ITB Conversion Kit?

[vintagetreffen]

I have a 79SC with 180K on the clock. Burns a little (more than normal) oil, leaks near the heads/cam towers; overall it is a bit tired and time for a refresh. So, a rebuild is on the horizon and am considering different induction methods. Yea, yea... CIS is great and has been so for 40 odd years, but we have rovers on Mars! This is a great time to modernize the motor, maybe squeeze a little more power and economy out of it. There is a lot of chatter about ITB conversions and a fairly wide gamut of choices on the market. The target of this car is a spicy daily driver; maybe a couple DE events. Would like to keep the conversion budget sub $9K excluding the motor rebuild.

After reading many posts on this topic, I ask The Forum their opinions or stories regarding ITB conversions. This ask is directed toward DIY converters presently in the process or who have finished and have advice for the novice.

> Did you purchase a kit or develop your own recipe and order the needed components separately? I.e. ECU, ITBs, sensors, etc. MoTec? Haltec? Link? MegaSquirt?

> Any favorite ignition system for max performance/min maintenance? Keep the dizzy? COP?

> If you purchased a configured kit, which did you decide to purchase and why?

> Were you satisfied with the instructions, manuals, printed diagrams?

> How about post install support?

> What were the major problems that you encountered you wish you could tell your younger self at the beginning of the project?

> Any other advice that you may offer?

Of course this question has been asked time and time again, but innovation happens every day.
////

[Dpmulvan]

https://www.x-faktory.com/

[Henry Schmidt]

We make our own but they are still in testing. Not ready for prime time.
New twist on an MFI design.
The manifold were cast using old Mahle pistons.

[jac1976]

Henry,
Anywhere we can read more about this?

[Cloggie]

I bought the Rasant kit which I found quite complete and very nice....not perfect by any stretch but pretty good.

Unfortunately they seem to be shutting down at this point, which is too bad as I think they had a pretty good offering.

BTW I went with PMO's, Motec M130, CoP dual plug ignition with the Rasant supplied harness - which was well made and well protected.

Because my car is still under construction (getting closer!) I can't report on how it runs, all I can say is so far, so good.

Rasant also made a great distributor replacement for ignition timing, I did not get it as I am using the stock Carrera flywheel set up which has those sensors on that location, but it looked pretty good if you were replacing a conventional distributor.

Henry, I am sure your stuff is excellent, always is....just offer the suggestion that maybe you look at taking over some of the Rasant stuff if Andrew is offering it for sale?

Might be an opportunity plus a real positive for us older 911 drivers and users.

Just a thot...

D.

[Jittery]

Greetings all! I am in a similar position as vintagetreffen and am planning a winter project, so have time to form a plan and acquire hardware. Subbed!

@Dpmulvan - I have seen references to Kosmel's kits in many threads. Do you have direct experience with his kit? His kits seem to offer good value and has a number of build threads here and in the 911 Tech forum, most are positive. Looking for reports from folks who have direct experience with his offerings.

@Henry - I echo jac1976: Where can we learn more??

@Cloggie - Sounds like a pretty sweet setup, sad to hear Rasant is going out of business.

Cheers!

[winders]

Here is a great setup:



AT Power ITBs with WeaponX CoP...

[Henry Schmidt]

Originally Posted by jac1976

Henry,
Anywhere we can read more about this?

Hi Jac and Jittery. We love these old engines and sometimes just make stuff to prove we can. This system is one of those things. I don't know if they'll ever be for sale. I was just kind of showing off a new idea. If it works well, maybe? Sorry about the tease.

We have used the new Clewitt system. https://www.clewett.com/
Richard is a great guy, incredibly knowledgeable and willing to help. He supports his products better than most. American made right here in So. Cal.
He knows as much about Electromotive Tec systems as anyone I know but with the demise of Electromotive, his new ECU is Haltec.
We've used his systems, Electro and Haltec, and was completely satisfied with his real-time support. [set up and tuning] I think we tested his first/or second, new design throttles off the production line. There was some development but that part was kind of cool.

[Henry Schmidt]

Originally Posted by Cloggie

I bought the Rasant kit which I found quite complete and very nice....not perfect by any stretch but pretty good.

Unfortunately they seem to be shutting down at this point, which is too bad as I think they had a pretty good offering.

BTW I went with PMO's, Motec M130, CoP dual plug ignition with the Rasant supplied harness - which was well made and well protected.

Because my car is still under construction (getting closer!) I can't report on how it runs, all I can say is so far, so good.

Rasant also made a great distributor replacement for ignition timing, I did not get it as I am using the stock Carrera flywheel set up which has those sensors on that location, but it looked pretty good if you were replacing a conventional distributor.

Henry, I am sure your stuff is excellent, always is....just offer the suggestion that maybe you look at taking over some of the Rasant stuff if Andrew is offering it for sale?

Might be an opportunity plus a real positive for us older 911 drivers and users.

Just a thot...

D.

I like Andrews products and I talked with him about continuing his product line but I couldn't really nailed down a way to produce the pieces. Rassant products were manufactured in-house and I don't have the room or time to add that challenge to my plate. We only build air-cooled 911 based engines and develop new products when needed. That has offered a lifetime of satisfaction.

[jac1976]

Originally Posted by Henry Schmidt

Hi Jac and Jittery. We love these old engines and sometimes just make stuff to prove we can. This system is one of those things. I don't know if they'll ever be for sale. I was just kind of showing off a new idea. If it works well, maybe? Sorry about the tease.

