air flow.

So whats next? The parts are in the CNC machine now, and I have to say, that I am super excited.

For a start we're going to make a few sets for the 3.6 engine. One set will go on my own daily driver and another on my '74 RSR project.

Additionally, we have 2 sets for the 3.0 which we will use for comparison purposes on two 3.0 builds that already have ITBs

Stay tuned!!!

[Nux]

From the machine shop a few days ago:



This is just a 3D print with velocity stack on. You can see the machined bits in the background.

A look down the rabbit hole




It's gong to be FUN!!!

[Nux]

A few more renderings





I will make some videos in the machine shop next week

stay tuned

[Dpmulvan]

How much?

[Nux]

Originally Posted by Dpmulvan

How much?

with the current exchange rate we hope to land at 5.000$ for a set, including fuel rails, TPS and link.

We do not ad VAT

[Clay.0]

Very cool. Interested to see the final setup

[Frog76S]

Thanks for sharing and look frwd to your future updates as applied to 3.6 & 3.0 liters. Been reading your threads the last few yrs. if I recall you’re an ER Dr? Would like some background info how you got started with this technology?

Thanks!

[3rd_gear_Ted]

How do current ECU's integrate with these units ????

[betterair]

swap,plug n play with KMS MP25 on a3.6L?

[MST0118]

Curious if you have any comments on how this design compares to the shaftless ITB design that AT Power makes? The 45mm size is about the same but wonder if this design flows better at part throttle or is about the same. Price seems reasonable but would be interested in more info and how they perform on your race and street motors. Good work!

[Nux]

Originally Posted by Frog76S

Thanks for sharing and look frwd to your future updates as applied to 3.6 & 3.0 liters. Been reading your threads the last few yrs. if I recall you’re an ER Dr? Would like some background info how you got started with this technology?

Thanks!

Correct, I'm ENT (Ear, Nose and Throat). I specialise in inner ear surgery and skull base surgery.

My mother was a race car driver in the 60's and 70's and I remember life at the pit lane when I was a very young boy.

Mix that with a general urge for knowledge and the fact that I like to get my hands dirty. I don't care if its red or black.

The old aircooled 911's have been a passion of mine for years. Unlike say, the ferrari's owners, these cars somehow encourage a strong community consisting of a great blend of peoples. These cars are purpose made and respond very well to modifications and general abuse. I can take my hot rodded 45 year old Porsche and drive to Italy and back without any issues at all. A Ferrari? No chance.

I have built a few 911 engines with ITB's. I love the planning proces, taking it apart and building it up again. Much like surgery really. However, there are obvious flaws with the current selection of ITB's, and I happen to know quite a few engineers. So, the idea came up from this guy who race Formula 2000 and have made these roller barrel ITBs for his own car. They worked tremendously well.

Well, the dice is cast

PS: I'm also in the process of engineering new medical equipment, so I guess it's just a thing for me

[Nux]

Originally Posted by 3rd_gear_Ted

How do current ECU's integrate with these units ????

There should be no difference. We use a common TPS and have vacuum ports and an easy spring loaded link.

Plug and play

[Nux]

Originally Posted by MST0118

Curious if you have any comments on how this design compares to the shaftless ITB design that AT Power makes? The 45mm size is about the same but wonder if this design flows better at part throttle or is about the same. Price seems reasonable but would be interested in more info and how they perform on your race and street motors. Good work!

I'm very excited to explore this subject too.

Even with a "shaftless" design, there is still turbulence and drag around the throttle plate. Naturally, the difference will be small on stock or mostly stock engines.

You can see the difference here:





Compared to AT power and Kinsler etc, I think we mostly will see the difference on modified engines.

We already have a few 3.0L lined up for comparison. Both some stock'isch but also a few heavily modified.

[Nux]

[Peter M]

Nux,
Love ya work and also have enjoyed reading your posts over the years.

With the throttle barrel, even though you intend to mount it on two ball bearings, I suspect you will have to have a fair bit of clearance between the rotating barrel and the housing to prevent the barrel jamming due to dirt ingress (far too many ITB owners appear to use no or very poor air filtration) or temperature variation between the components.

Have you thought this issue through as a jammed throttle isn't good for business! I wonder if this is the reason this approach has only been spasmodically used over the history of the internal combustion engine.

[Nux]

Originally Posted by Peter M

Nux,
Love ya work and also have enjoyed reading your posts over the years.

With the throttle barrel, even though you intend to mount it on two ball bearings, I suspect you will have to have a fair bit of clearance between the rotating barrel and the housing to prevent the barrel jamming due to dirt ingress (far too many ITB owners appear to use no or very poor air filtration) or temperature variation between the components.

Have you thought this issue through as a jammed throttle isn't good for business! I wonder if this is the reason this approach has only been spasmodically used over the history of the internal combustion engine.

Hi Peter

I believe the primary reason has been production cost. As I noticed above, this used to be F1 technology. However, today several companies have made efforts for street applications. The best example is probably Titan roller barrels for Caterham R500 - which is a production car for the street.

But even with refined and simplified production - it's still a costly affair and a time consuming assembly process.

We're in this for the fun of it - not for the money.

The tolerances are 0.1mm between housing and barrel. Given the physics of air dynamics, air will travel the easiest way through - which is the throttle opening. There will be a niglible amount going through on the sides.

(we have flow simulations proving this - pics don't load right now for some reason)

Heating dissapation is accounted for

The ball bearings are telfon coated and very heat resistant.

This specific design was developed by Jannik Sadolin. He is machanical engineer and a Formula 2000 champion him self and made the first Barrel ITBs for Ford Ecotech engines.

Has has 4 race cars with his ITBs on and they never had any issues in the past years.

I have never heard of issues with Caterhams ITBs either. A stuck throttle in a F1 would also be disastrous.

So in total: I believe we are in the clear. But I can't give your a 101% guarantee.

BTW we're looking into filtration options right now, as the ones available on the market are not as nice as I would like them to be. I really like those long exposed velocity stacks.

[Peter M]

Thanks Nux,
I wish you every success with this worthy venture.

Don't forget offering some simple adaptors for those who want to run a plenum on top!

[Nux]

Originally Posted by Peter M

Thanks Nux,
I wish you every success with this worthy venture.

Don't forget offering some simple adaptors for those who want to run a plenum on top!

we're on it

[HiWind]

wow looks great! Subscribed! (964 3.8 application)

[H-viken]

Very cool!

Johan