2.2E to 2.4S

[redducati750]

It seems to me projects get bigger and bigger the further into them you get, so instead of rebuilding the 2.2 in the 70E i am restoring i have decided to purchase a 2.4 73S motor that according the owner was rebuilt 40k miles ago. I think what i will do is have a top end rebulid done on the motor. The alure of 190hp over the 155 froom the E was too much for me. Plus, i think i can squeeze 200hp with my webbers and ANSA exhaust. What am i going to need to complete this swap. I have a clutch kit from sachs for 72-73 911, wil this work with my 901 trans.

[dtw]

Originally posted by redducati750
It seems to me projects get bigger and bigger the further into them you get, so instead of rebuilding the 2.2 in the 70E i am restoring i have decided to purchase a 2.4 73S motor that according the owner was rebuilt 40k miles ago. I think what i will do is have a top end rebulid done on the motor. The alure of 190hp over the 155 froom the E was too much for me. Plus, i think i can squeeze 200hp with my webbers and ANSA exhaust. What am i going to need to complete this swap. I have a clutch kit from sachs for 72-73 911, wil this work with my 901 trans.

The force is strong in this one...

-I think you'll stand to lose around 10 hp going from MFI to the webers, but I'll probably start a war by saying that. I don't think you'll get more power out of the 2.4 without massaging the heads.
-The 2.4S will have more power, but keep in mind that it is going to be a bit peakier than the E. If you are paying 2k for a long block plus a top end rebuild, you'll have just as much in the 2.4S as you would in the rebuilt 2.2E
-I don't believe the clutches are compatible, but I am at work and don't have the parts guide in front of me. Anyone else welcome to weigh in here...

[redducati750]

"its not the size of the ship, its the motion in the ocean"

[dtw]

Originally posted by redducati750
"its not the size of the ship, its the motion in the ocean"

"there's no subsitute for displacement"

-Carrol Shelby

[Tim Walsh]

there's no replacement for displacement?

[Tim Walsh]

there's no replacement for displacement... except boost

- a 930 owner

[jluetjen]

-I think you'll stand to lose around 10 hp going from MFI to the webers, but I'll probably start a war by saying that.

Yup. I haven't seen an engine yet that gained HP by switching from MFI to Carbs. Usually MFI (or a mapped EFI like Motec) is worth 10 HP over carbs in every engine that I've seen where there was a comparison.

I don't think you'll get more power out of the 2.4 without massaging the heads.

The heads aren't the issue with a 2.4S, keep in mind that the same heads are good for ~210 in a 2.7 Carrera motor. The limiting factors are cams or capacity. You could bump the 2.4 up to 2.7 with the same cams (and properly adjusted MFI) and have 210 HP right out of the box. Or you could change the cam to something like a Webcam 104/102 or a GE80 (once again changing the MFI to match) which would move the HP peak up to about 7500 RPM ( and about 235HP) and the torque peak up to about 5800 RPM.

In round figures those are your choices (excluding boost or nitrous).

BTW - I'd be skeptical that your headers will provide any more HP then the stock heat exchangers which are really pretty good.

[dtw]

Originally posted by jluetjen
... (and properly adjusted MFI) ....and have 210 HP right out of the box. ....Or you could change the cam ... (once again changing the MFI to match)...

Agreed. Megabucks come into the picture here, either for reground cams and MFI tune, or new PCs/cams/MFI. There don't appear to be many cheap solutions for 2.4s.

duc, you'll see mid-year 911 owners backdating to early exhaust like you've got. It's hard to beat. One thing I'd suggest if you're running webers is to take your existing one-in two-out muffler and have it converted to a twin pipe sport exhaust, a la factory race cars of the early 70s. I'm having this job done on an old muffler right now, that muffler will go on my hotrod motor.

Be careful going to aftermarket/mod exhaust with MFI. Search the archives. MFI likes a decent amount of exhaust backpressure to operate efficiently. Sounds like you're favoring webers, though. No problem there.

[redducati750]

i just want to know what the swap entails, what parts beisides the engine do i need to mate the 2.4 to my 901?

