Are you happy with your ITBs?

[OZCarrera3]

See my earlier post about PMOs. Let me know what your experience with ITB's has been.

I have also started a poll on PMOs - Are you happy with your PMOs?

[al lkosmal]

I am really liking the ITBs. I like carbs and I like MFI..........but if you put in the time to overcome the learning curve needed to understand and tune EFI/ITBs.........you won't be sorry. But the understanding of how the system works is the component that is most often missing from the system and why, I believe, many end up disappointed.

I've done a 3.2 intake on a 2.7, using the Tbitz kit and more recently I've built a proto system utilizing Triumph Throttle bodies and Megasquirt. Now I'm working on a system for my 3.2...........either the Triumph setup or TMW ITBs..............again with Megasquirt. Although I may look into adapting the Motronic to ITBs...anybody out there done this?


YouTube - koz77911's Channel

[OZCarrera3]

Thanks Al.

I think you hit the nail on the head with the Comment "but if you put in the time to overcome the learning curve needed to understand and tune EFI/ITBs.........you won't be sorry." That's what costs the big $'s for someone like me. I'd probably get someone else to do this for me.

Ok they have limitations (cold start and fuel economy), but from posts I have seen, Carbs are pretty much a 'plug and play' solution.

[al lkosmal]

Sheldon,

Well, I guess I've seen plenty of people, posting about jet sizing and synchronization of Webers (myself included) to believe that they're not totally plug and play, but there are definitely plenty of folks that have gone through that particular learning curve and can help out. ITB's w/EFI........is the new voodoo.........you still have to kill a few chickens and scatter the bones to get it to go..............at least it seems like it until you study up.................. I like it, but I'm easily amused.

[brads911sc]

love my ITB's. tuning was really not that difficult. I have no issues. no stumbles. no hesitation. no cold issues. took me about 2 hours to get it smooth through out the powerband. not sure why others report so much difficulty...starting with a good base map is key. There are MS Guru's like Jaime Novak that get you 75% there before you even do anything... (of course im in tx... it was 80 degrees today... )

[clutch-monkey]

was looking at the PMO ITB's for next year, was also curious about fuel consumption once fitted and tuned (not worried - it's a sportscar - just curious..)

[shahram]

I have PMO ITBs on one engine and Jenvey ITBs on my 3.6 conversion engine.
I like both but the look from Jenvey ITBs just rocks. The PMO setup is not finalized yet and i did not fire up the engine yet but the Jenvey set up runs very nice.
The Jenveys are running with a modified 993 ECU and I am thinking to use DTA for the PMOs.

[Jeff Alton]

I have run Jenveys and love them. But the ITB's are not a part that could put one off, the EFI system is. A better question is "which EFI system do you run, and how do you like it?"

Cheers

[Joe Bob]

Do ITBs give a SIGNIFICANT upgrade from the stock 3.6 injection system by themselves? Or is there a cam upgrade, mapping, etc required?

[Jeff Alton]

They would make a lazy throttle 3.6 into a lightning quick revving motor, and with the right tuning I would think you could increase the performance....

[sc_rufctr]

I voted PMO throttle bodies even though I haven't bought them yet.

I think carbs are great but I want added fuel economy and the ability to tune via a laptop.
I plan on driving this car a lot so fuel economy starts to become more important.
MOTEC will be my choice for ECU because it's Australian made and there's lots of local experience in setting up and tuning.

Meanwhile these are also locally made so therefore very tempting but I'm still leaning towards PMOs.



EDIT: I like the straight run design.

[clutch-monkey]

Originally Posted by sc_rufctr

I voted PMO throttle bodies even though I haven't bought them yet.

I think carbs are great but I want added fuel economy and the ability to tune via a laptop.
I plan on driving this car a lot so fuel economy starts to become more important.
MOTEC will be my choice for ECU because it's Australian made and there's lots of local experience in setting up and tuning.

Meanwhile these are also locally made so therefore very tempting but I'm still leaning towards PMOs.



EDIT: I like the straight run design.

looks great, what brand?
will ITB's degrade or improve fuel economy?

[Jeff Alton]

If you like the straight run design, why do you vote PMO?? From what we can tell, the only PMO advantage is aesthetics (look like webers) and the ability to use readily available weber style linkage. Don't get me wrong, I am sure they work well....

Cheers

[sc_rufctr]

Originally Posted by clutch-monkey

looks great, what brand?
will ITB's degrade or improve fuel economy?

The "brand" is Injection Perfection in Sydney NSWs.

Depending on tuning and how you drive the car. But generally yes they do improve fuel economy.
They should at least be better than the ancient CIS system on my car.

[sc_rufctr]

Originally Posted by Jeff Alton

If you like the straight run design, why do you vote PMO?? From what we can tell, the only PMO advantage is aesthetics (look like webers) and the ability to use readily available weber style linkage. Don't get me wrong, I am sure they work well....

Cheers

All ITBs like most thing Porsche are a compromised in some way.

As a consequence of the bend in the outer intact manifolds the PMOs fit better (more compact) in the engine bay. It's not just aesthetics.
Also... The ones I posted a picture of may or may not be available. (they stopped making them some time ago)

[regency]

This is probably a dumb question...........Currently working on a 1978 SC, rebuilding engine to a 3.2 Short Stroke.

Q: Can i use a EFI/ITB system in the place of the CIS and still be Calif SMOG legal?

Steve

73 911 T MFI Coupe, Aubergine

[brads911sc]

Not in Kalifornica...

Originally Posted by regency

This is probably a dumb question...........Currently working on a 1978 SC, rebuilding engine to a 3.2 Short Stroke.

Q: Can i use a EFI/ITB system in the place of the CIS and still be Calif SMOG legal?

Steve

73 911 T MFI Coupe, Aubergine

[jpnovak]

Bard and Steve. I thought a 73 was smog exempt in CA. In this case. Do whatever you want.

I love the ITBs. Everyone must realize that they are part of the overall system related to the full build of the motor. You will see some differences on a stock motor but these will be highly interconnected with the type of engine management system used. It has already been said that you can see increased throttle response, more overall power and increased mileage but this will be more dependent on the tuning parameters. if you know what you are doing (or have a good tuner) you will see all of these. You may not like the cost/benefit scenario.

Now, if you design your ITB system (and corresponding Engine managment) with an optimized intake tract length where each cylinder is getting the exact same acoustical resonance (read scavenging) tuning that is optimized for your cam choice and compression ratio you will see added benefit. This is where ITB/EFI really shines. It is no different than tuned runners from carbs or MFI except you have modern electronics providing optimal tuning EVERYWHERE along the engine load /rpm space.

Really, its all about maximizing efficiency everywhere. Hard to do with carbs and MFI.

Tuning the ITB setup has some issues compared to a common plenum. There are some tricks related to the subtle changes in MAP that you will not see using a common plenum. I will not give all the secrets. However, if you understand the tuning process they are easy to get around in just a few keystrokes on the laptop.