MFI question

[POKDUB]

I have recently acquired a 1969 registered 911E 2.2Ltr (no such 2.2 Ltr model listed in CMA book, only a 1970 911E, I assume borderline date, so the car should be classified as a 1970 911E). The part number on the MFI is 0408 126 009, according to the CMA book this is the part number for a 1970 911S MFI unit. This MFI unit was obviously a replacement in the past overhaul. What effect does this mismatch have on the car ? What should I look out for ? Both E and S would be 2.2Ltr, however there is a power differential from 175 to 200 HP respectively. Are there any other differences between E and S models ?

[jluetjen]

Generally it seems that E-pumps will work in S's and vice-versa. The compromises in the tuning don't appear to be noticeable to the driver. How does your car run?

[Jim Richards]

POKDUB, here's a little more info to help you understand differences between the different models (T, E, S) and different years for 911 MFI.
MFI Induction Chart

[POKDUB]

John, the car runs reasonably ok, however fuel consumption is hi. I am in the process of fine tuning the engine, but need to clear up a few hurdles, such as speedo, tach not working.

I was hoping that the mismatch of MFI unit and car did not complicate the setup and directions in the CMA book.

Jim, I will check to stack dimensions to be clear I what I have here also.

Rgds
Peter

[Jim Richards]

Peter, this thread (link below) shows torque curves for various MFI models and from it you might surmise the different fuel needs of the E and S. In general, I think (but I'm not an MFI expert) the S pump can be adjusted to operate leaner at idle and part throttle.

E or S. Which is the better driver?

[Rot 911]

Peter, what is your gas mileage. The MFI cars have never been known for good gas mileage. You can expect 12-15 around town and maybe 18-22 on the highway.

[POKDUB]

Jim, based on the thread you gave me, I can see the different power delivery between E and S. Is this a direct function of the MFI pump (E or S type) or are there other differences in the main engine setup itself ?

Kurt, wish I knew the gas mileage, as my speedo drive needs replacing. The only way I am currently measuring it, is through my bank balance, btw gas is around €1 per litre here in Ireland ($5.60 a gallon).

[Rot 911]

Peter, there is another member of this board from Dublin who also has an early 911 with MFI. Here is his screen name: Sean_irl. Maybe you two can compare notes.

[POKDUB]

Kurt, it appears Sean_Irl does not receive emails through the forum, so I will keep an eye out for him as he makes a post. Having read through his problems of old, I would be expecting him back as a regular, or maybe his luck has changed. I will keep a look out for his tangerine dream machine on the streets of Dublin. Hard to miss.

Rgds
Peter

[ed martin]

A couple of years ago I was faced with the dilemma of possibly replacing my pump. If I recall correctly I was talking to Phil at Supertech and he was telling me that you can make any of those pumps work for any engine. It's simply a matter of adjusting the rack for the right amount of fuel.

[jluetjen]

The MFI cars have never been known for good gas mileage. You can expect 12-15 around town and maybe 18-22 on the highway.

That's not true! Weber carbs suck gas big-time. A well tuned MFI car with non-race cams will get quite nice mileage considering the performance. For example my '69E 2.0 averages 20 MPG per tank full.

Here's the Specific fuel consumption data for the 2.2 engines from the factory shop manual ploted on the same axis. Note that after 4000 RPM, the MFI's space cam doesn't make any further adjustments. You'll notice that it looks like the E's fuel consumption shoots up above 5500 when the air-flow starts to get restricted -- while the fuel flow continues at a linear rate with rev's thus resulting in the specific fuel consumption going up.

In regards to this thread, note that if you adjust the E MFI into the S's range by using the part throttle adjustment, that it is pretty close. It will most likely be a little rich below 3000 RPM and a little lean from there to 5500 RPM. From there on up I would expect it to be pretty close to the S's normal specific fuel consumption for the reasons that I listed in the previous paragraph.

[Jim Richards]

Originally posted by jluetjen
In regards to this thread, note that if you adjust the E MFI into the S's range by using the part throttle adjustment, that it is pretty close. It will most likely be a little rich below 3000 RPM and a little lean from there to 5500 RPM. From there on up I would expect it to be pretty close to the S's normal specific fuel consumption for the reasons that I listed in the previous paragraph.

John, I believe he's trying to go the other way (S pump leaned to use with an E engine). Great graph, BTW!

[Early_S_Man]

Peter,

Your engine Serial Number [stamped on vertical surface on right side of fan support] and 'Type Number' of the form 901/xx or 911/xx ... stamped on a milled horizontal surface to the right of the fan support ... would give us a good idea what you are dealing with as far as engine internal components go, and what your engine left the factory as.

The normal differences between the 'E' and 'S' engines would be in the pistons and cams.

[jluetjen]

Ulp! Jim -- your right. So, adjusting an S pump down to an E range will be a touch lean at low RPM's, Rich in the mid-range and then I would expect it look like the E above 4000 RPM. Now you could adjust it to be spot-on at low RPM's, but then it will run richer in the mid-range which may be a better compromise.

[Jim Richards]

Originally posted by Early_S_Man
The normal differences between the 'E' and 'S' engines would be in the pistons and cams.

And cylinder head intake / exhaust port sizes, MFI pump "space cam" and intake stack / throttle body sizes.

[hot66]

Originally posted by POKDUB
Kurt, it appears Sean_Irl does not receive emails through the forum, so I will keep an eye out for him as he makes a post. Having read through his problems of old, I would be expecting him back as a regular, or maybe his luck has changed. I will keep a look out for his tangerine dream machine on the streets of Dublin. Hard to miss.

Rgds
Peter

for more irish & UK based early 911 owners try here:

www.ddk-online.com

[POKDUB]

Warren,
The engine number is 901 106101 5R, it is registered as a 911E.
Based on the good information on this thread I should expect to do a bit of balancing between hi/lo rpm and lean/rich settings.

Hot66, I have looked at other 911 forums but Pelican is streets ahead. Searches will almost always pull up relavent info.

[Jim Richards]

Peter, that's not your engine number. As Warren said, if you look at the right side of the engine fan, down low where the engine case is, you'll see a vertical surface. It has the engine number stamped on it I forget the format but it's only something like 6-8 numbers long. On the adjacent horixontal surface, but a bit hard to spot without a flashlight, is the engine type. It should be a 911/xx number. I don't recall the value of xx your 911E should have.

[hot66]

Originally posted by POKDUB
Warren,
The engine number is 901 106101 5R, it is registered as a 911E.
Based on the good information on this thread I should expect to do a bit of balancing between hi/lo rpm and lean/rich settings.

Hot66, I have looked at other 911 forums but Pelican is streets ahead. Searches will almost always pull up relavent info.

no probs, just Sean with the orange 911 frequents the ddk board

[POKDUB]

I will recheck the engine number, this was taken from top of fan casing.

hot66, I know its a 'small world afterall' (been to Eurodisney), and Dublin can even be smaller, I am sure I know this Sean, and the car in question. I think it belong to a figure in the Dublin freight business, not sure if Sean is recent owner or family.