T vs E mfi

[BK911]

Hello!

Besides the space cam in the mechanical MFI pump, are there any other differences in T vs. E MFI systems? Stack diameters, throttle bodies, etc..

Thanks!
BK

[Jim Richards]

Brian, this is a good thread to answer your questions:
MFI Induction Chart

[Grady Clay]

Yes: The intake runners in the heads, the throttle bodies, the intake stacks, distributor curve, and of course the camshafts. The P&Cs are different resulting in different compression ratio.
In a 2.0 there is a difference in valve size.
In a 2.0T and 2.2T the crankshaft is cast and without counterweights.
There is also the color of the fan shroud.

Best,
Grady

[BK911]

Awesome! That's what I needed. But now I am confused a little. I would think 2. and 3. should be the same dimension, as should 4. and 5. If not you have a 'step' in the intake path.

1. Top opening of stack
2. Bottom opening of stack
3. Top opening of throttle body
4. Bottom opening of throttle body
5. Cylinder intake port.

This shows the flow pattern going down into the cylinder.

Year..69'.......70/71'.....72/73'

T

1.......n/a........n/a......35mm
2.......n/a........n/a......32mm
3.......n/a........n/a......38mm
4.......n/a........n/a......29mm
5.......n/a........n/a......29mm

E

1.......39mm....38mm....38mm
2.......35mm....35mm....35mm
3.......38mm....38mm....38mm
4.......32mm....32mm....32mm
5.......32mm....32mm....32mm

[Scott Clarke]

Yes, there is a "step." All of the throttle plates (T,E, and S) are the same size, so steps are required to provide the various intake track diameters. Notice, however, that "4" and "5" always match.
-Scott

[fryardds]

This may be obvious, but the US 911T only had MFI on the 2.4L engines for '72 and part of '73. Elsewhere they remained carburetted.

[TargaT]

Waynes' rebuild book (pg. 201) indicates both the intake and exhaust ports are the same for the T and E 2.4. Is this correct or a typo? can anybody confirm.

Thanks, Joe

[Tim Walsh]

If I remember correctly T's and E's had the same exhaust port size (32mm) and they had the same distributor curve. The 2.2.s and 2.0's had different ignition curves as did the 2.7RS, but the 2.4T, E and S all used the same ignition curve.

[Lukesportsman]

Is there any visual way of knowing what curve you have installed? I know that you could measure it, but was curious if there was a visual color identifier in the distributor. I have an engine built to like RS spec, and was curious to verify ignition changes. It does have the higher rev limits installed.