ITB Length

[1972_911T]

How crucial is the length of intake stacks when using an ITB setup? Im planning on using MFI intake stacks on my 3.2 engine, to mount the EFI injector I plan on using the modified turbo injector blocks which is going to add about 2" to the total stack length Could this cause any negative effects?

Thanks Steve

[Henry Schmidt]

The additional length will not effect the engine performance in any noticeable way.
You may want to check air filter clearance with the additional height.
I know. PMO tall manifolds make more torque. Well I have never seen it on a dyno sheet.
Don't get me wrong, I like Richard and his products. This claim is just tuff to swallow.
It is common knowledge that you must change the intake runner about 5 inches in order the notice a difference.
I have no way to prove it but I would bet that the Varioram system offers 10 inches of change.

The long runner technology came from a study on intake pulses pioneered by Dave Long first in college and then in the Chrysler engine technologies department in the 50s.
For you old timers, Chrysler made a slant 6 engine that had a 4 foot long intake. The engine slanted towards the right fender then had the carbs mount right next to the left fender.
Some of you might even remember the old Dodge cross ram manifold.
How long were those runners? 2.5 ft ?

[cmonref]

Check the aim of the injectors. It is angled to the airflow and if mounted too high (very tall spacers?) it will spray onto the opposite side of the manifold instead of down into the airpath.

[1972_911T]

Thanks for the input Henry, as for the injector height im waiting on an order of the injector blocks to take a good look at them, I am a bit concerned about the eight of the block as the turbo cis injectors are quite long they hight right to the bottom of the block and spray directly into the port. Im hoping I can either shorten the block which will also minimise raising the throttle bodies too much, or get the injector further into the hole. Either way im hoping to get the injector tip right at the bottom of the block as it would be on the 3.2. As the turbo injector blocks are also plastic and wont conduct the heat like aluminium ones im hoping to do away with the spacer thats present on the 3.2 this will also help get the injector closer to the head and spraying into the port. Ive seen a similar thing done on a turbo EFI thread.

Steve

[Henry Schmidt]

If it is your plan to run 930 plastic injector blocks on a 3.2 head you will find that they are not compatible
The 930 blocks will not completely seal the manifold/port.

Special blocks are made for this purpose but 930 blocks fall short .

[1972_911T]

Originally posted by Henry Schmidt
If it is your plan to run 930 plastic injector blocks on a 3.2 head you will find that they are not compatible
The 930 blocks will not completely seal the manifold/port.

Special blocks are made for this purpose but 930 blocks fall short .

Hi Henry can you point me in the direction of a supplier of the blocks I will need? Why wont the turbo blocks seal? is it beacuse of the cut out in the head for the injector on the 3.2?

Thanks Steve

[Henry Schmidt]

Powerhaus ?
Phoenix AZ
480-948-4788

Ask for David and tell him Henry says "hi".

[RarlyL8]

Stock 930 phenolic blocks are only 32mm ID. You need more than that for a 3.2L with stock heads.