[Bobboloo]

You need to put your 2.2 clutch and pressure plate on the 2.4 flywheel.

If I was putting the 2.4S in a 70'E I would opt for putting the 2.2E cams and MFI on the 2.4 motor. It's a better street setup. That 190HP is just a number that you'll rarely meet on a street car.

[redducati750]

neither my E nor the S i am buying have the MFI.

[jluetjen]

Be careful going to aftermarket/mod exhaust with MFI. Search the archives. MFI likes a decent amount of exhaust backpressure to operate efficiently.

Near as I can tell, it is not so much the backpressure as the harmonics of the exhaust system. Analysing it takes some pretty sophisticated software (WAVE) which I don't have, but if you put a sport (2-in, 2-out) exhaust on a car with MFI which hasn't been adjusted to compensate you'll have a hole in your torque curve. I can't find it anywhere, but my memory says at about 3000-4000 RPM. If it was just a case of back pressure, then the engine would get flatter and flatter as the rev's increase and the amount of air passing through the exhaust increases proportionately.

Anyhow -- basically, the exhaust system has an increase or decrease in backpressure in a particular rev-range which the MFI hasn't "planned for". Keep in mind that an MFI system (unlike a CIS or metered EFI system) doesn't know how much air is going into (and out of) your engine. All it knows is that for a given throttle position/rev/temperature that it needs to deliver a certain amount of fuel. This is what the 3-D space cam controls. By changing the muffler to a sport muffler, the fuel requirements change and the engine won't be happy unless the 3-D space cam is changed to compensate. BTW - The same applies to megaphones too.

Racing 911s as well as the 906E's used the sport mufflers or megaphones combined with MFI and they were perfectly happy - they just weren't using the same intake, exhausts and 3-D Space cams as street 911's.

[redducati750]

im not going to be using MFI, i will be using webbers so i do not anticipate any issues there, i just wanted to know if swapping a 2.2 for a 2.4 was pretty straightforward

[Bobboloo]

Besides the clutch you'll also have to change the fuel pump to one for carbs. You can just install an inline filter from Pep Boys or what ever. It's much cheaper than using the a MFI filter. Other than that it's pretty straight foward. There may be some 14-pin issues but I doubt it. It won't hurt to check though.

[redducati750]

the engine i have in the car now is a running webbers. 14 pin? What does that refer to ?

[Bobboloo]

I was refering to the 14-pin connector on the engine wiring harness. I looked briefly at the schematic for the 70' 911 and it is the same one for all models T,E and S so the wiring shouldn't be an issue. The carbed cars just omitted the speed switch and also didn't have the cold start setup the MFI cars had so there should be no issues electrically. The wiring harness for the 2.2 and 2.4 motors are virtually the same. Both used external voltage regulators.

[zotman72]

Well I would check the numbers on the case and see if you can determine whether you really have an 2.4S motor and perhaps pull the carbs and check the port size. You might have T motor, but a dead giveaway will be the alloy jugs (cylinders). Aside from the clutch/flywheel setup, you probably will have little problem with the swap. On the left front side, is there a camshaft drive visible? Hopefully you have S cams but nothing is a given in the world of "rebuilt" motors. Do you know the pedigree of the rebuild? MM might be in the loop.... Before the swap, take off the valve covers and do a proper check of the valves and rocker shafts. Retorqueing the head might be prudent.
I did a 2.4T to 2.4S upgrade two years ago and love my motor. It is MFI and I have no real probs with the a two pipe sport muffler, at least I have not recognized them. Finding the MFI proper components was a bear.
HTH

[BK911]

I haven't read all the posts so excuse me if I'm repeating something. And I know this wasn't your original question, but I feel the need to voice my opinion!

If you keep your 2.2E and put in a 2.4 crank and rods, that engine will blow away a 2.4S engine. I have (had) a 2.4E with 8.5 compression that eats up the 2.4S's. If you use 2.2E pistons, you'll have about 9:1 compression. You're going to rebuild either way, go the cheap route that gives a better, more powerful street engine. You can reuse most of your parts except maybe the dizzy.

Good luck!
BK