We have used the new Clewitt system. https://www.clewett.com/
Richard is a great guy, incredibly knowledgeable and willing to help. He supports his products better than most. American made right here in So. Cal.
He knows as much about Electromotive Tec systems as anyone I know but with the demise of Electromotive, his new ECU is Haltec.
We've used his systems, Electro and Haltec, and was completely satisfied with his real-time support. [set up and tuning] I think we tested his first/or second, new design throttles off the production line. There was some development but that part was kind of cool.

Well, I’m sure the R&D is a worthwhile educational exercise whether or not you take anything to market. We appreciate the contribution either way.

[Henry Schmidt]

Clewett system mounted to a single plug 2.7

[Henry Schmidt]

Originally Posted by jac1976

Well, I’m sure the R&D is a worthwhile educational exercise whether or not you take anything to market. We appreciate the contribution either way.

We made 30 manifolds with a rudimentary process, sand casting low run parts, just like the old Porsche racing programs, was challenging and educational .

[OSC911]

I went with the Rasant kit - Motec M84, PMO and milspec harness. Really nice gear but the lead time was quite long and the tech support was pretty average.
If I had my time again, and knowing that Clewett are now using the Haltec ECU range, I would definitely go with them, just for the support they are known for. I don’t have any experience with his new ITB, but they look great.

[OSC911]

[Jeff Alton]

We have used plenty of different ones. Jenvey has been our go to for years. Henry's set up look like they use Jenveys. We have used PMO on the past but did not see the same power as with the Jenvey's. Could be many reasons for this.

We have a Clewett set up going on a 3.0 currenlty and a RHD set up going on a 2.7 as well. Will let you know what we think. The Clewett set up we have has a Haltech ECU as we have zero use for Electromotive products. We will run the RHD ones on a ECUMASTER EMU BLACK which we have used on plenty of on many different types of motors with good success.

Cheers

[winders]

Originally Posted by Jeff Alton

Jenvey has been our go to for years. Henry's set up look like they use Jenveys. We have used PMO on the past but did not see the same power as with the Jenvey's.

If you are looking for top end power yet good torque and drivability, you really should give the At Power ITBs a strong look. Due to the shaftless butterfly design, the 45mm version flows as much air as 49.5mm standard ITBs yet has air velocity of 45mm ITBs. The 48mmm version flows as much air as a 53mm standard ITB....again with the air velocity of a 48mm ITB.

William and I were astounded at how well they worked.

[RobFrost]

For a budget DIY setup you can fit a pair of triumph triple throttle bodies. You'd need a manifold to make the slight adaptation, which I believe can be 3d printed. I know of a guy in the UK who went this route and he swears by it. You can pick them up cheaply complete with injectors.

Sent from my SM-G988B using Tapatalk

[Jeff Alton]

Originally Posted by winders

If you are looking for top end power yet good torque and drivability, you really should give the At Power ITBs a strong look. Due to the shaftless butterfly design, the 45mm version flows as much air as 49.5mm standard ITBs yet has air velocity of 45mm ITBs. The 48mmm version flows as much air as a 53mm standard ITB....again with the air velocity of a 48mm ITB.

William and I were astounded at how well they worked.

They are on our list to try on a future build. I do not dought their potential what so ever.

Cheers

[jpnovak]

I have installed and worked on a bunch of different ITB setups. here are some of my thoughts.

PMO
-Easy to install and balance
-Linkage arms often need considerable adjustment to have same arc travel balance on each side.
-Good airflow
-Can use KN watershield air filters
-Can buy as ITB only if you are converting from Webers. Uses same manifolds and linkage.

Borla (formerly TWM)
-Easy to install and balance
-Linkage arms often need considerable adjustment to have same arc travel balance on each side.
-Good airflow
-Can use KN watershield air filters
-Can buy as ITB only if you are converting from Webers. Uses same manifolds and linkage.

Triumph Triple
-Budget adaptation
-Limited injector selection
-linkage is usually terrible.

Jenvey
-work well
-IMO Linkage is not easy to setup. But works well once going.
-Look very much pieced together.
-Challenge finding good filters for stacks.

RHD
-Linkage works well.
-Easy to setup and balance.
-Look very much pieced together.
-Challenge finding good filters for stacks.

I have not tried AT or JSR but they both look very interesting to me.

On a street car you will not noticed the difference between most of the readily available ITB setups. The end result will be your ECU choice and more specifically the tuner that completes the installation, setup and tuning process. This is where you get excellent or mediocre results.

for a street car I would make sure you have good filtration. There are many examples of cars with open stacks. This is just asking for water or dirt ingress leading to damage. I am not a fan of the snap on "mesh filters". to me they rob too much power.

[thetorch]

Recommend a 964 intake on a 3.0 / 3.2 / 3.4 -- this will require some customization, but it's been terrific on my 3.2/3.4. Torque is great from low RPM with stock 3.2 cams, and the curves seem to be shifted at least 500 RPM higher with the resonance flap opening at 5250 RPM.

Andrew at Rasant was insistent this would be the best performing intake for my setup, and as I recall the Rothsport and NineMeister 3.0/3.2/3.4 builds using the 964 intake had impressive numbers. I believe many go for the trumpets for the look and more choices available. I'm already making new 964 intakes in the event I build another hotrod.

I'm sure there are various opinions on this approach, but for the street, I just don't need more responsiveness, torque or HP than this. It really hustles a 2,300 lb car.

Having an idle air control really helps with cold starts. Not sure how other setups handle cold starts, but mine is like a modern car yet totally tunable. Hot or cold, turn the key, no pedal, fires right up and idles perfectly. Tuning cold start takes a lot of iterations, however, because your car isn't cold for more than a few minutes.

964 Resonant Intake
964 intake on 3.2?
964 Intake +Cam Choices