tips for a 2.4 w/ 2.2 cyls

[procan]

I threw out my idea to put a 3.2 in my '69 and instead decided to pull the trigger on a 2.4T because the price was too good to pass up. My new plan is to build a 2.4 with 2.2 pistons, the reasoning being that I don't have to run an oil cooler to the front, and a refresh of my 901 trans will handle the 2.4 just fine (I like the racing style shift pattern ok..)

So now the questions. I currently have a 2.0 911E. The "Porsche 911 Performance Handbook" says that it was originally good for 140hp and 129lb/ft of torque with 9.1:1 compression. As for a stock 2.4T engine, it says that it was originally good for 140hp and 148 lb/ft of torque with 7.5:1 compression. Wayne says that the 2.4 with 2.2 pistons bumps compression up to 9.6:1, worth +10hp and some torques.

Is it really that much different than my 2.0 911E? Thoughts? Anyone have experience with this 2.4 w/ 2.2 piston engine? As a side note, I will be running 40mm PMOs and 1-5/8" headers.

****EDIT: Ehen I origionally wrote this I wrote "cylinders" instead of "pistons". It was late, give me a break...*************

[Porboynz]

I can recommend a 2.4E with MFI and 2.4 S Pistons and barrels as a thoroughly driveable combination of low down torque and 7000 RPM top end power. By comparison the 2.4T with carbs I replaced was a fairly ordinary drive, I suspect you will need cams and compression to make a nice 2.4T.

[procan]

I am planning E cams as well. Left that bit out by accident.

[BK911]

The 2.2 and 2.4 cylinders are all essentially the same. The pistons are different.

2.4T pistons are almost flat. The worst of the 2.2/2.4s WRT compression ratio.
2.2S pistons have the highest dome and is what Wayne refers to in his book.

A bone stock 2.4T engine will come alive with E cams and ANY 2.2 piston. Definitely worth the upgrade over a stock 2.0.

1 5/8" headers? ID or OD? Either way I think they will be too big.

[procan]

Wayne's book says to use either 1-5/8" or 1-1/2" headers for a 2.4 engine. I was going to go with the 1-5/8" in case I ever wanted to up my engine to a 2.7 or something, that way I could reuse my headers and carbs. would 1-1/2" be better?

[cmcfaul]

Common recipe is 2.4 with higher compression (9.5) so no twin plugs needed. E cams or DC 30's (e cams with more lift). With stock, well tuned MFI. Makes 200 ish HP with good torque and screams to 7300 RPM no problem. Very reliable and drivable.

Chris

73 911 E (as above)

[kugelfischer]

+1 to cmfaul's suggestion.
The bore diameter of a 2.2 and 2.4 are the same. The difference in displacement is generated by a longer stroke (different cranks in the 2 engines).

[procan]

So as far as fuel injection, should I be ok with PMO carbs, or should I go the direction of MFI? I have zero experience with MFI, and tend to prefer carbs because they are easier to tinker with, plus the PMOs have that awesome clear float bowl thing.

[procan]

I meant pistons instead of cylinders. It was late when I posted this...

[kugelfischer]

I'm not sure if the 2.2 cyls can be used with a 2.4 crank due to the longer stroke.
You should be more than fine with the PMOs however, if you wanted to do something more original to the car and more fun in the long haul.. MFI is the way to go. Once MFI is set up it's rock solid.
The only down side is that MFI can cost a pretty penny to get into these days. You're probably in the $4-5K range to add a nice functional MFI if you are starting from zero.

[procan]

PMO carbs cost over $4k, so it's in the same price range as MFI.

[unclebilly]

Why not Webers or Zeniths?

One of my track cars has Webers, the other has Zeniths.

If I had discovered Zeniths first, they would both have Zeniths because in my opinion they are a better carb.

[procan]

I have zeniths on my 2.0E, but would those not be too restrictive on a 2.4?